發(fā)布時間：2018-04-27 01:32

  本文選題：種子萌發(fā)期 + 鹽脅迫　； 參考：《東北林業(yè)大學(xué)》2017年碩士論文

【摘要】：鹽脅迫是影響作物生長發(fā)育和產(chǎn)量的主要非生物脅迫之一,是目前制約農(nóng)業(yè)生產(chǎn)的一個全球性問題。種子萌發(fā)期作為影響作物在鹽逆境下生長發(fā)育的關(guān)鍵性時期,種子萌發(fā)期的耐鹽性機理研究具有更重要的研究意義。本研究前期發(fā)現(xiàn)在種子萌發(fā)期,擬南芥脲酶的缺失突變體能夠提高植物在種子萌發(fā)期對鹽脅迫的耐受性,可能是由尿素代謝途徑中脲酶催化尿素生成少量的NH_4~+,從而緩解了由高鹽脅迫產(chǎn)生的毒害作用。谷氨酰胺合成酶(GS)作為氮素代謝途徑中最終同化NH_4~+的關(guān)鍵酶,本研究為了進一步探討種子萌發(fā)期氮素代謝與植物耐鹽性之間的關(guān)系,開展擬南芥谷氨酰胺合成酶(AtGS1.1)基因在種子萌發(fā)期與鹽脅迫的應(yīng)答分析。研究結(jié)果發(fā)現(xiàn):AtGS1.1基因在野生型擬南芥的各個部位均有表達,且在種莢中表達量最高;此外,AtGS1.1基因在種子萌發(fā)期受NaCl及NH4Cl脅迫誘導(dǎo)上調(diào)表達。分析AtGS1.1基因過量表達、AtGS1.1基因缺失突變體(atgs1.1)及野生型擬南芥(WT)在鹽脅迫下的應(yīng)答,研究結(jié)果發(fā)現(xiàn):過量表達AtGS1.1基因與WT和atgs1.1植株相比在種子萌發(fā)期對鹽脅迫的抗性明顯增強;向1/2MS培養(yǎng)基中添加過量的NH4Cl處理,AtGS1.1過表達擬南芥的長勢要明顯優(yōu)于WT和atgs1.1。進一步分析GS酶活性與NH_4~+含量的結(jié)果顯示,在種子萌發(fā)期,鹽脅迫下AtGS1.1過表達擬南芥的根部和子葉中的GS酶活性顯著高于WT和atgs1.1;而AtGS1.1過表達擬南芥的根部和子葉中的NH_4~+含量要顯著低于WT和atgs1.1。此外,通過向NaCl脅迫培養(yǎng)基中添加兩種不同類型的谷氨酰胺合成酶抑制劑(L-methionine sulfoximine,MSX;Glufosinate ammonium)處理WT種子,隨著添加抑制劑濃度的不斷增加,顯著抑制了鹽脅迫WT種子的萌發(fā)。以上的這些研究結(jié)果暗示,通過增強氮素代謝途徑中GS酶的活性,促進NH_4~+的同化來降低植物體內(nèi)NH_4~+的過量積累,從而提高植物在種子萌發(fā)期對鹽脅迫的耐受性,這為提高鹽脅迫下的作物育種提供科學(xué)的理論基礎(chǔ)。
[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.
【學(xué)位授予單位】：東北林業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：Q945.78;Q943.2

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