Molecular characteristics and functional analysis of the β‐1,4‐endoglucanase <italic>Bm‐eng‐1</italic> gene of <italic>Bursaphelenchus mucronatus</italic> (Nematoda: Aphelenchoididae).

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