Novel Bioassay Demonstrates Attraction of the White Potato Cyst Nematode Globodera Pallida (Stone) to Non-volatile and Volatile Host Plant Cues

Abstract

Potato cyst nematodes (PCNs) are a major pest of solanaceous crops such as potatoes, tomatoes, and eggplants and have been widely studied over the last 30 years, with the majority of earlier studies focusing on the identification of natural hatching factors. As a novel approach, we focused instead on chemicals involved in nematode orientation towards its host plant. A new dual choice sand bioassay was designed to study nematode responses to potato root exudates (PRE). This bioassay, conducted together with a traditional hatching bioassay, showed that biologically active compounds that induce both hatching and attraction of PCNs can be collected by water extraction of incised potato roots. Furthermore, our results demonstrated that PCN also were attracted by potato root volatiles. Further work is needed to fully understand how PCNs use host plant chemical cues to orientate towards hosts. Nevertheless, the simple attraction assay used in this study provides an important tool for the identification of host-emitted attractants.

Coherent anti‐Stokes Raman scattering (CARS) spectroscopy in Caenorhabditis elegans and Globodera pallida: evidence for an ivermectin‐activated decrease in lipid stores

“…To induce hatching, dried cysts were placed in a solution of 1 part potato root exudate to 3 parts double‐distilled (dd) H 2 O. (Full‐strength potato root exudate was obtained by soaking 80 g of washed potato root for 1 h in 1 L of distilled water …”

Root-emitted volatile organic compounds: can they mediate belowground plant-plant interactions?

“…Depending on the plant species studied, volatile blends released belowground by plant roots can be characterized by compounds belonging to various chemical families, particularly terpenoids (Rasmann et al 2005;Lin et al 2007;Ali et al 2010), fatty acid derivatives (Gfeller et al 2013) or sulphur-containing compounds (Ferry et al 2007;Crespo et al 2012;Danner et al 2015). Important ecological roles have been associated with root-emitted VOCs (Fig.…”

“…Briefly, they have been shown to mediate interactions between plants and phytophagous pests such as insect herbivores (Sutherland and Hillier 1974;Guerin and Ryan 1984;Palma et al 2012;Weissteiner et al 2012;Robert et al 2012a) and plant parasitic nematodes (Ali et al 2011;Farnier et al 2012). Volatile cues released by roots damaged by insect herbivores are also implicated in belowground plant indirect defences because they attract organisms of the third trophic level, such as insect predators (Neveu et al 2002;Ferry et al 2007) and entomopathogenic nematodes (van Tol et al 2001;Boff et al 2002;Rasmann et al 2005;Ali et al 2011). In addition to the review articles published so far and focusing on belowground VOCs (Wenke et al 2010;Rasmann et al 2012;Peñuelas et al 2014), Table 1 presents a chronological literature review of the studies on root VOC production and VOC-mediated interactions between plant roots and soil organisms.…”

“…VOCs emitted by Brassica roots infested by cabbage root fly larvae (Delia radicum L.) were also shown to be attractive for insects of the third trophic level, such as females of the parasitoid species Trybliographa rapae Westwood, rove beetles (Aleochara bilineata and Aleochara bipustulata), and carabid beetles in the genus Bembidion (Neveu et al 2002;Ferry et al 2007). GC-MS and proton transfer reaction-mass spectrometry (PTR-MS) analyses have shown that insect-damaged Brassica roots release mainly highly volatile sulphur compounds (methanethiol, dimethyl sulphide, dimethyl disulphide and dimethyl trisulphide) and glucosinolate breakdown products (thiocyanates and isothiocyanates) in the soil, with a VOC emission pattern depending on the plant species studied Danner et al 2012;Crespo et al 2012;Danner et al 2015).…”

Olfactory circuits and behaviors of nematodes

“…Soil-dwelling plant-parasitic nematodes (PPNs) use the general cue CO 2 in combination with plant-specific odorants to specifically target the roots of host plants [70,76,77]. For at least some species, the attractive response to CO 2 may in fact be a response to low pH resulting from dissolved CO 2 rather than to the CO 2 itself [78].…”