Study On The Mechanism Of Waterlogging Tolerance Of Different Wheat Varieties At Flowering Stage

As one of the main wheat regions in China,Jianghan Plain is prone to suffer excessive rain and soil waterlogging in the middle and later period of wheat growth,which seriously affects the yield and quality of wheat.In order to explore the regulation mechanism and difference mechanism of waterlogging at anthesi on the yield and quality formation of different wheat varieties in Jianghan Plain,and having further research on the physiological and ecological mechanism of wheat yield formation in the middle and lower reaches of the Yangtze River,to further clarify the waterlogging resistance mechanism and the way of waterlogging resistance cultivation of wheat following rice in Hubei Province,which has important practical significance to improve the wheat yield and achieve effective and stable yield of wheat in Jianghan Plain.Based on the basis of previous studies and the actual situation of Jianghan Plain,the experiment was set up in the field and pot experiment for 2 years.The effects of waterlogging stress on yield,flag leaf SPAD value,chlorophyll fluorescence characteristics and protein metabolomics in flag leaves of wheat varieties with different sensitivity were studied by determination of physiological parameters and IEF/SDS-PAGE two-dimensional gel electrophoresis combined with subsequent mass spectrometry.To explore the regulatory effect and mechanism of waterlogging at anthesis on wheat yield and quality formation and the mechanism of different in waterlogging tolerance of different varieties at the molecular level,laying a theoretical foundation and technical support for the optimal cultivation of wheat stress resistance.In this study,six wheat varieties,Jingmai102(JM102),Xiangmai55(XM55),Zhengmai9023(ZM9023),Chuanmai104(CM104),Nongda195(ND195)and Yangmai158(YM158),were selected to be waterlogged for 7 days at anthesis through pot experiments in 2016-2018 and field experiments in 2017-2019.The effects of waterlogging at anthesis on SPAD value of flag leaf,chlorophyll fluorescence characteristics,grain filling rate,dry matter accumulation,dry matter transport,yield and yield components and proteomics of wheat varieties with different waterlogging tolerance were studied,by studying on the mechanism of influence in the flag leaf SPAD value,chlorophyll fluorescence characteristics,biomass,yield and yield components and proteomics of flag leaf,and so on.And the main results are as follows:1 The difference of physiological mechanism of waterlogging in different wheat varieties at anthesisThe SPAD values of flag leaves of six wheat varieties under waterlogging and control were measured by using SPAD-502 instrument at booting stage,anthesis,7days,14 days after anthesis to maturity,respectively.As for the CK,different wheat varieties had different SPAD values,and their SPAD values increased first and then decreased from booting to maturity,reaching the maximum value around 7 DAA.Waterlogging for 7 days at anthesis,the SPAD value of flag leaves of all varieties increased slowly and then decreased continuously,and the decreasing range increased with the development of growth period,among which YM158 and ND195 were more affected by water stress,JM102 and XM55 were least affected.The photochemical efficiency(Fv/Fm),potential PS ? activity(Fv/Fo),electron transport on PSII(Fm/Fo)and heat dissipation quantum ratio(Fo/Fm)of flag leaves in JM102 and YM158 under waterlogging and control were measured by MINI-PAM-II at 1d,3d,7d and 10 d after anthesis,respectively.Among them,Fv/Fm,Fv/Fo and Fm/Fo increased slowly at 3 days of waterlogging after anthesis,and then decreased gradually,which indicated that the wheat was inhibited by light under waterlogging condition.And YM158 was more sensitive to water stress than JM102.Water content of various organs and yellow leaf ratio of upper three leaves of different wheat varieties were measured under waterlogging at anthesis.Under waterlogging conditions,the water content of leaves was the first and most affected part.As for the water content of spike,stem and sheath,they decreased gradually,and the trend of change is similar to that of leaves,but the effect of decrease was not significant.The variation range of water content of overground and the water content of each organ in different wheat varieties is different under waterlogging condition.From the yellow leaf rate of each variety in 5 and 7 days of waterlogging after anthesis,waterlogging treatment will make the leaves wither and yellow prematurely.The leaf yellow rate of YM158 was the highest and the range of change is the largest in the two-year waterlogging experiment in pot,indicating that the leaves of YM158 were most affected by water stress.According to the dynamic changes of grain filling of different wheat varieties under waterlogging conditions,the speed of grain filling increased first and then decreased with the change of time after anthesis,and reached the maximum value around 14-20 days after anthesis.After waterlogging treatment after anthesis,there were significant differences in single grain weight and filling speed of different wheat varieties between WL and CK under waterlogging treatment at anthesis.From the accumulation and transportation of dry matter after anthesis of six wheatvarieties treated by waterlogging at anthesis,waterlogging at anthesis significantly affected the accumulation of dry matter after anthesis,and reduced the wheat yield,dry matter accumulation in vegetative organs of single stem at maturity and the contribution of dry matter accumulation to grain after anthesis,forcing the contribution of dry matter accumulation before anthesis to the grain improved under waterlogging conditions.Under the condition of waterlogging,the accumulation of dry matter,grain yield and dry matter transport efficiency were all affected by different degrees,due to the different wheat varieties showing different tolerance to water stress.JM102 and XM55 showed better resistance to water stress,and YM158 and ND195 showed stronger sensitivity.From the yield and composition of six varieties in maturity under waterlogging,waterlogging treatment made wheat premature senescence,accelerated the process of grain filling,made grain filling insufficient,significantly reduced the 1000 grain weight and the dry matte accumulation of wheat after anthesis,but had little effect on grain number per ear and spike number per mu,and ultimately affected wheat yield and receiving index.The yield and its components of different wheat varieties were affected differently by water stress.The yield of JM102 and XM55 decreased slightly,while that of YM158 and ND195 decreased significantly,showing significant difference to water stress.2 The difference of proteome expression of waterlogging in different wheat varieties at anthesisDifferences in physiological characteristics and yield results of different wheat varieties under waterlogging at anthesis,the i TRAQ-based proteomic strategy was applied to identify waterlogging-responsive proteins in wheat.A total of 7710 proteins were identified in waterlogging tolerant and sensitive wheat varieties XM55 and YM158 at anthesis under waterlogging or not.Sixteen proteins were differentially accumulated between XM55 and YM158 under waterlogging with cultivar specificity.Among them,eleven proteins were up-regulated and five proteins were down-regulated.The up-regulated proteins included Fe-S cluster assembly factor,heat shock cognate 70,GTP-binding protein SAR1A-like,and CBS domain-containing protein.The down-regulated proteins contained photosystem II reaction center protein H,carotenoid 9,10(9',10')-cleavage dioxygenase-like,psb P-like protein 1,and mitochondrial ATPase inhibitor.In addition,nine proteins were responsive to waterlogging with non-cultivar specificity.These proteins included 3-isopropylmalate dehydratase large subunit,solanesyl-diphosphate synthase 2,DEAD-boxATP-dependent RNA helicase 3,and three predicted or uncharacterized proteins.Sixteen out of the twenty-eight selected proteins showed consistent expression patterns between m RNA and protein levels by quantitative real-time PCR.These results provide a basis for the response of wheat to waterlogging stress and contribute to the study of waterlogging resistance of wheat.In summary,waterlogging at anthesis affects the synthesis of wheat chlorophyll,reduces the SPAD value of flag leaf in wheat,affects the chlorophyll fluorescence parameters of wheat,and reduces the yield of wheat.But the response mechanism of different wheat varieties under water stress is different,and the proteome metabolism pathway is different,which ultimately leads to different effects on their physiological basis mechanism.The response to yield is that the yield reduction range is different.