GWAS Of Husk Tightness And Its Relationship With Ear Water Content At Harvest Stage In Maize

Maize is an important crop in the national economic system.In recent years,the planting area of maize has been increasing,labor input has been increasing too.Therefore,the whole mechanization of maize is the trend of development in the future.The ear of maize mechanically harvested should have low water content,and ear water content(EWC)in mature periodis influenced by physiological and physical characters of husk,but the genetic basis of the characters is not clear.Therefore,the breeding process of low water content maize hybrid in harvest stage is postponed.Husk is a metamorphic leaf wrapped around the outer ear of maize.It affects the ear water content through physiological mechanism,such as aging and physical mechanism,such as tightness.However,there is no report on the contribution rate and genetic basis of husk tightness(HT)to the dehydration of ears at maturity.Therefore,the relationship between the husk tightness(HT)and the ear water content(EWC)in the harvest period of maize was analyzed,and the candidate genes regulating the husk tightness were predicted by Genome-wide Association Study,and the theoretical reference for selecting the fine husk traits and selecting the new germplasm suitable for the harvest was provided.1.Experiment investigate husk tightness and ear water content phenotypic date of the planted 2 repeat association populations for maize inbred lines in Liaoning,association populations HT is ranged from 2.50-16.88,EWC ranged from 8.00-92.00,The variation of two characters conforms to the normal distribution law,belong to quantitative traits,suitable for further analysis;the HT mean value is 6.56,the standard deviation is 2.09,the number in the interval of 5.625-6.25 is most,number is 45;EWC mean value is 34.56,the standard deviation is 14.34,the number in the interval of 24-28 is most,number is 41.Pearson correlation analysis found that husk tightness and ear water content is significant negative correlation at 0.05 unilateral levels.The results show that the husk more tight in the maize harvest period,the higher ear water content,the husk more looser,the lower ear water content.2.Association population phenotypic variation of HT is rich and conforming to normal distribution.Remove the influence of kinship and population structure,start the GWAS analysis.Detected a total of 27 independent SNP loci associated with HT,gene scans all significantly related to SNP loci within ±50kb,scaned a total of 139 encoding protein gene(Appendix),among them,2015 HN detected 62 genes on the 1,2,3,4,5,6 and 9 chromosomes;2016HN detected 7 genes in 1 and 5 chromosomes;2016LN detected 55 genes in 1,2,4,6,7,8,10 chromosomes;HN&LN detected 15 genes in 2,4,8 chromosomes.The most genes is 30 on the second chromosome.In the detected genes,GRMZM2G040095 has been proved to be highly expressed in maize husk,it may be specific to play a key regulatory role in husk.Contrastive query by maize GDB,select 40 gene as candidate gene,and is divided into 6 function types,of which metabolic pathway is 12(30%),transcriptional regulatory pathway is 11(27%),signal transduction pathway is 6(15%),cellular transport pathway is 5(13%),secretory pathway is 2(5%),multifunction gene is 4(10%).