The Relationship Between Membrane Lipids Alteration And Drought Adaptation In Leaves Of Maize Seedlings

With the global climate changing,the occurrence frequency of drought has increased,also the impact on crop production of drought is growing more and more severe.On the other hand,the increasing population demands more food production.Therefore,it is of great important to improve drought resistance ability of crops to enhance crop production,and reduce the effect of drought stress on crop production to ensure food security.Plant production arises mainly from photosynthesis,while photosynthesis occurs in the thylakoid membranes in chloroplasts.Previous studies have shown that multiple environment stresses,including drought,can affect the saturation degree and the varieties of membrane lipid fatty acids,and their distribution on bio-membranes,especially on thylakoid membranes.However,it still remains unclear that what the relationship is between membrane lipid alteration and drought resistance,drought recovery during drought period and subsequent re-watering of crops.Therefore,we randomly selected 18 maize cultivars to simulate the process of drought and re-watering,and measured the changes of membrane lipid fatty acid content,relative permeability of membranes,chlorophyll content,chlorophyll fluorescence,MDA content and H₂O₂ content.Through analyzing these physiological traits,we explored their relationship with drought adaptation ability in the process of drought and re-watering,how membrane lipid fatty acids response to drought and re-watering,also to explore its role in drought adaptation.The results are as follows:?1?The drought resistance,drought recovery and drought adaptability of different maize varieties.The biomass of maize decreased under drought stress condition and started to recover after re-watering,however,the degree of decrease and recovery was different among different maize cultivars.Higher drought adaptability of maize may be caused by strong drought resistance,such as Limin33 of the female parent and Xianyu 335varieties,or may also be due to strong recovery capacity caused by re-watering,such as Liangyu 99 male parent,or may be caused by both strong drought resistance and re-waterring,such as P3,B3-1 and Liangyu 66 male parent.Correlation analysis of drought resistance,drought recovery and drought adaptability showed that both drought resistance and drought recovery were positively correlated with drought adaptability,and the correlation coefficient between drought recovery and drought adaptability was greater than that between drought resistance and drought adaptation ability.?2?Effects of drought and re-watering on main physiological traits of different maize cultivars and the relationship between these physiological traits changes and drought resistance,drought recovery and drought adaptation.Drought stress resulted in the decrease of relative water content,chlorophyll content,Fv/Fm and total lipid content of maize,and the increase of H₂O₂ content and MDA accumulation.After the re-watering,these indexes all began to recover,but the degree of recovery varied with the different cultivars.During the drought stress period,the relative water content of leaves,the chlorophyll content,Fv/Fm and total lipid content were positively correlated with drought resistance,MDA and H₂O₂ contents were negatively correlated with drought resistance,while the change of total lipid content in stress period was positively correlated with drought recovery after re-watering,and the relative water content of leaves,the chlorophyll content,Fv/Fm,total lipid content,MDA and H₂O₂ content all had significant correlations with drought adaptability.The recovery degree of the relative water content and C16:3content of the leaves of maize has significant positive correlation with the recovery ability after re-watering of the maize.?3?Relationship between membrane lipid responses and drought adaptability in the process of drought and re-watering.Under the condition of drought stress,the content of saturated fatty acids?C16:0and C18:0?in maize leaves increased,and the degree of increase was different for different cultivars.The content of C16:1,C16:2 and C18:3 showed a downward trend,the C18:1 and C18:2 contents increased,while the trend of C16:3 was related to the variety.Under drought stress,the total lipid content of maize decreased,and the membrane lipid saturation decreased,mainly due to the decrease of C18:3,C16:2 and C16:1 content.It can be concluded that C18:3 was closely related to drought resistance of maize through the alteration of membrane lipid fatty acid composition in the process of drought and re-watering.Drought resistance of maize was more stronger,the decrease degree of C18:3 content was more lower during drought stress.The results of principal component analysis showed that C18:1,C18:2 and C18:3 had a prominent effect on the recovery of maize after drought,compared with other physiological indexes in the process of re-watering.The change of C18:3 content in the fatty acid composition has a more significant effect on the drought resistance and drought recovery during drought and subsequent re-watering condition.To sum up,improving the drought resistance of maize during drought stress,or improving the drought recovery ability of maize after re-watering can both enhance the drought adaptability of maize to drought-rehydration environment.The composition and content of membrane lipids are closely related to the drought resistance,recovery ability and adaptability of drought,and the regulation of membrane lipid content and components is not only an effective regulation way to adapt to environmental stress during drought stress,but also a kind of active regulation mechanism of crop itself during recovery period after re-water.It plays an irreplaceable role in the process of plant drought adaptation and repair after re-waterring.Therefore,the ability to control the synthesis of fatty acids is expected to be an effective way to enhance crop drought resistance.