Catabolismo de sacarose durante a mobilização do galactomanano e sua importância na estratégia de sobrevivência de plântulas de Sesbania virgata (Cav.) Pers.

Abstract

Catabolismo de sacarose durante a mobilização do galactomanano e sua importância na estratégia de sobrevivência de plântulas de Sesbania virgata (Cav.) Pers.Fábio Reis Dalle Molle 1 e Marco Aurélio Silva Tiné 2,3 Recebido: 14.08.2008; aceito: 16.04.2009 ABSTRACT -(Sucrose catabolism during galactomannan mobilisation and its importance in the survival strategy of Sesbania virgata (Cav.) Pers. plantlets). Seeds of Sesbania virgata have galactomannan as a storage polysaccharide in the endosperm. During mobilization, the degradation products are assimilated by the cotyledons which later supply this carbon source to the embryo. Sucrose is of prime importance in this source and sink relation between the organs. In the present work, the importance of the storage galactomannan in the establishment of plantlets of Sesbania virgata was investigated following the study of survival of plantlets with or without endosperm, as well as the diuturnal variations of the sucrose catabolism enzymes activity. The plantlets grown in the darkness with endosperm survived 16 days longer than the plantlets without the storage organ. Independent variations among the enzymes were detected, suggesting that the different enzymes are engaged in different physiological processes and, although sucrose is their common substrate, they take part in independent metabolic pathways. Key words: invertase, source-sink relations, storage, sucrose synthase RESUMO -(Catabolismo de sacarose durante a mobilização do galactomanano e sua importância na estratégia de sobrevivência de plântulas de Sesbania virgata (Cav.) Pers.). Sementes de Sesbania virgata possuem galactomanano como polissacarídeo de reserva no endosperma. Durante a mobilização, os produtos de degradação são absorvidos pelos cotilédones que, posteriormente, fornecem esse carbono ao eixo embrionário. A sacarose tem um papel fundamental nesta relação de fonte e dreno entre os órgãos. Neste trabalho, a importância da reserva de galactomanano no estabelecimento das plântulas de Sesbania virgata foi investigada através de estudo de sobrevivência de plântulas com e sem endosperma, assim como as variações diuturnas na atividade das enzimas de catabolismo de sacarose. As plântulas crescidas no escuro com endosperma sobreviveram 16 dias a mais que as plântulas sem endosperma. Foram observadas variações independentes entre as enzimas, sugerindo que as diferentes enzimas participam de diferentes processos fi siológicos e, embora tenham a sacarose como substrato em comum, participam de vias metabólicas independentes. Palavras-chave: invertase, relações fonte-dreno, reserva, sacarose sintase

Activities of α-galactosidase and polygalacturonase during hydration of Dalbergia nigra ((Vell.) Fr All. ex Benth.) seeds at different temperatures

“…The oligosaccharides of the raffinose family are reserves for rapid use, being the first to be mobilized by plants and used as an energy source during germination (Buckeridge et al, 2000;Molle and Tiné, 2009). The degradation of the oligosaccharides of the series results in a temporary accumulation of glycose and galactose in the cotyledons.…”

“…The germination process is a complex and ordered series of physiological and biochemical events, starting with renewed embryo growth and the subsequent rupture of the integument by the radicle (Nonogaki et al, 2007).…”

Germination and initial development of forest species under the action of catechin, presents in seeds of Sesbania virgata (Cav.) Pers. (Fabaceae)

“…Pers. (Fabaceae-Faboideae) is a fast-growing pioneer shrub native to South America (Molle & Tiné 2009), and found in south, southeast, and central-west Brazil, mainly in the Atlantic Forest and Cerrado biomes (Florentino et al 2009). The species has fast germination rates, high development index, and high ground cover potential (Coutinho et al 2005, Zanandrea et al 2009.…”