A study of male fertility control in Medicago truncatula uncovers an evolutionarily conserved recruitment of two tapetal bHLH subfamilies in plant sexual reproduction

What is it about?

In our study, we first characterized the M. truncatula anther development and then analyzed the empty anther1 (ean1), which is the first reported male-sterile mutant in Medicago. Cloning of the EAN1 reveals that it encodes a bHLH transcription factor, appearing to be the first key regulator of the tapetum degeneration characterized from legume species in general. We classified all the reported tapetum related bHLHs into two subfamilies, II and III(a+c)1, and EAN1 belongs to the subfamily II. We proposed that both II and III(a+c)1 bHLHs are core components in tapetum degradation and are evolutionarily conserved. The present study provided an over view of the phylogenetic distribution of tapetum, and the two tapetal associated bHLH subfamilies in plant kingdom. These may provide clues to understand the origin and evolution of sexual reproduction in plant kingdom.

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