Identification of a New ss-1,4-endoglucanase Gene Expressed in the Esophageal Subventral Gland Cells of Heterodera glycines.

Secretory proteins encoded by parasitism genes expressed in the esophageal gland cells of plant-parasitic nematodes play key roles in nematode-plant interactions. A fourth ss-1,4-endoglucanase full-length cDNA (designated Hg-eng-4) was isolated from a Heterodera glycines esophageal gland-cell long-distance polymerase chain reaction cDNA library. The cDNA hybridized to genomic DNA of H. glycines in Southern blots. The Hg-eng-4 cDNA contained an open reading frame encoding 352 amino acids, with the first 18 amino acids being a putative secretion signal. Hg-ENG-4 contained a family 5 endoglucanase catalytic domain and a peptide linker of repeat amino acids, but no cellulose binding domain. In-situ hybridization analyses showed that transcripts of Hg-eng-4 accumulated specifically in the subventral gland cells of pre-parasitic and parasitic second-stage juveniles of H. glycines.