IdentificaÃÃo e caracterizaÃÃo molecular de duas b-1,3 glucanases em carica papaya

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Brazil is the largest producer of Carica papaya in the world. Besides the economical importance of this crop it has a very important social role since it is produced all year long, generating new jobs annually. The discrete position of papaya fruit on the exportation market of fresh fruit in Brazil is due to fruit fragility and diseases after harvest, which makes the fruit inappropriate for exportation. The control of postharvest diseases of papaya fruit has been accomplished almost exclusively by mean of fungicides dip or drench after harvest. Due to increasing concerns with fungicide toxicity and development of resistance by pathogens most chemicals used for the control of papaya postharvest diseases have been withdrawn from the market. The search for quality associated to lower costs and environment safety concerns have directed efforts to search for new control alternatives such as the use of hot bath, irradiation (gama and UV) and natural compounds. In general, plants respond to attack of pathogenic microorganisms by the induction of expression of a large number of genes, which controls the expression of many proteins among which are the chitinases and the β-1,3-glucanases. The objective of the present study was, therefore, to determine if the gene of β-1,3-glucanase is present in the genome of C. papaya. Using Polymerase Chain Reactions, it was possible to amplify, identify and clone two different types of β-1,3-glucanases. Based on the sequence analysis of the protein, it was possible to construct a phylogenetic tree and to predict the secondary and tertiary structure of these proteins. The identification of these two distinct types of β-1,3-glucanases is, probably, explained by the fact that either these could be different alleles of the same gene, be different genes or it could be both. Other facts may contribute for the existence of these distinct types of the same enzyme in C. papaya. First, the necessity of a high expression level of the enzyme in the plant or differential localization of the expression in the plant. Considering that in many plant pathogen systems β-1,3-glucanases are involved in resistance to diseases, knowing the gene sequence of these enzymes could help to produce transformed papaya with high level of resistance against fungi. This could increase fruit quality and shelf life, reducing losses and increasing growers profit

ASSUNTO(S)

biologia molecular protein structure -1,3 - glucanases -1,2 glucanases resistÃncia pcr resistance carica papaya estrutura protÃica β β pcr carica papaya

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