High-throughput phenotyping to detect drought tolerance QTL in wild barley introgression lines.

Nora Honsdorf,Klaus Pillen,Mark Tester,Timothy John March,Bettina Berger,Tianzhen Zhang

doi:10.1371/journal.pone.0097047

Abstract

Drought is one of the most severe stresses, endangering crop yields worldwide. In order to select drought tolerant genotypes, access to exotic germplasm and efficient phenotyping protocols are needed. In this study the high-throughput phenotyping platform “The Plant Accelerator”, Adelaide, Australia, was used to screen a set of 47 juvenile (six week old) wild barley introgression lines (S42ILs) for drought stress responses. The kinetics of growth development was evaluated under early drought stress and well watered treatments. High correlation (r = 0.98) between image based biomass estimates and actual biomass was demonstrated, and the suitability of the system to accurately and non-destructively estimate biomass was validated. Subsequently, quantitative trait loci (QTL) were located, which contributed to the genetic control of growth under drought stress. In total, 44 QTL for eleven out of 14 investigated traits were mapped, which for example controlled growth rate and water use efficiency. The correspondence of those QTL with QTL previously identified in field trials is shown. For instance, six out of eight QTL controlling plant height were also found in previous field and glasshouse studies with the same introgression lines. This indicates that phenotyping juvenile plants may assist in predicting adult plant performance. In addition, favorable wild barley alleles for growth and biomass parameters were detected, for instance, a QTL that increased biomass by approximately 36%. In particular, introgression line S42IL-121 revealed improved growth under drought stress compared to the control Scarlett. The introgression line showed a similar behavior in previous field experiments, indicating that S42IL-121 may be an attractive donor for breeding of drought tolerant barley cultivars.

Highlights

Barley (Hordeum vulgare ssp. vulgare, hereafter abbreviated with Hv) is ranked fourth among the worldwide production of cereals
Trait Performance of S42 population to develop ILs (S42ILs) For most traits, means were higher under well watered treatment than under drought stress (Fig. 3 and Fig. 4, Table S2), e.g. 2.2 g of biomass dry (BMD) vs. 0.9 g
The same was true for plant hue integral (HUEI), Specific plant weight (SPW), and Water Use Efficiency (WUE) but differences were marginal

Summary

Introduction

Barley (Hordeum vulgare ssp. vulgare, hereafter abbreviated with Hv) is ranked fourth among the worldwide production of cereals. There is limited genetic diversity remaining in the elite barley gene pool for abiotic and biotic stress tolerance. The current loss of genetic variation in the elite gene pool tends to limit the breeding success of improved cultivars [4]. To overcome this problem several authors, e.g. Zamir [5], proposed to use wild relatives of crop species as donors of exotic germplasm to enhance elite varieties. Lines produced by advanced backcrosses ideally contain only one single introgression from the wild parent and are referred to as introgression lines (ILs). A set of ILs ideally represents the whole genome of a wild donor plant in the genetic background of a single elite variety [5]

Objectives

Methods

Results

Discussion

Conclusion