Genome‐wide association mapping of time‐dependent growth responses to moderate drought stress in Arabidopsis

Abstract

Large areas of arable land are often confronted with irregular rainfall resulting in limited water availability for part(s) of the growing seasons, which demands research for drought tolerance of plants. Natural variation was observed for biomass accumulation upon controlled moderate drought stress in 324 natural accessions of Arabidopsis. Improved performance under drought stress was correlated with early flowering and lack of vernalization requirement, indicating overlap in the regulatory networks of flowering time and drought response or correlated responses of these traits to natural selection. In addition, plant size was negatively correlated with relative water content (RWC) independent of the absolute water content (WC), indicating a prominent role for soluble compounds. Growth in control and drought conditions was determined over time and was modelled by an exponential function. Genome-wide association (GWA) mapping of temporal plant size data and of model parameters resulted in the detection of six time-dependent quantitative trait loci (QTLs) strongly associated with drought. Most QTLs would not have been identified if plant size was determined at a single time point. Analysis of earlier reported gene expression changes upon drought enabled us to identify for each QTL the most likely candidates.

Leaf Growth Response to Mild Drought: Natural Variation in Arabidopsis Sheds Light on Trait Architecture

“…The lack of a strong correlation between size reduction caused by mild drought stress and the size under well-watered conditions for the third leaf and rosette area indicates that larger accessions are not per se more sensitive to mild drought stress, nor do smaller accessions tolerate the stress better in terms of size reduction. The size independency of the mild drought response has recently also been observed when the water deficit was applied later during development (Bac-Molenaar et al, 2016). This observation fits within the current ideas that mild drought/osmotic stress actively reduces growth, rather than being a secondary effect of insufficient resources (water, and indirectly, due to stomatal closure, also carbon) (Skirycz et al, 2011a(Skirycz et al, , 2011b.…”

Variation in relative water content, proline accumulation and stress gene expression in two cowpea landraces under drought

“…Plant populations adapted to arid climates can also be distinguished by direct measurement of RWC or indirectly by measuring the ratio of carbon isotope delta C13 (McKay et al, 2003). There is likely to be a range of physiological adaptations as RWC itself varies amongst Arabidopsis ecotypes in well-watered conditions and under drought (Bac-Molenaar et al, 2016). Midday RWC drop is a parameter that allows discrimination between some cowpea ecotypes (Kumar et al, 2008;Hayatu et al, 2014).…”

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“…For the heat experiment, 8 plants of each accession were grown in controlled conditions (Bac-Molenaar et al, 2015). Five replicates received a heat treatment and 3 replicates served as controls.…”

“…For the Heat experiment, the model included fixed effects for treatment, genotype and genotype x treatment interaction. For the Drought experiment, we fitted the mixed model used in (Bac-Molenaar et al, 2015).…”

“…For the drought experiments the Phenopsis phenotyping platform was used, preventing position related differences in plant growth within the climate chamber (Granier et al, 2006;Bac-Molenaar et al, 2015).…”