The soybean cystnematode (SCN, Heteroderaglycines),a sedentary root parasite, is one of the most economically important pathogens of soybean and causesa devastating disease in this crop around theworld.SCNsecond stage juveniles (J2) reco gnize chemical signals in the soil environment by usingtheir amphids, the nematode’s main chemoreception organ, to locate host roots and toselect infection site which is the initial step for nematode infection and establishing parasitism. Previous studies have indicated that the signaling pathways of plant hormones, such as SA, JA, BR, ABA, and ETare involved in the defenseresponse of host plants to nematodes. However, less was known about how plant hormone modulates the early interaction between plant and nematodes.

The scientists in the group of Agricultural Pest Control found that ethylene pathway could modulate the early interaction between plants and SCN. Roots of soybean treated with the ethylene (ET)-synthesis inhibitor aminoethoxyvinylglycine (AVG) were more attractive to SCN than untreated roots, and significantly more nematodes penetrated into roots, indicating ethylene synthetic pathway involved in nematode attraction. Further studies were conducted with a series of ethylene mutants of model plant Arabidopsis. The results showed that Arabidopsis ET insensitive mutants (ein2, ein2-1,ein2-5, ein3-1, ein5-1, and ein6) weremore attractive than wild-type plants and the constitutive triple-response mutant ctr1-1,was less attractive to SCN, suggesting ET signal pathway negatively modulate attractiveness of plant roots to SCN. Furthermore, expression of the reporter construct EBS: β-glucuronidase (GUS) was detected in Arabidopsisroot tips as early as 6 h post infection, indicating thatET signaling was activated in Arabidopsis early by SCN infection. These results suggest that an active ET signaling pathway reducesroot attractiveness to SCN in a way similar to thatreported for root-knot nematodes, but opposite to that suggested for the sugarbeet cyst nematode Heteroderaschachtiiwhich is more close to SCN. These studies would provide valuable information for new control strategy.

This study was published in the Journal ‘Scientific Reports’. Dr.  Yanfeng Hu is as first author and Dr. Congli Wang was as corresponding author. The article:

Hu, Y., You, J, Li, C., Williamson, V. M., Wang, C. (2017) Ethylene response pathway modulates attractiveness of plant roots to soybean cyst nematode Heteroderaglycines. Scientific Reports7, 41282; doi:10.1038/srep41282.