Genetic approaches for breeding heat stress tolerance in faba bean (Vicia faba L.)

Vicia faba L. (faba bean) is an important legume and is cultivated essentially as a cool-season crop. Changes in sowing dates and lack of precipitation expose faba bean crop to drought and heat stresses. The gradual rise in global temperatures owing to climate change is likely to exacerbate the detrimental effects of hot and dry climatic conditions on faba bean cultivation. High temperature stress is particularly damaging to faba bean during the flowering period, when the viability of pollen is critical for successful reproduction. Recent studies have shown that maintenance of protein homeostasis through synthesis of heat shock proteins plays a key role in the heat response of plants. To date, there has been no significant work linking the heat response of faba bean to the repertoire of its heat shock proteins. While quantitative trait loci have been identified for resistance against biotic stresses in faba bean, there is no parallel success with abiotic stresses in this species. Programs aiming at genetic improvement of the heat/drought resistance of this crop by both conventional breeding and molecular breeding methods are hampered because of the large and majorly ill-analyzed genome of faba bean plants. Likewise, molecular and biotechnology-related tools are poorly developed for faba bean; as a result, the fruits of transgenic research developed with model plant species are not reaching this crop. While specifically discussing the prospects for the genetic improvement of faba bean against heat and drought stresses, we highlight the areas of research which need to be strengthened on faba bean.