Effect of drought and re-watering on fructan metabolism in Vemonia herbacea (Vell.) Rusby

Autor(es)

Garcia, Paola M. A. ^[1] ; Asega, Amanda F. ^[1] ; Silva, Emerson A. ^[1] ; Carvalho, Maria Angela M. ^[1]

Afiliação do(s) autor(es)

^[1] Inst Bot, Nucleo Pesquisa Fisiol & Bioquim Plantas, BR-01031970 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Plant Physiology and Biochemistry; v. 49, n. 6, p. 664-670, JUN 2011.
• Citações Web of Science: 24

Resumo

Vemonia herbacea (Vell.) Rusby, a native species from the Brazilian Cerrado, accumulates about 80% of fructans in the rhizophores, the underground reserve organs. Besides their role as reserve, fructans have been recognized as protective compounds against drought. This physiological function attributed to fructans seems consistent with the wide occurrence of these carbohydrates in the cerrado, a biome that undergoes seasonal drought. The aim of this work was to analyze fructan composition and the activities of the enzymes involved in fructan synthesis, sucrose:sucrose 1-frutosyltransferase (1-SST) and fructan:fructan 1-frutosyltransferase (1-FFT), and depolymerization, fructan 1-exohydrolase (1-FEH) in plants submitted to water suppression. The plants were divided into 3 groups receiving 3 treatments: daily watering (control), water suppression for 23 days (WS) and re-watering after 15 days (RW). Samples were taken at the beginning of the experiment (Time 0) and after 3, 7, 11, 15, 17 and 23 days of water suppression. 1-SST and 1-FFT activities increased at the beginning of the water restriction period, coinciding with a decrease in 1-FEH activity, the onset of the reduction in soil water potential and in leaf water potential. Increases in 1-FEH and invertase activities led to a high yield of reducing sugars at the 23rd day after water suppression, and together with 1-FFT, 1-FEH also seemed to act in the redistribution of fructan molecules after re-watering. The increase in reducing sugars and in the fructo-oligo:fructopolysaccharide ratio were associated to the maintenance of rhizophore turgor. Considering that WS plants showed changes in fructan metabolism that favored water retention and absorption after rewatering, the occurrence of osmotic adjustment mechanisms is suggested, reinforcing the hypothesis of fructans as protective agents against abiotic stresses, such as drought. (C) 2011 Elsevier Masson SAS. All rights reserved. (AU)

• Processo FAPESP: 05/04139-7 - Carboidratos de plantas tropicais como moduladores de processos ecofisiológicos e indicadores de respostas a estresses ambientais
• Beneficiário: Marcia Regina Braga
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 06/58722-8 - Variacoes no metabolismo de frutanos em vernonia herbacea (vell.) rusby (asteraceae) em resposta ao deficit hidrico e sua relacao com a tolerancia a seca.
• Beneficiário: Paola Mitie Aparecida Garcia
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 09/01570-0 - Relações hídricas e respostas ao déficit hídrico em espécies da Mata Atlântica e do Cerrado: mecanismos de manutenção do status hídrico.
• Beneficiário: Emerson Alves da Silva
• Modalidade de apoio: Auxílio à Pesquisa - Regular