Functional characterization of the mitochondrial adenine nucleotide transporter (ADNT1) in Arabidopsis thaliana under dark-induced senescence

• Ano de defesa: 2013
• Autor(a) principal: Pereira, Paula da Fonseca
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: ADNT1; Arabidopsis thaliana; Senescência Induzida; Ciências Biológicas
• Link de acesso: http://www.locus.ufv.br/handle/123456789/9925

Unlike other ADP/ATP carriers, ADNT1 is the only one that mediates an antiport of ATP, AMP, and, to a lesser extent, ADP and the corresponding deoxyadenine nucleotides. Previous work observed that ADNT1 expression is much stronger in root tips and senescing tissues. Considering the high expression of ADNT1 in senescing tissues, we have investigated the role of ADNT1 during the process of dark-induced senescence. Under these conditions, Arabidopsis thaliana mutants deficient in the expression of ADNT1 transporter displayed a similar, yet milder, early onset of senescence as evidenced both by the visual phenotype of plants following growth in extended periods of darkness and the loss of chlorophyll and photosynthetic competence. The extended dark treatment led in general to a more rapidly decline in the mutants than in the wild type in the levels of sucrose and protein. By contrast, the levels of total amino acids and TCA cycle intermediates malate, fumarate and isocitrate generally increased significantly in the mutants at the end of dark treatment. The NADH/NAD + and NADPH/NADP+ ratios also increased in mutants in comparison to the wild type with progression of the darkness. Additionally, the mutant plants exhibited symptoms of early senescence in comparison to the wild type even under optimal conditions. Altogether the data obtained demonstrate that ADNT1 is not functionally redundant to the previously characterized ADP/ATP carriers, especially during carbon starvation and reinforce the potential function for ADNT1 in the provision of energy which is required to support growth in heterotrophic plant tissues.