The white-tip nematode, Aphelenchoides besseyi, exhibits an auxin-orientated behaviour affecting its migration and propagation

Abstract

Aphelenchoides besseyi is an obligate parasite that often causes white-tip symptoms in rice plants. The nematode exhibits ectoparasitic behaviour with its infection rate matching the development of rice plants. Few studies have analysed how A. besseyi migration is influenced by chemical and host factors. Here, we focused on the effects of auxins on nematode migration and propagation. Exposure of A. besseyi to an auxin gradient created by a Pluronic F-127 gel resulted in nematode aggregation at the highest auxin concentration tested, 100 pm . Inoculation on the susceptible cv. Ningjingl produced more nematodes than on the resistant rice cv. Tetep, which correlated with their endogenous auxin levels. Young panicles treated with 1-naphthaleneacetic acid produced more grains and nematodes, whereas plants treated with the auxin transport inhibitor, 2,3,5-triiodobenzoic acid, led to fewer nematodes in the seeds. In addition, A. besseyi rarely migrated and multiplied in the plants of the male sterile rice cv. Zhenshan97A, which had insufficient auxin level in pollen and thus could not generate any grains in most panicles. However, large numbers of nematodes were observed in seeds of cv. Zhenshan97A that had received pollens from the maintainer cv. Zhenshan97B. The results indicate that auxin might play a key role in the migration and propagation of A. besseyi.

Three dimensional study of wounded plant roots recruiting entomopathogenic nematodes with Pluronic gel as a medium

“…Simply speaking, transparency of the gel allowed close examination in real time of behavioral changes as the nematode approached and made contact with the roots. Formation of a stable gradient in the gel made the test quantitative and reproducible (Feng et al, 2014;Fudali et al, 2013;Sasaki-Crawley et al, 2012;Wang et al, 2009aWang et al, ,b, 2010. The gel proved to be a powerful and valuable medium to study the interaction between EPN and host-habitat plant, and potentially study tritrophic interactions of EPN, the insect host, the associated plant habitat and as well as other related aspects.…”

“…Recently, a non-toxic and thermo-reversible transparent copolymer, Pluronic F-127, widely used in medical, pharmaceutical and cosmetic fields (Barichello et al, 1999;Farrugia et al, 2014;Marsh et al, 2003;Morishita et al, 2001;Zhang et al, 2010), has received more attention and proven to be a useful medium to study interactions between plant-parasitic nematodes and plants, including nematode host-seeking behavior and nematode chemotaxis (Feng et al, 2014;Fudali et al, 2013;Sasaki-Crawley et al, 2012;Wang et al, 2009aWang et al, ,b, 2010. A 23% solution of Pluronic is a semisolid gel at room temperature but a liquid at 15°C and below.…”

“…A 23% solution of Pluronic is a semisolid gel at room temperature but a liquid at 15°C and below. A stable gradient could be formed in the Pluronic gel in the presence of roots or chemicals (Feng et al, 2014;Fudali et al, 2013;Sasaki-Crawley et al, 2012;Wang et al, 2009aWang et al, ,b, 2010. The transparency and semisolid states allow nematodes to move freely in the gel fostering three-dimensional assay and allowing direct and real time observation of interactions between nematodes and the root system.…”

Detection and Development of Infestation Rate of Aphelenchoides besseyi on Various Rice Seed Varieties

“…The number of nematodes did not affect the symptoms that appeared in plants. A high number of the nematode population does not always cause symptoms in plants but can lead to yield loss (Feng et al, 2014).…”

Transcriptional responses of wheat and the cereal cyst nematode Heterodera avenae during their early contact stage

“…PPNs can be attracted to plant roots 7 and both volatile and non-volatile root extracts have been shown to attract potato cyst nematode ( G. pallida Stone) 8 . Ethylene and auxin signaling pathways affect the attraction or repulsion of the roots to nematodes 2 , 9 – 11 . Increases in ethylene production reduced the attraction to the host by RKN 10 , while high auxin concentrations attracted Aphelenchoides besseyi Christie 11 and RKN 2 .…”