Tomato genotypes with contrasting cadmium (Cd) tolerance and their reciprocal grafts: Cd uptake, accumulation, and evaluation of biochemical, molecular, and physiological parameters

• Ano de defesa: 2021
• Autor(a) principal: Marques, Deyvid Novaes
• 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: Solanum lycopersicum; Abiotic stresse tolerance; Antioxidantes; Antioxidants; Cadmium uptake kinetics; Cinética de absorção de cádmio; Enxertias recíprocas; Expressão gênica; Fitoquelatinas; Food security; Fosfoproteômica; Gene expression; Heavy metals; Metais pesados; Phosphoproteomics; Phytochelatins; Proteômica; Proteomics; Reciprocal grafting; Segurança alimentar; Tolerância a estresses abióticos
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/11/11144/tde-04082021-125829/

Cadmium (Cd) is a heavy metal whose concentration has increased considerably over the last few decades in several countries (due to anthropogenic activities). This metal is potentially harmful to human health and plants, and is one of the most threatening contaminants to the environment. However, there are few studies that deal with the development of management strategies to reduce the Cd contamination of edible parts of plants, in line with the understanding of the roles played by root and shoot in the tolerance pattern, as well as focusing on related endogenous mechanisms. Even though studying genotypes with contrasting Cd tolerance is able to reveal important contrasts related to Cd tolerance, accumulation and uptake, there is a lack of studies focused on reciprocally grafted tomato plants regarding Cd tolerance (that is, Cd-tolerant and Cd-sensitive genotypes grafted with each other as rootstock or scion). Here, we performed a study on grafted tomato plants using tomato genotypes with contrasting Cd tolerance. For the present work, reciprocal grafting between tolerant and sensitive tomato genotypes was used as a unprecedented tool, in order to provide a first insight into the organ-tissue-specific contribution of the tomato genotypes to Cd tolerance mechanisms, uptake and accumulation at early stages of exposure to Cd. We studied the Cd uptake kinetics of the tomato genotypes. Further, we studied enzymatic antioxidant responses in tomato plants. Evaluations of six antioxidant enzymes were performed in addition to the study of Cd accumulation, oxidative stress, bioconcentration factor, phytochelatin synthesis, expression of genes encoding phytochelatin synthases and root transporters, nutrient status and plant growth evaluations. The results showed that, compared with seedlings grafted onto the sensitive root, seedlings grafted onto the tolerant one showed lower Cd uptake, accumulation, and higher efficiency of the enzymatic antioxidant system in response to Cd exposure, in addition to higher concentrations of PCs in roots. Finally, we evaluated the chlorophyll content, proteome and phosphoproteome in leaves of grafted tomato plants. The results provide early evidence for the positive influence of the root system of a tolerant cultivar on the Cd-exposed tomato proteome coupled to Cd-induced phosphoproteomic responses in grafted tomato at an early stage of plant exposure.