Root growth restraint can be an acclimatory response to low pH and is associated with reduced cell mortality: a possible role of class III peroxidases and NADPH oxidases

Autor(es)

Gracas, J. P. ^[1] ; Ruiz-Romero, R. ^[2] ; Figueiredo, L. D. ^[1] ; Mattiello, L. ^{[1, 3]} ; Peres, L. E. P. ^[1] ; Vitorello, V. A. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Escola Super Agr Luiz de Queiroz, BR-13416000 Piracicaba, SP - Brazil

^[2] Univ Sao Paulo, Ctr Energia Nucl Agr, CP 96, Av Centenario 303, BR-13416000 Piracicaba, SP - Brazil

^[3] Univ Estadual Campinas, Lab Genoma Func, Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Plant Biology; v. 18, n. 4, p. 658-668, JUL 2016.
• Citações Web of Science: 7

Resumo

Low pH (<5.0) can significantly decrease root growth but whether this is a direct effect of H+ or an active plant response is examined here. Tomato (Solanum lycopersicum cv Micro-Tom) roots were exposed directly or gradually to low pH through step-wise changes in pH over periods ranging from 4 to 24h. Roots exposed gradually to pH 4.5 grew even less than those exposed directly, indicating a plant-coordinated response. Direct exposure to pH 4.0 suppressed root growth and caused high cell mortality, in contrast to roots exposed gradually, in which growth remained inhibited but cell viability was maintained. Total class III peroxidase activity increased significantly in all low pH treatments, but was not correlated with the observed differential responses. Use of the enzyme inhibitors salicylhydroxamic acid (SHAM) or diphenyleneiodonium chloride (DPI) suggest that peroxidase and, to a lesser extent, NADPH oxidase were required to prevent or reduce injury in all low pH treatments. However, a role for other enzymes, such as the alternative oxidase is also possible. The results with SHAM, but not DPI, were confirmed in tobacco BY-2 cells. Our results indicate that root growth inhibition from low pH can be part of an active plant response, and suggest that peroxidases may have a critical early role in reducing loss of cell viability and in the observed root growth constraint. (AU)

• Processo FAPESP: 09/53998-3 - EMU: aquisição de sistema com plataforma para microdissecção por captura a laser aplicada em estudos de biologia celular e molecular
• Beneficiário: Tsai Siu Mui
• Linha de fomento: Auxílio à Pesquisa - Programa Equipamentos Multiusuários