A genetic link between leaf carbon isotope composition and whole‐plant water use efficiency in the C4 grass Setaria. (2nd March 2020)

• Record Type: Journal Article
• Authors: Ellsworth, Patrick Z.; Feldman, Max J.; Baxter, Ivan; Cousins, Asaph B.
• Is Part Of: Plant journal. Volume 102:Number 6(2020)
• Page Start: 1234
• Page End: 1248
• Publication Date: 2020-03-02
• Subjects: quantitative trait loci -- leaf carbon isotopes -- C4 photosynthesis -- Setaria -- water use efficiency -- phenotyping -- genetic architecture -- drought -- recombinant inbred lines; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.14696
• Languages: English
• ISSNs: 0960-7412

Abstract

Summary: Genetic selection for whole‐plant water use efficiency (yield per transpiration; WUEplant ) in any crop‐breeding programme requires high‐throughput phenotyping of component traits of WUEplant such as intrinsic water use efficiency (WUEi ; CO2 assimilation rate per stomatal conductance). Measuring WUEi by gas exchange measurements is laborious and time consuming and may not reflect an integrated WUEi over the life of the leaf. Alternatively, leaf carbon stable isotope composition (δ 13 Cleaf ) has been suggested as a potential time‐integrated proxy for WUEi that may provide a tool to screen for WUEplant . However, a genetic link between δ 13 Cleaf and WUEplant in a C4 species has not been well established. Therefore, to determine if there is a genetic relationship in a C4 plant between δ 13 Cleaf and WUEplant under well watered and water‐limited growth conditions, a high‐throughput phenotyping facility was used to measure WUEplant in a recombinant inbred line (RIL) population created between the C4 grasses Setaria viridis and S. italica . Three quantitative trait loci (QTL) for δ 13 Cleaf were found and co‐localized with transpiration, biomass accumulation, and WUEplant . Additionally, WUEplant for each of the δ 13 Cleaf QTL allele classes was negatively correlated with δ 13 Cleaf, as would be predicted when WUEi influences WUEplant . These results demonstrate that δ 13 Cleaf is genetically linked to WUEplant, likely to be through their relationship with WUEi, and can be used as a high‐throughput proxy to screen for WUEplant in these C4 species. Significance Statement: Improving whole‐plant water use efficiency (WUEplant ) can reduce agricultural demand for freshwater but it can be difficult to measure. Therefore, leaf carbon isotopic composition (δ 13 Cleaf ) has been proposed as a proxy for WUEplant in C4 plant species. We found that the δ 13 Cleaf shares a similar genetic architecture with WUEplant and its component traits (biomass accumulation and transpiration) in the C4 grass Setaria, suggesting that δ 13 Cleaf can be an effective screening tool for WUEplant .