Effect Of Trehalose On Floret Degradation Of Wheat Under Low Temperature Stress At Booting Stage

The grain number of spikes is decided by floret development and fruiting in wheat.The booting period is the key period for the development of floret.At this time,Huanghuai area,the main winter wheat growing regions,is vulnerable to suffering late spring coldness in China,which makes wheat production decrease significantly.As a protective agent,which has received increasing attention,trehalose has been shown to play a beneficial role in plant stress.However,there is not clear that whether trehalose is beneficial to the florets development of wheat under low temperature stress.Based on this,we took “Xinong 979” as plant material,and simulated the late spring coldness artificially at the booting stage,combined with exogenous application of trehalose,to explore the effects of trehalose on wheat floret development under low temperature stress at the booting stage.At the same time,in combination with the metabolome,hormones,and antioxidant enzymes,we investigated the physiological mechanism of that trehalose alleviates the damage of low temperature stress on wheat floret in late spring.The main conclusions are as follows:1.The floret development of wheat was inhibited by low temperature stress significantly.Under low temperature stress condition,the number of wheat spikelets decreased by 38.2%,and the number of fertile florets decreased by 40.0%.The application of trehalose exogenously significantly alleviated the lowering effect of low temperature stress on the number of wheat grain and fertile florets.Exogenous spraying of trehalose significantly increased the number of wheat grain and fertile florets at low temperature stress.Compared with stress treatment,the number of wheat grain and fertile florets in wheat treated with trehalose exogenously increased by 21.8% and 18.2%,respectively.However,exogenously-supplied trehalose had no significant effect on spike length and total floret number.2.Metabolic profile analysis was performed on wheat spikelets treated with normal control,low temperature stress and trehalose sprayed at low temperature condition.302 different metabolites were detected between the control and low temperature stress treated spikelets,175 were down-regulated and 127 were up-regulated.Differential metabolites are mainly concentrated in amino acids and derivatives,phenylpropanoid,nucleotides and derivatives,flavonoids,organic acids and derivatives,lipids and sugars.The main metabolites include sucrose,fructose-6-phosphate,glucose-6-Phosphoric acid,citrate,fumaric acid,cis-aconitic acid,aspartic acid,methionine,glutamic acid,etc.,which are involved in metabolic pathways involved in sugar metabolism,amino acid metabolism and TCA cycles.167 different metabolites were detected between low temperature stress treatment and trehalose sprayed at low temperature condition treatment,96 were down-regulated and 71 were up-regulated.Differential metabolites are mainly concentrated in amino acids and derivatives,phenylpropanoid,nucleotides and derivatives,organic acids and derivatives,lipids and carbohydrates.The main metabolites include cryptochlorogenic acid,isoferulic acid and erucic acid,Kynurenine,glutamic acid,sucrose,threose,etc.,which involved in metabolic pathways such as phenylpropanoid synthesis,amino acid metabolism,and sugar metabolism.Exogenous trehalose mainly improves wheat sugar metabolism,TCA,amino acid and phenylpropanoid metabolic pathways,and improves resistance of wheat spike under low temperature stress by promoting the production of energy metabolism,antioxidant secondary metabolites and amino acids.3.Under low temperature stress condition,the MDA content in the wheat leaves,and stems were increased significantly.In the leaves of wheat,SOD,POD,APX enzyme activities were increased significantly,and CAT enzyme activity were decreased.The activities of SOD,CAT,POD and APX were increased in the stem.In the leaves,the soluble sugar content were increased significantly,and the soluble protein content were decreased.However,the soluble protein content were increased significantly in the stems.The ABA content were increased in the leaves,and the ZR content were decreased.Compared with low temperature stress treatment,exogenous spraying of trehalose reduced the MDA content in wheat leaves and stems under low temperature stress,increased SOD activity and CAT activity in leaves,and inhibited POD activity.The activities of SOD and APX were increased while the activities of CAT and POD were decreased in the stems.The content of soluble sugar and soluble protein were increased in the leaves,while the content of soluble sugar and soluble protein were decreased in the stems.In the leaves,the ABA content were decreased,and the ZR content were increased.Exogenous spraying of trehalose can reduce plant membrane lipid peroxidation damage,regulate antioxidant enzyme activity and osmotic adjustment substances,and hormones,thereby could improve the tolerance of wheat at low temperature at booting stage and reduce the degradation of florets.