Screening And Genome-wide Association Analysis Of Waterlogging Tolerance In Sweet Corn At Seedling Stage

With the increasing global climate change,flooding disasters have become the primary issue for agricultural production and global food security.Maize germplasm is rich in resistance to waterlogging,and excavating excellent waterlogging resistance genes in waterlogging resistant varieties,with played an important role in studying the corn's waterlogging resistance mechanism and cultivating new varieties.In this study,135 inbred lines were used to identify the waterlogging resistance at seedling stage,and the physiological and biochemical effects of waterlogging stress on two inbred lines(K85 and K61)with significant differences in waterlogging resistance were analyzed.The method was used to perform genome-wide association analysis on the traits related to waterlogging resistance of seven maize seedlings at the seedling stage,and the genetic locus controlling the waterlogging resistance was identified.The main results are as follows:1.Seedlings of 135 inbred lines were seedling-tolerant with phenotypes such as stem length,root length,stem fresh weight,root fresh weight,stem weight,root dry weight,total dry weight and leaf greenness.Sexuality was identified and it was found that there were significant differences in response to waterlogging stress in different inbred lines.Using the above phenotypes,135 inbred lines were evaluated and 6 stain resistant materials such as K11,K28,K46,K105,K85,and 3 water sensitive materials such as K18,K61,and K119 were selected.2.The most sensitive material K85 and the most sensitive material K61 physiological indexes were detected.It was found that 4 days after waterlogging treatment,the POD and SOD enzyme activity of the inbred line K85 reached the maximum,while the POD and SOD enzyme activity of the inbred line material K61 root POD and SOD enzyme activity decreased obviously,and the root enzyme activity began to increase after the waterlogging reached 8.It is further verified that K85 is a waterlogging inbred line while K61 is a sensitive inbred line.3.Phenotypic identification of 135 inbred lines in two different environments to obtain the stain tolerance coefficients of 7 traits(seed height tolerance,root length tolerance,stem fresh weight tolerance,root fresh weight Waterlogging resistance index,stem weight tolerance coefficient,root dry weight tolerance coefficient,and total dry weight tolerance coefficient).Using genome-wide association analysis,a total of 90 SNPs related loci were identified,including 43 candidates.gene.The gene GRMZM2G018950 on chromosome 7 was associated with multiple significant loci.The gene encodes a class of proteases belonging to the alpha/beta hydrolase family and participates in many important aspects such as processing,modification and degradation of polypeptides and proteins in the process of plant growth and development.Overall,this study focused on the stain-tolerant traits of sweet corn,based on phenotypic traits,physiological and biochemical changes,the resistant inbred line K85 and sensitive inbred line K61 were selected.At the same time,a series of stain-associated candidate genes were identified in combination with genome-wide association analysis,which provided a theoretical basis for the study on the genetic mechanism of sweet corn tolerance and the selection of resistant varieties.