De novo shoot organogenesis and leaf development in Passiflora edulis Sims.: a morpho-physiological and molecular approach

• Ano de defesa: 2019
• Autor(a) principal: Fernandes, Amanda Mendes
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Análise foliar; Morfogênese; Hormônios vegetais; Botânica - Morfologia; Fisiologia Vegetal
• Link de acesso: https://locus.ufv.br//handle/123456789/27683

Leaf development is a coordinate process that involves a plethora of events and signaling molecules. Passiflora edulis Sims is a tropical herbaceous plant and one of the most economically important species of the family Passifloraceae. P. edulis presents a dramatic change in leaf morphology during its development, which distinguishes the juvenile from the adult phase. Although some studies have characterized leaf morphology and some molecular aspects associated with developmental events, there is still a lot to be clarified in the scope of leaf morphogenesis in this species. Therefore, this study aimed to reveal morpho-physiological and molecular mechanisms modulating leaf development and shoot organogenesis in P. edulis. The first chapter evaluated the influence of regulators added to the culture media on morphogenesis and the expression of the miR156/SPL pathway in P. edulis leaves induced in vitro. As a result, we found that phytohormones modulate in vitro responses of cotyledonary, leaf, apical and nodal explants and that for greenhouse-grown plants, the late physiological condition in leaf explants is a limiting factor for inducing organogenic responses. Also, we produced evidence that the cytokinin:auxin balance up-regulated the expression of miR172, suggesting that this gene is regulated by multiple hormones. The second chapter investigated the effect of cytokinin on the expression of miRNAs and SPL9 and their impact on organogenesis of cotyledonary explants of P. edulis. The results achieved in this study point BA as an inhibitor of the expression of miR319 and miR164; thus, we propose a novel link between cytokinin and miR164 as a key regulatory output of cytokinin in the regulation of SAM function. Lastly, the third chapter evaluated physiological, structural and biochemical properties of P. edulis leaves with the aid of hyperspectral and biochemical analyses. As a result, we estimated changes over the course of leaf age and development. Leaf ontogeny affected biochemical, structural and physiological parameters, and some vegetation indexes were shown to be good predictors of pigment levels in leaves of P. edulis.