Effects Of Temperature Regulation In Late Winter And Early Spring On Physiological And Biochemical Characteristics And Proteome Effects Of Winter Wheat Flag Leaves

The North China Plain is an important winter wheat growing area in China.However,due to the rapid warming in spring,the development time of wheat ear is shortened,resulting in a decrease in the number of grains per spike.The high temperature during the filling stage and the dry hot air in the later stage of growth make the filling time shorter,resulting in a decrease in grain weight.Directly caused a significant drop in production.In view of the contradiction between the optimum temperature required for the growth and development of winter wheat in the North China Plain and the actual temperature of the environment,this study used’Hengguan 35’as the experimental material.Under the field test conditions,the greenhouse was set up in late winter and early spring to study the temperature rise before the jointing stage.After the jointing,the physiological and biochemical characteristics of the flag leaf senescence of winter wheat were observed by using the relative cooling of the plastic film,and the protein changes in the flag leaf of wheat were analyzed by iTRAQ proteomics technique.The purpose of this study was to explore the regulation effect of stage warming on the senescence of wheat flag leaves.The molecular mechanism of heat stress induced premature senescence of wheat flag leaves was further elucidated,which provided a theoretical basis for the study of heat tolerance and senescence regulation of winter wheat.The results show:1.Effects of Temperature Increase in Late Winter and Early Spring on Growth Process,Water Use Efficiency and Yield of Winter WheatThe increase of temperature in late winter and early spring caused the growth process of wheat to be different.The warming treatment was 7-8 days earlier than the control flowering,and the maturity was 3 to 4 days earlier,which prolonged the grain filling time of wheat;the flag leaf area increased during flowering.27%,the dry matter quality increased by 17.3%,which provided a material basis for grouting.Grain yield increased by22.8%at harvest,dry matter quality increased by 19.0%,and water use efficiency increased by 15.2%.The warming of early winter and early spring increased the accumulation of dry matter and prolonged the filling time of wheat,alleviated the harm of“cold spring”to wheat and evaded the influence of“dry hot wind”on wheat in late growth stage,and obtained high yield.With the advancement of warming time and the increase of coverage time,the accumulation of dry matter increased significantly,the number of grouting days was significantly prolonged,and the yield and water use efficiency were significantly improved.2.Effects of Temperature Increase in Late Winter and Early Spring on Physiological Activity and Photosynthetic Characteristics of Winter Wheat Flag LeavesThe winter wheat in the pre-jointing stage and the relative cooling of the winter wheat were increased by 24.9%,the chlorophyll relative SPAD increased by 13.3%,and the superoxide dismutase（SOD）activity increased by 17%.Hydrogenase（CAT）activity increased by 17%,peroxidase（POD）activity increased by 14.2%,and membrane lipid peroxidation product malondialdehyde（MDA）content decreased by 22.7%,thereby significantly maintaining high photosynthesis in flag leaves.And delayed the aging of flag leaves.In this study,the post-anthesis temperature was significantly negatively correlated with the net photosynthetic rate（P_n）and stomatal conductance（G_s）of flag leaves,and was significantly positively correlated with the CO₂ concentration（C_i）of flag leaves.The decrease of net photosynthetic rate（P_n）and leaf stomatal conductance（G_s）of flag leaves increased,and the intercellular CO₂ concentration（C_i）decreased significantly.This indicates that the increase of net photosynthetic rate（P_n）of flag leaves is mainly due to non-stomatal factors.This may be related to the degree of damage to the photosynthetic system and the degree of chlorophyll attenuation.3.Effect of Temperature Increase in Late Winter and Early Spring on Flag Leaf ProteomeUsing the untreated winter wheat as the control,the iTRAQ technique was used to analyze the differentially proteomic analysis of the flag leaves of the winter wheat with the same growth period in the late winter and early spring,and 323 differentially expressed proteins were identified.Up 194,down 129.GO biological process and KEGG metabolic pathway enrichment analysis found that differential proteins are mainly involved in carbohydrate metabolism process,protein metabolism activity,stress response,redox regulation,senescence regulation process,and photosynthesis related processes.In the early winter and early spring,the warming process advances the growth process of winter wheat.After the film is uncovered,the winter wheat is properly cold acclimated,which increases the expression of cold response protein,which enhances the heat resistance of flag leaves,reduces the accumulation of ABA,and delays.The flag leaves are aging.Moreover,it effectively relieves heat stress during flowering and filling,and reduces the formation of ROS and the secretion of senescence-related proteases,effectively alleviating the senescence of flag leaves and prolonging the functional period of flag leaves.The study also found that heat stress caused wheat flag leaf gluconeogenesis to be inhibited,and saccharide synthesis was blocked;TCA cycle enhanced and oxidative phosphorylation accelerated,cells maintained at higher energy levels,and due to the destruction of complex III It also caused ROS oxidative stress;the decomposition of cell wall and polysaccharide resulted in the destruction of the inherent morphology of organs and plants;the decrease of membrane fatty acids decreased,impaired membrane fluidity and permeability;accelerated amino acid metabolism,nitrogen utilization efficiency Reduced;in the process of protein synthesis,not only is inhibited at the initial stage of translation but also inhibited during the extension and termination stages.Although protein synthesis is blocked,some molecular chaperones accumulate significantly,which in turn enhances protein folding and modification.Refolding the protein,although the molecular chaperone helps the protein to fold and modify correctly and restore the correct conformation to a certain extent,the heat stress also causes a large number of irreversible misfolding and accumulation and decomposition of the modified protein,which leads to premature aging of the flag leaf;In the system,although the light-trapping protein is enhanced,due to P SII is destroyed and the main enzymes in carbon fixation are inhibited,which leads to the inhibition of LEF,which leads to weakened photosynthesis,hindered synthesis of organic matter,and accelerates ROS production.In terms of stress response,flag leaves repair misfolded proteins by overexpressing molecular chaperones.The ROS clearance was enhanced by over-expressing 2-Cys Prxs and GR,and the damage of aldehydes caused by ROS to flag leaves was alleviated by over-expressing ALDH.