Molecular characteristics and functional analysis of the beta-1,4-endoglucanase Bm-eng-1 gene of Bursaphelenchus mucronatus (Nematoda: Aphelenchoididae)

The pine nematode Bursaphelenchus mucronatus has been associated with pine wilt in China. This work was intended to investigate the role of the pathogenicity-related beta-1,4-endoglucanase gene of B.mucronatus in the infection of pines. In this study, the full-length cDNA of the Bm-eng-1 gene was cloned and characterized from a B.mucronatus isolate. Phylogenetic analysis suggested that the Bm-eng-1 gene of B.mucronatus may be acquired from fungi through horizontal gene transfer. The function of the gene was demonstrated using RNA interference. RNA interference indicated that Bm-eng-1 was involved in the dispersal, reproductive ability and pathogenicity of B.mucronatus. In situ hybridization showed that Bm-eng-1 was specifically expressed in the oesophageal gland of B.mucronatus. Furthermore, to investigate the relation between beta-1,4-endoglucanase activities and virulence of different isolates, the beta-1,4-endoglucanase activities and the expression levels of Bm-eng-1 were detected in six B.mucronatus isolates with different virulence. beta-1,4-Endoglucanase activity was generally higher in pathogenic isolates than in non-pathogenic isolates, and the Bm-eng-1 expression levels in different isolates were positively correlated with the beta-1,4-endoglucanase activity. These findings suggested that beta-1,4-endoglucanase plays important roles in the pathogenic process of B.mucronatus, and the differential expression of the gene may underlie the different activity levels of beta-1,4-endoglucanase, subsequently influencing variations in virulence of B.mucronatus isolates.