Mutations affecting tomato (Solanum lycopersicum L. cv. Micro-Tom) response to salt stress and their physiological meaning

• Ano de defesa: 2016
• Autor(a) principal: Sa, Ariadne Felicio Lopo de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Abscisic acid; Ácido abscísico; Ácido salicílico; Auxin; Auxina; Crescimento vegetativo/reprodutivo; Estrigolactona; Ethylene; Etileno; Flower induction; Gibberellin; Giberelina; Heterose; Heterosis; Hormônios vegetais; Indução floral; Mutant; Mutante; Plant hormones; Productivity; Produtividade; Resistance; Resistencia; Salicylic acid; Salinidade; Salinity; Senescence; Senescência; Strigolactone; Tolerance; Tolerância; Vegetative/reproductive growth
• Link de acesso: http://www.teses.usp.br/teses/disponiveis/11/11144/tde-26092016-125619/

Salinity is a challenge for crop productivity. Hence, plants exposed to saline environments reduce their vegetative and reproductive growth due to adverse effects of specific ions on metabolism and water relations. In order to cope with salinity, plants display physiological mechanisms based on three main aspects: i) source-sink relationships, ii) resource allocation and iii) alterations in endogenous hormone levels. The roles of developmental and hormonal mechanisms in salt response were investigated here. We employed mutants and transgenic tomato plants affecting different aspects of plant development and hormone response in the same genetic background (cultivar Micro-Tom). The following genotypes were used: Galapagos dwarf (Gdw), Lanata (Ln), lutescent (l), single flower truss (sft), sft heterozygous (sft/+), diageotropica (dgt), entire (e), Never ripe (Nr), epinastic (epi), procera (pro), notabilis (not), anti sense Chloroplastic carotenoid cleavage dioxygenase 7 (35S::asCCD7) and Salicylate hydroxylase (35S::nahG). Among the developmental genotypes studied, sft and l, involved in flower induction and senescence, respectively, were less affected when exposed to salt stress. Although l is considered deleterious due to its precocious senescence, it presented greater shoot biomass and leaf area during salinity. The heterozygous sft/+, whose high productivity was recently linked to an improved vegetative-to-reproductive balance, changed this balance and lowered its yield more than the control MT upon salt treatment. In the analysis of genotypes affecting hormonal status/signaling four kinds of salt responses among the genotypes were observed: i) High shoot growth in spite of high Na:K ratio presented by the strigolactone deficient and high branching CCD7 transgene; ii) High shoot growth and reduced accumulation of Na in tissues (probably due to dilution) presented by the auxin constitutive response e mutant; iii) The opposite response observed in \"ii\" presented by the low auxin sensitivity dgt mutant and iv) growth inhibition combined with reduced levels of Na and higher accumulation of K presented by the not mutant, which produces less ABA. Taken together, the results presented here points to novel developmental mechanisms, such as the promotion of moderate senescence and vegetative growth, and hormonal imbalances to be explored in the pursuing of crops resistant to salt stress.