Abstract
Potato (Solanum tuberosum) is a widely consumed staple food crop worldwide whose production is threatened by potato cyst nematodes (PCN). To infect a host, PCN eggs first need to be stimulated to hatch by chemical components in the host root exudates, yet it remains unknown how most root exudate components influence PCN behavior. Here, we evaluated the influence of eight compounds identified by LC-QqQ-MS in the root exudate of potato on the hatching response of the PCN, Globodera rostochiensis at varying doses. The eight compounds included the amino acids tyrosine, tryptophan and phenylalanine; phytohormones zeatin and methyl dihydrojasmonate; steroidal glycoalkaloids α-solanine and α-chaconine and the steroidal alkaloid solanidine. We additionally tested two other Solanaceae steroidal alkaloids, solasodine and tomatidine, previously identified in the root exudates of tomato, an alternative host for PCN. In dose-response assays with the individual compounds, the known PCN hatching factors α-chaconine and α-solanine stimulated the highest number of eggs to hatch, ∼47 and ∼42%, respectively, whereas the steroidal alkaloids (aglycones), solanidine and solasodine and potato root exudate (PRE) were intermediate, 28% each and 21%, respectively, with tomatidine eliciting the lowest hatching response 13%. However, ∼60% of the hatched juveniles failed to emerge from the cyst, which was compound- and concentration-dependent. The amino acids, phytohormones and the negative control (1% DMSO in water), however, were generally non-stimulatory. The use of steroidal glycoalkaloids and their aglycones in the suicidal hatching of PCN offers promise as an environmentally sustainable approach to manage this pest.
Highlights
Potato cyst nematodes (PCN) have been of great economic importance to potato production since their introduction to Europe in the mid 1880’s
Chemical analysis of the potato root exudates, by LC-QqQ-MS, identified 9 compounds belonging to four classes; amino acids, phytohormones, triterpenoid and steroidal alkaloids (Figure 1 and Table 1)
Root exudates are utilized by soil dwelling microbes for various biological processes and they can function as semiochemicals, growth inhibitors and growth promoters, among
Summary
Potato cyst nematodes (PCN) have been of great economic importance to potato production since their introduction to Europe in the mid 1880’s. In the rest of Europe, the market value of losses is approximately seven times higher (€300 million annually) (Moxnes and Hausken, 2007). Both species of PCN have been detected in Kenya (Mwangi et al, 2015; Mburu et al, 2018), where potato is the second most important food crop (CIP, 2019). PCN poses a major threat to potato production on a regional level (Mburu et al, 2018)
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