Role of sucrose hydrolysing enzymes in flooding tolerance in Brachiaria species

A pot culture experiment was conducted to assess the role of sucrose hydrolysing enzymes on flooding tolerance in Brachiaria mutica (tolerant) and B. brizantha (intolerant). Sucrose synthase activity in roots increased two fold in B. mutica and reduced to half the value in B. brizantha under flooding. Sucrose synthase activity in leaves decreased in both the species while α-amylase activity increased two fold in B. mutica and 40% in B. brizantha under flooding. Acid invertase activity increased while alkaline invertase activity decreased in roots of both the species under flooding. Levels of reducing sugars were lower in B. mutica roots than in B. brizantha roots under normal condition and increased three fold in B. mutica under flooding. Sucrose concentration increased three fold in roots under flooding in both the species. Levels of sucrose in leaves also increased under flooding in both the species. Accumulation of sugars in roots under flooding condition indicates that carbohydrate supply is not a limiting factor in anaerobic metabolism. Further, increased activity of sucrose synthase in B. mutica roots under flooding may have an important role in adaptation to flooding. representing a greater capacity to utilise sucrose in anaerobic tissue.