4D confocal image analyses of floral meristems from genotypes with modified activity of miR156-regulated and GA-controlled pathways

• Grant number: 18/13316-0
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: September 01, 2018
• End date: February 28, 2019
• Field of knowledge: Biological Sciences - Genetics - Plant Genetics
• Principal Investigator: Fabio Tebaldi Silveira Nogueira
• Grantee: João Paulo de Oliveira Corrêa
• Supervisor: Robert Werner Marin Sablowski
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Institution abroad: John Innes Centre, England
• Associated to the scholarship: 16/05073-4 - Study of the role of pathways regulated by microRNA156 in the control of early ovary development in tomato (Solanum lycopersicum L.) by transcriptional and post-translational mechanisms, BP.DR

Abstract

The study of fruit development concerns the understanding of a broad number of processes that range from the transition of a vegetative to a floral meristem to the final ripening. Genetic processes that regulate even the earliest stages of fruit development determine characteristics of the fully developed fruit. In tomato, a fleshy fruit species, mutations that lead to increased floral meristem size have already been associated with the production of fruits with increased size and number of locules. Our preliminary data shows that plants with alterations in the miR156/SBP- and gibberellin(GA)-associated pathways produce fruits with similar alterations in fruit development. p35S:MIR156 (156OE) plants and procera (pro, SlDELLA loss of function mutant) produce fruits with increased number of locules and undetermined growth. The undetermined growth is characterized by fruit-like structures growing from the stylar end of the fruit. Both 156OE and pro closed buds showed increased expression of GOBLET (GOB), which controls organ boundary establishment. Fruits produced from the double mutant 156OEpro show extremely modified fruits, with amorphous shape and numerous fruit-like structures growing from the fruit. This suggests an additive effect of GA and miR156 pathways in controlling ovary development through separate pathways that converge in the regulation of common target genes. Primordia of fruit-like structures are detectable at very early stages of ovary development, before ovaries are formed. Altered locule number is also determined very early in flower development, being dependent of the number of carpels that constitute the ovary. Considering that these traits are determined early in floral development, detectable modifications at the floral meristem level may be related to modified fruit structure. The aim of this project is to use 4D time lapse confocal images of flower meristems of selected genotypes to assess average cell size in the meristems, cell division rate and meristem size of each genotype. This will help us to understand how GA and miR156 pathways control early aspects of meristem and fruit development. (AU)