Apomixis at high resolution: unravelling diplospory in Asteraceae

Abstract

Apomictic plants are able to produce clonal seeds. This reproductive system allows the one-step fixation of any valuable trait for subsequent generations and would pave the way for a revolution in the agricultural system. Despite this, the introduction of apomixis in sexually reproducing crops has been hampered due to the difficulty in characterizing its genetic regulation. In this study, we described the high-resolution characterization of apomeiosis in the apomictic model species Erigeron annuus, Chondrilla juncea, and Taraxacum officinale. We showed that apomeiosis differs from meiosis in a few critical steps, including homologous chromosome synapsis and segregation during meiosis I. We then compared megasporogenesis in three T. officinale genetic backgrounds, showing that diplospory is superimposed on the sexual pathway without severely altering the expression of crucial meiotic genes. Our findings will contribute to the identification of pivotal players controlling this intriguing asexual reproductive strategy.

Keywords: Apomixis; clonal progeny; diplospory; megasporogenesis; meiosis; nuclear restitution; ovule; plant reproduction.