Abstract
A qualidade de sementes está associada à soma dos atributos genéticos, físicos, fisiológicos e sanitários que afetam sua capacidade para realizar as funções vitais, estando relacionada à germinação, ao vigor e à longevidade. A expressão de genes associados à qualidade fisiológica pode ser avaliada por meio de análises de germinação e vigor, e ainda pelas análises de transcritos e de proteínas em sementes. Objetivou-se com este trabalho fazer uma revisão sobre a relevância das enzimas do grupo das amilases relacionadas à qualidade fisiológica de sementes de milho. Dentro do grupo das amilases, a α-amilase (1,4-α-D-glucan-glucanohydrolase E.C 3.2.1.1) é uma enzima importante na hidrólise do amido, sendo responsável por 90% da atividade amilolítica em sementes de milho. Essa enzima, a exemplo da dextrose, causa a conversão de amido em açúcares que são utilizados no crescimento do embrião. Já a β-amilase (1,4-α-glucan maltohydrolase E.C 3.2.1.2) é uma α-1,4-D-glucano maltohidrolise que catalisa a liberação de maltose e dextrinas a partir das extremidades não redutoras do amido. Pesquisas comprovam que as enzimas amilases estão ligadas diretamente à qualidade fisiológica de sementes de milho. A α-amilase e a β-amilase estão envolvidas principalmente no processo de germinação e na heterose das sementes, podendo ser também utilizadas como marcadores moleculares relacionadas à tolerância de secagem das sementes.
Highlights
Maize (Zea mays) is a crop of great economic importance, and an important component of both domestic and international agricultural markets
Seed physiological quality is influenced by genotype, environment, and interactions among them (JOSÉ et al, 2004a; MEYER et al, 2012; ANDRADE, 2015), and genotype assessment is important component of the seed selection process in breeding programs
It constitutes a family of endoamylases that catalyze the hydrolysis of glycosidic linkages between α-1.4 starch, glycogen, and other carbohydrates (FRANCO et al, 2002). β-amylase is an α-1.4-D-glucan maltohydrolase (EC 3.2.1.2.) is synthesized during the seed development process (OLIVEIRA, 2013), and catalyzes the release of maltose and dextrins from the non-reducing ends of starch These two enzymes are known to be related to seed quality, studies of gene expression in these enzymes my help us to better understand their genetic behavior, and may assist in breeding programs focused on seed physiological quality
Summary
Maize (Zea mays) is a crop of great economic importance, and an important component of both domestic and international agricultural markets. Β-amylase is an α-1.4-D-glucan maltohydrolase (EC 3.2.1.2.) is synthesized during the seed development process (OLIVEIRA, 2013), and catalyzes the release of maltose and dextrins from the non-reducing ends of starch These two enzymes are known to be related to seed quality, studies of gene expression in these enzymes my help us to better understand their genetic behavior, and may assist in breeding programs focused on seed physiological quality.
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