Genome-wide Association Analysis Was Used To Explore Candidate Genes For Flooding-related Traits At The Seedling Stage Of Maize

Corn is one of the main crops in China,and plays a pivotal role in our daily life.In recent years,with the changing global climate and increasing precipitation in China,maize is often faced with flooding stress during its growth period,resulting in a reduction in yield.As an important cash crop in China,maize has been greatly affected.Therefore,cultivating waterlogging tolerant maize varieties and studying the mechanism of waterlogging tolerance in maize have an important role in improving the impact of current extreme weather.Based on the simplified genome sequencing of 329 maize inbred lines using natural populations of maize as materials,this study used GWAS method to conduct correlation analysis on six maize waterlogging tolerance correlations to explore the basis of maize waterlogging tolerance.The main results are as follows:1.In this study,we collected phenotypic data from 329 natural population maize inbred lines after 7 days of flooding treatment at the three leaf and one heart stage to analyze their waterlogging tolerance.We found that there were significant differences in phenotypes among different maize varieties after being subjected to flooding stress.The SPAD value,plant height,root length,aboveground dry weight,underground dry weight,and total dry weight of the flooded group decreased compared to the control group after 7 days,indicating that flooding stress has a significant impact on the growth of maize inbred lines.Based on 306 valid data obtained,the waterlogging resistance coefficient of 6 traits was calculated,and the average of 6 traits was calculated as the basis for germplasm selection.It was found that 10 inbred lines had a flooding resistance rate of<10%,which was defined as having a strong flooding resistance;There are 6 inbred lines with a flooding resistance rate between 0-20%,defined as having strong flooding resistance;There are 14 inbred lines with a flooding resistance rate between 20-40%,which is defined as having strong flooding resistance;There are 57 inbred lines with a flooding resistance rate between 40-60%,which is defined as medium flooding resistance;There are 90 inbred lines with a flooding resistance rate between 60% and 80%,which is defined as being sensitive to flooding;There are 57 inbred lines with a flooding resistance rate between 80-100%,which is defined as being sensitive to flooding;There are 72 inbred lines with a flooding resistance rate>100%,which is defined as extremely sensitive to flooding.2.Population structure analysis of 329 natural population maize materials showed that the materials could be divided into 12 subgroups,indicating that the materials had genetic diversity and were suitable for association analysis.Genome wide association analysis was conducted using Farm CPU model for six traits,and a total of 49 significant loci related to SPAD value,plant height,root length,aboveground dry weight,underground dry weight,and total dry weight were detected.There are 16 significant bits associated with SPAD values;There are 9 significant loci associated with maize plant height(PH);There are 5 significant loci associated with root length(RL)in maize;There are 5 significant loci associated with maize shoot dry weight(SDW);There were 8 significant loci associated with dry weight(RDW)in maize underground;There are 6 significant loci associated with total dry weight(RDW)in maize.3.The obvious sites found in the roots found 18 genes related to 6 traits,and there were 7 genes related to SPAD.ZM00001D028001 and ZM00001D028000 are homologous relationships,and their functions are related to the function of chloroplasts;genes ZM00001D028974 have a high amount of expression on the tip of the leaf,which can reduce the sensitivity of plants to ethylene.ZM00001D034962 genes can encode protein-related proteins related to chloroplasts in Arabilia.The ZM00001D014294 gene can encode a acetyl acelase A carboxylase,which has a very important role in the photosynthesis of corn;there are 4 genes related to plant height.ZM00001D028915 gene can encode chloroplastin.ZM00001D039002 and ZM00001D039003,the two have similar functions,can encode the protein of flowering plant RL2 gene domains to maintain the nutrition of plants;there are 3 genes related to root length.ZM00001D006310 gene can encode a Nudix hydrolyzed enzyme.The ZM00001D006311 gene is mainly expressed in the root system,but the specific function has not yet been studied;the above-ground dry weight has not tapped significant related genes;there are 2 genes related to the underground dry weight.The ZM00001D044084 gene is a predecessor research is a gene related to the synthesis of L-Arabic sugar biology;one gene related to the total dry weight is in total.The ZM00001D042932 gene has a high amount of expression in the root system and one-leaf period.According to predecessors,the gene can encode the FLC upstream protein,and there is a high expression in a low temperature environment.To sum up,this study used genome-wide association analysis of the correlation between maize waterlogging tolerance and the genotypes of natural populations to identify a number of candidate genes related to waterlogging tolerance,providing theoretical basis for the study of the genetic mechanism of maize waterlogging tolerance and the selection of waterlogging tolerant varieties.