Manipulation of two α‐endo‐β‐1,4‐glucanase genes, AtCel 6 and GmCel 7 , reduces susceptibility to H eterodera glycines in soybean roots

Summary Plant endo‐β‐1,4‐glucanases ( EG ases) include cell wall‐modifying enzymes that are involved in nematode‐induced growth of syncytia (feeding structures) in nematode‐infected roots. EG ases in the α‐ and β‐subfamilies contain signal peptides and are secreted, whereas those in the γ‐subfamily have a membrane‐anchoring domain and are not secreted. The A rabidopsis α‐ EG ase A t1g48930, designated as AtCel 6 , is known to be down‐regulated by beet cyst nematode ( H eterodera schachtii ) in A rabidopsis roots, whereas another α‐ EG ase, AtCel 2 , is up‐regulated. Here, we report that the ectopic expression of AtCel 6 in soybean roots reduces susceptibility to both soybean cyst nematode ( SCN ; H eterodera glycines ) and root knot nematode ( M eloidogyne incognita ). Suppression of GmCel 7 , the soybean homologue of AtCel 2 , in soybean roots also reduces the susceptibility to SCN . In contrast, in studies on two γ‐ EG ases, both ectopic expression of AtKOR 2 in soybean roots and suppression of the soybean homologue of AtKOR 3 had no significant effect on SCN parasitism. Our results suggest that secreted α‐ EG ases are likely to be more useful than membrane‐bound γ‐ EG ases in the development of an SCN ‐resistant soybean through gene manipulation. Furthermore, this study provides evidence that A rabidopsis shares molecular events of cyst nematode parasitism with soybean, and confirms the suitability of the A rabidopsis– H . schachtii interaction as a model for the soybean– H . glycines pathosystem.