Effect Of Polymine And Ethylene On Grain Filling Of Wheat Inferiors And Its Mechanism

The filling stage of wheat is an important period in grain weight and quality formation.The condition of grain filling is different due to their different positions on the spike: the grain filling of superior grains is good and grain weight is heavier,and the grain filling of inferior grains is poor and grain weight is lighter.Polyamine and ethylene are two important plant growth regulators,which play an important regulatory role on the growth and development of plants.In polyamine and ethylene synthesis,polyamine and ethylene share a common precursor,S-adenosyl-L-methionine(SAM).Therefore,there may be interactions between polyamine and ethylene significantly affecting the grain filling especially inferior grains filling,and affecting directly the wheat yield.However,the effects of polyamine and ethylene as well as their interactions on grain quality and how to regulate wheat grain filling are also lacking.In this study,two wheat cultivars with different grain weight were selected as materials.After anthesis,different plant growth regulators were sprayed to explore the effects of exogenous polyamine(Spd)and ethylene(Eth)on wheat grain quality.Meanwhile,the transcriptome sequencing was conducting on inferior grains of wheat to explore the molecular mechanism of polyamine and ethylene on regulating the grain filling,which will provide the theoretical basis for better regulation of wheat grain filling,improving wheat yield and quality.The results are as follows:1.The exogenous Spd,and ethephon were sprayed on Zhoumai 22 and Xinong 538 after anthesis,and the superior and inferior grains weight,the content of protein components,processing quality indicators and amylose content were determined after harvest.The results show:(1)The exogenous spd promoted superior and inferior grain filling and increased grain weight of wheat,but the effect of spd on superior and inferior grains were different.Spd significantly increased the weight of inferior grains,and the superior grains weight increased but did not reach a significant level.However,the exogenous ethylene significantly inhibited superior and inferior grain filling and reduced grain weight.(2)The spd sprayed at filling stage was beneficial to formation of good grain quality.Ethylene only increased the content of albumin and globulin in grains,which had a negative effect on other indexes and resulted in the deterioration of wheat quality.Therefore,it is possible to improve the quality of wheat to a certain extent by increasing the spd concentration or decreasing the ethylene concentration in wheat grains by chemical regulation.2.Spd and Eth,combined with polyamine inhibitor(MGBG)and ethylene inhibitor(CoCl2 · 6H2O)were sprayed on Zhoumai22,The treatment sprayed with water was used as the control.After twelve days,the inferior grains of each treatment were sequenced.The main results are as follows:(1)Spd regulated inferior grain filling by improving the efficiency of genetic information processing in grains and promoting the synthesis of genetic material such as nucleic acid and protein.While ethylene showed a significant inhibitory effect.(2)Spd improved the antioxidant activity of inferior grains and decreased the stress degree to promote grain filling,but ethylene might induce stress to increase,which resulted in reducing filling intensity and grain weight.In addition,ethylene significantly inhibited starch synthesis and promoted starch hydrolysis,which could result in reducing starch synthesis and accumulation,finally decreasing grain weight.