Backcross reciprocal monosomic analysis of leaf relative water content, stomatal resistance, and carbon isotope discrimination in wheat under pre-anthesis water-stress conditions

Abstract

Monosomic plants from an Australian variety (Oxley) having low stomatal resistance (SR), low leaf relative water content (LRWC), and high carbon isotope discrimination (Δ) were crossed with variety Falchetto having opposite characters in order to produce F2 backcross reciprocal monosomic families. The families were assessed under pre-anthesis water-stress conditions in a controlled growth chamber. F2 backcross reciprocal monosomic analysis suggested possible allelic variations between chromosomes 1A, 3A, 6A, 7A, 7B, 1D, and 4D of Falchetto and their homologues in Oxley for LRWC. This analysis also suggested possible allelic variation between chromosomes 5A, 1A, and 3A of Falchetto and their homologues in Oxley for SR. Extending the analysis to the F3 disomic generation and the assessment of LRWC at this generation confirmed that reciprocals for chromosomes 3A and 6A showed significant differences. F2 backcross reciprocal monosomic analysis for Δ suggested allelic variations on chromosomes 1D, 4D, and 5D. However, chromosome 1D from Falchetto had the highest difference from its homologue in Oxley. Assessing the reciprocals of this chromosome for vegetative evapotranspiration efficiency (ETEveg) at the F3 disomic generation indicated that the observed variation for Δ was translated into differences for ETEveg. These results indicate that chromosome 1D of Falchetto is promising in reducing Δ and that the improvement of wheat varieties for ETEveg can be done by selection for Δ. Finally, plieotropic effects of some chromosomes were observed for the characters under study. This suggests the existence of genetic factors on these chromosomes affecting more than one character. However, some pleiotropic effects could also be due to non-genetic developmental interactions.