Objective Identification and nematicidal activity against Meloidogyne incognita of an Actinomyces strain were investigated for root-knot disease control.
Method An Actinomycete strain, JXJA01, previously isolated from the rhizosphere soil of Dioscorea alata Lirm. sp in Ganzhou, China was positively identified by morphological, physiological, and biochemical examinations as well as a molecular evolution analysis. The supernatant of JXJA01 fermentation broth was co-cultured with a suspension of the second stage parasite juveniles (J2) or fresh nematode eggs to determine the nematicidal activity of the isolated strain.
Result JXJA01 was identified as Streptomyces europaeiscabiei. The 2-fold dilution of the supernatant of the bacterial fermentation broth displayed the strongest biological activity against J2s among all preparations with an adjusted mortality rate in 24h of 95.53%. It also had a robust suppressive effect on egg-hatching with a relative inhibition rate of 44.00% after 7 d of treatment. On potted tomatoes, it showed 40.88% efficacy in controlling the root-knot nematodes in 60d and significantly increased the fresh weight of roots by 71.42 % over control. Moreover, the fermentation supernatant was not sensitive to temperature or light and maintained the nematicidal activity in storage at 4 ℃ for 21 d.
Conclusion Identified as S. europaeiscabiei, JXJA01 exhibited a promising potential to be used as a biological agent for controlling root-knot nematodes on tomatoes.
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