Stay‐green alleles individually enhance grain yield in sorghum under drought by modifying canopy development and water uptake patterns

Abstract

SummaryStay-green is an integrated drought adaptation trait characterized by a distinct green leaf phenotype during grain filling under terminal drought. We used sorghum (Sorghum bicolor), a repository of drought adaptation mechanisms, to elucidate the physiological and genetic mechanisms underpinning stay-green.Near-isogenic sorghum lines (cv RTx7000) were characterized in a series of field and managed-environment trials (seven experiments and 14 environments) to determine the influence of four individual stay-green (Stg1-4) quantitative trait loci (QTLs) on canopy development, water use and grain yield under post-anthesis drought.The Stg QTL decreased tillering and the size of upper leaves, which reduced canopy size at anthesis. This reduction in transpirational leaf area conserved soil water before anthesis for use during grain filling. Increased water uptake during grain filling of Stg near-isogenic lines (NILs) relative to RTx7000 resulted in higher post-anthesis biomass production, grain number and yield. Importantly, there was no consistent yield penalty associated with the Stg QTL in the irrigated control.These results establish a link between the role of the Stg QTL in modifying canopy development and the subsequent impact on crop water use patterns and grain yield under terminal drought.

Mapping QTL for stay-green and agronomic traits in wheat under diverse water regimes

“…In crop plants species, stay-green enables a plant to maintain greenness and continue photosynthesising even under stress (Borrell et al 2014). Staygreen is associated with antioxidant status and photosystem II of the mesophyll cells (De Simone et al 2014;Luo et al 2013b).…”

“…Chlorophyll content (SPAD value) was used for assessment of staygreen in sorghum, and four stay-green QTL were identified (Harris et al 2007). It was reported that individual alleles for stay-green enhanced grain yield in sorghum under drought by modifying canopy development and water uptake patterns (Borrell et al 2014). …”

Transcriptome Profiling of Tiller Buds Provides New Insights into PhyB Regulation of Tillering and Indeterminate Growth in Sorghum

“…The reduced leaf area of low tillering varieties would conserve soil moisture for the grain-filling stage in drought-prone regions (Islam and Sedgley, 1981;Kebrom and Richards, 2013). Reduced tillering associated with stay-green drought tolerance loci is also important for grain sorghum production in water-limited environments (Borrell et al, 2014). A more complete understanding of the genetic and biochemical basis of tiller production in sorghum will accelerate progress toward optimal crop canopy architectures and higher yield.…”

Prioritization of feasible physiological parameters in drought tolerance evaluation in sorghum: a grey relational analysis

“…Moreover, superior morphological, physiological and biochemical traits were also selected for evaluating drought tolerance of crops (Chen et al, 2012). For example, sorghum with stay-green trait expressed drought tolerance under drought conditions (Borrell et al, 2014). It was noted that these traits could eventually contribute to final yield particularly under drought conditions.…”

“…Although sorghum is considered as a drought-tolerant crop (Shan, Xu, 2009), its production often suffers from drought in those regions. Sorghum breeders seek to utilize drought tolerant germplasm to mitigate drought stress risk to sorghum production (Borrell et al, 2014). During the sorghum breeding process, it is crucial to improve the screening efficiency and identifying accuracy.…”