Asexual reproduction through seeds has been engineered in rice (a plant that normally reproduces sexually), reports a paper published online in Nature this week. These findings demonstrate the feasibility of asexual reproduction in crops and could represent a significant development in agricultural plant breeding.
Asexual reproduction through seeds occurs naturally in many plant species, but not in the important crop species. Inducing asexual reproduction in crop plants could help promote desired genetic traits in breeding programmes, and enhance so-called ‘hybrid vigour’ (first generation hybrid plants with increased vigour). Hybrids can result in higher crop yields due to greater genetic variety. However, the process that triggers the generation of embryos post-fertilization is not well understood in plants.
Venkatesan Sundaresan and colleagues investigated the feasibility of breeding rice (Oryza sativa) via asexual reproduction through seeds. First, the authors identified that the gene BABY BOOM1 (BBM1), carried by sperm cells, is key to the production of embryos, even in the absence of fertilization. The authors then used CRISPR/Cas-9 genome editing to eliminate meiosis (cell division that produces reproductive cells) in rice strains that expressed BBM1 in egg cells. These strains were able to reproduce asexually and the so-called Synthetic-Apomictic (S-Apo) strain produced clonal, hybrid offspring with desired genetic diversity. The traits for asexual reproduction persisted through two further generations of S-Apo rice.