GWAS Analysis Of Stank Length And Functional Verification Of Key Candidate Gene In Maize

The stank was the only channel for the photosynthetic products produced by the stem and leaf to transport to the ear.The stank length is not only related to the dry matter content of corn grain and corn yield,but also related to the tightness of bracts surrounding the ear.During the growth and development,the dehydration rate of grain is also affected by the stank.In addition,the length of stank affected the harvesting efficiency during mechanical harvesting.Therefore,analyzing the regulatory mechanism of stank length at the genetic and molecular levels would be beneficial to grain dehydration and yield accumulation,as well as improving the quality and quantity of mechanical harvest.In this experiment,the associated population composed of 508 inbred lines from a wide range of sources was used as the test material to determine the stank length of maize in heishengmu,locate the SNP locus for significant regulation of stank length,and analyze the genetic basis of ear stalk length;The candidate gene ZmGRF10 selected by genome-wide association study was re-sequenced,and polymorphism analysis was performed based on the sequence of ZmGRF10 to unearth natural mutation sites related to spike stank length and analyze the differences of haplotypes favoring mechanical harvest.The result of this experimental study are as follows.1.The phenotypes of stank length of related populations showed normal distribution.The analysis of variance showed that the genotype and environmental variation of the inbred lines within the associated population reached extremely significant levels,and the variation was mainly from environmental variation.The broad heritability of panicle stank length was medium,indicating that genetic factor was the main factor affecting panicle stank length in related population.2.In this study,the BLUP values of stank length in 508 inbred lines were genome-wide association study-analyzed under multiple environments.A total of 21 SNP loci that exceeded the threshold were located on chromosomes 1,2,3,5,6,and 7,respectively,of which eight were independent significant SNP loci,which accounted for up to 6.1% of the phenotypic contribution to stank length,and the growth regulator ZmGRF10 gene on chromosome 7 was identified as a candidate gene.3.Molecular identification and phenotypic observation of Mutator and EMS mutants and overexpressed plants of ZmGRF10 revealed that mutant traits such as panicle stank length,plant height,panicle height,leaf width and leaf length were increased to different extents as compared with wild plants.Traits such as stank length,plant height,spike height,leaf width and leaf length of the overexpressed plants were significantly reduced.It was confirmed that ZmGRF10 had a negative regulation function on ear stalk length of maize.4.Candidate gene resequencing and polymorphism analysis of ZmGRF10 revealed 84 SNPs and 42 Indels.There were more natural mutation sites in the intron region than in the exon region of the gene sequence.For linkage imbalance analysis of polymorphic sites,there were some LD intervals with strong linkage in the sequence of ZmGRF10 gene.Using the MLM mixed linear model,the association analysis was performed between the natural mutation site of ZmGRF10 gene and the panicle stank length phenotype of the associated population,and two significant polymorphic sites were detected,namely,SNP1668 and Indel2173.Among them,the Indel2173 mutation site was located in the relatively strong LD interval.5.The associated populations were divided into three haplotypes based on the two detected natural mutation sites of spike stank length.The analysis of variance of spike stank length of each haplotype was performed,and the results showed that there was significant difference between haplotype Hap1 and haplotype Hap2,and between haplotype Hap2 and haplotype Hap3;And haplotype Hap1 contains nearly half of the inbred lines of the associated population,and haplotype Hap3 has the least number of inbred lines.In conclusion,ZmGRF10 is an important gene that negatively regulates the development of stank in maize,and the specific mechanism needs to be further studied.The results of this study lay a foundation for clarifying the molecular mechanism of ZmGRF10 regulating corn Shank development,and the discovered natural variation loci provide important molecular markers for the genetic improvement of Shank length.