Redefining the hormonal control of tomato (Solanum lycopersicum cv. Micro-Tom) fruit development

• Autor(a) principal: Achon Forno, Ignacio
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: http://www.teses.usp.br/teses/disponiveis/11/11144/tde-16082017-144059/
• topic: Desenvolvimento do fruto; Fruit development; Gene reporter GUS L.; Gene reporter GUS L.; Hormones; Hormônios; Tomate; Tomato

The hormonal control of tomato (Solanum lycopersicum) fruit development have been extensively studied, mainly during ripening. Notwithstanding, considerable gaps still exist in our understanding of the function and spatial-temporal distribution of hormones during fruit development. Here, we performed histochemical analysis of tomato cv. Micro-Tom transgenic lines harboring the gene reporter GUS fused to five different promoter responsive to the hormones, auxin, cytokinins (CKs), gibberellins (GAs), abscisic acid (ABA) and ethylene, in order to redefine their spatial-temporal distribution during tomato fruit development, from early pre-anthesis stages to red ripe (RR) stage. CKs levels were high during pre-anthesis, initially in placental tissues and subsequently in ovule, indicating a major function of this hormone during pre-fertilized ovary growth. At early post-fertilization stages, CKs contents were high in seeds, and afterward in the outer and inner epidermical and subepidermical layer of pericarp. High auxin content was observed, during all pre-anthesis and fruit development stages, in pedicel, suggesting a basipetal transport to the mother plant. Ethylene contents increased during pre-anthesis ovary growth. Interestingly, ethylene contents did not decrease, immediately, post-fertilization. The content of GAs and ABA was low at pre-anthesis and early post-fertilization stages, specific in placental tissues and pericarp. Conversely, these hormones accumulated mainly during cell expansion phase of fruit growth. Pollen grains that reached the stigma, post anther dehiscence, showed high content of auxin and ABA. In addition, we reported an antagonism between ethylene and GAs contents during tomato fruit development, where the level of ethylene started to decrease during the cell expansion phase of the fruit growth, moment when the level of GAs started to increase in placental tissues and pericarp.