CHARACTERIZATION OF AN MESSENGER-RNA ENCODING A POLYGALACTURONASE EXPRESSED DURING POD DEVELOPMENT IN OILSEED RAPE (BRASSICA-NAPUS L)

Pod shatter in oilseed rape is associated with the degradation of the pectin-rich middle lamella at the site of dehiscence. It has been repo rted that, accompanying pod development, there is an increase in the a ctivity of polygalacturonase (EC 3.2.1.15) and that this rise is restr icted to the tissue undergoing cell separation, Using a PCR strategy a fragment of a polygalacturonase encoding an mRNA that is up-regulated specifically in the dehiscence zone tissue during pod development has been cloned. A full length clone (SAC66) complementary to this mRNA h as been isolated from a dehiscence zone cDNA library and sequenced. Th e mRNA encoded by SAC66 shares significant amino acid homology with en dopolygalacturonases from fruit of Actinidia deliciosa and Lycopersico n esculentum. The transcript size of the SAC66 mRNA is 1.7 kb. Norther n analysis has revealed that expression of SAC66 mRNA increases at 30 d after anthesis (DAA), reaching a plateau at 45 DAA, and that the up- regulation is restricted to the site where dehiscence takes place.