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草业学报 ›› 2024, Vol. 33 ›› Issue (10): 96-107.DOI: 10.11686/cyxb2023463

• 研究论文 • 上一篇    下一篇

铅胁迫下吲哚乙酸对狗牙根铅累积及生理特性的影响

朱城强(), 温绍福, 江润海, 张梅, 蔡治宏, 何玥琛, 陈鑫, 侯秀丽()   

  1. 昆明学院农学与生命科学学院,高原湖泊生态与环境健康云南省高校协同创新中心,云南 昆明 650214
  • 收稿日期:2023-11-30 修回日期:2023-12-25 出版日期:2024-10-20 发布日期:2024-07-15
  • 通讯作者: 侯秀丽
  • 作者简介:Corresponding author. E-mail: hxlyn@aliyun.com
    朱城强(1995-),男,浙江温州人,在读硕士。E-mail: zcqlxg13@163.com
  • 基金资助:
    国家自然科学基金(42167009);云南省高校联合基金项目(2018FH001-004);云南省教育厅云南高原湖泊-北美五大湖国际联合科技创新团队和云南省大学生创新创业项目(S202311393070)

Effects of 3-indoleacetic acid on lead accumulation and physiological properties of Cynodon dactylon under lead stress

Cheng-qiang ZHU(), Shao-fu WEN, Run-hai JIANG, Mei ZHANG, Zhi-hong CAI, Yue-chen HE, Xin CHEN, Xiu-li HOU()   

  1. Yunnan Collaborative Innovation Center for Plateau Lake Ecology and Environmental Health,College of Agronomy and Life Sciences,Kunming University,Kunming 650214,China
  • Received:2023-11-30 Revised:2023-12-25 Online:2024-10-20 Published:2024-07-15
  • Contact: Xiu-li HOU

摘要:

为明确外源生长素对狗牙根在铅(Pb)胁迫下的作用与机制,本研究以Pb耐性植物狗牙根为对象,在盆栽试验条件下,对处于324.4 mg·kg-1土壤Pb胁迫下的狗牙根叶面喷施不同浓度的(0、1、10、100 mg·L-1)吲哚乙酸(IAA)与5、10 mg·L-1的生长素极性运输抑制剂(NPA),探究外源IAA对狗牙根的生长、生理特性及Pb积累的影响。结果表明:外源IAA使狗牙根IAA与细胞分裂素(CTK)含量升高,脱落酸(ABA)含量及吲哚乙酸氧化酶(IAAO)活性降低,促进了狗牙根在Pb胁迫下株高、根长、地上和地下部干重的增加。其中,喷施10 mg·L-1 IAA效果最好。与对照相比,10 mg·L-1 IAA叶面喷施处理使株高、根长及地上与地下部干重分别提高了32.4%、30.1%、32.2%和25.5%,叶绿素a、叶绿素b、胡萝卜素含量分别升高到对照组的1.35、1.36和1.21倍,叶与根中的Ca2+与可溶性蛋白含量显著上升。10 mg·L-1 IAA叶面喷施还改善了狗牙根体内的抗氧化指标,表现为丙二醛(MDA)含量相较于对照组显著下降,过氧化物酶(POD)活性显著升高。此外,10 mg·L-1 IAA叶面喷施促进了根对Pb的吸收和固定,同时抑制Pb的根-冠转移。但喷施NPA加重了Pb对狗牙根的生长抑制且该生长抑制具有对NPA的剂量依赖效应,10 mg·L-1 NPA的抑制效果最强,削弱了狗牙根内源激素对Pb的应激效应、降低了叶绿素荧光参数与光合色素含量、提高了狗牙根地上部分Pb含量、导致MDA含量升高。综合分析表明,本试验条件下狗牙根喷施10 mg·L-1 IAA效果最佳,通过增强狗牙根对Pb的激素应激反应、提高光合作用和抗氧化能力改善了植株生长;同时通过提升胞内Ca2+与可溶性蛋白含量抑制了Pb的根冠迁移,从而降低膜脂质过氧化水平,缓解了Pb胁迫下狗牙根的氧化损伤。本研究结果丰富了狗牙根耐Pb机制,并为应用外源IAA缓解植物Pb毒害提供了科学依据。

关键词: 铅胁迫, 吲哚乙酸, 狗牙根, 生长素极性运输, 铅耐性

Abstract:

This research explored the stress alleviation effect of exogenous auxin in Pb-stressed plants of Cynodon dactylon, a naturally lead tolerant species, and the underlying physiological mechanism. In a pot experiment, the foliar surface of C. dactylon under 324.4 mg·kg-1 soil Pb stress was sprayed with different concentrations (0, 1, 10, and 100 mg·L-1) of 3-indoleacetic acid (IAA) along with 5 and 10 mg·L-1 of polar transport inhibitor of IAA (NPA). Plant growth, physiological response, Pb accumulation in the roots, and its translocation to the shoots were systematically investigated. The findings demonstrated that exogenous IAA significantly increased the contents of IAA and cytokinin (CTK), and lowered the abscisic acid (ABA) level and indoleacetic acid oxidase (IAAO) activity, which promoted an increase in plant height, root length, and above- and belowground dry weight of C. dactylon under Pb stress. Among the different IAA treatments, foliar spraying of 10 mg·L-1 IAA exhibited the most pronounced stress alleviation effect. Compared to the control, foliar spraying of 10 mg·L-1 IAA increased plant height, root length, aboveground and belowground dry weight by 32.4%, 30.1%, 32.2%, and 25.5%, respectively. Meanwhile, the contents of chlorophyll a, chlorophyll b, and carotenoids in plants treated with 10 mg·L-1 IAA were 1.35, 1.36, and 1.21 times those in the control, and the contents of Ca2+ and soluble protein in leaves and roots were also significantly increased. Foliar spraying of 10 mg·L-1 IAA also improved the antioxidant indexes in C. dactylon, which was demonstrated by the significantly decreased malondialdehyde (MDA) content and increased peroxidase (POD) activity as compared to the control treatment. More importantly, foliar spraying of 10 mg·L-1 IAA promoted the adsorption of Pb by roots, and inhibited the Pb translocation from root to shoot. In contrast, foliar spraying of NPA aggravated the growth inhibition effect of Pb on C. dactylon. This effect exerted dose dependence on NPA, with 10 mg·L-1 NPA exhibiting the strongest inhibitory effect, as well as reducing the chlorophyll fluorescence, and decreasing photosynthetic pigment contents, and increasing the shoot uptake of Pb, which led to a rise of MDA content. In summary, foliar spraying of 10 mg·L-1 IAA exerted the best growth promotion and stress alleviation effects on C. dactylon. Exogenous IAA improved C. dactylon plant growth by stimulating hormone mediated stress response, enhancing photosynthetic capacity, and promoting anti-oxidative capacity. Exogenous IAA also increased cellular Ca2+ and soluble protein contents, which impeded the translocation of Pb from root to shoot, ultimately decreasing the level of membrane lipid peroxidation and oxidative damage induced by Pb stress. The results from the present study extend knowledge of mechanisms underlying Pb tolerance of C. dactylon and indicate a strategy for alleviating Pb poisoning in plants by applying exogenous IAA.

Key words: Pb stress, IAA, Cynodon dactylon, auxin polar transport, Pb tolerance