The SINGLE FLOWER (SFL) gene encodes a MYB transcription factor that regulates the number of flowers produced by the inflorescence of chickpea

Abstract

SUMMARYresearch conducted & rationaleLegume species usually have compound inflorescences, where flowers appear in secondary inflorescences (I2), at lateral positions of the primary inflorescence (I1), in contrast to simple inflorescences, as in Arabidopsis, where flowers are formed in the primary inflorescence stem. The number of flowers per I2, characteristic of each legume species, determines inflorescence diversity, and the number of pods produced, which can affect yield. Gene Regulatory Network that controls the activity of I2 meristems, and therefore the number of flowers per secondary inflorescence is mostly unknown, as well as how specific are factors controlling this trait and whether they share this function in other meristems.methodsChickpea produces one flower per I2 but single flower (sfl) mutants produce two (double-pod phenotype). By mapping the sfl-d mutation and identification and analysis of a second mutant allele we have isolated SFL. We used scanning electron microscopy to study the effect of sfl mutations on inflorescence ontogeny and in situ hybridization to study the expression of SFL and of meristem identity genes in the developing chickpea inflorescence.key resultWe show that the SFL gene corresponds to CaRAX1/2a, encoding a MYB transcription factor. Our results show that CaRAX1/2a / SFL is specifically expressed in the I2 meristem, possibly activated by CaVEGETATIVE1.main conclusion & key points for discussionOur findings reveal that SFL plays a central role in the control of chickpea inflorescence architecture, specifically acting in the I2 meristem to control the time length for which it is active, and therefore determining the number of floral meristems that it can produce.