Modelling the genetic architecture of flowering time control in barley through nested association mapping.

Andreas Maurer,Vera Draba,Benjamin Kilian,Jochen Christoph Reif,Rajiv Sharma,Erika Schumann,Florian Schnaithmann,Yong Jiang,Klaus Pillen

doi:10.1186/s12864-015-1459-7

Abstract

BackgroundBarley, globally the fourth most important cereal, provides food and beverages for humans and feed for animal husbandry. Maximizing grain yield under varying climate conditions largely depends on the optimal timing of flowering. Therefore, regulation of flowering time is of extraordinary importance to meet future food and feed demands. We developed the first barley nested association mapping (NAM) population, HEB-25, by crossing 25 wild barleys with one elite barley cultivar, and used it to dissect the genetic architecture of flowering time.ResultsUpon cultivation of 1,420 lines in multi-field trials and applying a genome-wide association study, eight major quantitative trait loci (QTL) were identified as main determinants to control flowering time in barley. These QTL accounted for 64% of the cross-validated proportion of explained genotypic variance (pG). The strongest single QTL effect corresponded to the known photoperiod response gene Ppd-H1. After sequencing the causative part of Ppd-H1, we differentiated twelve haplotypes in HEB-25, whereof the strongest exotic haplotype accelerated flowering time by 11 days compared to the elite barley haplotype. Applying a whole genome prediction model including main effects and epistatic interactions allowed predicting flowering time with an unmatched accuracy of 77% of cross-validated pG.ConclusionsThe elaborated causal models represent a fundamental step to explain flowering time in barley. In addition, our study confirms that the exotic biodiversity present in HEB-25 is a valuable toolbox to dissect the genetic architecture of important agronomic traits and to replenish the elite barley breeding pool with favorable, trait-improving exotic alleles.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1459-7) contains supplementary material, which is available to authorized users.

Highlights

Barley, globally the fourth most important cereal, provides food and beverages for humans and feed for animal husbandry
Parents and the Halle exotic barley (HEB)-25 population could be clearly separated in a principal component analysis (PCA) (Additional file 3)
These findings point to the high genetic diversity that is present among Halle Exotic Barley 25’ (HEB-25) and its parents

Summary

Introduction

Globally the fourth most important cereal, provides food and beverages for humans and feed for animal husbandry. Maximizing grain yield under varying climate conditions largely depends on the optimal timing of flowering. Regulation of flowering time is of extraordinary importance to meet future food and feed demands. In this regard, time of flowering is expected to play a major role in future crop improvement. Time of flowering is expected to play a major role in future crop improvement It is a key trait for the successful completion of a plant’s life cycle and, it has a strong impact on grain yield [14].

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