Toward improved drought tolerance in bioenergy crops: QTL for carbon isotope composition and stomatal conductance in Populus

Abstract

Dedicated non‐food bioenergy crops like poplar are needed as sustainable, low‐input feedstocks for renewable energy in a future drier climate, where they can be grown on marginal soils. Such plants should have a low water, carbon, and chemical footprint. Capturing natural variation in traits associated with water use efficiency (WUE) is the first step to developing trees that require less water and may be adapted to drier environments. We have assessed stomatal conductance (gs) and leaf carbon isotope composition (δ13C, an indirect indicator of leaf WUE) in two Populus species, P. deltoides and P. trichocarpa and their F2 progeny, grown in the United Kingdom and in Italy. Populus deltoides leaves showed lower δ13C than P. trichocarpa, suggesting a higher WUE in P. trichocarpa, although without drought preconditioning, gs of P. trichocarpa was less responsive to dehydration and abscisic acid treatment than P. deltoides, suggesting that leaf anatomy may also contribute to δ13C in Populus. Quantitative trait loci (QTL) were identified for δ13C on eight linkage groups (LG) and two QTL for gs. From these. QTL and differential gene expression in response to drought from microarray data, we focused on three hotspots and identified 23 novel candidate genes on LG VI, X, and XVI. We have begun to unravel the genetic basis of WUE in bioenergy Populus revealing important underpinning data for breeding and improvement in poplar genotypes for a future drier climate.

Quantitative Trait Loci Associated with Drought Tolerance in Brachypodium distachyon

“…Co-localization of QTLs for physiological traits and/or with agronomic traits have been reported in plants exposed to drought stress, suggesting a link between individual QTLs and multiple traits (Viger et al, 2013; Borrell et al, 2014; Kapanigowda et al, 2014; Merewitz et al, 2014; Khan et al, 2015). Overlapping QTLs for the chlorophyll fluorescence parameters and plant water status traits were identified in sunflower under drought stress (Kiani et al, 2008).…”

Rhizosphere engineering: Enhancing sustainable plant ecosystem productivity

“…With forecasted global changes in temperature and precipitation, drought will increasingly impose a challenge not only to food and feed but also to biomass production (Ings et al, 2013;Quinn et al, 2015;Yin et al, 2014). Most of the bioenergy crops have some degree of drought susceptibility as revealed for example through measures of low water-use efficiency (WUE) in Miscanthus (Ings et al, 2013;Yin et al, 2014) and poplar (Viger M et al, 2013). Thus, in addition to the urgent need of developing droughttolerant crops for food security (Lopes et al, 2011), it becomes imperative to improve drought tolerance and WUE in bioenergy crop plantations for sustainable biomass production in arid and semi-arid regions (Ings et al, 2013;Quinn et al, 2015;Yin et al, 2014).…”

New resources for genetic studies in Populus nigra: genome‐wide SNP discovery and development of a 12k Infinium array

“…; Viger et al . ). SNPs outside the candidate regions were also selected to provide genomic control tools to characterize neutral genetic diversity and detect population structure.…”