Abstract
Plant growth and productivity are greatly affected by drought, which is likely to become more threatening with the predicted global temperature increase. Understanding the genetic architecture of complex quantitative traits and their interaction with water availability may lead to improved crop adaptation to a wide range of environments. Here, the genetic basis of 20 physiological and morphological traits is explored by describing plant performance and growth in a Brassica rapa recombinant inbred line (RIL) population grown on a sandy substrate supplemented with nutrient solution, under control and drought conditions. Altogether, 54 quantitative trait loci (QTL) were identified, of which many colocated in 11 QTL clusters. Seventeen QTL showed significant QTL–environment interaction (Q×E), indicating genetic variation for phenotypic plasticity. Of the measured traits, only hypocotyl length did not show significant genotype–environment interaction (G×E) in both environments in all experiments. Correlation analysis showed that, in the control environment, stomatal conductance was positively correlated with total leaf dry weight (DW) and aboveground DW, whereas in the drought environment, stomatal conductance showed a significant negative correlation with total leaf DW and aboveground DW. This correlation was explained by antagonistic fitness effects in the drought environment, controlled by a QTL cluster on chromosome A7. These results demonstrate that Q×E is an important component of the genetic variance and can play a great role in improving drought tolerance in future breeding programmes.
Highlights
Plant growth is greatly affected by environmental abiotic stresses, of which drought is the most common factor impeding crop productivity
Physiology/morphology in response to changes in environmental conditions (Schlichting, 1986). When this plasticity differs between genotypes, it is classified as genotype–environment interaction (G×E) (Via and Lande, 1985)
Upon screening the recombinant inbred line (RIL) population, this work found significant G×E between control and drought environments for stomatal conductance, leaf number, root length, and root diameter. This G×E was reflected in QTL–environment interaction (Q×E) detected using the multienvironment analysis (MEA) approach for these traits, except for leaf number
Summary
Plant growth is greatly affected by environmental abiotic stresses, of which drought is the most common factor impeding crop productivity. Three categories of plant adaptive strategies to drought have been recognized: drought escape by early flowering, drought tolerance via increasing water use efficiency and drought avoidance via reduced transpiration and increasing water uptake (Levitt, 1972) Evaluating those responses in many genotypes in several environments may show phenotypic plasticity, which is defined as the ability of an individual organism to alter its. Trade offs can be maintained in nature (e.g. by antagonistic pleiotropy), when alleles at a locus underlying a fitness component show clear home-site advantages (Rose, 1982; Anderson et al, 2013) Considering such antagonistic fitness effects is crucial while selecting for desirable QTL during marker-assisted breeding programmes
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