ABSTRACT. The reduced longevity of coffee seeds has been attributed to their sensitivity to desiccation. Studies related to gene expression and enzyme activity in coffee seeds under drying are important for understanding the effects of drying on their physiological quality. The aim of this study was to investigate the molecular aspects of seeds under different drying methods and associate them with physiological quality. Coffee seeds with different water contents were dried both slowly and rapidly. Enzymatic activity was analysed, as well as the expression of genes that encode the enzymes superoxide dismutase, catalase, peroxiredoxins, isocitrate lyase, and endo-ß-mannanase. There was a significant effect of drying speed and final water content on enzyme activity and on the expression of the different genes analysed. In seeds under rapid drying, there was greater expression of the genes that encode the enzymes catalase and endo-ß-mannanase. Greater expression of the 1 CYS PRX and SOD genes and greater activity of the ICL isoenzymes were found in seeds with superior physiological quality, but greater activity of the endo-β-mannanase and CAT enzymes occurred in seeds with lower physiological quality.

O objetivo deste trabalho foi avaliar a concentração de ricina em sementes de mamona (Ricinus communis L.) de 20 acessos do Banco de Germoplasma de Mamoneira da Embrapa Algodão, por meio de ensaio imunoabsorvente de ligação de enzimas. Foram observadas diferenças significativas entre os acessos. O BRA 3271 apresentou a maior concentração de ricina nas sementes (32,18 ng µg-1), e o BRS Paraguaçu a menor (3,53 ng µg-1). Há possibilidade de seleção de genótipos com diferentes concentrações de ricina, que poderão ser utilizados dependendo do interesse dos programas de melhoramento.

The objective of this work was to evaluate ricin concentration in castor bean seeds (Ricinus communis) of 20 accessions from the Banco de Germoplasma de Mamoneira of the Embrapa Algodão, Campina Grande, PB, Brazil, using the Enzyme Linked Immunosorbent Assay. Significant differences were observed among accessions. BRA 3271 had the highest ricin concentration in seeds (32.18 ng µg-1), and BRS Paraguaçu had the lowest (3.53 ng µg-1). There is the possibility of selecting genotypes with different ricin concentrations, which can be used according on the interest of the breeding programs.