The role of miR156-targeted squamosa promoter binding proteins in the control of shoot branching in Solanum lycopersicum L.

Abstract

The development of lateral branches is essential for determining the shoot architecture and it strongly correlates with crop yield. This process is divided in two steps: the initiation of axillary meristems (AMs) and axillary buds; subsequent axillary bud dormancy or outgrowth. Transcription factors from the Squamosa Promoter Protein Binding Protein (SPL/SBP) family are targeted by microRNA miR156 and are known to regulate several processes in plant development, including the formation of axillary meristems. In Arabidopsis, SPL9 and SPL15 negatively regulate the GRAS transcription factor Lateral Supressor (LAS), inhibiting the AM formation pathway. Results from our research group has shown that overexpression of miR156 in tomato is associated with higher branching patterns and reduced auxin response. However, shoot branching is reduced in ls mutants, even in a miR156-overexpressing background. This proposal aims to understand the molecular mechanisms of the interaction among the miR156/SPL module, transcription factors and phytohormones in the control of axillary meristems formation and bud outgrowth. (AU)