Non-Invasive Phenotyping Reveals Genomic Regions Involved in Pre-Anthesis Drought Tolerance and Recovery in Spring Barley.

Sidram Dhanagond,Yusheng Zhao,Kerstin Neumann,Jochen Reif,Michele Grieco,Dijun Chen,Andreas Graner,Benjamin Kilian,Guozheng Liu

doi:10.3389/fpls.2019.01307

Abstract

With ongoing climate change, drought events are becoming more frequent and will affect biomass formation when occurring during pre-flowering stages. We explored growth over time under such a drought scenario, via non-invasive imaging and revealed the underlying key genetic factors in spring barley. By comparing with well-watered conditions investigated in an earlier study and including information on timing, QTL could be classified as constitutive, drought or recovery-adaptive. Drought-adaptive QTL were found in the vicinity of genes involved in dehydration tolerance such as dehydrins (Dhn4, Dhn7, Dhn8, and Dhn9) and aquaporins (e.g. HvPIP1;5, HvPIP2;7, and HvTIP2;1). The influence of phenology on biomass formation increased under drought. Accordingly, the main QTL during recovery was the region of HvPPD-H1. The most important constitutive QTL for late biomass was located in the vicinity of HvDIM, while the main locus for seedling biomass was the HvWAXY region. The disappearance of QTL marked the genetic architecture of tiller number. The most important constitutive QTL was located on 6HS in the region of 1-FEH. Stage and tolerance specific QTL might provide opportunities for genetic manipulation to stabilize biomass and tiller number under drought conditions and thereby also grain yield.

Highlights

Barley breeding has not substantially changed total biomass (Austin et al, 1980; Gifford et al, 1984; Horie et al, 2005) but rather its distribution resulting in an increased harvest index (Abeledo et al, 2003; Reynolds et al, 1999)
Non-invasive phenotyping allows for resolving the timing of QTL appearance
It can resolve which genetic loci are responsible for early growth vigor, growth per se, drought tolerance, and recovery from stress

Summary

Introduction

Barley breeding has not substantially changed total biomass (Austin et al, 1980; Gifford et al, 1984; Horie et al, 2005) but rather its distribution resulting in an increased harvest index (Abeledo et al, 2003; Reynolds et al, 1999). Genetic Arcitecture of Biomass Under Stress frequency of drought periods (Lloyd-Hughes and Saunders, 2002; Lehner et al, 2006), affecting plant growth and causing yield losses world-wide (Jones and Corlett, 1992; Boyer and Westgate, 2004). Ongoing drought leads to a reduction in photosynthesis (Jedmowski et al, 2014) All these factors result in a reduced dry matter production with negative effects on grain yield. Though barley is well adapted to a wide range of climatic conditions (Ceccarelli and Grando, 1996), improvement of yield under drought environments has been challenging for plant breeders (Richards et al, 2002) as the effect of drought is highly depending on the time of onset, duration, and stress intensity. There is evidence that selection for individual traits contributing to drought tolerance can improve grain yield (Edmeades et al, 1999; Richards, 2006)

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Discussion

Conclusion