microRNA156-targeted SPL/ SBP box transcription factors regulate tomato ovary and fruit development

Author(s)

Ferreira e Silva, Geraldo Felipe ^{[1, 2]} ; Silva, Eder Marques ^[1] ; Azevedo, Mariana da Silva ^[3] ; Corazon Guivin, Mike Anderson ^[1] ; Ramiro, Daniel Alves ^[2] ; Figueiredo, Cassia Regina ^[3] ; Carrer, Helaine ^[2] ; Pereira Peres, Lazaro Eustaquio ^[3] ; Silveira Nogueira, Fabio Tebaldi ^{[1, 2]}

Affiliation

^[1] State Univ Sao Paulo, Inst Biociencias, Lab Mol Genet Plant Dev, BR-18618970 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Ctr Biotecnol Agr, Escola Super Agr Luiz de Queiroz, BR-13418900 Sao Paulo - Brazil

^[3] Univ Sao Paulo, Lab Hormonal Control Plant Dev, Escola Super Agr Luiz de Queiroz, Dept Biol Sci, BR-13418900 Sao Paulo - Brazil

• Document type: Journal article
• Source: Plant Journal; v. 78, n. 4, p. 604-618, MAY 2014.
• Web of Science Citations: 71

Abstract

Fruit ripening in tomato (Solanum lycopersicum L.) is well understood at the molecular level. However, information regarding genetic pathways associated with tomato ovary and early fruit development is still lacking. Here, we investigate the possible role(s) of the microRNA156/SQUAMOSA promoter-binding protein-like (SPL or SBP box) module (miR156 node) in tomato ovary development. miR156-targeted S.lycopersicum SBP genes were dynamically expressed in developing flowers and ovaries, and miR156 was mainly expressed in meristematic tissues of the ovary, including placenta and ovules. Transgenic tomato cv. Micro-Tom plants over-expressing the AtMIR156b precursor exhibited abnormal flower and fruit morphology, with fruits characterized by growth of extra carpels and ectopic structures. Scanning electron microscopy and histological analyses showed the presence of meristem-like structures inside the ovaries, which are probably responsible for the ectopic organs. Interestingly, expression of genes associated with meristem maintenance and formation of new organs, such as LeT6/TKN2 (a KNOX-like classI gene) and GOBLET (a NAM/CUC-like gene), was induced in developing ovaries of transgenic plants as well as in the ovaries of the natural mutant Mouse ear (Me), which also displays fruits with extra carpels. Conversely, expression of the MADS box genes MACROCALYX (MC) and FUL1/TDR4, and the LEAFY ortholog FALSIFLORA, was repressed in the developing ovaries of miR156 over-expressors, suggesting similarities with Arabidopsis at this point of the miR156/SPL pathway but with distinct functional consequences in reproductive development. Altogether, these observations suggest that the miR156 node is involved in maintenance of the meristematic state of ovary tissues, thereby controlling initial steps of fleshy fruit development and determinacy. (AU)

• FAPESP's process: 12/51146-2 - Functional analysis of the role(s) of microRNAs in the control of plant architecture and fruit development
• Grantee: Fabio Tebaldi Silveira Nogueira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 09/12710-7 - The role of metabolic pathways regulated by the microRNA156 in bud outgrowth
• Grantee: Geraldo Felipe Ferreira e Silva
• Support Opportunities: Scholarships in Brazil - Master