Cenome-wide Association Identify Loci For Callus Differentiation In Desert Tree Populus Euphratica

Differentiation ability is an important indicator in the process of callus differentiation.It is closely related to the ability of callus to differentiate into young shoots and affect the regeneration of plant cells.A better understanding of the genetic regulation mechanism of callus differentiation will provide theoretical guidance for better construction of Populus euphratica regeneration system and improvement of its artificial reproduction efficiency.In this study,we evaluated and quantified the callus differentiation ability of all genotypes based on 297 samples of Populus euphratica,then combined with their high-density SNP markers.Binary and growth-parameter-based genome-wide association study(GWAS)was used to analyze the genetic structure of callus differentiation regulation of Populus euphratica,screening for genes involved in callus differentiation and building related gene regulatory networks.The main results are as follows:(1)142 of all 297 samples have the ability of differentiation;(2)3 significant SNPs were located by binary GWAS for whether callus can differentiate;(3)3 equations were used to fit the dynamic data of the differentiation,and four growth parameters were obtained,then a growth-genome-based GWAS for the extent of callus differentiation was conducted,and a total of 43 significant SNPs were screened;(4)a gene regulatory network was constructed to visualize how each QTL interacts uniquely with other variants,and 8 core QTLs were found;(5)important candidate genes were identified,including gene LOG1,LOG7 and WOX1.This study is the first time to use GWAS to deeply explore the genetic variation of callus differentiation in forest trees.The results indicate that callus differentiation may be a quality-quantitative trait controlled by a major gene and multiple minor genes.This research helps us to design more complex and targeted molecular tools to systematically study plant regeneration.