Suppression of ERECTA signaling for gaining drought tolerance functions in soybean (Glycine max (L) Merril)
Erecta gene; supression; drought tolerance
Drought is a major limiting factor for plant growth and development, directly compromising agricultural production. The development of cultivars capable of tolerating prolonged periods of drought is important for the food production. The ERECTA (ER) family of genes, encoding leucine-rich repeat receptor-like kinase, besides influencing plant morphology, also regulates physiological aspects, and reportedly plays an important role in abiotic stresses such as drought and heat. In this study, transgenic soybean plants, suppressed in ER signaling, were evaluated over three generations, T2, T3 and T4, for phenotypic performance and response to drought conditions. First, a strong inverse correlation of transgene expression with the index of agronomic performance of soybean plants was observed. Among the T2 plants submitted to drought stress, only stunted plants showed tolerance to water deficit. However, two T3 lines were identified that expressed the transgene as well as showed favorable agronomic properties. The drought stress experiments on the progenies T4 from these lines, however, found no significant gain in water use efficiency and stomatal conductance. This observation indicates that reduced plant growth through the modulation of ER signaling in the stunted plants leads to reduced water demand rather than drought tolerance in the transgenic plants. Acoordingly, the selected transgenic plants that showed higher biomass, demanded more water, and became more susceptible to periods of water withholding.