Abstract
BackgroundLand plants have evolved several measures to maintain their life against abiotic stresses. The accumulation of proline is the most generalized response of plants under drought, heat or salt stress conditions. It is known as an osmoprotectant which also acts as an instant source of energy during drought recovery process. But, both its role and genetic inheritance are poorly understood in agriculture crops. In the present work, advanced backcross quantitative trait locus (AB-QTL) analysis was performed to elucidate genetic mechanisms controlling proline accumulation and leaf wilting in barley under drought stress conditions.ResultsThe analysis revealed eight QTL associated to proline content (PC) and leaf wilting (WS). QTL for PC were localized on chromosome 3H, 4H, 5H and 6H. The strongest QTL effect QPC.S42.5H was detected on chromosome 5H where drought inducible exotic allele was associated to increase PC by 54%. QTL effects QPC.S42.3H, QPC.S42.4H and QPC.S42.6H were responsible to heighten PC due to the preeminence of elite alleles over the exotic alleles which ranged from 26% to 43%. For WS, QTL have been localized on chromosome 1H, 2H, 3H and 4H. Among these, QWS.S42.1H and QWS.S42.4H were associated to decrease in WS due to the introgression of exotic alleles. In addition, two digenic epistatic interaction effects were detected for WS where the additive effect of exotic alleles imparted a favorable increase in the trait value.ConclusionsThe present data represents a first report on whole-genome mapping of proline accumulation and leaf wilting in barley. The detected QTL are linked to new alleles from both cultivated and wild accessions which bring out an initial insight on the genetic inheritance of PC and WS. These QTL alleles are fixed in the isogenic background of Scarlett, which will allow for positional cloning of underlying genes and to develop drought resilient barley cultivars.
Highlights
Land plants have evolved several measures to maintain their life against abiotic stresses
A lower heritability of proline content (PC) was observed among the 301 BC2DH lines but these lines displayed heritable responses for wilting score (WS) at h2 =0.75
The present study brings out a QTL map that reveals a new insight into the genetic inheritance of PC and WS in barley (Figure 5)
Summary
Land plants have evolved several measures to maintain their life against abiotic stresses. The advent of molecular tools has made it possible to dissect genetic inheritance of this trait-complex and several successful QTL analyses have been performed in barley and related species [5,6,7,8,9,10,11,12,13,14,15,16] These studies revealed that crop plants evolved a number of drought adaptive traits to maintain their life in water deficit conditions. Sanchez et al [7] identified four major QTL for stay-green, the most important agronomic trait for sorghum cultivation under drought conditions These data showed that leaf wilting (drying) is a vital drought adaptive trait which offers a straightforward determination of drought tolerance in plants. No report of QTL mapping for leaf wilting was found in barley
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