拟南芥AtGS1.1基因在种子萌发期与植物耐盐性关系的探讨

发布时间：2018-04-27 01:32

本文选题：种子萌发期 + 盐胁迫　；参考：《东北林业大学》2017年硕士论文

【摘要】：盐胁迫是影响作物生长发育和产量的主要非生物胁迫之一,是目前制约农业生产的一个全球性问题。种子萌发期作为影响作物在盐逆境下生长发育的关键性时期,种子萌发期的耐盐性机理研究具有更重要的研究意义。本研究前期发现在种子萌发期,拟南芥脲酶的缺失突变体能够提高植物在种子萌发期对盐胁迫的耐受性,可能是由尿素代谢途径中脲酶催化尿素生成少量的NH_4~+,从而缓解了由高盐胁迫产生的毒害作用。谷氨酰胺合成酶(GS)作为氮素代谢途径中最终同化NH_4~+的关键酶,本研究为了进一步探讨种子萌发期氮素代谢与植物耐盐性之间的关系,开展拟南芥谷氨酰胺合成酶(AtGS1.1)基因在种子萌发期与盐胁迫的应答分析。研究结果发现:AtGS1.1基因在野生型拟南芥的各个部位均有表达,且在种荚中表达量最高;此外,AtGS1.1基因在种子萌发期受NaCl及NH4Cl胁迫诱导上调表达。分析AtGS1.1基因过量表达、AtGS1.1基因缺失突变体(atgs1.1)及野生型拟南芥(WT)在盐胁迫下的应答,研究结果发现:过量表达AtGS1.1基因与WT和atgs1.1植株相比在种子萌发期对盐胁迫的抗性明显增强;向1/2MS培养基中添加过量的NH4Cl处理,AtGS1.1过表达拟南芥的长势要明显优于WT和atgs1.1。进一步分析GS酶活性与NH_4~+含量的结果显示,在种子萌发期,盐胁迫下AtGS1.1过表达拟南芥的根部和子叶中的GS酶活性显著高于WT和atgs1.1;而AtGS1.1过表达拟南芥的根部和子叶中的NH_4~+含量要显著低于WT和atgs1.1。此外,通过向NaCl胁迫培养基中添加两种不同类型的谷氨酰胺合成酶抑制剂(L-methionine sulfoximine,MSX;Glufosinate ammonium)处理WT种子,随着添加抑制剂浓度的不断增加,显著抑制了盐胁迫WT种子的萌发。以上的这些研究结果暗示,通过增强氮素代谢途径中GS酶的活性,促进NH_4~+的同化来降低植物体内NH_4~+的过量积累,从而提高植物在种子萌发期对盐胁迫的耐受性,这为提高盐胁迫下的作物育种提供科学的理论基础。
[Abstract]:Salt stress is one of the main abiotic stresses affecting crop growth and yield, and it is a global problem restricting agricultural production at present. Seed germination is the key period to affect the growth and development of crops under salt stress. The study on the mechanism of salt tolerance in seed germination is of more important significance. In the early stage of this study, it was found that the mutant of Arabidopsis thaliana urease deficiency could improve the tolerance of plants to salt stress during seed germination. It may be that urease catalyzes the production of a small amount of NH _ 4 ~-by urea metabolism pathway in Arabidopsis thaliana. Thus, the toxic effect of high salt stress was alleviated. Glutamine synthase (Glutamide synthase) is the key enzyme for assimilation of NH4 ~ in nitrogen metabolism pathway. In order to further study the relationship between nitrogen metabolism and salt tolerance of plants during seed germination, glutamine synthase (GSH) was used as the key enzyme for assimilation of NH4 ~ in nitrogen metabolism pathway. The response of Arabidopsis thaliana glutamine synthase (AtGS1.1) gene to salt stress during seed germination was studied. The results showed that: AtGS1.1 gene was expressed in all parts of wild-type Arabidopsis thaliana and had the highest expression in seed pods, in addition, it was upregulated by NaCl and NH4Cl stress during seed germination. The response of AtGS1.1 gene to salt stress was analyzed. The results showed that the overexpression of AtGS1.1 gene was significantly higher than that of WT and atgs1.1 plants during seed germination. The growth of Arabidopsis thaliana overexpressed by AtGS1.1 was significantly better than that of WT and ATGS 1.1 by adding excessive NH4Cl to 1/2MS medium. The results of further analysis of GS enzyme activity and NH4- content showed that, during seed germination, The activity of GS enzyme in roots and cotyledons of Arabidopsis thaliana was significantly higher than that in roots and cotyledons of Arabidopsis thaliana under salt stress, while the content of NH4 ~ in roots and cotyledons of Arabidopsis thaliana was significantly lower than that in roots and cotyledons of Arabidopsis thaliana. In addition, WT seeds were treated with two different types of glutamine synthase inhibitor, L-methionine sulfoximine Glufosinate ammonium, in NaCl stress medium, and the germination of WT seeds was significantly inhibited with the increasing concentration of inhibitors. These results suggest that, by enhancing the activity of GS enzyme in nitrogen metabolism pathway and promoting the assimilation of NH _ 4 ~, the excessive accumulation of NH _ 4 ~ in plants can be reduced, and the tolerance of plants to salt stress can be improved during seed germination. This provides a scientific theoretical basis for improving crop breeding under salt stress.
【学位授予单位】：东北林业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q945.78;Q943.2

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