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A novel pilin subunit from Xenorhabdus nematophila, an insect pathogen, confers pest resistance in tobacco and tomato

Kumari, Punam, Mahapatro, Gagan Kumar, Banerjee, Nirupama, Sarin, Neera Bhalla
Plant cell reports 2015 v.34 no.11 pp. 1863-1872
Helicoverpa armigera, Southern blotting, Western blotting, Xenorhabdus nematophila, agglutination, bacteria, bioassays, crops, cytotoxicity, gene overexpression, genes, hemocytes, insects, larvae, mortality, pathogens, pest control, pest resistance, reverse transcriptase polymerase chain reaction, tobacco, tomatoes, toxins, transgenic plants
KEY MESSAGE : Overexpression of insecticidal pilin subunit from Xenorhabdus nematophila protects transgenic tobacco and tomato plants against Helicoverpa armigera. Xenorhabdus nematophila is a pathogenic bacterium producing toxins that kill the larval host. Previously, we characterized a pilin subunit of X. nematophila which was found to be a pore-forming toxin and cytotoxic to the larval hemocytes of Helicoverpa armigera by causing agglutination and lysis of the cells. In the present study, we report the efficacy of the insecticidal pilin subunit expressed in transgenic tobacco and tomato plants for control against H. armigera. A 537 bp mrxA gene encoding the 17 kDa insecticidal pilin subunit was transferred into the genome of tobacco and tomato, respectively, via Agrobacterium-mediated transformation. The stable integration of the 537 bp mrxA gene in the transgenic plants was confirmed by Southern blot analysis and expression of mrxA gene was confirmed by RT-PCR and Western blot analyses. The transgenic plants appeared healthy and phenotypically normal but proved toxic to the insects in insect bioassays, showing 100 % insect mortality and reduced damage of the transgenic plants. Based on these observations, it is suggested that pilin subunit can be used as a potential candidate for control of H. armigera and may open new strategies for pest control in agricultural plants.