Two venom allergen‐like proteins, HaVAP1 and HaVAP2, are involved in the parasitism of Heterodera avenae

Abstract

Summary Despite the fact that venom allergen‐like proteins (VAPs) have been identified in many animal‐ and plant‐parasitic nematodes, studies on VAPs in Heterodera avenae , which is an important phytonematode, are still in their infancy. Here, we isolated, cloned and characterized two VAP s, named HaVAP1 and HaVAP2 , from H. avenae . The two encoded proteins, HaVAP1 and HaVAP2, harbour an SCP‐like domain each, but share only 38% identity with each other. HaVAP1 and HaVAP2 are expressed in subventral and dorsal oesophageal glands, respectively. HaVAP1 is expressed mainly at the early stages, whereas HaVAP2 accumulates principally at the late stages. Both HaVAP1 and HaVAP2 are secreted when expressed in Nicotiana benthamiana leaves, but HaVAP1 is delivered into chloroplasts, whereas HaVAP2 is translocated to the nucleus without signal peptides. Knocking down HaVAP1 increased the virulence of H. avenae . In contrast, silencing of HaVAP2 hampered the parasitism of H. avenae . Both HaVAP1 and HaVAP2 suppressed the cell death induced by BAX in N. benthamiana leaves. Moreover, HaVAP2 physically interacted with a CYPRO4‐like protein (HvCLP) of Hordeum vulgare in the nucleus of the plant. It is reasonable to speculate that the changes in the transcript of HvCLP are associated with HaVAP2 during the parasitism of H. avenae . All results obtained in this study show that both HaVAP1 and HaVAP2 are involved in the parasitism of H. avenae , but they possess different functions, broadening our understanding of the parasitic mechanism of H. avenae .

Analyses of the Root-Knot Nematode (Meloidogyne graminicola) Transcriptome during Host Infection Highlight Specific Gene Expression Profiling in Resistant Rice Plants

“…Importantly, VAPs are key players in the modulation of plant immunity. Knocking down the expression of VAP genes can severely affect nematode virulence [ 45 , 56 , 57 , 58 ]. In particular, expression of VAP genes are required for the onset of parasitism at the time of root invasion and migration through host tissues [ 58 , 59 ].…”

“…In addition, A. thaliana lines overexpressing nematode VAP genes loose basal immunity to unrelated pathogens, including fungi, bacteria, and oomycetes [ 46 ]. Modulation of plant immunity involves interaction of nematode VAPs with host proteases [ 45 , 57 ]. In tomato, Gr-VAP1 specifically interacts with and inhibits the apoplastic papain-like cysteine protease (PLPC) Rcr3pim, increasing the susceptibility of tomato plants to G. rostochiensis [ 45 ].…”

“…In tomato, Gr-VAP1 specifically interacts with and inhibits the apoplastic papain-like cysteine protease (PLPC) Rcr3pim, increasing the susceptibility of tomato plants to G. rostochiensis [ 45 ]. Additionally, Luo et al [ 57 ] showed that ectopic expression in tobacco cells of the protein HaVAP2 (minus its signal peptide) from the cereal cyst nematode H. avenae allowed its transfer into the host cell nucleus where it can interact with the Hordeum vulgare HvCLP peptidase. VAPs also contain a SCP/CAP domain able to bind lipids, such as leukotrienes and sterols, but little is known about endogenous ligands that are bound during parasitism [ 54 ].…”

Identification and Functional Analysis of AopN, an Acidovorax Citrulli Effector that Induces Programmed Cell Death in Plants

“…To generate BiFC constructs, the full-length cDNA of AopN was cloned into a pSPYNE ® 173 vector [ 44 ], and the full-length cDNA of ClHIPP and ClLTP was cloned into the pSPYCE (M) vector [ 44 ]. The constructs were co-expressed in N. benthamiana leaves for analysis, as previously described [ 44 , 45 ]. After 48 h, at an excitation wavelength of 488 nm to acquire fluorescent images, the plasma membrane marker dye (Dil, D3911, Thermo Scientific, Waltham, MA, USA) was used as the control for PM localization.…”

Resistance to Cereal Cyst Nematodes in Wheat and Barley: An Emphasis on Classical and Modern Approaches

“…Similarly, the transient expression of Ha-annexin led to the down-regulation of the host hypersensitive (HR) response induced by BAX protein and different pathogen associated molecular patterns (PAMPs) such as flagellin [100]. Very recently two venom allergen-like effector proteins (HaVAP1 and HaVAP2) from H. avenae have been characterized through gene silencing [101]. The results indicated that both of them are involved in the suppression of programmed cell death induced by BAX in Nicotiana benthamiana leaves.…”