Comparison of the in-soil hatching responses of Globodera rostochiensis and G. pallida in the presence and absence of the host potato crop cv. British Queen

Abstract

Experiments were conducted in a field in Co. Cork, Ireland, to investigate the hatching behaviour of the two potato cyst nematode (PCN) species, Globodera rostochiensis and G. pallida, in soil in the presence and absence of a host potato crop cv. British Queen. In order to compare the hatching behaviour of the two PCN species in the field, standardised populations of each PCN species (produced under identical conditions for the two previous generations and extracted without desiccation) were inserted into the field in tissue-embedding cassettes by means of a novel 'harpoon' insertion tool. Inserting cassettes of both PCN species at different distances from host potato plants and destructively sampling the contents of the cassettes over the first 8 weeks after plant emergence revealed that there was no significant difference in the hatch of either PCN species around the host plant. Hatches in excess of 80% for both PCN species were recorded 8 weeks after plant emergence over a range of depths (10-40 cm) and distances (10-50 cm) around the host potato plants. Substantial hatches of G. rostochiensis (82%) and G. pallida (88%) were also recorded at a depth of 20 cm in the furrow at harvesting. Monitoring the rate of spontaneous hatching of G. rostochiensis and G. pallida in the absence of host potato plants over the spring and summer months (a 20-week period) revealed that there was a significant difference in the rate of spontaneous hatching between the two PCN species, with G. rostochiensis juveniles hatching in greater numbers over the first 14 weeks than G. pallida juveniles. However, by mid-August the mean spontaneous hatch for both PCN species within the top 30 cm of soil was found to be 37%.

Hatching Induction of Cyst Nematodes in Bare Soils Drenched With Root Exudates Under Controlled Conditions

“…The low hatch observed at 25 cm depth meant either that the root exudates did not reach the 25 cm level or that the quantity that attained this level was insufficient to stimulate the levels of hatch observed within the top 15 cm soil depth. These observations are in line with those of Ryan and Devine (2005) who demonstrated a progressive increase in PCN hatch over a period of 8 weeks postplanting, depending on the distance at which encysted eggs were incubated from the host plant. Earlier report by Rawsthorne and Brodie (1987) also demonstrated that root exudates produced near the root tip were biologically more active in hatching induction.…”

Belowground Chemical Interactions: An Insight Into Host-Specific Behavior of Globodera spp. Hatched in Root Exudates From Potato and Its Wild Relative, Solanum sisymbriifolium

“…In the past two decades, a major effort was directed for identifying the unique G. pallida hatching factors and study chemicals involved in nematode orientation toward its host plant (Twomey, 1995;Perry and Gaur, 1996;Schenk et al, 1999;Devine and Jones, 2000;Devine et al, 2001;Ryan and Devine, 2005;Farnier et al, 2012;Fleming et al, 2017;Sikder and Vestergård, 2020). The current study is an effort to increase our understanding of the impact of root exudates on nematode behavior prior to the root invasion.…”

“…Solanum sisymbriifolium seeds (synthetic cross II -SisSynII, obtained from Chuck Brown, USDA-ARS, Prosser, WA, United States) were germinated in peat moss-based germination media and transferred to the sandy loam soil mix under similar greenhouse conditions. The root exudate was harvested by a soil percolation method (Ryan and Devine, 2005) 6 and 8 weeks later. In short, the soil was drenched with deionized (DI) water until saturation and left for 2 h. After that period, additional 200 ml of DI water per pot was added, and the flow-through was collected.…”