Functional identification of Medicago truncatula MtRAV1 in regulating growth and development

Related to ABI3 and VP1 (RAV) transcription factors belong to the AP2 and B3 superfamily. RAVs genes have been reported to be involved in plant growth and development regulation. This study screened three RAV genes from Medicago truncatula and named one of them MtRAV1. The MtRAV1 overexpressing plants exhibits traits such as plant dwarfing, delayed flowering, reduced leaf and floral organs, increased branching, and reduced pods and seeds. Gene expression analysis results showed that overexpression of MtRAV1 inhibited the expression of Flowering Locus T (MtFTa1), Suppressor of Overexpression of CO 1 (MtSOC1), GA3-oxidase1 (MtGA3OX1), DWARF14 (MtD14) and Carotenoid Cleavage Dioxygenase 7 (MtCCD7). To further investigate the regulation pathway involved by MtRAV1, RNA-sequencing (RNA-seq) and DNA affinity purification sequencing (DAP-seq) analysis were conducted. RNA-seq results indicated that MtRAV1 might affect plant growth and development by regulating some genes in photosynthesis, circadian rhythm and plant hormone signaling pathways, especially the auxin signaling pathway. Conjoint analysis of DAP-seq and RNA-seq revealed that MtRAV1 might inhibit the expression of Ferredoxin (MtFd-l3), Light-harvesting Chlorophyll a/b Binding Protein 1 (MtLhcb-l2) and Small Auxin Up-regulated RNA (MtSAUR-l), which related to photosystem II and auxin signaling pathway. Summarily, MtRAV1 was preliminarily proven to be a key growth inhibitory factor in M. truncatula.