| Maize,as an important crop which integrates food crops,energy and feed crops,plays an unparalleled role in the modern industrial system.Maize is threatened by a variety of natural disasters.Drought,as a common abiotic stress,bears the brunt.Drought during grain filling stage is especially fatal for maize.Inadequate filling will directly lead to production reduction.With the progress of science and technology,the research of maize has been deepened from physical and chemical experiments to molecular level.However,previous pot experiments at seedling stage could not fully reveal the molecular mechanism of maize drought resistance.Two maize cultivars with different drought resistance were prepared as experimental materials.During the period from field cultivation to grain filling,drought and water control treatments were conducted respectively.After the treatment,all the plants showed different degrees of wilting,and the plant height was significantly different.Compared with water control,5769 genes were up-regulated and 7352 genes were down regulated in the drought tolerant cultivar Nong Dan 476;7255 genes were up-regulated and 5877 genes were down-regulated in Zhong Xin 978,a drought intolerant cultivar.Among the up-regulated genes specifically expressed in drought resistant materials,genes related to nitrogen metabolism and biosynthesis were widely enriched;in the down regulated part,genes related to protein phosphorylation and phospholipid signaling pathway were widely enriched.Three important gene sets with biological significance were screened by Venn diagram,among which 1305 DEGs were included in the set of drought resistance differences among cultivars.These 1305 genes accounted for 29.36%of the total SD_TD gene set,which may be the reason for the significant difference of drought resistance between sensitive cultivar and tolerant cultivar.Key genes such as malate dehydrogenase,o-glycohydrolase,plant hormones and organic acid metabolism are widely enriched.Among these 1305 DEGs,77 DEGs encoded transcription factors,corresponding to 256 transcripts,of which 137 were down regulated and 119 were up-regulated.The main TF families include AP2/ERF,Hb and myb_Related,NAC and bHLH correspond to 42 DEGs,accounting for 54.55%of the total.Different from the overall down-regulation trend,there was no obvious up-regulation or down-regulation trend of DEGs encoding TFs.KEGG enrichment analysis showed that among 1305 DEGs,52 DEGs were annotated in the second level of glucose metabolism.In addition,there are amino acid metabolism(29),lipid metabolism(23),energy metabolism(22),and biosynthesis of other secondary metabolites(21).Based on the above results,we draw the following conclusions:Drought resistance of maize is related to the regulation and expression of key genes such as biosynthesis related genes,nitrogen metabolism process,phospholipid signaling pathway,MYB,AP2/ERF,Hb transcription factor,malate dehydrogenase,o-glycosylhydrolase,plant hormones and organic acid metabolism.These studies further analyzed the molecular regulatory network of drought resistance in maize,and provided alternative resources and theoretical basis for the follow-up study of gene function,making our experiment closer to production practice. |
