Engineering apomixis in crops

Abstract

Apomixis is an asexual mode of reproduction through seeds where progeny are clones of the mother plants. Naturally apomictic modes of reproduction are found in hundreds of plant genera distributed across more than 30 plant families, but are absent in major crop plants. Apomixis has the potential to be a breakthrough technology by allowing the propagation through seed of any genotype, including F1 hybrids. Here, we have summarized the recent progress toward synthetic apomixis, where combining targeted modifications of both the meiosis and fertilization processes leads to the production of clonal seeds at high frequencies. Despite some remaining challenges, the technology has approached a level of maturity that allows its consideration for application in the field.

Fig. 1

Engineering apomeiosis and parthenogenesis. Mutations in three meiotic genes (MiMe) alter crucial stages of meiosis to result in a mitotic-like division of chromosomes, mimicking and providing a tool to implement apomeiosis (A). Embryogenesis in many plants results from fertilization of the female-derived ovule and central cell by the male-derived pollen to give rise to a diploid zygote and triploid endosperm (B, left). Prior to fertilization, BBM1 and PAR are expressed in the male gamete; redirecting their expression to the ovule can result in the formation of haploid zygotes (B, right). Alternatively, mutations in MTL/PLA1/NLD, DMP, or CENH3 can hinder fertilization by disrupting one parental gamete contribution, and can produce haploid zygotes (C). By pairing MiMe with male expressed BBM1/PAR or mutations in MTL/PLA1/NLD, DMP, or CENH3, clonal progeny can be obtained that represent synthetic apomicts (D). Figure created with BioRender.com