The 8D05 Parasitism Gene of Meloidogyne incognita Is Required for Successful Infection of Host Roots

Abstract

Parasitism genes encode effector proteins that are secreted through the stylet of root-knot nematodes to dramatically modify selected plant cells into giant-cells for feeding. The Mi8D05 parasitism gene previously identified was confirmed to encode a novel protein of 382 amino acids that had only one database homolog identified on contig 2374 within the Meloidogyne hapla genome. Mi8D05 expression peaked in M. incognita parasitic second-stage juveniles within host roots and its encoded protein was limited to the subventral esophageal gland cells that produce proteins secreted from the stylet. Constitutive expression of Mi8D05 in transformed Arabidopsis thaliana plants induced accelerated shoot growth and early flowering but had no visible effects on root growth. Independent lines of transgenic Arabidopsis that expressed a double-stranded RNA complementary to Mi8D05 in host-derived RNA interference (RNAi) tests had up to 90% reduction in infection by M. incognita compared with wild-type control plants, suggesting that Mi8D05 plays a critical role in parasitism by the root-knot nematode. Yeast two-hybrid experiments confirmed the specific interaction of the Mi8D05 protein with plant aquaporin tonoplast intrinsic protein 2 (TIP2) and provided evidence that the Mi8D05 effector may help regulate solute and water transport within giant-cells to promote the parasitic interaction.

Plant-mediated RNA interference of effector gene Mc16D10L confers resistance against Meloidogyne chitwoodi in diverse genetic backgrounds of potato and reduces pathogenicity of nematode offspring

“…Previous studies aimed at creating stable transgenic RNAi plants to down-regulate nematode genes made use of a single genetic background of the recipient plant species (Huang et al, 2006b;Fairbaim et al, 2007;Sindhu et al, 2009;Xue et al, 2013;Dinh et al, 2014). Solarium sect.…”

RNAi-induced silencing of an effector confers transcriptional oscillation in another group of effectors in the root-knot nematode, Meloidogyne incognita

“…In a recent report, host-derived RNAi of 8E10B/msp-40 suppressed RKN parasitism and reproduction in Arabidopsis plants and transient expression of this gene negatively regulated plant innate immunity (Niu et al, 2016). Despite the localisation of msp-9 (Xue et al, 2013), msp-16 (Huang et al, 2006a, b) and msp-40 (Niu et al, 2016) in subventral glands, and their strong upregulation in early parasitic stages, the majority of the pioneer genes are expressed in the dorsal gland of M. incognita (Huang et al, 2003).…”

“…In parallel, 16D10 was shown to interact with the SCARECROW-like transcription factor of Arabidopsis using yeast two-hybrid assays (Huang et al, 2006b). Host-delivered RNAi of the 8D05/msp-9 gene perturbed the infection ability of RKN in Arabidopsis and, additionally, the msp-9 protein was shown to interact with plant aquaporin that regulates solute and water transport within giant cells (Xue et al, 2013). Although a number of these pioneer genes contained nuclear localisation domains, experimental proof indicated that only the 7H08/msp-8 effector is imported to the nucleus and exhibits transcriptional activation activity in planta (Zhang et al, 2015).…”

“…To date, very few of the effectors have been functionally characterised in detail in various species of plantparasitic nematodes using diverse strategies such as effector overexpression in plants, effector silencing via RNAi and identifying target host proteins using proteomic analyses (Huang et al, 2006b;Hewezi et al, 2008Hewezi et al, , 2010Lee et al, 2011;Hamamouch et al, 2012;Jaouannet et al, 2012;Xue et al, 2013;Zhang et al, 2015). However, all these studies had analysed only a single effector at a time.…”

Host-delivered RNAi-mediated root-knot nematode resistance in Arabidopsis by targeting splicing factor and integrase genes

“…2013;Klink et al 2009;Li et al 2010;Lourenço-Tessutti et al 2015;Niu et al 2012Niu et al , 2016Papolu et al 2013;Rosso et al 2009;Sindhu et al 2009;Steeves at al. 2006;Xue et al 2013;Yadav et al 2006). Varying levels of resistance have been demonstrated in different studies, and genes involved in nematode parasitism, development and reproduction have been targeted in a wide variety of plant systems including Arabidopsis, tobacco, tomato and soybean (Tamilarasan and Rajam 2013).…”