Overcoming cross-incompatibility in genus Arachis via in situ embryo rescue

The cultivated peanut, Arachis hypogaea L., is an important source of edible oil and highly digestible protein. Wild incompatible Arachis species outside section Arachis are ideal gene reservoirs for genetic improvement of the peanut crop. Among these, A. glabrata Benth. stands out for its noted resistance to various stresses. Traditional in vitro embryo rescue techniques have been fraught with challenges, including time consumption, resource intensiveness, late intervention timing, and limited effectiveness. In this study, we employed three hormone formulations in an innovative in situ embryo rescue approach to facilitate the production of intersectional Arachis hybrids. Through this method, hybrid seeds resulting from the crossing of two incompatible species, namely A. glabrata and A. paraguariensis, with four high-oleic peanut varieties were successfully obtained. Molecular marker analysis and observation of plant characteristics confirmed the hybrid nature of these seeds. This breakthrough represents a significant advancement in expediting the utilization of incompatible wild Arachis species in peanut breeding programs. Moreover, the in situ embryo rescue technique showcased in this study holds promise for application in other plant species characterized by post-zygotic cross-incompatibility.