Cloning and Sequence Analysis of Endopolygalacturonase Genes in Venturia nashicola and Venturia pirina

Abstract

Genes encoding endopolygalacturonase (endoPG) were isolated from pathogens of the Asian pear scab, Venturia nashicola races 1, 2, 3, and 4, and European pear scab, V. pirina. The Vnpgr1 gene of the V. nashicola race 1 consists of a 1,116-bp open reading frame, encoding a protein of 372 amino acids with an estimated molecular mass of 37.5 kDa and an isoelectric point (pI) of 6.56. The sequences of Vnpg genes from different races and Vppg gene from V. pirina showed high identities (95-100%). The deduced amino acid sequence of the V. nashicola race 1 endoPG showed 63-68% identity to the endoPG sequences of Penicillium olsonii, Colletotrichum lindemuthianum, Cryphonectria parasitica, Fusarium oxysporum, Sclerotinia sclerotiorum, and Alternaria citri. The deduced amino acid sequence of the race 1 endoPG was identical to the N-terminal amino acid sequence of the previously purified endoPG enzyme from the mycelia of this race. The results of a southern blot analysis indicated that V. nashicola race 1 (isolate JS-115) had a single copy of the Vnpgr1. Restriction fragment length polymorphism (RFLP) analysis of the polymerase chain reaction (PCR) products of the endoPG gene digested with HincII, BspEI, and BsrGI was performed; thereafter, agarose gel electrophoresis yielded race-specific RFLP patterns.