干旱胁迫下γ-氨基丁酸保护玉米幼苗光合系统的生理响应

引用本文

王泳超, 张颖蕾, 闫东良, 何灵芝, 李卓, 燕博文, 邵瑞鑫, 郭家萌, 杨青华. 干旱胁迫下γ-氨基丁酸保护玉米幼苗光合系统的生理响应. 草业学报, 2020,29(6): 191-203
WANG Yong-chao, ZHANG Ying-lei, YAN Dong-liang, HE Ling-zhi, LI Zhuo, YAN Bo-wen, SHAO Rui-xin, GUO Jia-meng, YANG Qing-hua. Physiological role of γ-aminobutyric acid in protecting the photosynthetic system of maize seedlings under drought stress. Acta Prataculturae Sinica,2020,29(6): 191-203 复制到剪切板

Doi:10.11686/cyxb2019377
Permissions

本文属于开放获取期刊。

干旱胁迫下γ-氨基丁酸保护玉米幼苗光合系统的生理响应

王泳超, 张颖蕾, 闫东良, 何灵芝, 李卓, 燕博文, 邵瑞鑫, 郭家萌, 杨青华^*

河南农业大学农学院,河南郑州 450002

*通信作者Corresponding author. E-mail: yangqh2000@163.com

作者简介:王泳超(1987-),男,黑龙江齐齐哈尔人,讲师,博士。E-mail: wangyongchao723@163.com

收稿日期: 2019-09-02

基金项目:河南省教育厅项目(19A210019)和河南农业大学博士科研启动金(30500562)资助

摘要

为明确干旱胁迫下γ-氨基丁酸(GABA)保护玉米幼苗光合系统的生理响应,以郑单958为试验材料,依据玉米幼苗生长数据,选择1 mmol·L^-1为γ-氨基丁酸(GABA)供试浓度,设置空白对照(CK)、1 mmol·L^-1 GABA(G)、20%聚乙二醇(PEG-6000)模拟干旱胁迫(D)、20%聚乙二醇(PEG-6000)模拟干旱胁迫和1 mmol·L^-1 GABA(DG)4个处理开展玉米水培试验。结果表明:不同浓度GABA能缓解干旱胁迫的抑制作用,使玉米幼苗恢复生长,其中1 mmol·L^-1 GABA效果最好。干旱胁迫下,外源施用1 mmol·L^-1 GABA能显著提高叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,减少丙二醛(MDA)、超氧阴离子($O_{2}^{-}$)和过氧化氢(H₂O₂)积累,降低叶片相对电导率。此外,外源GABA能显著提高干旱胁迫下叶片内可溶性蛋白、可溶性糖和脯氨酸含量,从而提高细胞保水能力。外源施用GABA能显著降低叶片干旱胁迫下初始荧光( F₀),提高暗适应下最大可变荧光( F_v)、最大荧光( F_m)和最大光量子效率( F_v/ F_m),从而降低叶片光化学损伤。在干旱胁迫第5天,与D处理相比,DG处理SPAD数值、净光合速率( P_n)、蒸腾速率( T_r)和气孔导度( G_s)分别提高8.25%、7.69%、9.13%和7.38%,胞间CO₂浓度( C_i)降低2.93%。因此,外源GABA能通过降低叶片的氧化损伤和提高细胞保水能力来改善叶片对干旱胁迫的适应能力,从而保护玉米幼苗光合系统。

关键词: γ-氨基丁酸(GABA);; 玉米; 干旱胁迫; 光合作用

Physiological role of γ-aminobutyric acid in protecting the photosynthetic system of maize seedlings under drought stress

WANG Yong-chao, ZHANG Ying-lei, YAN Dong-liang, HE Ling-zhi, LI Zhuo, YAN Bo-wen, SHAO Rui-xin, GUO Jia-meng, YANG Qing-hua^*

College of Agronomy, Henan Agricultural University, Zhengzhou 450002, China

Abstract

This research aimed to clarify the physiological role of γ-aminobutyric acid (GABA) in the protection of the photosynthetic system of maize seedlings under drought stress. The maize variety studied was Zheng Dan 958, and the exogenous application of GABA at a concentration of 1 mmol·L^-1 was used tested in a hydroponic culture experiment where drought stress was simulated by adding PEG-6000. The experiment comprised four treatments: Blank control (CK), 1 mmol·L^-1 GABA treatment (G), 20% PEG (PEG-6000) simulated drought stress (D), 20% PEG (PEG-6000) simulated drought stress and 1 mmol·L^-1 GABA treatment (DG). It was found that: Application of 1 mmol·L^-1 exogenous GABA significantly improved the activities of superoxide dismutase, peroxidase and catalase and decreased the malondialdehyde, superoxide anion and hydrogen peroxide concentrations of leaf tissue. Leaf relative conductivity was also reduced. Furthermore, exogenous GABA significantly increased the content of soluble protein, soluble sugar and proline in leaves under drought stress, thereby improving the water retention capacity of cells. Exogenous application of GABA significantly reduced the chlorophyll fluorescence F₀ value; and improved the F_v, F_m and F_v/ F_m values, thereby reducing photochemical damage in leaves. Compared with the D treatment, SPAD, P_n, T_r and G_s of the DG treatment were increased by 8.25%, 7.69%, 9.13% and 7.38%, respectively in 5th day after stress. In addition, C_i was decreased by 2.93%. In summary, exogenous GABA improved the drought resistance in leaves by reducing oxidative damage and increasing the capacity for cell water retention, thereby protecting the photosynthetic system in maize seedlings.

Keyword: γ-aminobutyric acid (GABA);; maize; drought stress; photosynthesis

Show Figures

水资源短缺是当前全球农业发展和粮食安全所面临的一个严峻生态问题, 尤其是进入21世纪以来, 在全球气候变暖、极端气候事件趋多增强的背景下, 干旱的强度和频率都呈现明显增加的趋势, 成为限制农作物产量的主要因素^[1]。目前中国受干旱影响的地区较多, 给农作物生产带来的影响也日渐严重^[2]。玉米(Zea mays)是我国重要的粮食、经济和饲料作物, 其在生育期间需水量较大, 对干旱胁迫较为敏感, 其中苗期干旱灾害已成为制约玉米增产的重要因素^[1]。因此研究干旱胁迫下玉米的适应及保护机制, 对玉米生产具有重要的理论意义和实际价值。

光合作用作为植物最基本的生命活动, 对干旱胁迫非常敏感。干旱胁迫下, 气孔和非气孔限制共同导致光合作用下降, 而植物对干旱胁迫的首要响应就是关闭气孔^[3], 这会造成CO₂吸收减少, 引起CO₂同化量降低, 净光合速率下降, 从而导致光系统Ⅱ (PSⅡ )光能过剩, 进而引起活性氧代谢障碍, 丙二醛(malondialdehyde, MDA)等有害物质在膜系统的积累, 损害叶片光合机构。植物会通过减少光能的捕获、提高体内抗氧化酶活性、积累渗透调节物质等途径来减少氧化损伤, 从而维持细胞膜正常生理功能, 并以此来提高植物对干旱胁迫的抵抗能力^{[4, 5]}。但植物通过改变自身生理生化代谢来适应干旱胁迫的能力是有限的, 仅在干旱初期阶段具有显著效果, 而随着干旱时间和程度的增加, 植物自身代谢出现紊乱, 最终影响生长, 甚至死亡^[6]。

目前, 在农业生产中可以通过多种栽培耕作措施和调控手段来减少干旱胁迫对作物生长的危害, 其中外源施用化学调控物质具有效率高、成本低等特点而被广泛应用。γ -氨基丁酸(γ -aminobutyric acid, GABA)是一种以自由态存在于各种生物中的四碳非蛋白质氨基酸, 在作物的非生物胁迫中^[7], GABA具有能维持作物体内C/N平衡、作为信号传导物质、改善抗氧化酶系统活性、提高渗透调节物质含量等功能, 因此其与作物的抗逆境调控密切相关^[8]。近年来, 关于外源GABA调控作物生理功能来提高作物抗逆性的研究已取得一定进展, Harsh等^[9]的研究表明, 1 mmol· L^-1的GABA处理高温胁迫的水稻(Oryza sativa)幼苗, 会缓解高温胁迫对幼苗光合特性的损伤, 使叶绿素含量、最大光量子效率(maximum opticon efficiency, F_v/F_m)得到恢复, 减小高温胁迫对光合作用的损害。外源GABA处理显著提高了超氧化物歧化酶(superoxide dismutase, SOD)、过氧化物酶(peroxidase, POD)等活性, 分别比NaCl处理提高7.62%和37.55%, 而对过氧化氢酶(catalase, CAT)活性无显著影响^[10]。此外, 外源施用GABA能明显地降低番茄(Solanum lycopersicum)幼苗叶片活性氧产生速率、过氧化氢(hydrogen peroxide, H₂O₂)和丙二醛含量, 增加可溶性蛋白、可溶性糖等渗透调节物质的积累, 降低脯氨酸含量, 从而缓解干旱胁迫对番茄幼苗生长的抑制作用^[11]。因此, 本研究以郑单958为试验材料, 采用向营养液中加入聚乙二醇(PEG-6000)模拟干旱胁迫的方法, 通过叶片喷施GABA, 研究干旱胁迫下GABA保护玉米幼苗光合系统的生理响应, 以期为GABA缓解干旱胁迫的研究提供理论依据, 为玉米的抗旱生产提供新的技术手段。

1 材料与方法

1.1 试验材料

试验所用品种为郑单958(河南农业科学院提供), 供试调控剂为γ -氨基丁酸(购自Sigma公司), 干旱模拟剂为聚乙二醇(PEG-6000)(购自Sigma公司)。

1.2 试验设计

本试验于2018年在河南农业大学农学院人工气候光照培养箱进行, 播种前种子用10%(V/V)的次氯酸钠(NaClO)消毒10 min, 蒸馏水冲洗3次, 浸种8 h后在(26± 1) ℃的恒温培养箱中黑暗催芽48 h, 之后将出芽的种子播种于50 cm× 30 cm的塑料托盘中, 以沙子为基质。待玉米幼苗生长到二叶一心时, 选择长势一致的幼苗定植于装有2.5 L的1/2 Hoagland营养液[pH为(6.5± 0.1)]的水槽中培养, 幼苗生长环境为:光周期为12 h/12 h(昼/夜), 昼/夜温度为(28± 1) ℃/(25± 1) ℃, 光照强度约为400 μ mol· m^-2· s^-1, 培养箱内相对湿度为60%~70%, 每3 d更换一次营养液, 待幼苗生长到三叶一心时进行处理。1)对照(CK), 正常施加营养液, 叶片喷施清水; 2)GABA处理(G), 正常施加营养液, 叶面喷施不同浓度的GABA(0.25、0.5、1、2、5、10 mmol· L^-1), 每天喷施一次, 连续喷施2 d; 3)干旱处理(D), 施用含有浓度为20%(M/V)PEG-6000的Hoagland营养液, 叶面喷施清水; 4)干旱+GABA处理(DG), 施用含有浓度为20%(M/V)PEG-6000的Hoagland营养液, 叶面喷施不同浓度的GABA(0.25、0.5、1、2、5、10 mmol· L^-1)。干旱处理在喷施GABA结束后进行, 处理期间每天进行pH的测定和调整, 于干旱胁迫的1、3和5 d分别取完全展开的倒2叶进行指标测定。每个处理3次生物学重复。

1.3 测定指标

1.3.1 幼苗生长指标的测定于胁迫后5 d每个处理选取3株幼苗, 用最小刻度为1 mm的米尺测量株高, 用CI-203型叶面积仪(美国CID公司, 产地:美国)测定单株叶面积。将用清水冲洗干净的幼苗表面水分吸干, 于烘箱内105 ℃杀青30 min, 之后80 ℃烘干至恒重, 测定整株干鲜重, 单位为g· 株^-1。于胁迫第5天取植株根系进行根系扫描。

1.3.2 抗氧化酶活性测定超氧化物歧化酶(SOD)活性采用氮蓝四唑(nitro-blue tetrazolium, NBT)还原法测定^[12], 过氧化物酶(POD)活性采用愈创木酚法测定^[13], 过氧化氢酶(CAT)采用高俊凤^[14]的方法测定。

1.3.3 氧化损伤指标测定丙二醛(MDA)含量采用硫代巴比妥酸法测定^[15], 超氧阴离子含量( ${O_{2}}^{-}$ )采用羟氨氧化法测定^[16], 过氧化氢(H₂O₂)含量参照Mukherjee等^[17]的方法测定。过氧化氢(H₂O₂)和超氧阴离子( ${O_{2}}^{-}$ )染色分别采用二氨基联苯胺显色法和氮蓝四唑原位显色法测定。

1.3.4 渗透调节物质测定脯氨酸(proline, Pro)含量采用磺基水杨酸法测定^[18]。可溶性糖含量参照薄晓培等^[19]的测定方法。可溶性蛋白含量采用G-250方法测定^[20]。

1.3.5 叶片相对电导率和叶片相对含水量测定为取各植株相同部位叶片, 首先测定植物叶片的鲜重M₁, 后将叶片浸入蒸馏水中5~6 h, 使叶片吸水达到饱和状态, 取出擦干叶片至表面无水分残留, 再称重, 得植物叶片的饱和鲜重M₂, 最后将植物叶片放进烘箱, 105 ℃杀青30 min, 再于80 ℃环境下烘至恒重, 得叶片干重M₃。叶片相对含水量按公式计算:(M₁-M₃)/(M₂-M₃)× 100%。参照郝再彬等^[21]的方法测定叶片相对电导率。以相对电导率的大小表示质膜相对透性即质膜受害程度:质膜相对透性=L₁/L₂× 100%, L₁表示组织杀死前外渗液电导值, L₂表示组织杀死后外渗液电导值。

1.3.6 光合指标测定使用FMS-2脉冲调制式叶绿素荧光仪(Hansatech, UK)测定F₀:初始荧光、F_v:暗适应下最大可变荧光、F_m:最大荧光等荧光参数, 通过这些参数可计算出PSⅡ 的F_v/F_m:最大光量子效率、F_v/F₀:PSⅡ 潜在活性等值。测定前叶片暗适应时间为20 min, 光化学强度为400 μ mol· m^-2· s^-1, 饱和闪光强度为8000 μ mol· m^-2· s^-1。叶绿素含量采用CCM-200+手持叶绿素测定仪(澳作生态仪器有限公司, 产地:北京)进行测定, 以SPAD数值代表叶绿素相对含量(chlorophyll relative content)。使用LI-6400便携式光合仪(LI-COR公司, 产地:美国)测定C_i(胞间CO₂浓度)、T_r(蒸腾速率)、G_s(气孔导度)和P_n(净光合速率)。

1.4 数据处理与分析

试验数据取平均值, 每个处理3次生物学重复。采用SPSS 17.0进行方差分析, 采用LSD最小显著性差异法进行多重比较, 植株生长数据采用胁迫后5 d数据, 采用Microsoft Excel 2010 作图。

2 结果与分析

2.1 干旱胁迫下不同浓度GABA对玉米幼苗生长的影响

图1所示, 与正常处理(CK)相比, 干旱胁迫明显抑制幼苗生长, 外源施用GABA可以缓解干旱胁迫带来的抑制作用。外源施用GABA能提高干旱胁迫下玉米幼苗株高、叶面积、全株干重, 降低根冠比(表1); 但不同浓度的GABA缓解抑制作用的能力不同, 其浓度为1 mmol· L^-1时效果最好。与D处理相比, 喷施1 mmol· L^-1 GABA的幼苗株高、叶面积、茎叶干重和根系干重分别增加20.45%、37.41%、31.92%和49.41%, 根冠比降低13.34%, 且差异显著(表1)。表2表明, 在干旱胁迫条件下, 1 mmol· L^-1的GABA缓解干旱胁迫的效果最好, 与D处理相比, 1 mmol· L^-1的GABA浓度下根长、根表面积、根体积和根尖数分别增加了37.92%、52.50%、85.42%和37.40%, 且差异显著。因此, 选取1 mmol· L^-1的GABA进行后续试验。

Figure Option
View Download New Window

图1 干旱胁迫下不同浓度GABA对玉米幼苗形态的影响
CK:对照; D:仅干旱胁迫; 0.25、0.5、1、2、5、10分别表示干旱胁迫下GABA的不同浓度, 单位为mmol· L^-1。Fig.1 Effect of different concentrations of GABA on maize seedling morphology under drought stress
CK: Control; D: Only drought stress; 0.25, 0.5, 1, 2, 5, 10 represent the different concentrations of GABA under drought condition, the unit is mmol· L^-1.

表1 干旱胁迫下不同浓度GABA对玉米幼苗生长的影响 Table 1 Effect of different concentrations of GABA on maize seedling growth under drought stress

表2 干旱胁迫下不同浓度GABA对玉米幼苗根系的影响 Table 2 Effect of different concentrations of GABA on maize seedling roots under drought stress

2.2 干旱胁迫下GABA对玉米幼苗抗氧化酶活性的影响

超氧化物歧化酶(SOD)能歧化两个 ${O_{2}}^{-}$ 自由基成为H₂O₂和O₂, 这一过程对于保护细胞至关重要。图2A所示, 随着胁迫天数增加, 对照和G处理叶片SOD活性呈现先升后降的趋势, D和DG处理呈现下降的趋势。与对照相比, G处理能提高叶片的SOD活性, 但差异不显著。干旱胁迫后1 d, D处理的SOD活性高于对照, 而胁迫后的3和5 d显著低于对照, 分别降低了6.52%和13.95%。外源施用GABA能显著提高叶片SOD活性, 在胁迫后的1、3和5 d, 与D处理相比, DG处理SOD活性分别提高14.03%、37.21%和62.16%。

Figure Option
View Download New Window

图2 干旱胁迫下GABA对玉米幼苗抗氧化酶活性的影响
CK:对照; G:叶面喷施1 mmol· L^-1 GABA; D:干旱胁迫; DG:干旱胁迫下叶面喷施1 mmol· L^-1 GABA; 相同取样天数的不同字母表示差异显著(P< 0.05)。下同。Fig.2 Effect of GABA on antioxidant enzyme activity of maize seedlings under drought stress
CK: Control; G: Spraying the concentration of 1 mmol· L^-1 GABA in leaves; D: Drought stress; DG: Spraying the concentration of 1 mmol· L^-1 GABA in leaves under drought stress; Different letters in the same sampling period indicate significant difference (P< 0.05). The same below.

H₂O₂对细胞会产生毒害作用, 过氧化物酶(POD)被认为是活性氧清除系统中主要的H₂O₂清除酶。随着胁迫天数增加, 对照、G和DG处理呈先升后降的趋势, D处理呈下降趋势(图2B)。与对照相比, G处理叶片POD活性提高, 但差异不显著。在干旱胁迫后1 d, 叶片POD活性显著升高, 第3和5天显著降低(图2B)。外源施用GABA会显著提高干旱胁迫下叶片内POD活性, 与D处理相比, DG处理在胁迫后的1、3和5 d分别升高13.33%、52.14%和53.69%(图2B)。

过氧化氢酶(CAT)能将H₂O₂分解成为H₂O和O₂, 从而降低H₂O₂含量。随着胁迫天数的增加, 对照和G处理呈先升后降的趋势, D和DG处理呈下降趋势(图2C)。正常条件下, 外源施用GABA能促进叶片的CAT活性升高, 但差异不显著(图2C)。干旱胁迫下, CAT活性在3和5 d低于对照, 分别下降4.14%和11.61%(图2C)。外源施用GABA可缓解干旱胁迫对叶片的伤害, 显著提高CAT活性, 与D处理相比, DG处理的叶片CAT活性在胁迫后的1、3和5 d分别升高8.01%、15.95%和37.71%, 差异显著(图2C)。

2.3 干旱胁迫下GABA对玉米幼苗氧化损伤的影响

丙二醛(MDA)是膜脂过氧化的产物, 过量积累对细胞膜具有损害作用。随着胁迫天数的增加, 叶片MDA含量逐渐升高。正常条件下, 外源施用GABA对MDA含量没有显著影响(图3)。干旱胁迫导致叶片内MDA含量显著升高, 与对照及G处理相比差异显著。施用外源GABA会显著降低干旱胁迫下叶片内MDA含量, 在胁迫后的1、3和5 d, DG处理的MDA含量分别是D处理的0.82、0.63和0.60倍(图3)。

	Figure Option View Download New Window
	图3 干旱胁迫下GABA对MDA含量的影响Fig.3 Effect of GABA on MDA content under drought stress

氧气在植物体内产生氧自由基时第一个产生的就是超氧阴离子, 其本身具有毒性, 进行一系列的反应后会产生其他的氧自由基, 对细胞有毒害作用。对叶片中的 ${O_{2}}^{-}$ 进行显色反应, 其中蓝色斑点越深, 表示叶片中 ${O_{2}}^{-}$ 含量越高。由图4A可知, 干旱处理会使叶片中 ${O_{2}}^{-}$ 含量明显增加, 外源施加GABA可以使干旱胁迫下叶片中 ${O_{2}}^{-}$ 含量降低。图4B所示, 随着胁迫天数的增加, 叶片内超氧阴离子( ${O_{2}}^{-}$ )含量呈逐渐增加趋势。正常生长条件下, 外源施用GABA对 ${O_{2}}^{-}$ 含量没有显著影响。干旱胁迫下 ${O_{2}}^{-}$ 含量显著升高, 与对照相比, D处理 ${O_{2}}^{-}$ 含量在胁迫后的1、3和5 d分别升高35.06%、51.30%和73.10%。外源施用GABA能减少叶片内 ${O_{2}}^{-}$ 的积累, 缓解其对叶片的损伤。与D处理相比, 胁迫后的1~5 d, DG处理叶片 ${O_{2}}^{-}$ 含量分别降低16.41%、19.92%和24.08%, 差异显著。

	Figure Option View Download New Window
	图4 干旱胁迫下GABA对玉米幼苗 ${O_{2}}^{-}$ 含量的影响Fig.4 Effect of GABA on ${O_{2}}^{-}$ content of maize seedlings under drought stress

H₂O₂对细胞会产生毒害作用, 对叶片中的H₂O₂进行显色反应, 其中褐色斑点越深, 表明叶片H₂O₂含量越高。由图5A可知, 干旱胁迫会增加叶片中H₂O₂含量, 而DG处理H₂O₂含量明显降低。由图5B可知, 随着处理时间的增加, CK和G处理的叶片中H₂O₂含量并没有明显变化, D处理和DG处理呈现逐渐升高的趋势。在正常生长条件下, 外源施加GABA对叶片内H₂O₂含量没有显著影响, 而在干旱胁迫下, 外源施加GABA可以降低叶片内H₂O₂的含量, 特别在处理第5天, 与D处理相比, DG处理的叶片内H₂O₂含量降低14.58%, 差异显著。

	Figure Option View Download New Window
	图5 干旱胁迫下GABA对玉米幼苗H₂O₂含量的影响Fig.5 Effect of GABA on H₂O₂ content in maize seedlings under drought stress

2.4 干旱胁迫下GABA对玉米叶片渗透调节物质的影响

可溶性蛋白是重要的渗透调节物质和营养物质, 其增加和积累能提高细胞的保水能力, 对细胞的生命物质及生物膜起到保护作用。图6A显示, 随着胁迫天数的增加, 叶片内可溶性蛋白含量逐渐升高。正常生长条件下, 外源GABA对叶片可溶性蛋白含量没有显著影响, 而在干旱胁迫下可溶性蛋白含量显著升高。与对照相比, 胁迫后1、3和5 d的D处理可溶性蛋白含量分别升高72.55%、62.52%和68.67%。干旱胁迫下, 外源施用GABA能提高叶片内可溶性蛋白含量, 提高叶片保水能力。与D处理相比, DG处理在胁迫后的1、3和5 d可溶性蛋白含量分别升高16.43%、53.93%和74.39%, 且胁迫3和5 d时差异显著。

	Figure Option View Download New Window
	图6 干旱胁迫下GABA对玉米幼苗渗透调节物质的影响Fig.6 Effect of GABA on osmotic regulators in maize seedlings under drought stress

可溶性糖作为植物的营养成分, 其含量变化可以反映植物的生长状态。图6B显示, 与对照相比, G处理可溶性糖含量没有显著变化。在干旱胁迫条件下, 随着处理时间的增加, D处理的可溶性糖含量逐渐增加, 而外源喷施GABA使叶片可溶性糖含量进一步增加, 与D处理相比, DG处理在胁迫后的1、3、5 d叶片可溶性糖含量分别增加11.72%、3.45%和19.08%。

脯氨酸含量可以反映植物遭受干旱胁迫的情况。由图6C可知, 在正常生长情况下, 外源施加GABA对叶片内脯氨酸含量没有显著影响。干旱胁迫会明显提高叶片脯氨酸含量, 尤其是在干旱胁迫第5天, 脯氨酸含量明显增加。外源施加GABA可以提高干旱胁迫下叶片的脯氨酸含量, 与D处理相比, 干旱胁迫的第1、3、5天, DG处理叶片内脯氨酸含量分别提高26.19%、23.63%和29.81%。

2.5 干旱胁迫下GABA对玉米叶片相对电导率及相对含水量的影响

叶片相对含水量多少可代表抗干旱能力的大小, 因此是判断抗旱性的重要指标。图7A显示, 随着胁迫天数增加, 对照和G处理叶片相对含水量呈上升趋势, 而D和DG处理呈下降趋势。正常生长条件下外源施用GABA对叶片相对含水量没有显著影响。干旱胁迫会显著降低叶片相对含水量, 胁迫后第5天, D处理相对含水量比对照降低24.31%, 差异显著。外源施用GABA能显著提高干旱胁迫下叶片相对含水量, 提高叶片持水能力。与D处理相比, DG处理在胁迫后第5天叶片相对含水量提高10.63%, 差异显著。

	Figure Option View Download New Window
	图7 干旱胁迫下GABA对玉米叶片相对含水量及相对电导率的影响Fig.7 Effect of GABA on relative water content and relative electric conductivity of maize leaves under drought stress

叶片的相对电导率可以判断细胞膜受伤害的程度。由图7B可知, 随着处理时间的增加, 叶片的相对电导率呈现逐渐增加的趋势, 但是G处理和CK相比差异不显著。干旱胁迫下, 叶片的相对电导率显著增加, 外源喷施GABA可以降低叶片的相对电导率, 在处理的第1、3、5天, 与D处理相比, DG处理的叶片相对电导率分别降低14.95%、29.49%和32.21%, 差异显著。

2.6 干旱胁迫下GABA对玉米幼苗叶绿素含量的影响

叶绿素是光合作用的物质基础, 负责光能的捕获、传递、分配和转化等过程, 其含量变化能够反映光合作用的强弱, 而SPAD数值的大小能直接反映出叶绿素含量的多少。如图8所示, 随着胁迫天数增加, 对照和G处理的SPAD值呈小幅上升的趋势, D和DG处理呈现逐渐下降的趋势。G处理SPAD数值与对照相比在所有取样天数差异不显著, 这表明正常生长条件下施用外源GABA对叶绿素含量无明显影响。干旱胁迫会导致SPAD数值显著降低, 外源施用GABA能显著提高叶片SPAD数值, 与D处理相比, DG处理在胁迫后1、3和5 d叶片SPAD数值分别升高8.97%、10.73%和8.25%。

	Figure Option View Download New Window
	图8 干旱胁迫下GABA对玉米幼苗叶绿素含量的影响Fig.8 Effect of GABA on chlorophyll content of maize seedlings under drought stress

2.7 干旱胁迫下GABA对玉米幼苗叶绿素荧光参数的影响

F₀代表最小荧光强度, 是已经暗适应的光合机构全部PSⅡ 中心都开放时的荧光强度。图9A显示, 随着胁迫天数增加, F₀呈逐渐上升的趋势。与对照相比, G处理的F₀下降, 但只有胁迫后第5天差异显著。干旱胁迫下, F₀显著升高, 与对照相比, D处理F₀在胁迫后1、3和5 d分别升高9.01%、11.38%和15.43%。外源施用GABA能显著降低干旱胁迫下的F₀, 与D处理相比, DG处理F₀在胁迫后1、3和5 d分别下降5.44%、6.34%和7.53%。

	Figure Option View Download New Window
	图9 干旱胁迫下GABA对玉米幼苗叶绿素荧光参数的影响Fig.9 Effect of GABA on chlorophyll fluorescence parameters of maize seedlings under drought stress

F_v代表黑暗中最大可变荧光强度, 图9B所示, 随着胁迫天数的增加, 对照和G处理的F_v呈上升趋势, D和DG处理呈下降趋势。正常生长条件下, 外源施用GABA对F_v没有显著影响, 而干旱胁迫会显著降低F_v, 且与对照相比差异显著。干旱胁迫下施用外源GABA能提高F_v, 与D处理相比, DG处理的F_v在胁迫后1、3和5 d分别升高6.95%、8.76%和15.04%, 且差异显著。

F_m代表黑暗中最大荧光, 是已经暗适应的光合机构全部PSⅡ 中心都关闭时的荧光强度。由图9C可知, 正常生长条件下, 外源GABA对F_m没有显著影响, 而干旱胁迫下F_m显著降低, 与对照相比差异显著。外源施用GABA会显著升高干旱胁迫下的F_m, 与D处理相比, DG处理的F_m在胁迫后1、3和5 d分别升高3.46%、4.27%和7.79%。

F_v/F_m代表没有遭受环境胁迫并充分暗适应的叶片PSⅡ 最大的或潜在的量子效率。图9D所示, 对照和G处理随着胁迫天数的增加F_v/F_m无明显变化, 而D和DG处理的F_v/F_m有小幅下降。正常条件下, 外源施用GABA会提高F_v/F_m, 但与对照相比差异不显著。干旱胁迫下F_v/F_m下降, 但差异不显著。外源施用GABA能提高干旱胁迫下的F_v/F_m, 但差异不显著。

2.8 干旱胁迫下GABA对玉米幼苗光合参数的影响

净光合速率(P_n)可以直接反映植物光合作用的强弱。由图10A可知, 非胁迫条件下, 外源施用GABA会提高叶片净光合速率, 但差异不显著。干旱胁迫下, 叶片净光合速率显著降低, 外源喷施GABA可以缓解干旱胁迫导致的损伤, 净光合速率上升。与D处理相比, 处理的第1、3和5天, DG处理净光合速率分别提高了9.42%, 6.85%和9.13%。

	Figure Option View Download New Window
	图10 干旱胁迫下GABA对玉米幼苗光合参数的影响Fig.10 Effect of GABA on photosynthetic parameters of maize seedlings under drought stress

蒸腾速率(T_r)可以反映植物对矿物质吸收和运输能力的高低。由图10B可知, 随着处理时间的增加, CK和G处理的叶片蒸腾速率都呈现出先下降后上升的趋势, 外源施加GABA会提高叶片的蒸腾速率。干旱胁迫会导致蒸腾速率降低, 处理的第1、3和5天, D处理的蒸腾速率分别降低了17.05%、16.9%和54.3%。DG处理可以显著提高干旱胁迫下幼苗的蒸腾速率, 处理的第1、3和5天, DG处理叶片的蒸腾速率分别提高了6.75%、1.79%和7.69%。

气孔导度(G_s)可以反映二氧化碳和水汽通过气孔的难易程度。由图10C可知, 随着处理时间的增加, CK和G处理的气孔导度逐渐增加。在干旱胁迫条件下, D处理的叶片气孔导度逐渐降低, 与D处理相比, DG处理的第1、3和5天叶片的气孔导度分别提高了6.89%、5.28%和7.38%。

胞间CO₂浓度(C_i)可以间接反映光合作用强弱。由图10D可知, 随着处理时间的增加, CK和G处理的叶片胞间CO₂浓度逐渐降低, D和DG处理的逐渐增加。与CK相比, G处理的叶片胞间CO₂浓度在培养的第1、3和5天分别降低了7.06%、11.63%和8.43%。在干旱胁迫条件下, 与D处理相比, DG处理的叶片胞间CO₂浓度在培养的第1、3和5天分别升高了9.97%、8.73%和2.93%。

3 讨论

干旱是影响玉米生长和发育最常见的环境胁迫, 当玉米遭受干旱胁迫时, 其在形态和生理上会产生抗旱应对策略, 如干物质以及根冠比的调整等^[22]。本研究中, 在干旱胁迫下, 玉米幼苗的株高、叶面积和幼苗干重都出现明显下降, 而根冠比出现明显升高, 表明干旱胁迫对地上部分干物质积累的抑制作用要大于地下部分, 与李丽杰等^[23]采用外源亚精胺处理干旱胁迫幼苗的结论相似。在轻度和重度干旱胁迫中, 外源施用GABA能明显提高甜瓜(Cucumis melo)幼苗的株高、茎粗、叶面积和整株干鲜重, 缓解干旱胁迫给生长造成的抑制作用^[24]。本研究中, 干旱胁迫下外源施用GABA能显著的恢复玉米幼苗的生长, 缓解干旱胁迫的抑制作用, 且GABA浓度在1 mmol· L^-1时效果最佳。根冠比的显著下降也表明GABA对干旱胁迫下地上部分的促进作用大于地下部分。

植物适应环境的变化需要植物细胞体内多种途径之间的协调平衡来实现, 非生物胁迫下, 这种平衡被破坏, 特别是当植物暴露于水势急剧下降时, 体内活性氧(reactive oxygen species, ROS)等物质大量积累, 从而对蛋白质、DNA和脂质等造成损伤^[25]。膜质损伤会造成MDA、 ${O_{2}}^{-}$ 和H₂O₂含量显著增加, 细胞膜流动性被破坏, 细胞膜透性增加, 影响正常的细胞功能。研究表明, 外源施用GABA能明显降低MDA、H₂O₂和 ${O_{2}}^{-}$ 含量^[24]。本研究中, 干旱胁迫下外源施用GABA使玉米幼苗叶片内MDA、H₂O₂和 ${O_{2}}^{-}$ 含量显著降低, 并且随着胁迫时间的增加, 施用GABA处理的叶片MDA、H₂O₂和 ${O_{2}}^{-}$ 的积累速度逐渐下降, 植物的生长抑制得到缓解。

当植物遭遇干旱胁迫, 植物自身抗氧化酶系统活性会出现明显升高, 以便于清除活性氧, 减少膜质过氧化物的积累, 保证细胞膜的完整性和正常的功能^[26]。本研究发现, 在干旱胁迫下, SOD、POD和CAT活性在胁迫1 d时高于对照, 之后出现显著下降, 且明显低于对照。这表明干旱胁迫初期玉米植株能通过自身的保护系统清除体内有害物质, 而随着胁迫时间的延长其生理功能受到严重影响, 自身调控能力减弱, 植株的生长受到抑制。外源施用GABA能显著提高SOD、POD和CAT的活性, 有效缓解干旱胁迫对玉米叶片的损伤, 与杨丽文等^[11]在番茄幼苗上的研究有相似的结论, 即外源施加GABA不仅能提高SOD、POD、CAT的活性, 且升高幅度也逐渐增加, 进而有效缓解胁迫带来的损伤。

当植株遭受干旱胁迫, 玉米叶片内脯氨酸、可溶性糖、可溶性蛋白等渗透调节物质含量会明显升高, 以便于维持细胞膨压, 保持细胞正常生理功能, 提高玉米幼苗的渗透调节能力, 进而缓解干旱胁迫带来的氧化损伤。GABA是一种四碳非蛋白质氨基酸, 由于其特殊结构使其在逆境胁迫中具有同脯氨酸类似的功能。Liu等^[27]研究水分胁迫对烟草(Nicotiana tabacum)叶片中GABA和脯氨酸含量的影响中发现, GABA作为一种渗透调节物质其维持细胞膨压, 降低活性氧含量的作用明显高于脯氨酸。本研究发现, 干旱胁迫下, 外源施用GABA除能起到渗透调节作用外还能提高叶片内脯氨酸、可溶性糖和可溶性蛋白含量, 证明其不仅能作为一种渗透调节物质, 也能促进其他渗透调节物质的积累。同时, 在干旱胁迫下, 外源喷施GABA可以显著增加叶片的相对含水量, 降低叶片相对电导率, 从而改善叶片生理状态, 维持植株的正常生长。

玉米幼苗有机物质的积累与叶片光合特性密切相关, 其中叶绿素在光合作用中发挥着重要作用, 其参与对光的吸收、传递以及原初光化学反应等重要过程^[28]。研究表明, 干旱胁迫下玉米叶肉细胞中的叶绿素含量显著减少, 而维管束鞘细胞的叶绿素减少并不显著^[29]。在对水稻幼苗的研究中发现, 干旱胁迫能抑制叶绿素合成途径中关键酶基因的表达, 从而使酶活性降低, 进而造成叶绿素合成受阻^[30]。但Kaewsuksaeng^[31]的研究却认为干旱胁迫下叶绿素含量降低主要是由于色素加速降解导致。本研究中, 干旱胁迫降低了叶片SPAD数值, 并且随着胁迫天数的增加, SPAD数值下降速度加快, 与对照相比差异显著。Esmaeil等^[32]在黑孜然(Nigella sativa)上的研究结果表明, 外源施用不同浓度的GABA都能明显提高不同干旱程度下叶绿素a和叶绿素b含量, 改善光合作用。这种更好的持绿性可能是因为外源GABA对某些酶的激活作用, 从而启动了光合保护机制, 以及其干旱胁迫期间对代谢的调节作用^[33]。本研究中虽未对叶绿素a和叶绿素b单独测定, 但SPAD数值能准确反映出叶片中叶绿素含量。外源施用GABA能显著的提高干旱胁迫下叶片SPAD数值, 缓解干旱胁迫下叶绿素分解速率或提高其合成速率, 从而改善光合能力。

维持光合器官的稳定和较高的光化学效率是植物响应抗旱的主要机制, 也是探究植物在干旱胁迫下光合机构是否受到损伤的主要依据^[34]。较多的研究已证实, 干旱胁迫对植物的PSⅡ 反应中心造成很大程度的损伤, 促使电子传递速率下降和光化学效率受到抑制, 而PSⅡ 的受损导致过量激发能产生, 与氧气反应产生大量活性氧, 加速叶绿素降解和加剧PSⅡ 结构中复合蛋白变性失活程度, 导致光抑制的加剧, 造成植物的光能转化效率显著降低^[35]。本研究中, 干旱胁迫下, 玉米叶片F₀显著升高, F_v和F_m显著下降, 与对照相比, 干旱处理的F_v/F_m虽没有明显变化, 但干旱处理降低了F_v/F_m, 这表明叶片PSⅡ 反应中心受到胁迫伤害, 从而降低了电子传递速率和光化学效率。王日明等^[36]研究表明, 高温胁迫下, 外源施用5 mmol· L^-1的GABA能明显地提高F_v/F_m、ETR(电子传递速率, electron transport rate)、qP(荧光猝灭)等荧光参数, 有效地改善了PSⅡ 的功能。而本研究中, 干旱胁迫下, 外源施用GABA能显著地降低F₀, 提高F_v和F_m, 但F_v/F_m没有显著变化, 这可能是由于GABA对不同的逆境胁迫的调控机制不同导致的。

光合作用是影响作物生产力的重要因素。干旱导致作物产量降低主要是由于光合速率下降、降低了同化产物合成, 抑制了作物生长。干旱胁迫下, 植物的光合作用受到抑制, 光合作用的抑制作用主要是多种因素共同作用的结果, 如果胞间CO₂浓度和气孔导度均减少, 则净光合速率主要受气孔限制作用, 如果气孔导度减少, 但胞间CO₂浓度不变或增加, 则净光合速率减少可归因于非气孔限制因素^[37]。本试验研究发现, 干旱胁迫下叶片的净光合速率、蒸腾速率、气孔导度降低, 胞间CO₂浓度升高, 这表明光合作用受到气孔和非气孔限制因素的共同限制。外源施加GABA能显著缓解干旱胁迫带来的损伤^[38], 增加叶片的净光合速率、蒸腾速率、气孔导度, 使叶片的胞间CO₂浓度降低, 有效缓解干旱胁迫对玉米幼苗叶片光合作用的气孔和非气孔限制作用, 提高干旱胁迫下玉米幼苗的光合能力。

4 结论

干旱胁迫下, 外源施用GABA能显著提高玉米叶片SOD、POD和CAT活性, 减少MDA的积累, 从而缓解干旱胁迫对细胞膜的损害, 使叶片的相对电导率下降。此外, 渗透调节物质含量的升高, 可以提高细胞吸水、保水能力, 维持细胞的正常形态。同时, 外源施用GABA能显著降低叶片F₀, 提高F_v、F_m和F_v/F_m, 从而有效地减少叶片光化学损伤, 缓解干旱胁迫对叶绿素及光合作用的负面效应, 使玉米幼苗恢复生长。外源施加GABA还可以提高叶片的蒸腾速率、净光合速率、气孔导度, 缓解干旱胁迫对幼苗光合作用的影响, 提高植株在干旱胁迫下的适应能力。

参考文献

View Option

[1]	Shan L. To cope rationally with agricultural drought. Agricultural Research in the Arid Areas, 2011, 29(2): 1-5. 山仑. 科学应对农业干旱. 干旱地区农业研究, 2011, 29(2): 1-5. [本文引用:2]
[2]	Yang X C, Ming B, Tao H B, et al. Spatial distribution characteristics and impact on spring maize yield of drought in Northeast China. Chinese Journal of Eco-Agriculture, 2015, 23(6): 758-767. 杨晓晨, 明博, 陶洪斌, 等. 中国东北春玉米区干旱时空分布特征及其对产量的影响. 中国生态农业学报, 2015, 23(6): 758-767. [本文引用:1]
[3]	Cai F, Mi N, Ji R P, et al. Effects of drought stress and subsequent rewatering on major physiological parameters of spring maize during the key growth periods. Chinese Journal of Applied Ecology, 2017, 28(11): 3643-3652. 蔡福, 米娜, 纪瑞鹏, 等. 关键发育期干旱及复水过程对春玉米主要生理参数的影响. 应用生态学报, 2017, 28(11): 3643-3652. [本文引用:1]
[4]	Zhang R H, Zheng Y J, Ma G S, et al. Effects of drought stress on photosynthetic traits and protective enzyme activity in maize seeding. Acta Ecologica Sinica, 2011, 31(5): 1303-1311. 张仁和, 郑友军, 马国胜, 等. 干旱胁迫对玉米苗期叶片光合作用和保护酶的影响. 生态学报, 2011, 31(5): 1303-1311. [本文引用:1]
[5]	Du W L, Gao J, Hu F L, et al. Responses of drought stress on photosynthetic trait and osmotic adjustment in two maize cultivars. Acta Agronomica Sinica, 2013, 39(3): 530-536. 杜伟莉, 高杰, 胡富亮, 等. 玉米叶片光合作用和渗透调节对干旱胁迫的响应. 作物学报, 2013, 39(3): 530-536. [本文引用:1]
[6]	Miller G, Suzuki N, Ciftci-Yilmaz S, et al. Reactive oxygen species homeostasis and signalling during drought and salinity stress. Plant Cell and Environment, 2010, 33: 453-467. [本文引用:1]
[7]	Christensen H N, Greene A A, Kakuda D K, et al. Special transport and neurological significance of two amino acids in a configuration conventionally designated as D. Journal of Experimental Biology, 1994, 196: 297-305. [本文引用:1]
[8]	Jia Y, Zhao H W, Wang J G, et al. Research progress on γ-aminobulyric acid metabolism and function of crops under stress. Crops, 2014, 5: 9-15. 贾琰, 赵宏伟, 王敬国, 等. 逆境胁迫下作物中γ-氨基丁酸代谢及作用的研究进展. 作物杂志, 2014, 5: 9-15. [本文引用:1]
[9]	Harsh N, Ramanpreet K, Simranjit K, et al. γ-aminobutyric acid (GABA) imparts partial protection from heat stress injury to rice seedlings by improving leaf turgor and upregulating osmoprotectants and antioxidants. Journal of Plant Growth Regulation, 2014, 33: 408-419. [本文引用:1]
[10]	Luo H Y, Gao H B, Xia Q P, et al. Effects of exogenous GABA on reactive oxygen species metabolism and chlorophyll fluorescence parameters in tomato under NaCl stress. Scientia Agricultura Sinica, 2011, 44(4): 753-761. 罗黄颖, 高洪波, 夏庆平, 等. γ-氨基丁酸对盐胁迫下番茄活性氧代谢及叶绿素荧光参数的影响. 中国农业科学, 2011, 44(4): 753-761. [本文引用:1]
[11]	Yang L W, Li J R, Gao H B, et al. Effects of exogenous substances on active oxygen metabolism and photosynthesis in tomato seedlings under drought stress. Journal of Hebei Agricultural University, 2012, 35(2): 18-24. 杨丽文, 李敬蕊, 高洪波, 等. 干旱胁迫下外源物质对番茄幼苗活性氧代谢及光合作用的影响. 河北农业大学学报, 2012, 35(2): 18-24. [本文引用:2]
[12]	Giannopolitis C N, Ries S K. Purification and quantitative relationship with water-soluble protein in seedling. Plant Physiology, 1977, 59: 315-318. [本文引用:1]
[13]	Zeng S X, Wang Y R, Liu H X. Some enzymatic reactions related to chlorophyll degradation in cucumber cotyledons under chilling in the light. Acta Phytophysiologica Sinica, 1991, 17(2): 177-182. 曾韶西, 王以柔, 刘鸿先. 低温光照下与黄瓜子叶叶绿素降低有关的酶促反应. 植物生理学报, 1991, 17(2): 177-182. [本文引用:1]
[14]	Gao J F. Plants physiology experimentation guidance. Beijing: Higher Education Press, 2006. 高俊凤. 植物生理学实验指导. 北京: 高等教育出版社, 2006. [本文引用:1]
[15]	Kuk Y I, Shin J S, Burgos N R, et al. Antioxidative enzymes offer protection from chilling damage in rice plants. Crop Science, 2003, 43: 2109-2117. [本文引用:1]
[16]	Xie Z, Duan L, Tian X, et al. Coronatine alleviates salinity stress in cotton by improving the antioxidative defense system and radical scavenging activity. Journal of Plant Physiology, 2008, 165: 375-384. [本文引用:1]
[17]	Mukherjee S P, Choudhuri M A. Implications of water stress-induced changes in the levels of endogenous ascorbic acid and hydrogen peroxide in vigna seedlings. Physiologia Plantarum, 1983, 58(2): 166-170. [本文引用:1]
[18]	Collino D J, Dardanelli J L, Sereno R, et al. Physiological responses of argentine peanut varieties to water stress. Field Crops Research, 2011, 70: 177-184. [本文引用:1]
[19]	Bo X P, Wang M X, Cui L, et al. Evaluation on correlations of three kinds of osmoregulation substances in tea fresh leaves with low temperature during winter and spring respectively and their difference among cultivars. Scientia Agricultura Sinica, 2016, 49(19): 3807-3817. 薄晓培, 王梦馨, 崔林, 等. 茶树3类渗透调节物质与冬春低温相关性及其品种间的差异评价. 中国农业科学, 2016, 49(19): 3807-3817. [本文引用:1]
[20]	Monreal J A, Jiménez E T, Remesal E, et al. Proline content of sugar beet storage roots: Response to water deficit and nitrogen fertilization at field conditions. Environmental and Experimental Botany, 2007, 60: 257-267. [本文引用:1]
[21]	Hao Z B, Cang J, Xu Z. Plant physiological experiment. Harbin: Harbin Institute of Technology Press, 2004. 郝再彬, 苍晶, 徐仲. 植物生理实验. 哈尔滨: 哈尔滨工业大学出版社, 2004. [本文引用:1]
[22]	Liu F, Stützel H. *Biomass partitioning, specific leaf area, and water use efficiency of vegetable amaranth ( Amaranthus* spp. ) in response to drought stress*. Scientia Horticulturae*, 2004, 102(1): 15-27. [本文引用:1]
[23]	Li L J, Gu W R, Meng Y, et al. Physiological and biochemical mechanism of spermidine improving drought resistance in maize seedlings under drought stress. Chinese Journal of Applied Ecology, 2018, 29(2): 554-564. 李丽杰, 顾万荣, 孟瑶, 等. 干旱胁迫下亚精胺对玉米幼苗抗旱性影响的生理生化机制. 应用生态学报, 2018, 29(2): 554-564. [本文引用:1]
[24]	Yu L Y, Yao Q, Li P L, et al. Effects of exogenous γ-aminobutyric acid on growth of melon seedlings under drought stress. Journal of Shanghai Jiaotong University (Agricultural Science), 2018, 35(5): 22-27. 于立尧, 姚琪, 李彭丽, 等. 外源γ-氨基丁酸对干旱胁迫下甜瓜幼苗生长的影响. 上海交通大学学报(农业科学版), 2018, 35(5): 22-27. [本文引用:2]
[25]	Peter K, Corey E. Integrated approach to the mechanisms of thyroid toxins: Electron transfer, reactive oxygen species, oxidative stress, cell signaling, receptors, and antioxidants. Journal of Receptor and Signal Transduction Research, 2010, 30(3): 133-142. [本文引用:1]
[26]	Jia H, Qi L M G, Li T R G, et al. Sodium nitroprusside role on antioxidant enzymes activities in leaves of different potato cultivars under drought stress. Acta Botanica Boreali-Occidentalia Sinica, 2016, 36(3): 551-557. 贾慧, 其力木格, 李特日根, 等. 外源SNP对干旱胁迫下不同马铃薯品种叶片抗氧化酶活性的影响. 西北植物学报, 2016, 36(3): 551-557. [本文引用:1]
[27]	Liu C, Zhao L, Yu G. *The dominant glutamic acid metabolic flux to produce γ-aminobutyric acid over proline in Nicotiana tabacum* leaves under water stress relates to its significant role in antioxidant activity*. Journal of Integrative Plant Biology*, 2011, 53(8): 608-618. [本文引用:1]
[28]	Wang S, Zhou Q, Zhu Z L. *Physiological and biochemical characteristics of Carpinus betulus* seedlings under drought stress*. Acta Botanica Boreali-Occidentalia Sinica, 2013, 33(12): 2459-2466. 王飒, 周琦, 祝遵凌. 干旱胁迫对欧洲鹅耳枥幼苗生理生化特征的影响*. 西北植物学报, 2013, 33(12): 2459-2466. [本文引用:1]
[29]	Alberte R S, Thornber J P, Fiscus E L. Water stress effects on the content and organization of chlorophyll in mesophyll and bundle sheath chloroplasts of maize. Plant Physiology, 1977, 59(3): 351-353. [本文引用:1]
[30]	Dalal V K, Tripathy B C. Modulation of chlorophyll biosynthesis by water stress in rice seedlings during chloroplast biogenesis. Plant Cell & Environment, 2012, 35(9): 1685-1703. [本文引用:1]
[31]	Kaewsuksaeng S. Chlorophyll degradation in horticultural crops. Walailak Journal of Science & Technology, 2011, 8(1): 987-1005. [本文引用:1]
[32]	Esmaeil R C, Seyyed M S, Elnaz E, et al. *Exogenous application of gamma-aminobutyric acid (GABA) alleviates the effect of water deficit stress in black cumin ( Nigella sativa* L. )*. Industrial Crops & Products*, 2018, 112: 741-748. [本文引用:1]
[33]	Farooq M, Nawaz A, Chaudhry M, et al. Improving resistance against terminal drought in bread wheat by exogenous application of proline and gamma-aminobutyric acid. Journal of Agronomy and Crop Science, 2017, 203: 464-472. [本文引用:1]
[34]	Wingler A, Quick W P, Bungard R A, et al. The role of photorespiration during drought stress: An analysis utilizing barley mutants with reduced activities of photorespiratory enzymes. Plant Cell & Environment, 2010, 22(4): 361-373. [本文引用:1]
[35]	Cao H, Xu X, Han Z, et al. Changes of physiological characteristic on photosynthesis in malus seedling leaves during water stress. Acta Horticulturae Sinica, 2004, 31(3): 285-290. [本文引用:1]
[36]	Wang R M, Wang Z Q, Xiang Z X. Effect of exogenous γ-aminobutyric acid on the antioxidant defense system and phytohormones metabolism under high temperature stress in perennial ryegrass. Pratacultural Science, 2019, 36(1): 111-122. 王日明, 王志强, 向佐湘. 外源γ-氨基丁酸对高温胁迫下黑麦草抗氧化防御系统及激素代谢的影响. 草业科学, 2019, 36(1): 111-122. [本文引用:1]
[37]	Farquhar G D, Sharkey T D. Stomatal conductance and photosynthesis. Annual Review of Plant Physiology, 1982, 33: 317-345. [本文引用:1]
[38]	Jutur P, Reddy A R. BpaI and BpnI: Novel type II restriction endonucleases from Bacillus pasteurii and Bacillus pantothenticus. Biotechnology Letters, 2004, 26(11): 929-932. [本文引用:]

2011

0.0

... 水资源短缺是当前全球农业发展和粮食安全所面临的一个严峻生态问题,尤其是进入21世纪以来,在全球气候变暖、极端气候事件趋多增强的背景下,干旱的强度和频率都呈现明显增加的趋势,成为限制农作物产量的主要因素^[1] ...

... 玉米(Zea mays)是我国重要的粮食、经济和饲料作物,其在生育期间需水量较大,对干旱胁迫较为敏感,其中苗期干旱灾害已成为制约玉米增产的重要因素^[1] ...

2015

0.0

. 2015, 23(6):758-767

Spatial distribution characteristics and impact on spring maize yield of drought in Northeast China. Chinese Journal of

中国东北春玉米区干旱时空分布特征及其对产量的影响

Yang X C , Ming B , Tao H B

杨晓晨, 明博, 陶洪斌

Global warming has caused strong increase in temperature in China and this especially evident in Northeast China. As a consequence, drought stress has been more frequent, severe and over larger areas in this region. The severe drought stress has increased the risk of spring maize production in this major maize cultivation area of China. Thus understanding the spatial distribution of drought in relation to spring maize growth and yield formation was critical for in depth understanding of policy and decision making to deter yield reduction in Northeast China. Daily meteorological data for the period 19612012 were collected at 69 meteorological stations to analyze the effects of global warming on drought stress and yield of maize in Northeast China. Also spring maize growth and yield data were collected for the same period in the study area. The Penman-Monteit method was used to calculate potential evapotranspiration (PET). Based on the PET, the Standardized Precipitation Evapotranspiration Index (SPEI) was calculated (SPEI PM ), which was used to classify drought grade of the study area. The drought hazard index in each meteorological station was calculated then with weight and occurrence rating score of every drought grade. The trend in SPEI was calculated for five growth stages using the Mann-Kendall test and the relationship between SPEI PM and climate-driven maize yield determined using regression analysis. The results showed West Jilin Province and West Liaoning Province were high drought risk areas during maize growing season, while East Jilin Province and East Liaoning Province were low drought risk areas. Drought risk also increased with maize growth in East Heilongjiang Province. Moreover, drought intensity and drought-affected area decreased at maize seedling stage but increased at later growth stages of maize for the 52-year study period. High correlations were observed between SPEI PM3 -7 (SPEI PM from May to July) and climate-driven maize yield in West Liaoning Province for 1991–2012 and also between SPEI PM3 -8 (SPEI PM from June to August) for West Jilin Province, East Jilin Province as well as Songnen Plain ( P P < 0.05). Generally, drought intensity and drought- affected area in spring drought areas such as Songnen Plain, West Jilin Province, West Liaoning Province and South Liaoning Province decreased gradually. However, drought intensity in study area increased in frequency and severity at late growth stages in Northeast China, especially in the east. In areas with abundant rainfall (e.g., East Jilin Province), the axis of symmetry of the regression equation between climate-driven yield and drought index was closed to 0, suggesting that normal rainfall was sufficient to ensure high yield in the area. In areas with scarce rainfall (e.g., West Liaoning Province and West Jilin Province), the axis of symmetry of the regression equation between climate-driven yield and drought index was closed to 1, suggesting that irrigation was necessary to improve both yield and water use efficiency.

为了研究东北地区春玉米不同生育阶段干旱时空分布规律及其对产量的影响, 基于研究区域1961— 2012年69个气象站点逐日气象资料和春玉米生育时期及产量资料, 采用Penman-Monteit法计算潜在蒸散量, 在此基础上利用农业干旱指标标准化降水蒸散指数(SPEI PM )划分干旱等级, 最后利用干旱等级权重及发生概率评分等级计算每个站点的干旱危险指数(DHI); 利用Mann-Kendall检验法计算5个生育阶段的SPEI变化趋势, 利用回归分析进行SPEI与玉米气候产量的关系分析。结果表明, 吉林省西部和辽宁省西部在玉米生长季内始终为干旱高风险区, 吉林省东部和辽宁省东部则为干旱低风险区, 黑龙江省东部干旱风险随生育进程增大; 近52 a玉米苗期干旱强度和范围有减小趋势, 而生育后期在增加; 1991—2012年辽宁省西部玉米气候产量与SPEI PM3 -7(5—7月份的SPEIPM)以及吉林省西部、吉林省东部和松嫩平原气候产量与SPEI PM3 -8(6—8月份的SPEI PM )的关系达极显著( P PM )关系达显著水平( P <0.05)。春旱严重地区如松嫩平原、吉林省西部、辽宁省西部和南部的干旱强度和范围正在减小, 而东北干旱程度在玉米生育后期整体呈增强趋势, 其中东部最明显。在降水充沛的吉林省东部, 气候产量与干旱指数的回归方程对称轴在0附近, 表明正常降水情况下即能保证高产和稳产。降水较少的地区如辽宁省西部和吉林省西部等地, 回归方程对称轴在1附近, 提高玉米产量需增加灌溉和提高水分利用效率。

... 目前中国受干旱影响的地区较多,给农作物生产带来的影响也日渐严重^[2] ...

2017

0.0

... 干旱胁迫下,气孔和非气孔限制共同导致光合作用下降,而植物对干旱胁迫的首要响应就是关闭气孔^[3],这会造成CO₂吸收减少,引起CO₂同化量降低,净光合速率下降,从而导致光系统Ⅱ ...

2011

0.0

. 2011, 31(5):1303-1311

Effects of drought stress on photosynthetic traits and protective enzyme activity in maize seeding

干旱胁迫对玉米苗期叶片光合作用和保护酶的影响

Zhang R H , Zheng Y J , Ma G S

张仁和, 郑友军, 马国胜

Drought is a major limiting factor affecting maize growth, development and yield mainly in arid and semiarid regions of China. But the physiological mechanism related to simultaneous comparison of photosynthetic response and protective enzyme activity, which could be useful for identifying differences in maize cultivars under drought stress, remains unclear. The objective of this study was to investigate the effects of drought stress on the photosynthetic characteristics of the different maize cultivars at the seedling stage and to offer a theoretical basis and technical parameters for saving-water and high yield cultivation of maize. Two maize cultivars, zhengdan958 (drought tolerance) and shandan 902 (drought sensitive) grown in pots experiment in greenhouse were subjected to three different drought treatments (mild drought, moderate drought, severe drought) and compared to normal irrigation. The gas exchange, chlorophyll fluorescence, and protective enzyme activity were tested. The results showed that:(1) the onset of drought stress caused an increase of leaf's net photosynthetic rate ( P n ) and stomatal conductance ( G s ), furthermore, intercellular CO 2 concentration ( C i ) decreased and then increased, but reversible, stomatal limits ( L s ) increased and then decreased under drought stress in two cultivars. This suggested that reductions in P n resulted from stomatal limitations under mild and moderate drought stress; and from non-stomatal limitations under the severe drought stress in both cultivars. (2) In the chlorophyll fluorescence parameters, leaf's the quantum yield ( φ PSⅡ), electron transport rate ( ETR ), photochemical quenching ( qP ) decreased with increasing drought stress, however, non-photochemical quenching ( qN ) of photosystem Ⅱ (PSⅡ) activity increased significantly with the developing of drought stress, indicating that photoprotection was effective, whereas severly drought stress caused the inhibition of photosynthetic electron transport leading to damage of PSⅡ in the two cultivars. (3) Under drought stress the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) obviously increased and then decreased rapidly. The increase of enzyme activities in drought tolerance zhengdan958 was greater than that in drought sensitive shandan902. malondialdehyde (MDA) contents increased continuously, being significantly higher than that of the control, the increase of MDA contents in drought sensitive shandan 902 was greater than that in drought tolerance zhengdan958, which contributing to regulate activity of the protection system during the initial phase of drought stress, and the negative effects of drought during the stress period were observed. These results implied that drought stress depressed P n significantly, which induced by stomatal limitation and non-stomatal factors at seedling stage, under the moderate drought stress the decreased P n were mainly due to stomatal limitations through stomatal regulation, the enhance of thermal dissipation and antioxidant enzyme jointly; under the severe drought stress major non-stomatal limitations responsible for reduction in P n were associated with the impairment of PSⅡ and antioxidant enzyme system. At same time, the change range of all physiological parameters were smaller in zhengdan958 than in shandan902. Base the above results, we speculate that zhengdan958 maintains the higher photosynthesis function and the better oxidative enzyme defense system's ability to eliminate reactive oxygen compared to shandan902 under drought stress, which can be considered as the major physiological traits for its higher yield and drought tolerance.

以玉米品种郑单958(抗旱性强)和陕单902(抗旱性弱)为材料,采用盆栽控水试验,设置3个干旱处理(轻度干旱,中度干旱,重度干旱)和正常灌水,研究了干旱胁迫对玉米苗期叶片光合速率、叶绿素荧光以及相关生理指标的影响。结果表明:(1)干旱胁迫下2个品种叶片净光合速率( P n )和气孔导度( G s )显著下降,胞间CO 2 浓度( C i )出现了先下降后上升,而气孔限制值( L s )上升后下降,说明中度干旱胁迫下叶片 P n 下降是气孔因素引起的,重度干旱胁迫下 P n 降低主要由非气孔因素引起的。(2)随着干旱胁迫的加剧,2个品种叶片光系统Ⅱ(PSⅡ)的实际量子产量( φ PSⅡ)、电子传递速率( ETR )和光化学猝灭( qP )一直下降,而非光化学猝灭( qN )上升后下降,说明中度干旱下热耗散仍是植株重要光保护机制,重度干旱时叶片光合电子传递受阻,PSⅡ受到损伤。(3)干旱胁迫下2个品种叶片的超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性先升高后降低,而丙二醛(MDA)含量一直升高,说明干旱胁迫初期对保护系统酶活性升高有诱导作用,重度胁迫下活性氧清除酶的活性下降,导致细胞膜伤害。这些结果暗示,轻度和中度干旱胁迫下2个玉米品种通过减少光捕获、热耗散和酶活性调节协同作用稳定了光合机构功能,是 P n 下降的气孔限制因素;而重度干旱胁迫下光系统Ⅱ和抗氧化酶系统损伤,是 P n 下降的非气孔限制因素;郑单958的各生理参数比陕单902受旱影响小,干旱胁迫下仍具有较高的光合效率和较强的保护酶活性是郑单958抗旱的主要生理原因。

... 植物会通过减少光能的捕获、提高体内抗氧化酶活性、积累渗透调节物质等途径来减少氧化损伤,从而维持细胞膜正常生理功能,并以此来提高植物对干旱胁迫的抵抗能力^[4,5] ...

2013

0.0

. 2013, 39(3):530-536 DOI:10.3724/SP.J.1006.2013.00530

Responses of drought stress on photosynthetic trait and osmotic adjustment in two maize cultivars

玉米叶片光合作用和渗透调节对干旱胁迫的响应

Du W L , Gao J , Hu F L

杜伟莉, 高杰, 胡富亮

College of Agronomy, Northwest A & F University / Key Laboratory of Biology and Genetic Improvement of Maize in Arid Area of Northwest Region, Ministry of Agriculture, Yangling 712100, China?

The responses of gas exchange, chlorophyll fluorescence parameters and osmotic adjustment were studied in two different maize hybrids Zhengdan 958 (drought resistance) and Shaandan 902 (drought sensitive) under three different drought stresses (mild drought, moderate drought, severe drought) and normal irrigation in pot experiment. The results showed that drought stress caused disorder in photosynthesis, damage in the integrity of cellular membranes and increase the amounts of osmotic active substance (proline and soluble sugar) in both two cultivars. Thus these may have an important role in acclimation process to drought stress. However, compared with drought-stressed Shaandan 902, drought-stressed Zhengdan 958 showed higher values of maximum leaf net photosynthetic rate ( P nmax ), apparent quantum efficiency (AQY), light saturation point (LSP), maximum rate of electron transport driving RuBP regeneration ( J max ), maximum rate of RuBP carboxylatuin ( V c max ), PSII actual quantum yield ( Φ PSII ) and photochemical quenching ( q P ); higher contents of soluble sugars and proline and lower content of MDA. These results indicate that Zhengdan 958 have a better self-protection of photosynthetic system, greater accumulation of substances for osmotic adjustment for eliminating the negative effects on cellular membranes may be the major physiological traits in the adapt ability to drought conditions.

以 2 个不同抗旱性玉米品种郑单 958 ( 抗旱性强 ) 和陕单 902 ( 抗旱性弱 ) 为材料，采用盆栽控水试验，设置 3 个干旱处理 ( 轻度干旱、中度干旱、重度干旱 ) 和正常灌水，研究了干旱胁迫对 2 个玉米品种气体交换、叶绿素荧光参数和渗透调节物质的影响。结果显示 , 重度干旱造成 2 个玉米品种叶片光合机构紊乱，破坏细胞膜完整性；同时增加了渗透调节物质，这对增强叶片的保水能力，维持光合速率有重要的作用。但与陕单 902 相比，干旱胁迫下郑单 958 表现出较高的最大净光合速率 ( P nmax ) ，表观量子效率 (AQY) ，光饱和点 (LSP) ，最大电子传递速率 ( J max ) ，最大羧化速率 ( V cmax ) ， PSII 的实际量子产量 ( Φ PSII ) 和光化学猝灭系数 ( q P ) ；较高的脯氨酸 (Pro) 和可溶性糖含量 (SS) ；较低的丙二醛含量 (MDA) 。这些结果表明，干旱胁迫下抗旱品种郑单 958 具有较强的渗透物质能力，减轻细胞膜质过氧化程度，维持较高的光合性能是其适应干旱环境的生理基础。

2010

0.0

... 但植物通过改变自身生理生化代谢来适应干旱胁迫的能力是有限的,仅在干旱初期阶段具有显著效果,而随着干旱时间和程度的增加,植物自身代谢出现紊乱,最终影响生长,甚至死亡^[6] ...

1994

0.0

... -aminobutyric acid,GABA)是一种以自由态存在于各种生物中的四碳非蛋白质氨基酸,在作物的非生物胁迫中^[7],GABA具有能维持作物体内C/N平衡、作为信号传导物质、改善抗氧化酶系统活性、提高渗透调节物质含量等功能,因此其与作物的抗逆境调控密切相关^[8] ...

2014

0.0

2014

0.0

... 近年来,关于外源GABA调控作物生理功能来提高作物抗逆性的研究已取得一定进展,Harsh等^[9]的研究表明,1 mmol· ...

2011

0.0

. 2011, 44(4):753-761

Effects of exogenous GABA on reactive oxygen species metabolism and chlorophyll fluorescence parameters in tomato under NaCl stress

γ-氨基丁酸对盐胁迫下番茄活性氧代谢及叶绿素荧光参数的影响

Luo H Y , Gao H B , Xia Q P

罗黄颖, 高洪波, 夏庆平

(河北农业大学园艺学院)

【Objective】The objective of this study was to investigate the effects of exogenous γ-aminobutyric acid GABA application on the alleviation of tomato injury of salt stress. 【Method】 Hydroponic experiments were performed to investigate the effects of exogenous GABA application (5 mmol?L-1) on growth, reactive oxygen species metabolism, chlorophyll contents, Pn and chlorophyll fluorescence parameters in seedlings of tomato cultivar ‘Jinpeng No.1’ under NaCl stress (50 mmol?L-1). 【Result】 It was found that exogenous GABA significantly increased activities of SOD, POD, CAT, GR and productive rate of , but slightly affected the growth, APX activity, contents of AsA, H2O2, MDA in tomato leaves under normal nutrient solution. On the other hand, exogenous GABA application to normal nutrient solution had no significant effects on chlorophyll contents, Pn, maximal photochemical efficiency of photosystem II (Fv/Fm) and non-photochemical quenching coefficient (NPQ), but Chl a/b, electron transport rate (ETR), actual photochemical efficiency (ΦPSⅡ) and photochemical quenching coefficient (qP) significant increased in tomato leaves. In comparison to NaCl stress, exogenous GABA application led to a marked increase in leaves growth, activities of SOD, POD, APX and GR, contents of AsA and GSH, as well as decrease in accumulation of , H2O2 and content of final product of membrane lipid peroxidation MDA, but little influence on CAT activity in leaves. Meanwhile, the addition of GABA to the salinized nutrient solution could maintain higher PSⅡ activity through significantly improving chlorophyll content, Pn, Fv/Fm, ETR, ΦPSⅡ and qP, as well as decreasing NPQ. 【Conclusion】Exogenous GABA application enhanced salt tolerance in tomato seedlings and alleviated the salt stress damage to PSII center via enhancing the antioxidant enzymes activities and the contents of antioxidants, reducing the accumulation of H2O2 and protecting the stabilization of membrane from peroxidation.

【目的】探讨外源γ-氨基丁酸(GABA)对提高番茄耐盐性的作用。【方法】采用营养液水培法,以番茄‘金棚1号’为材料,研究外源添加GABA(5 mmol?L-1)对NaCl(50 mmol?L-1)胁迫下番茄幼苗的生长、活性氧代谢、叶绿素含量、净光合速率(Pn)及叶绿素荧光参数的影响。【结果】在正常营养液中添加GABA对番茄幼苗的生长、APX、AsA、H2O2、MDA影响不大,但显著提高了SOD、POD、CAT、GR活性及的积累;此外,叶绿素含量、Pn、最大光化学效率(Fv/Fm)和非光化学猝灭系数(NPQ)没有发生显著变化,而Chla/b、光合电子传递速率(ETR)、光系统Ⅱ实际量子效率(фPSⅡ)和光化学猝灭系数(qP)明显提高;NaCl胁迫下,外源GABA明显提高了番茄叶片生长速率、SOD、POD、APX、GR的活性以及AsA、GSH含量,减少了、H2O2和膜脂过氧化产物MDA的积累,但对CAT影响不明显;外源添加GABA处理显著提高了盐胁迫下叶绿素含量、Pn、Fv/Fm、ETR、фPSⅡ和qP,而NPQ显著降低,维持较高的光系统Ⅱ活性。【结论】NaCl胁迫下,外源添加GABA通过促进抗氧化酶活性和抗氧化剂含量的提高,降低H2O2和MDA的积累,保护了细胞膜结构的稳定性,从而减轻盐胁迫对番茄光系统Ⅱ的伤害,增强番茄的耐盐性。

... 55%,而对过氧化氢酶(catalase, CAT)活性无显著影响^[10] ...

2012

0.0

... 此外,外源施用GABA能明显地降低番茄(Solanum lycopersicum)幼苗叶片活性氧产生速率、过氧化氢(hydrogen peroxide, H₂O₂)和丙二醛含量,增加可溶性蛋白、可溶性糖等渗透调节物质的积累,降低脯氨酸含量,从而缓解干旱胁迫对番茄幼苗生长的抑制作用^[11] ...

... 外源施用GABA能显著提高SOD、POD和CAT的活性,有效缓解干旱胁迫对玉米叶片的损伤,与杨丽文等^[11]在番茄幼苗上的研究有相似的结论,即外源施加GABA不仅能提高SOD、POD、CAT的活性,且升高幅度也逐渐增加,进而有效缓解胁迫带来的损伤 ...

1977

0.0

... 2 抗氧化酶活性测定超氧化物歧化酶(SOD)活性采用氮蓝四唑(nitro-blue tetrazolium,NBT)还原法测定^[12],过氧化物酶(POD)活性采用愈创木酚法测定^[13],过氧化氢酶(CAT)采用高俊凤^[14]的方法测定 ...

1991

0.0

2006

0.0

2003

0.0

... 3 氧化损伤指标测定丙二醛(MDA)含量采用硫代巴比妥酸法测定^[15],超氧阴离子含量( O2-)采用羟氨氧化法测定^[16],过氧化氢(H₂O₂)含量参照Mukherjee等^[17]的方法测定 ...

2008

0.0

1983

0.0

2011

0.0

... 4 渗透调节物质测定脯氨酸(proline, Pro)含量采用磺基水杨酸法测定^[18] ...

2016

0.0

. 2016, 49(19):3807-3817 DOI:10.3864/j.issn.0578-1752.2016.19.012

Evaluation on correlations of three kinds of osmoregulation substances in tea fresh leaves with low temperature during winter and spring respectively and their difference among cultivars

茶树3类渗透调节物质与冬春低温相关性及其品种间的差异评价

Bo X P , Wang M X , Cui L

薄晓培, 王梦馨, 崔林

1 Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, China Jiliang University, Hangzhou 310018 2 Jiangsu Yinchunbiya Tea Co. Ltd, Danyang 212345, Jiangsu

【Objective】 The content dynamics of three types of osmoregulation substances in fresh leaves of two cultivars of tea plants and their correlations with air temperatures during winter and early spring were investigated, to evaluate the differences in their responsiveness to the low temperature between the two tea cultivars. 【Method】 Two early bud tea cultivars, ‘Pingyangtezao’ and ‘Zhongcha 102’, were chosen, and air temperatures around their tea shoots were recorded every day from Oct. 21 to April 5 for two consecutive years. The temperature of the dry and wet bulb thermometer at 8:00, 14:00 and 20:00 was daily recorded, and the average of the three dry bulb thermometers set in the experimental tea plantations three times per day standard for the temperature of tea shoot habitat. During these two testing periods adult tea leaves of each cultivar were sampled on the fifth, fifteenth and twenty-fifth days of each month. The soluble sugar contents in the tea fresh leaves were measured by anthrone colorimetric method, the remaining clean fresh leaves were processed into the steamed green tea samples, whereas the contents of proline and free amino acids were determined by SDE-HPLC method. 【Result】The test phase was divided into two stages, the overwintering period (2013/10/21-2014/3/52014/10/21-2015/3/5) and early spring period (2014/3/6-2014/4/52015/3/6-2015/4/5) according to the developmental threshold temperature and the dormancy temperature of the tea plant. Accompanied with initial gradual drops and then maintaining at low air temperatures during the two winters (2013/10/21-2014/3/5, 2014/10/21-2015/3/5), the soluble sugar contents in fresh tea leaves of the two cultivars increased continuingly, negatively correlated with the 10-day average air temperatures. The proline contents increased first and then kept at a high level, also negatively correlated with the 10-day average air temperatures. The free amino acid contents dropped first and then stayed at a low level, which was positively correlated with the 10-day average air temperatures. When the temperature appeared the lowest value, the content of soluble sugars and the content of proline also correspondingly appeared the highest values subsequently, then the content of free amino acids also correspondingly appeared the lowest value. When the temperature was the highest value, the content of soluble sugar and the content of proline also correspondingly appeared the lowest value later, the content of the free amino acids also correspondingly appeared the highest value soon afterwards. During the two spring seasons (2014/3/6-2014/4/5, 2015/3/6-2015/4/5), as air temperatures increased gradually, the soluble sugar contents decreased, while the proline and the free amino acid contents appeared to increase. The frost-resistance of tea plant closely related with air temperature, and soluble sugar, the contents of proline and free amino acids in tea leaves closely related with the frost-resistance of tea plants. During the two winter seasons, compared with ‘Zhongcha 102’, when suffered from the low temperature stress in winter, the content of each of three kinds of osmoregulation substances of ‘ pingyangtezao’ more sensitively response to low temperature than ‘Zhongcha 102’, and the contents of the three kinds of substances in cultivar ‘pingyangtezao’ were slightly high. 【Conclusion】 Tea plants are vulnerable to frost, freeze and the late spring coldness from late autumn to Qingming Festival. As important cold-resisting indices of tea plants, the contents of soluble sugars, proline and the free amino acids varied sensitively in responses to the low temperatures, and showed significant correlations with the 10-day average air temperatures during the winter and early spring seasons. The responsiveness of cultivar ‘Pingyangtezao’ to the low temperatures was greater than that of cultivar ‘Zhongcha 102’.

【目的】探讨2个茶树品种可溶性糖、脯氨酸和游离氨基酸等3类渗透调节物质含量变化及其与冬春期间气温的相关性,评价其对低温的响应程度及其品种间的差别。【方法】选早芽品种‘平阳特早’和‘中茶102’,连续2年于10月21日至翌年4月5日逐日记载茶梢间气温,每天8：00、14：00、20：00记录干湿球温度计的温度,每日3次测得的每块茶园3支干球温度计的平均值即为当日茶梢生境气温；测温期间每月5日、15日、25日采摘成叶,以蒽酮比色法测定茶鲜叶可溶性糖含量,将剩余擦拭干净的鲜叶蒸青、烘干制成蒸青茶样,用SDE-HPLC方法测定茶干叶脯氨酸和游离氨基酸含量。【结果】根据茶树的发育起点温度和休眠温度,将试验阶段分为越冬期（2013/10/21—2014/3/5,2014/10/21—2015/3/5）和早春期（2014/3/6—2014/4/5,2015/3/6—2015/4/5）2个阶段。①连续2年试验的越冬期间（2013/10/21—2014/3/5,2014/10/21—2015/3/5）,气温先逐渐下降,再持续低温；2个品种成叶的可溶性糖含量相应地升高、再升高,与旬平均气温显著负相关；脯氨酸含量升高、保持,与旬平均气温显著负相关；游离氨基酸含量则为下降、保持,与旬平均气温显著正相关；当温度出现最低值时,可溶性糖含量和脯氨酸含量相应出现最高值,游离氨基酸含量也跟随着出现最低值,而当温度出现最高值时,可溶性糖含量和脯氨酸含量随后也就相应地出现最低值,游离氨基酸含量随之也相应地出现最高值。②2年试验的早春期间（2014/3/6—2014/4/5,2015/3/6—2015/4/5）气温渐升,可溶性糖含量趋于减少,脯氨酸、游离氨基酸含量趋于增加；③茶树抗冻性与温度密切相关,茶鲜叶可溶性糖、脯氨酸和游离氨基酸含量与茶树的抗冻性密切相关,2年越冬期间,与‘中茶102’相比,在遭受冬季低温胁迫时,‘平阳特早’3类渗透调节物质对低温的响应性、响应幅度分别更灵敏、更大,‘平阳特早’3类渗透调节物质含量稍多。【结论】深秋至清明期间茶树易受冻害和倒春寒,其中越冬期间可溶性糖、脯氨酸和游离氨基酸皆能敏感地响应低温变化,三者含量分别与旬平均气温显著相关,是茶树的重要抗冻指标；‘平阳特早’品种对于低温响应程度大于‘中茶102’。

... 可溶性糖含量参照薄晓培等^[19]的测定方法 ...

2007

0.0

... 可溶性蛋白含量采用G-250方法测定^[20] ...

2004

0.0

... 参照郝再彬等^[21]的方法测定叶片相对电导率 ...

2004

0.0

... 3 讨论干旱是影响玉米生长和发育最常见的环境胁迫,当玉米遭受干旱胁迫时,其在形态和生理上会产生抗旱应对策略,如干物质以及根冠比的调整等^[22] ...

2018

0.0

... 本研究中,在干旱胁迫下,玉米幼苗的株高、叶面积和幼苗干重都出现明显下降,而根冠比出现明显升高,表明干旱胁迫对地上部分干物质积累的抑制作用要大于地下部分,与李丽杰等^[23]采用外源亚精胺处理干旱胁迫幼苗的结论相似 ...

2018

0.0

... 在轻度和重度干旱胁迫中,外源施用GABA能明显提高甜瓜(Cucumis melo)幼苗的株高、茎粗、叶面积和整株干鲜重,缓解干旱胁迫给生长造成的抑制作用^[24] ...

... 研究表明,外源施用GABA能明显降低MDA、H₂O₂和 O2-含量^[24] ...

2010

0.0

... 植物适应环境的变化需要植物细胞体内多种途径之间的协调平衡来实现,非生物胁迫下,这种平衡被破坏,特别是当植物暴露于水势急剧下降时,体内活性氧(reactive oxygen species, ROS)等物质大量积累,从而对蛋白质、DNA和脂质等造成损伤^[25] ...

2016

0.0

... 当植物遭遇干旱胁迫,植物自身抗氧化酶系统活性会出现明显升高,以便于清除活性氧,减少膜质过氧化物的积累,保证细胞膜的完整性和正常的功能^[26] ...

2011

0.0

... Liu等^[27]研究水分胁迫对烟草(Nicotiana tabacum)叶片中GABA和脯氨酸含量的影响中发现,GABA作为一种渗透调节物质其维持细胞膨压,降低活性氧含量的作用明显高于脯氨酸 ...

2013

0.0

... 玉米幼苗有机物质的积累与叶片光合特性密切相关,其中叶绿素在光合作用中发挥着重要作用,其参与对光的吸收、传递以及原初光化学反应等重要过程^[28] ...

1977

0.0

... 研究表明,干旱胁迫下玉米叶肉细胞中的叶绿素含量显著减少,而维管束鞘细胞的叶绿素减少并不显著^[29] ...

2012

0.0

... 在对水稻幼苗的研究中发现,干旱胁迫能抑制叶绿素合成途径中关键酶基因的表达,从而使酶活性降低,进而造成叶绿素合成受阻^[30] ...

2011

0.0

... 但Kaewsuksaeng^[31]的研究却认为干旱胁迫下叶绿素含量降低主要是由于色素加速降解导致 ...

2018

0.0

... Esmaeil等^[32]在黑孜然(Nigella sativa)上的研究结果表明,外源施用不同浓度的GABA都能明显提高不同干旱程度下叶绿素a和叶绿素b含量,改善光合作用 ...

2017

0.0

... 这种更好的持绿性可能是因为外源GABA对某些酶的激活作用,从而启动了光合保护机制,以及其干旱胁迫期间对代谢的调节作用^[33] ...

2010

0.0

... 维持光合器官的稳定和较高的光化学效率是植物响应抗旱的主要机制,也是探究植物在干旱胁迫下光合机构是否受到损伤的主要依据^[34] ...

2004

0.0

... 结构中复合蛋白变性失活程度,导致光抑制的加剧,造成植物的光能转化效率显著降低^[35] ...

2019

0.0

... 王日明等^[36]研究表明,高温胁迫下,外源施用5 mmol· ...

1982

0.0

... 干旱胁迫下,植物的光合作用受到抑制,光合作用的抑制作用主要是多种因素共同作用的结果,如果胞间CO₂浓度和气孔导度均减少,则净光合速率主要受气孔限制作用,如果气孔导度减少,但胞间CO₂浓度不变或增加,则净光合速率减少可归因于非气孔限制因素^[37] ...

2004