Sequence Diversity Of ZmLEC1and Association Analysis Of Embryogenic Calli Formation Ability In Maize

The embryogenic calli induced from maize immature embryos are often used as receptor systemsin maize genetic transformation, due to their higher capacity of subculture and regeneration intissue culture. The genotype is a critical factor affecting maize immature embryo culture, therefore,the receptor materials are restricted to only a few cultivars, such as A188, B73, Zong31and HiⅡ.Researches at home and abroad have shown the embryogenic calli formation is a complicatedquantitative trait regulated by polygenes. China has abundant maize germplasm resources, and it isof great significance for enriching the transgenic receptor materials and backcross breeding tofurther investigate the existing germplasm resources and screen out some materials with highimmature embryo culture efficiency, excellent comprehensive characters and high adaptability.Association analysis is the bridge between the structural genomics and phenomics. Therefore, theassociation analysis based on candidate genes has become an effective way to discover thefunctional allelic variants related to phenotypic variation.In this study, an association mapping population which consisted of a mini core collection of95maize inbred lines and3elite maize accessions(A188, HiⅡ, Zong31) often used for genetictransformation was analyzed for the sequence diversity and linkage disequilibrium of ZmLEC1,which is a candidate gene of regeneration ability in maize. A candidate gene association strategywas used to reveal the relationship between this gene and embryogenic calli formation ability anddiscover favorable alleles and genotypes which can enhance the embryogenic calli formation ability.The results were as follows:(1) There existed significant differences in abilities of embryogenic calli formation andregeneration among these accessions. The calli induced from Yue267-1-1were very similar tothose of HiⅡ,the popularly used genotype in maize transformation, which had the highestembryogenic calli formation and regeneration ability and could be a new candidate forimmature embryo-based genetic transformation.(2) The polymorphism analysis of the95obtained ZmLEC1gene sequences showed that a total of42polymorphic sites were detected in the852bp coding region, including33SNPs and9INDELs. Of those42polymorphic sites,32were nonsynonymous mutation and10weresynonymous mutation.The LD between all of the informative polymorphisms decayed rapidlyto about300bp at R2=0.1.(3) The association analysis between polymorphic sites in the ZmLEC1gene and phenotypiccharacter showed4polymorphic sites(site466,501,528,539) weresignificantly associatedwith embryogenetic calli formation ability. Among those, the sites501,528and538were a haplotype of complete linkage.