RH17 acts in repression of reproductive fate and autonomous seed coat development in sexual Arabidopsis

Plant sexual and asexual reproduction through seeds (apomixis) is tightly controlled by complex gene regulatory programs. These are to date not fully understood. Recent findings suggest that RNA helicases are required for plant germline development. This resembles their crucial roles in animals, where they are involved in controlling gene activity and the maintenance of genome integrity. Here we identified novel roles of Arabidopsis RH17 during reproductive development. Interestingly, RH17 is involved in repression of reproductive fate and of elements of seed development in the absence of fertilization. In lines carrying a mutant rh17 allele, development of supernumerary reproductive cell lineages in the female flower tissues (ovules) was observed, occasionally leading to formation of two embryos per seed. Furthermore, seed coat and putatively also endosperm development frequently initiated autonomously. Such induction of several features phenocopying distinct elements of apomixis by a single mutation is rather exceptional and suggests that RH17 acts in regulatory control of plant reproductive development. In longer terms, an in depth understanding of its action might provide a basis for harnessing for agricultural applications.