Contribution of Chromosomes 1HchS and 6HchS to Fertility Restoration in the Wheat msH1 CMS System under Different Environmental Conditions.

Exploiting hybrid wheat heterosis has been long pursued to increase crop yield, stability and uniformity. Cytoplasmic male sterility (CMS) systems based in the nuclear-cytoplasmic incompatible interactions are a classic way for hybrid seed production, but to date, no definitive system is available in wheat. The msH1 CMS system results from the incompatibility between the nuclear genome of wheat and the cytoplasmic genome of the wild barley Hordeum chilense. Fertility restoration of the CMS phenotype was first associated with the disomic addition of the short arm of chromosome 6H from H. chilense. In further studies it was observed that chromosome arm 1HchS was also implicated, and the combination of genes in both chromosome arms restored fertility more efficiently. In this work we aim to dissect the effect of each chromosome in fertility restoration when combined in different genomic backgrounds and under different environmental conditions. We propose a model to explain how restoration behaves in the msH1 system and generate valuable information necessary to develop an efficient system for hybrid wheat production.