西瓜对干旱胁迫的响应机制及丛枝菌根真菌的缓解效应

发布时间：2018-01-14 18:44

  本文关键词：西瓜对干旱胁迫的响应机制及丛枝菌根真菌的缓解效应　出处：《西北农林科技大学》2016年博士论文　论文类型：学位论文

  更多相关文章： 西瓜 干旱 抗氧化 基因表达谱 丛枝菌根真菌

【摘要】：干旱是影响植物正常生长并减少作物产量的主要非生物胁迫之一。西瓜[Citrullus lanatus(thunb.)Matsum.Nakai.]是一种重要的水果型经济园艺作物,但它既怕涝又怕旱,整个生育期需要大量水分。近年来,频繁发生的自然干旱灾害严重制约了西瓜产业的发展。因此,挖掘和利用新的抗旱种质资源,深入了解抗性种质的抗旱机制对于改良现有栽培西瓜品种的抗旱性具有重要的实际意义。此外,随着人们节水理念的不断提升及发展有机农业的倡导,利用有益微生物的生态效应提高作物的抗旱性也将成为未来抗旱节水栽培的一个重要发展方向。前人的报道指出,利用丛枝菌根真菌(arbuscular mycorrhiza fungi,AMF)可以提高水分亏缺灌溉条件下西瓜的果实产量和植株的水分利用效率,但对其作用的机理机制还知之甚少。本研究以来源于不同地区、具有不同生态类型的12个西瓜基因型为试材,采用盆栽控水的方式进行持续干旱处理,依据旱害指数和隶属函数值法对其抗旱性进行了综合评价。在此基础之上,进一步比较了两个具有明显抗旱性差异的西瓜基因型在干旱及复水条件下的生长、气孔特征、光合作用、抗氧化酶活性及抗逆相关基因表达的变化情况;同时采用RNA-Seq技术研究了两者在干旱胁迫下叶片基因的表达谱异同。最后再以敏感西瓜种质Y34作为供试材料,以地表球囊霉属(G.versiforme,GV)作为供试菌种,研究了AMF提高西瓜抗旱性的具体机理机制。主要研究结果如下:(1)干旱处理下,12个西瓜基因型对干旱胁迫的耐受能力存在明显差异,各基因型开始出现旱害症状的时间和发生旱害的程度各不相同。根据旱害指数和隶属函数值的统计结果,分析认为3个野生型材料M20、KY-3和Y-2为抗旱性强的西瓜种质,Y34、金美人和04-1-2为敏感种质,而其余基因型为中抗种质。(2)干旱胁迫下,敏感材料Y34的叶片发生萎蔫和黄化的时间比抗性材料M20早、程度深,表明Y34受到的伤害效应更大。干旱抑制了两个西瓜基因型的植株生长,但却提高了根冠比,M20比Y34的提高幅度大。电镜观察结果显示,M20具有更密的表皮毛密度。干旱条件下,M20能更早地调控WRKY70-like和MYB96-like基因的表达水平而关闭气孔,减少蒸腾,从而维持较高的叶片相对含水量。与Y34相比,M20的光系统II效率、初始Rubisco酶活性和叶绿素含量下降程度小,表明M20能更有效地平衡光化学和非光化学的能量分配,从而减轻干旱对光合器官造成伤害。干旱处理下,两个西瓜基因型的SOD,CAT,APX和GR酶活性都有所增加,但M20比Y34的提高程度大;此外,抗氧化酶相关编码基因(除APX外)的表达量也在M20植株中更高。因此,干旱胁迫下,M20叶片的H2O2、O2-和MDA含量增长幅度小。为了适应不断减少的土壤含水量,M20能积累更多的可溶性糖和脯氨酸含量而提高渗透势。这些抗旱机制使得M20在复水之后得以更快恢复正常的生理代谢。(3)基因表达谱分析显示,干旱会引起西瓜植株体内的转录水平发生大的变化。抗性材料M20通过上调相关基因表达水平而更早地启动抗氧化还原、自我平衡调节等抗逆反应,而敏感材料则更早地启动自噬生物学过程,并在后期大量上调蛋白水解生物学过程的相关基因。与Y34相比,M20具有更高水平的包括抗坏血酸氧化酶、过氧化物酶等在内的抗氧化酶基因、以及部分抗病和抗逆相关基因的基础表达量。(4)干旱胁迫下,接种AMF处理可以提高西瓜幼苗的叶片相对含水量和叶绿素含量,促进植株的生长,特别是促进根系的生长。干旱使得西瓜叶片的叶绿体超微结构发生明显改变并受到一定损伤,接种AMF处理缓解了干旱对叶绿体的伤害效应,同时降低了干旱对Pn,初始Rubisco酶活性,Fv/Fm,ΦPSⅡ,ETR和qP的抑制作用,并进一步提高了植株的瞬时水分利用效率和NPQ值。和非菌根植株相比,干旱条件下接种植株的SOD,CAT,APX,GR和MDHAR酶活性分别提高了23.47%,24.58%,10.28%,69.49%和25.85%,相关基因的表达水平也有所增加。因此,菌根植株MDA、O2-和H2O2的含量较低,而ASA/DHA和GSH/GSSG的比值也维持在相对较高的水平。所有这些综合效应使AMF最终增强了西瓜幼苗的抗旱性。(5)接种AMF能增加西瓜幼苗根系总表面积、总体积、分叉数和细小根系的比例,并提高根系活力。干旱胁迫下,西瓜幼苗根系MDA、H2O2和O2-大量积累。接种AMF诱导了根系抗氧化酶活性的提高,维持了抗氧化物质含量的正常水平并提高了其还原型和氧化型的比值,进而抑制了ROS的大量产生;同时还促进了根系可溶性糖和脯氨酸含量的积累。总之,接种AMF可以通过改善西瓜根系形态结构、增强根系抗氧化能力和渗透调节作用来提高西瓜幼苗对干旱胁迫的抗性。
[Abstract]:Drought is the normal growth of plants and reduce the major abiotic stress in crop production of watermelon. [Citrullus Lanatus (thunb.) Matsum.Nakai.] is an important economic fruit horticultural crops, but it is also afraid of drought and waterlogging, during the whole growth period, need a lot of water. In recent years, the frequent occurrence of natural disasters of drought has seriously hampered the development of watermelon industry. Therefore, mining and utilization of germplasm resources of new drought resistant, drought resistant germplasm understanding mechanism has important practical significance for improving drought resistance of existing cultivated Watermelon Cultivars. In addition, with the improvement of people's water-saving ideas and developing organic agriculture advocacy, improve crop drought resistance using the ecological effects of beneficial microorganisms it will become an important future direction of development of drought resistance and water saving cultivation. The previous reports pointed out that the use of arbuscular mycorrhizal fungi (arbuscular mycorrhiza, f Ungi, AMF) can watermelon fruit yield and plant water use efficiency of water deficit irrigation condition, but the mechanism of its action is still poorly understood. This study originated from different regions, 12 watermelon genotypes with different ecological types as test materials, continuous drought treatment with pot culture the way on the basis of drought index and subordinate function value method to the comprehensive evaluation of drought resistance. On this basis, a further comparison of the two has obvious drought resistance of Different Watermelon genotypes under the condition of water in drought and growth, stomatal characteristics, photosynthesis, antioxidant enzyme activity and changes of resistance related gene expression the similarities and differences; and RNA-Seq technique was used to study the expression of stress genes in leaves of both drought spectrum. Then the sensitivity of Watermelon Germplasm Y34 as tested materials, on the surface of glomus (G.versifo RME, GV) as tested strains, the specific mechanism of AMF on improving drought resistance of watermelon. The main results are as follows: (1) under drought treatment, 12 watermelon genotypes have obvious difference on drought tolerance, each genotype appeared drought symptoms and occurrence time of drought degree different. According to the statistical results of drought index and the value of membership function, analysis of 3 wild type materials M20, KY-3 and Y-2 for the drought resistance of watermelon germplasm, Y34, and 04-1-2 for gold beauty sensitive germplasm, while the remaining genotypes resistant germplasm. (2) under drought stress, leaf sensitivity the occurrence of Y34 material wilting and yellowing resistance than material M20 early, deep level, indicate the damage effect of Y34 was greater. Drought inhibited the two watermelon genotypes of plant growth, but increased the ratio of root to shoot, M20 than the Y34 increase. Electron microscope results showed that M 20 has a fur density meter density. Under drought conditions, the expression level of M20 can earlier regulation of WRKY70-like and MYB96-like genes and stomatal closure, reduce transpiration, so as to maintain a relatively high water content in leaves. Compared with Y34, the II efficiency of the optical system of M20, the initial Rubisco enzyme activity and chlorophyll content decreased. Results show that M20 can effectively balance the photochemical and non photochemical energy distribution, so as to alleviate the drought on photosynthetic organ damage. Under drought treatment, two watermelon genotypes SOD, CAT, APX and GR activity were increased, but the ratio of M20 to improve the degree of Y34; in addition, antioxidant enzyme related genes encoding (except APX) the expression of M20 in higher plants. Therefore, under drought stress, M20 leaf H2O2, O2- and MDA content increase. In order to adapt to the continuous decrease of soil moisture, M20 can accumulate more proline and soluble sugar Increased acid content of osmotic potential. The drought resistance mechanism makes the M20 to restore the normal physiological metabolism faster in water. (3) gene expression profiling revealed that the drought will cause the transcription level of watermelon plant change. Resistant materials M20 level earlier start by upregulating the expression of genes related to anti-oxidation, self balanced regulation resistance response, and sensitive material is earlier start autophagy related genes in the biological process, and the hydrolysis of up-regulated protein biological processes. Compared with Y34, M20 has higher levels including ascorbic acid oxidase, peroxidase and other antioxidant enzyme gene expression, as well as a fundamental part of disease resistance and resistance related genes the amount. (4) under drought stress, AMF inoculation treatment can improve watermelon seedlings relative water content and chlorophyll content, promote plant growth, especially Is to promote the growth of roots. The drought caused the chloroplast ultrastructure of Watermelon Leaves changed obviously and suffered some damage, alleviate the damage effect of AMF inoculation treatment of drought on chloroplasts, while reducing drought on Pn, Rubisco enzyme activity, initial Fv/Fm, PS II, inhibition of ETR and qP, and further improve the instantaneous plant water use efficiency and NPQ value. Compared with non mycorrhizal plants, SOD, inoculated plants under drought conditions CAT, APX, GR and MDHAR activity were increased by 23.47%, 24.58%, 10.28%, 69.49% and 25.85%, the related gene expression level also increased. Therefore, the contents of O2- and MDA mycorrhizal plants. H2O2 is low, and the ratio of ASA/DHA and GSH/GSSG are also maintained at a relatively high level. All of these make the comprehensive effect of AMF eventually enhance drought resistance of watermelon seedlings. (5) AMF inoculation can increase watermelon seedling root system surface area, total volume, Branch number and fine root proportion, and increased root vigor. Under drought stress, watermelon seedling root MDA, accumulation of H2O2 and O2-. AMF inoculation induced antioxidant enzyme activity in root increased, maintain the normal level of antioxidant content and improve the ratio of reduced and oxidized, thereby inhibiting produced ROS; at the same time also promoted the root soluble sugar and proline accumulation. In conclusion, AMF inoculation can improve the morphological structure of watermelon root, enhance the antioxidant capacity of the root system and the role of osmotic adjustment to improve watermelon seedlings on dry resistance to drought stress.

【学位授予单位】：西北农林科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S651;S423
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本文编号：1424851