Biochemical and histological characterization of tomato mutants

Abstract

Neste trabalho, analisamos as respostas bioquímicas inerentes ao sistema antioxidante, assim como propriedades morfológicas e anatômicas de mutantes fotomorfogenéticos e hormonais de tomateiro. Comparados ao não mutante Micro-Tom (MT), observamos que o conteúdo de malondialdeído (MDA) aumentou nos mutantes diageotropica (dgt) e lutescent (l), enquanto os maiores níveis de H2O2 foram encontrados nos mutantes high pigment 1 (hp1) e aurea (au). Análises de enzimas antioxidantes mostraram que todos os mutantes reduziram a atividade de catalase (CAT) quando comparado a MT. A guaiacol peroxidase (GPOX) aumentou em ambos os mutantes sitiens (sit) e notabilis (not), enquanto no mutante not houve aumento da atividade de ascorbato peroxidase (APX). Baseado nas análises de PAGE, as isoformas III, IV, V e VI de glutationa redutase (GR) aumentaram nas folhas do mutante l, enquanto a isoforma III de superóxido dismutase (SOD) reduziu nas folhas dos mutantes sit, epi, Never ripe (Nr) e green flesh (gf). Análises por microscopia revelaram que os mutantes hp1 e au tiveram um aumento nos espaços intercelulares de folhas, enquanto o mutante sit mostrou um decréscimo. Micrografias eletrônicas revelaram que a superfície foliar dos mutantes au e hp1 apresenta reduzida distribuição de tricomas. A caracterização destes mutantes é essencial para que possam ser utilizados em estudos de desenvolvimento e ecofisiologia, tais como estresses abióticos e bióticos no metabolismo oxidativo.

Biochemical responses inherent to antioxidant systems as well morphological and anatomical properties of photomorphogenic, hormonal and developmental tomato mutants were investigated. Compared to the non-mutant Micro-Tom (MT), we observed that the malondialdehyde (MDA) content was enhanced in the diageotropica (dgt) and lutescent (l) mutants, whilst the highest levels of hydrogen peroxide (H2O2) were observed in high pigment 1 (hp1) and aurea (au) mutants. The analyses of antioxidant enzymes revealed that all mutants exhibited reduced catalase (CAT) activity when compared to MT. Guaiacol peroxidase (GPOX) was enhanced in both sitiens (sit) and notabilis (not) mutants, whereas in not mutant there was an increase in ascorbate peroxidase (APX). Based on PAGE analysis, the activities of glutathione reductase (GR) isoforms III, IV, V and VI were increased in l leaves, while the activity of superoxide dismutase (SOD) isoform III was reduced in leaves of sit, epi, Never ripe (Nr) and green flesh (gf) mutants. Microscopic analyses revealed that hp1 and au showed an increase in leaf intercellular spaces, whereas sit exhibited a decrease. The au and hp1 mutants also exhibited a decreased in the number of leaf trichomes. The characterization of these mutants is essential for their future use in plant development and ecophysiology studies, such as abiotic and biotic stresses on the oxidative metabolism.