The Mechanism Study Of Pollination Methods On Seed Vigor Of Different Parts Of The Ear On Maize

Seed is the core of agricultural production.Seed vigor is a complex characteristic of the field performane.High vigor seeds show strong resistance and germinate fast and regularly.So it plays an important role in agricultural production.There is significant difference about seed vigor among the seed from different maize ear.However,the mechanism for the seed vigor difference was still unclear.In this study,we used two methods of pollination,one was repeated pollination during spinning,another was single pollination after spined.To clear the mechanism of seed vigor difference at different positions of ear in maize,we detected the seed vigor,hundred-grain weight,endogenous hormone ABA and GA₄ content and RNA-seq and qPCR analysis was studied in seeds at different positions of ear.The main results are as following:1.The seed vigor were different among the seed at different parts of the ear.The middle part's seed vigor were higher than bottom parrt's,what's more,the top part's seed vigor were lowest.The weight of plant after budded result in the significant difference in middle part's and bottom parrt's seed during seed vigor analysis relate to top part's seed.Single pollination and repeated pollination shared the same pattern about seed vigor at different positions of ear.However,the difference of seed vigor among different positions of ear were decreased in single pollination ear.Hundred-grain weight were highest in bottom part's seeds and lowest in top part's seeds.Hundred-grain weight had no effect on seed vigor.2.The ABA and GA₄ content in embryo among different part's of ear were significant different,however,there were no different in endosperm.ABA content in embryo from middle part's were less than bottom part's.GA₄ content in embryo were highest in bottom part's and lowest in top part's.The value of ABA/GA₄ in embryo from top part's of ear were highest and were significant different relate to middle and bottom part's.Single pollination and repeated pollination shared the same pattern about ABA/GA₄ value in embryo.However,the difference of ABA/GA₄ value among different positions of ear were decreased in single pollination ear.3.The transcriptome analysis consisted of four combinations: MvsT,CK_MvsCK_T,BvsT and CK_BvsCK_T?Repeated pollination was marked as CK,T was the top part of the ear,M was the middle part of the ear,B was the bottom part of the ear?.Organonitrogen compound metabolic process had the most different expression genes between GO_biological processes which was related to metabolism in different combinations,and the gene expression related to protein synthesis in the middle and bottom seeds of the ear was significantly higher than that of the top seed,the difference of seed vigor was related to the nitrogen metabolism pathway.The middle and bottom seed compared to the top seed,the same different expression gene which was related to antioxidant enzymes was up-regulated,and the gene related to chromatin condensation and histone was down-regulated,the difference of seed vigor was related to antioxidant stress and chromatin condensation.The same GO_terms in different combinations of repeated pollination were mostly related to the response to oxygen levels and chromatin assembly or disassembly;The same GO_terms in different combinations of once pollination were focused on the amino acid metabolic process and carbohydrate metabolic process.