The complex genetic architecture of drought tolerance challenges the genetic adaptation of crops to climate change by plant breeding. In wheat, ca. 800 QTLs for drought-tolerant traits have been described, but no large-effect, stable QTL that controls many drought tolerance related traits has been identified.
Ddw1 belongs to the group of gibberellin (GA) sensitive dwarfing genes. Noteworthy in this context, it is becoming increasingly evident that the GA class of plant hormones is of pivotal relevance in the response of plants to drought stress.
Basic research on the model species Arabidopsis thaliana has substantially expanded our understanding on the role of gibberellin (GA) in plant responses to drought stress. These fundamental data suggest that in GA-sensitive semi-dwarf rye a root signal contributing to temperature-induced shoot growth cannot trigger stem growth (to the same extend) as in tall rye, resulting in an optimized allocation of dry matter to the grain even under elevated temperature. Furthermore, a genetic factor regulating GA biosynthesis conferred drought tolerance in Arabidopsis by suppressing endogenous bioactive GA. This knowledge corresponds with the observation that chemically induced GA deficiency confers both, lodging and drought tolerance in cereals. Indeed the up-regulation of the GA deactivation gene ScGA2ox12 in rye carrying Ddw1 coincide with the data in Arabidopsis.
In the background of this knowledge Ddw1 alters the GA content in a favorable manner and depicts a genetic strategy to tackle the climate change by plant breeding. By conducting transnational field trials with semi-dwarf rye in target environments of rye cultivation, RYE-SUS represents an unexampled opportunity for the proof of concept, that natural gene variants suppressing endogenous bioactive GA provide valuable biodiversity to create lodging tolerant and climate-smart crops.