Genome-wide Association Study Of Growth Dynamics Of Coleoptile In Diverse Chinese Wheat Landraces

Wheat(Triticum aestivum L.)is one of the most important grain crops in the world.Coleoptile is an important trait for influencing plant architecuture establishment to affect crop yield.To identify the genetic basis of coleoptile growth is the foundation basis to improve wheat yield.In this study,a core collection of 697 wheat landraces,from 10 agro-ecological zones,was used to evaluate coleoptile length in six consecutive days with three repetitions.The coleoptile growth curve was modelled by logistic function.A genome-wide association study was performed to identify marker-trait associations.Based on the Chinese Spring Reference Genome information,candidate genes were identified.The main results were described as follows:1.Significant variation(p < 0.01)was observed among the 697 accessions for coleoptile length of the 1st,2nd,3rd,4th,5th and 6th day,respectively.Coleoptile length significantly(P < 0.01)increased in the first five days.The variation of coleoptile length was not significant between the 5th day and 6th day.It indicated that the coleoptile had stopped growth at the 6th day and showed their highest/final coleoptile length.2.The Gompertz function and logistic function were used to model coleoptile growth.Comparing the goodness-of-fit and coleoptile final length “Amax” calculated by two functions,the logistic function was better modelled in this study.The Amax was highly correlated with coleoptile length measured on the 6th day.3.Coleoptile final length was significant(P < 0.01)and positive with heading date,flowering date,flag leaf length,flag leaf width,seedling habits and spike length,and significant and negative with peduncle length.No significant correlation was observed between coleoptile final length and plant height in the taller plant height group.Plant height was independent of coleoptile length in the taller plant height group.4.A total of 21 significant(-lg(p)? 4.72)markers were identified using two models for coleoptile length and the parameters.These markers were distributed on chromosomes 2B,2D,3B,4A,6A,6B and 7D.On chromosomes 4A and 6B,a hot genomic region was identified,respectively.The effect of the loci on chromosome 6B was validated in a F2:3 population.5.The gene Traes CS6B01G282600 was identified as a candidate gene on the loci of chromosome 6B.This gene may be involved in cell division and cell differentiation in coleoptile growth.Two genes Traes CS4A01G422900 and Traes CS4A01G423500 were identified as candidate genes on the loci of chromosome 4A.These two genes may be involved in ethylene regulation and finally affect coleoptile growth.