Effects of gibberellin deficiency in the root-shoot adjustments during water deficit in tomato plants

• Ano de defesa: 2017
• Autor(a) principal: Garcia, Rebeca Patricia Omena
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Plantas - Crescimento; Hormônios vegetais; Giberelinas; Análise foliar; Raízes; Deficiência hídrica; Fisiologia Vegetal
• Link de acesso: https://locus.ufv.br//handle/123456789/27562

Gibberellins (GAs) belong to a class of plant hormones with multiple functions in the regulation of physiological processes associated with growth and development. It has been suggested that GAs also play an important role for plant tolerance to a range of adverse conditions. Especially on water deficit, little is known about the physiological and metabolic implications of changes in the endogenous GAs levels in plants. GAs are synthesized in young and actively growing organs in both leaves and roots being able to act locally or be transported to other tissues or organs. For a better understanding of the GAs effects on growth and tolerance to water deficit distinct experimental approaches were adopted. The first approach aimed to identify the physiological and metabolic effects of reduced GAs levels in tomato mutant plants, defective in GA biosynthesis, exposed to water deficit. The second approach aimed to understand the role of GA in root growth, morphology and primary metabolism, while the third approach aimed at understanding the regulation of organ growth through long-distance traffic of signaling molecules by conducting vessels in GA-deficient plants. The results presented in this thesis provided new information for the current knowledge involving GAs such as: (i) GA content promotes acclimatization and tolerance to water deficiency by altering the metabolism of proline and directing the biomass partitioning to the roots, maintaining leaf turgor; (ii) GAs alter the metabolism of amino acids and organic acids promoting greater root growth compared to shoot suggesting that root growth and primary metabolism is decoupled from shoot in GA deficient plants; (iii) shoot and root growth is reversed in scions and rootstocks mutant probably due to long-distance signals transport between these organs, and the GAs mobility may be strongly involved. Thus, the results presented here demonstrate that GAs are involved not only in regulating plant growth as a whole but also in stress responses.