Résumé
Transgenic research using the DREB group of transcription factors has received much attention in developing drought-tolerant and climate-ready varieties of crop plants. While many reports have demonstrated increased tolerance to water deficits under laboratory and greenhouse conditions, only a few have tested possible effects under field conditions, with limited success in most cases. Here, we present evidence of a transgenic solution for enhanced drought tolerance in peanut (Arachis hypogaea L.), which is an important grain legume and a valuable cash crop for smallholder and resource-poor farmers occupying the largest portion of the farming systems in low income food deficit countries. The presence, integration, expression and inheritance of the transgene in advancing generations of the transgenic peanut plants were assessed using PCR, Southern blot, inverse-PCR, RT-PCR and q-PCR techniques. Four trials were conducted in various water stress regimes under varying vapour pressure deficits (VPDs), and drought tolerance was studied using various component traits of drought. A substantial yield improvement of up to 24 % in drought trials under field conditions was achieved across a wide range of stress intensities and was related to higher harvest indices (HIs). All transgenic events had significantly higher seed filling under drought and displayed 20-30 % lower pod yield reduction than their untransformed counterpart under drought stress. Two transgenic events showed yield advantage under drought stress that consistently had higher pod and seed yield than the untransformed parent under drought stress across all trials, without displaying any yield penalty under irrigated conditions.