Management of root-knot nematode in kiwifruit using resistance-inducing Bacillus altitudinis

Root-knot nematodes (RKNs) are soil-borne pathogens that cause significant economic losses on kiwifruit plants. It has been shown that endophytic bacteria are effective biocontrol agents against nematodes. However, their efficacy against RKNs on kiwifruit has not been studied yet. The antagonistic effects of endophytic bacteria against Meloidogyne incognita (Mi) on kiwifruit plants were investigated. The kiwifruit seedlings were inoculated with the endophytic bacterium, the Bacillus altitudinis 123.en (Bac), before nematode inoculation. Bac improved the plant growth parameters (fresh weight and dry weight of root) and reduced the number of galls, egg masses and juvenile populations in the soil. To understand the underlying molecular mechanisms of resistance, RT-qPCR was employed to monitor the expression of two key pathogenesis-related genes ( PR-1 and PR-5 ) in kiwifruit plants. The gene transcripts were quantified three and seven days post nematode inoculation on pre-treated kiwifruit plants with Bac. The pre-treated plants with Bac showed higher level of expression of selected pathogenesis-related genes, PR-1 and PR-5 . This finding indicates that Bac prepares plants against RKN by induction of pathogenesis-related genes.