Location: Soybean Genomics and Improvement
Title: Manipulation of two alpha-endo-beta-1,4-glucanase genes, AtCel6 and GmCel7, reduces susceptibility to Heterodera glycines in soybean roots Authors
Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 15, 2014
Publication Date: May 21, 2014
Citation: Woo, M., Beard, H.S., Macdonald, M.H., Brewer, E.P., Youssef, R., Kim, H., Matthews, B.F. 2014. Manipulation of two alpha-endo-beta-1,4-glucanase genes, AtCel6 and GmCel7, reduces susceptibility to Heterodera glycines in soybean roots. Molecular Plant Pathology. DOI:15.10.1111/mpp.12157. Interpretive Summary: The soybean cyst nematode (SCN) is the most destructive pathogen of soybean in the US. Currently grown soybean varieties are not resistant to all field populations of SCN. The root-knot nematode (RKN) has a wide host range and causes damage to many plants. We genetically engineered soybean roots to overexpress two Arabidopsis genes. When we over expressed the Arabidopsis gene encoding an alpha-endoglucanase in soybean roots, the roots displayed increased resistance to both SCN and RKN. However, when we overexpressed a gene encoding a different family member, gamma-endoglucanase, in soybean roots, no increase in resistance was observed. Our results indicate that the gene encoding an alpha-endoglucanase may be useful in developing soybean with increased resistance to SCN and RKN.
Technical Abstract: Plant endo-beta-1,4-glucanases (EGases) include cell-wall-modifying enzymes that are involved in nematode-induced growth of syncytia (feeding structures) in nematode-infected roots. EGases in the alpha and beta subfamilies contain signal peptides and are secreted, while those in the gamma subfamily have a membrane-anchoring domain and are not secreted. The Arabidopsis alpha-EGase At1g48930, designated AtCel6, is known to be down-regulated by beet cyst nematode (Heterodera schachtii) in Arabidopsis roots, while another alpha-EGase, AtCel2, is up-regulated. Here we report that ectopic expression of AtCel6 in soybean roots reduced susceptibility to both soybean cyst nematode (SCN; Heterodera glycines) and root knot nematode (Meloidogyne incognita). Suppression of GmCel7, the soybean homolog of AtCel2, in soybean roots also reduced susceptibility to SCN. In contrast, in studies on two gamma-EGases, both ectopic expression of AtKOR2 in soybean roots and suppression of the soybean homolog of AtKOR3 had no significant effect on SCN parasitism. Our results suggest that secreted alpha-EGases are likely to be more useful than membrane-bound gamma-EGases in the development of an SCN-resistant soybean through gene manipulation. Furthermore, this study provides evidence that Arabidopsis shares molecular events of cyst nematode parasitism with soybean, and confirms the suitability of the Arabidopsis-H. schachtii interaction as a model for the soybean-H. glycines pathosystem.