Enhanced resistance to soybean cyst nematode Heterodera glycines in transgenic soybean by silencing putative CLE receptors

Abstract

CLE peptides are small extracellular proteins important in regulating plant meristematic activity through the CLE-receptor kinase-WOX signalling module. Stem cell pools in the SAM (shoot apical meristem), RAM (root apical meristem) and vascular cambium are controlled by CLE signalling pathways. Interestingly, plant-parasitic cyst nematodes secrete CLE-like effector proteins, which act as ligand mimics of plant CLE peptides and are required for successful parasitism. Recently, we demonstrated that Arabidopsis CLE receptors CLAVATA1 (CLV1), the CLAVATA2 (CLV2)/CORYNE (CRN) heterodimer receptor complex and RECEPTOR-LIKE PROTEIN KINASE 2 (RPK2), which transmit the CLV3 signal in the SAM, are required for perception of beet cyst nematode Heterodera schachtii CLEs. Reduction in nematode infection was observed in clv1, clv2, crn, rpk2 and combined double and triple mutants. In an effort to develop nematode resistance in an agriculturally important crop, orthologues of Arabidopsis receptors including CLV1, CLV2, CRN and RPK2 were identified from soybean, a host for the soybean cyst nematode Heterodera glycines. For each of the receptors, there are at least two paralogues in the soybean genome. Localization studies showed that most receptors are expressed in the root, but vary in their level of expression and spatial expression patterns. Expression in nematode-induced feeding cells was also confirmed. In vitro direct binding of the soybean receptors with the HgCLE peptide was analysed. Knock-down of the receptors in soybean hairy roots showed enhanced resistance to SCN. Our findings suggest that targeted disruption of nematode CLE signalling may be a potential means to engineer nematode resistance in crop plants.