Nematicidal Activity of Cry1Ea11 from Bacillus thuringiensis BRC-XQ12 Against the Pine Wood Nematode (Bursaphelenchus xylophilus)

Abstract

The nematicidal activity of 92 Bacillus thuringiensis strains against the pine wood nematode Bursaphelenchus xylophilus, one of the world's top 10 plant-parasitic nematodes, was determined. The insecticidal crystal proteins (ICPs) from Bacillus thuringiensis BRC-XQ12 were the most toxic to Bursaphelenchus xylophilus, with a lethal concentration 50 (LC) of 32.13 μg/ml. Because the ICPs expressed by Bacillus thuringiensis BRC-XQ12 were closest to Cry1Ea6 and B. thuringiensis BRC-XQ12 contained four kinds of cry1 subgenes (cry1Aa, cry1Cb, cry1Ea, and cry1Ia), Cry1Ea was most likely to be the key active component against the nematode. The 3,516-bp cry1Ea11 gene from BRC-XQ12, as designated by the B. thuringiensis δ-endotoxin nomenclature committee, was expressed in Escherichia coli. Purified Cry1Ea11 showed an LC of 32.53 and 23.23 μg/ml at 24 and 48 h, with corresponding virulence equations of Y = 32.15X + 1.38 (R = 0.9951) and Y = 34.29X + 3.16 (R = 0.9792), respectively. In order to detect the pathway of B. thuringiensis Cry1Ea11 into Bursaphelenchus xylophilus, the nematode was fed with NHS-rhodamine-labeled GST-Cry1Ea11. The results of confocal laser-scanning microscopy showed that the 159-kDa GST-Cry1Ea11 could be detected in the stylet and the esophageal lumen of the pine wood nematode, indicating that GST-Cry1Ea11 could enter into the nematode through the stylet. As far as we know, no Cry1 proteins have been shown to have activity against plant-parasitic nematodes before. These results demonstrate that Cry1Ea11 is a promising nematicidal protein for controlling pine wilt disease rendered by B. xylophilus, further dramatically broadening the spectrum of Bacillus thuringiensis ICPs.

Identification and characterization of Vietnamese coffee bacterial endophytes displaying in vitro antifungal and nematicidal activities

“…Altogether these results support the hypothesis that the effect could be attributed to some potentially unknown nematicidal compounds as those recently discovered by several authors (Gao et al, 2016;Geng et al, 2017;Huang et al, 2018;Luo et al, 2018;Zeng et al, 2015;Zheng et al, 2018) In the present work, five endophytic bacteria isolates (CCBLR15, CCBLR14, CCBLR1, CCBLR13, and CCBMTR4) all belonging to the Bacillus genus were able to lead to 100% of mortality on both R. duriophilus and P. coffeae. The analysis of their 16S rDNA sequences revealed that these isolates shared between 98.7% and up to 100% identity with sixteen species all belonging to the Bacillus cereus sensu lato group including B. albus, B.…”

Secondary metabolites produced by endophytic bacteria against the Root-Knot Nematode (Meloidogyne sp.)

“…(Munaganti et al 2016). B. thuringiensis produces crystal proteins which have nematicidal effect against plant-parasitic nematodes such as Bursaphelenchus xylophilus, M. hapla, Pratylenchus scribneri, Tylenchorhynchus sp., and Ditylenchus destructor (Huang et al 2018;Quan et al 2008). In general, B. thuringiensis performed best and seen as a biocontrol agent for Meloydogyne sp.…”

Nematotoxicity of a Cyt‐like protein toxin from Conidiobolus obscurus (Entomophthoromycotina) on the pine wood nematode Bursaphelenchus xylophilus

“…Furthermore, it has been demonstrated that resorcinol can increase the frequency of stylet thrusting and thereby stimulate uptake 27 . In response to resorcinol treatment, it was observed that GST‐Cry1Ea11 (159 kDa) was delivered through the stylet into the B. xylophilus digestive tract 9 . The size (21.97 kDa) of CytCo is considerably less than that of Cry1Ea, and its three‐dimensional structure comprising a single domain (the center of β‐strands being wrapped with a layer of α‐helices) is also simpler than that of three‐domain Cry proteins 19 .…”

“…emamectin benzoate and abamectin), monitoring and controlling B. xylophilus vectors, and breeding of resistant trees 2,5,6 . Screening nematotoxic biological materials, such as protein toxins and plant essential oils, has been conducted to develop new strategies for B. xylophilus control 7–9 . Regarding nematocidal protein toxins, several membrane pore‐forming toxins (PFTs), such as Bacillus thuringiensis crystal proteins, have been found to be effective 8–10 …”