本文關鍵詞：西瓜對干旱脅迫的響應機制及叢枝菌根真菌的緩解效應　出處：《西北農(nóng)林科技大學》2016年博士論文　論文類型：學位論文

  更多相關文章： 西瓜 干旱 抗氧化 基因表達譜 叢枝菌根真菌

【摘要】：干旱是影響植物正常生長并減少作物產(chǎn)量的主要非生物脅迫之一。西瓜[Citrullus lanatus(thunb.)Matsum.Nakai.]是一種重要的水果型經(jīng)濟園藝作物,但它既怕澇又怕旱,整個生育期需要大量水分。近年來,頻繁發(fā)生的自然干旱災害嚴重制約了西瓜產(chǎn)業(yè)的發(fā)展。因此,挖掘和利用新的抗旱種質(zhì)資源,深入了解抗性種質(zhì)的抗旱機制對于改良現(xiàn)有栽培西瓜品種的抗旱性具有重要的實際意義。此外,隨著人們節(jié)水理念的不斷提升及發(fā)展有機農(nóng)業(yè)的倡導,利用有益微生物的生態(tài)效應提高作物的抗旱性也將成為未來抗旱節(jié)水栽培的一個重要發(fā)展方向。前人的報道指出,利用叢枝菌根真菌(arbuscular mycorrhiza fungi,AMF)可以提高水分虧缺灌溉條件下西瓜的果實產(chǎn)量和植株的水分利用效率,但對其作用的機理機制還知之甚少。本研究以來源于不同地區(qū)、具有不同生態(tài)類型的12個西瓜基因型為試材,采用盆栽控水的方式進行持續(xù)干旱處理,依據(jù)旱害指數(shù)和隸屬函數(shù)值法對其抗旱性進行了綜合評價。在此基礎之上,進一步比較了兩個具有明顯抗旱性差異的西瓜基因型在干旱及復水條件下的生長、氣孔特征、光合作用、抗氧化酶活性及抗逆相關基因表達的變化情況;同時采用RNA-Seq技術研究了兩者在干旱脅迫下葉片基因的表達譜異同。最后再以敏感西瓜種質(zhì)Y34作為供試材料,以地表球囊霉屬(G.versiforme,GV)作為供試菌種,研究了AMF提高西瓜抗旱性的具體機理機制。主要研究結果如下:(1)干旱處理下,12個西瓜基因型對干旱脅迫的耐受能力存在明顯差異,各基因型開始出現(xiàn)旱害癥狀的時間和發(fā)生旱害的程度各不相同。根據(jù)旱害指數(shù)和隸屬函數(shù)值的統(tǒng)計結果,分析認為3個野生型材料M20、KY-3和Y-2為抗旱性強的西瓜種質(zhì),Y34、金美人和04-1-2為敏感種質(zhì),而其余基因型為中抗種質(zhì)。(2)干旱脅迫下,敏感材料Y34的葉片發(fā)生萎蔫和黃化的時間比抗性材料M20早、程度深,表明Y34受到的傷害效應更大。干旱抑制了兩個西瓜基因型的植株生長,但卻提高了根冠比,M20比Y34的提高幅度大。電鏡觀察結果顯示,M20具有更密的表皮毛密度。干旱條件下,M20能更早地調(diào)控WRKY70-like和MYB96-like基因的表達水平而關閉氣孔,減少蒸騰,從而維持較高的葉片相對含水量。與Y34相比,M20的光系統(tǒng)II效率、初始Rubisco酶活性和葉綠素含量下降程度小,表明M20能更有效地平衡光化學和非光化學的能量分配,從而減輕干旱對光合器官造成傷害。干旱處理下,兩個西瓜基因型的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,抗氧化酶相關編碼基因(除APX外)的表達量也在M20植株中更高。因此,干旱脅迫下,M20葉片的H2O2、O2-和MDA含量增長幅度小。為了適應不斷減少的土壤含水量,M20能積累更多的可溶性糖和脯氨酸含量而提高滲透勢。這些抗旱機制使得M20在復水之后得以更快恢復正常的生理代謝。(3)基因表達譜分析顯示,干旱會引起西瓜植株體內(nèi)的轉錄水平發(fā)生大的變化�？剐圆牧螹20通過上調(diào)相關基因表達水平而更早地啟動抗氧化還原、自我平衡調(diào)節(jié)等抗逆反應,而敏感材料則更早地啟動自噬生物學過程,并在后期大量上調(diào)蛋白水解生物學過程的相關基因。與Y34相比,M20具有更高水平的包括抗壞血酸氧化酶、過氧化物酶等在內(nèi)的抗氧化酶基因、以及部分抗病和抗逆相關基因的基礎表達量。(4)干旱脅迫下,接種AMF處理可以提高西瓜幼苗的葉片相對含水量和葉綠素含量,促進植株的生長,特別是促進根系的生長。干旱使得西瓜葉片的葉綠體超微結構發(fā)生明顯改變并受到一定損傷,接種AMF處理緩解了干旱對葉綠體的傷害效應,同時降低了干旱對Pn,初始Rubisco酶活性,Fv/Fm,ΦPSⅡ,ETR和qP的抑制作用,并進一步提高了植株的瞬時水分利用效率和NPQ值。和非菌根植株相比,干旱條件下接種植株的SOD,CAT,APX,GR和MDHAR酶活性分別提高了23.47%,24.58%,10.28%,69.49%和25.85%,相關基因的表達水平也有所增加。因此,菌根植株MDA、O2-和H2O2的含量較低,而ASA/DHA和GSH/GSSG的比值也維持在相對較高的水平。所有這些綜合效應使AMF最終增強了西瓜幼苗的抗旱性。(5)接種AMF能增加西瓜幼苗根系總表面積、總體積、分叉數(shù)和細小根系的比例,并提高根系活力。干旱脅迫下,西瓜幼苗根系MDA、H2O2和O2-大量積累。接種AMF誘導了根系抗氧化酶活性的提高,維持了抗氧化物質(zhì)含量的正常水平并提高了其還原型和氧化型的比值,進而抑制了ROS的大量產(chǎn)生;同時還促進了根系可溶性糖和脯氨酸含量的積累�？傊�,接種AMF可以通過改善西瓜根系形態(tài)結構、增強根系抗氧化能力和滲透調(diào)節(jié)作用來提高西瓜幼苗對干旱脅迫的抗性。
[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.

【學位授予單位】：西北農(nóng)林科技大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：S651;S423
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本文編號：1424851