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草业学报 ›› 2024, Vol. 33 ›› Issue (10): 55-73.DOI: 10.11686/cyxb2023460

• 研究论文 • 上一篇    下一篇

紫花苜蓿MsBBX20基因克隆及耐盐功能分析

周昕越1(), 蒋庆雪1, 贾会丽2, 马琳1, 樊璐1, 王学敏1()   

  1. 1.中国农业科学院北京畜牧兽医研究所,北京 100193
    2.山西农业大学草业学院,山西 太原 030032
  • 收稿日期:2023-11-09 修回日期:2024-01-12 出版日期:2024-10-20 发布日期:2024-07-15
  • 通讯作者: 王学敏
  • 作者简介:Corresponding author. E-mail: wangxuemin@caas.cn
    周昕越(1998-),男,蒙古族,内蒙古赤峰人,在读博士。E-mail: zhouxinyuenmg@163.com
  • 基金资助:
    财政部和农业农村部:国家现代农业产业技术体系(CARS-34);国家科技资源共享服务平台作物种质资源库(NICGR-63)

Cloning and salt-tolerance functional analysis of alfalfa MsBBX20 gene

Xin-yue ZHOU1(), Qing-xue JIANG1, Hui-li JIA2, Lin MA1, Lu FAN1, Xue-min WANG1()   

  1. 1.Institute of Animal Sciences,Chinese Academy of Agricultural Sciences,Beijing 100193,China
    2.College of Grassland Science,Shanxi Agricultural University,Taiyuan 030032,China
  • Received:2023-11-09 Revised:2024-01-12 Online:2024-10-20 Published:2024-07-15
  • Contact: Xue-min WANG

摘要:

BBX家族转录因子参与光形态建成、成花生理、避荫反应、种子生长发育、激素信号转导及对逆境胁迫的响应等植物重要生长发育过程。紫花苜蓿是耐盐性较强的牧草饲料作物,其品质优良,有“牧草之王”的美誉。发掘并探索紫花苜蓿MsBBX20基因响应非生物胁迫的分子机理,有助于揭示紫花苜蓿抗逆生物学基础,为紫花苜蓿抗逆分子育种提供新的基因资源。通过RT-PCR、3′/5′RACE PCR技术克隆得到MsBBX20基因cDNA序列,生物信息学分析发现其CDS全长834 bp,编码278个氨基酸,该基因编码的蛋白质为锌指结构蛋白家族成员。利用qRT-PCR技术分析MsBBX20在紫花苜蓿不同组织和不同非生物胁迫下的表达模式。通过基因枪轰击技术,在洋葱表皮瞬时表达MsBBX20进行亚细胞定位。克隆得到大小为1737 bp的MsBBX20启动子序列并分析了顺式作用元件,该启动子可驱动GUS报告基因在烟草的叶、茎和根中高效表达。将MsBBX20启动子序列与包含GUS基因的pCAMBIA-1301载体连接,瞬时转化烟草并通过组织化学染色对不同组织进行GUS活性分析。构建pCAMBIA3301-MsBBX20植物超表达载体,通过农杆菌介导的方法遗传转化野生型拟南芥,获得超表达MsBBX20的拟南芥株系。用不同浓度盐溶液(150、200和300 mmol·L-1 NaCl)处理拟南芥转基因株系并分析其MDA含量和抗氧化酶活性。进化分析表明紫花苜蓿MsBBX20蛋白与红三叶TpBBX20的亲缘关系最近。MsBBX20蛋白定位于细胞核。MsBBX20基因在花中表达量最高,且MsBBX20可以响应干旱、盐、冷、脱落酸、赤霉素、光照等多种非生物胁迫。遗传转化获得MsBBX20过表达拟南芥株系,并选择3个高表达阳性株系进行功能验证。在不同浓度NaCl处理条件下,过量表达MsBBX20的拟南芥株系的丙二醛(MDA)含量显著低于对照,而超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性均显著高于对照。克隆获得紫花苜蓿锌指蛋白转录因子基因MsBBX20,该基因在花中表达量最高,能够响应多种非生物逆境胁迫和外源激素处理,表明MsBBX20可能参与紫花苜蓿的多个逆境响应过程。进一步的研究证明MsBBX20可能通过调节植物的抗氧化酶系统,缓解逆境造成的植物细胞氧化损伤,提高转基因拟南芥对盐胁迫的抗性,进而增强植株的耐盐性。

关键词: 紫花苜蓿, MsBBX20, 基因克隆, 耐盐性, 功能分析

Abstract:

The BBX family of transcription factors is involved in plant growth and development processes such as photomorphogenesis, flowering physiology, shade avoidance, seed development, hormone signaling, and responses to environmental stress. Medicago sativa, commonly known as alfalfa, is a forage crop with strong salt tolerance and high forage quality, and has been called the “queen of forages”. Uncovering and investigating the molecular mechanisms of the alfalfa MsBBX20 gene in response to abiotic stress can reveal the biological basis for alfalfa stress resistance and provide new genetic resources for molecular breeding for stress resistance. The MsBBX20 gene cDNA sequence was cloned using RT-PCR and 3′/5′ RACE PCR techniques, and bioinformatics analysis showed that its CDS is 834 bp long, encoding 278 amino acids, and the protein is a member of the zinc finger protein family. The expression pattern of MsBBX20 in different alfalfa tissues and under various abiotic stresses was analyzed using qRT-PCR technique. Subcellular localization was performed by transiently expressing MsBBX20 in Allium cepa epidermis via a gene gun. The MsBBX20 promoter sequence, with a length of 1737 base pairs, was cloned and its cis-acting elements were analyzed. This promoter can efficiently drive the expression of the GUS reporter gene in the leaves, stems, and roots of Nicotiana tabacum. The MsBBX20 promoter sequence was linked to the pCAMBIA-1301 vector containing the GUS gene, and then transiently transformed into N. tabacum and GUS activity in different tissues was analyzed by histochemical staining. A pCAMBIA3301-MsBBX20 plant overexpression vector was constructed and genetically transformed into wild-type Arabidopsis thaliana using the Agrobacterium-mediated method, A. thaliana lines overexpressing MsBBX20 were thus obtained. Transgenic lines of A. thaliana were treated with different concentrations of salt solution (150, 200, and 300 mmol·L-1 NaCl) and the malondialdehyde (MDA) content and antioxidant enzyme activity of different lines were analyzed. Evolutionary analysis indicated that the MsBBX20 protein of alfalfa is most closely related to the TpBBX20 of red clover (Trifolium pratense). The MsBBX20 protein is localized to the nucleus. The MsBBX20 gene is most highly expressed in flowers and can respond to various abiotic stresses such as drought, salt, cold, abscisic acid, gibberellin, and light. Transgenic A. thaliana lines overexpressing MsBBX20 were obtained, and three highly expressed positive lines were selected for functional validation. Under different concentrations of NaCl, the MDA content of A. thaliana lines overexpressing MsBBX20 was significantly lower than the control, while the activities of superoxide dismutase, catalase, and peroxidase were significantly higher than the control. The MsBBX20 gene, a zinc finger protein transcription factor from alfalfa, is highly expressed in flowers and can respond to a variety of abiotic stresses and exogenous hormone treatments, indicating that MsBBX20 may be involved in multiple stress response processes in alfalfa. Further research demonstrated that MsBBX20 may enhance the resistance of transgenic A. thaliana to salt stress by regulating the plant’s antioxidant enzyme system, mitigating oxidative damage to plant cells caused by stress, and thereby improving plant salt tolerance.

Key words: Medicago sativa, MsBBX20, gene cloning, salt tolerance, function analysis