Gene discovery in cereals through quantitative trait loci and expression analysis in water‐use efficiency measured by carbon isotope discrimination

Abstract

Drought continues to be a major constraint on cereal production in many areas, and the frequency of drought is likely to increase in most arid and semi-arid regions under future climate change scenarios. Considerable research and breeding efforts have been devoted to investigating crop responses to drought at various levels and producing drought-resistant genotypes. Plant physiology has provided new insights to yield improvement in drought-prone environments. Crop performance could be improved through increases in water use, water-use efficiency (WUE) and harvest index. Greater WUE can be achieved by coordination between photosynthesis and transpiration. Carbon isotope discrimination (D 13C) has been demonstrated to be a simple but reliable measure of WUE, and negative correlation between them has been used to indirectly estimate WUE under selected environments. New tools, such as quantitative trait loci (QTL) mapping and gene expression profiling, are playing vital roles in dissecting drought resistance-related traits. The combination of gene expression and association mapping could help identify candidate genes underlying the QTL of interest and complement map-based cloning and markerassisted selection. Eventually, improved cultivars can be produced through genetic engineering. Future efficient and effective breeding progress in cereals under targeted drought environments will come from the integrated knowledge of physiology and genomics.

Genotypic Variability in Carbon Isotope Discrimination and Water Use Efficiency among Recombinant Inbred Lines of Sunflower (Helianthus annuus L.)

“…Another previous study was reported by Zhao, Kondo, Maeda, Ozaki, & Zhang (2004) where CID under water stress significantly decreased of all analyzed plant parts measured at tillering in two cultivars of upland rice. Furthermore, the general trend of decreasing CID under water stress support the idea that there is negative relationship between CID and WUE, as noted by previous authors (Centritto, Lauteri, Monteverdi, & Serraj, 2009;Chen, Chang, & Anyia, 2011) that WUE increased when water deficit due to higher conductance reduction than assimilation reduction and extended drought can substantially increase WUE.…”

“…Evaluating the genotypic variation for understanding the genetic basis of CID and WUE is essential for crop improvement (breeding) (Chen, Chang, & Anyia, 2011). It has been known that in breeding populations, with sufficient attention to sampling scenarios, CID is a highly heritable and reliable trait which is relatively easy to be manipulated .…”

“…Nevertheless, the problem has been overcome since Farquhar, Ehleringer, & Hubick (1989) proved the negative correlation between WUE and CID in tissue of C3 plant species. CID during plant growth and development could be used as an excellent surrogate for determining WUE, which is usually directly measured in the field Brendel et al, 2008;Brugnoli, Hubick, von Caemmerer, Wong, & Farquhar, 1988;Chen, Chang, & Anyia, 2011;Ebdon & Kopp, 2004).…”

Stable Carbon Isotope Discrimination Is under Genetic Control in the C4 Species Maize with Several Genomic Regions Influencing Trait Expression

“…C was found to be under polygenic control of many independently inherited loci, most explaining only a small proportion of the total variance (for review, see Chen et al, 2011). This is in accordance with our results for the C 4 species maize.…”

Genetic Control of Water Use Efficiency and Leaf Carbon Isotope Discrimination in Sunflower (Helianthus annuus L.) Subjected to Two Drought Scenarios

“…QTL mapping provides a starting point in breeding programs [15]–[16] and for cloning of the causal mutations by fine mapping.…”