Plant architecture regulation of tomato by the pathway miR156-SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL)

Abstract

The architecture of the lateral branches of plants is an important factor that determines the agronomic field production. The formation of lateral buds and their subsequent outgrowth (branching) are key factors that control both leaf biomass production as the number of inflorescences. Interestingly, several members of gene families involved in mechanisms of formation and growth of lateral buds are targets of non-coding RNAs, suggesting that these RNAs are involved in this aspect of plant development. One such example is the family of transcription factors Squamosa (SQUA) promoter binding protein-like (SPL), in which some members are regulated post-transcriptionally by microRNA156 (miR156). MicroRNAs (miRNAs) are non-coding RNAs of 20-22 nucleotides (nt) that play a unique role in plant development, observation confirmed by phenotypic and molecular characterization of transgenic plants and mutants defective in the production of such RNAs. Overexpression of miR156 in Arabidopsis and tomato (this transgenic produced by our research group) promotes severe reduction in apical dominance, leading to increased production of lateral branches and increased biomass. While it is clear the role of miRNA in axillary branches formation, so far there are no studies which elucidate genetic pathways associated with branching altered in response to ectopic expression of miR156. Such studies may contribute not only to a better understanding of the mechanisms associated with the process of formation of lateral organs, but also have potential applications in plant breeding.