Contribution of the LeGAMYB1/microRNA 159 pathway in the regulation of development of lateral organs and fruit formation in tomato (Solanum Lycopersicum) cv micro

Abstract

The formation and development of axillary buds are considered very important factors that determine plant architecture, affecting the biomass and inflorescence number. The transition from inactive stage for active stage of development of lateral bud is a highly complex and organized process, and includes changes on the phytohormones perception (auxin, cytokinin, gibberellin and strigolactone), response to environmental conditions (luminosity and temperature) and modifications on the expression of some genes. In the last years, researches have tried to elucidate the role of genes during the formation and development of lateral branches in several species. The gibberellic acid (GA), when is biologically active, acts like an important regulator associated with several factors related to growth and development, including, seeds germination, stem elongation, leaves expansion, start of flowering and fruit development. GA is also important for axillary bud outgrowth after dormancy release. The transcription factor GAMYB, which responds to GA signal, was firstly described in aleurone cells from barley. Since then, it has been studied the role of this gene in several processes of physiological importance. Interestingly, GAMYB gene is regulated post-transcriptionally by the microRNA 159 (miR159). MiRNAs are a group of small no coding RNAs (21-22 nt) that act regulating post-transcriptionally genes in plants and animals. The miR159 expression in axillary buds of sugarcane (Ortiz-Morea et al., submitted) suggests strongly that this miRNA hasa relevant role during the process of differentiation of these tissues. Considering the information available about the GAMYB gene on different and important physiological factors, and also because the negative correlation with miR159 and because both are expressed in axillary buds, the objective of this work is to investigate through the analysis of transgenic plants of tomato (Solanum lycopersicum) cv Micro, the contribution of the gene regulation pathway of LeGAMYB1 and miR159 during the outgrowth and development of lateral organs, and also to assess the participation of this pathway on the formation and development of fruits. (AU)