Mitigating Root Knot Nematode Propagation on Transgenic Tobacco via <i>in Planta</i> Hairpin RNA Expression of <i>Meloidogyne incognita</i>—Specific PolA1 Sequence

Abstract

Root knot nematodes are top priority nematode pests that significantly constrain agricultural productivity globally especially in developing countries. However, expressing double stranded RNA (dsRNA) of essential nematode genes in susceptible plants is known to confer protection against these pests via RNA silencing. This molecular-based strategy is called host induced gene silencing (HIGS) and the selection of appropriate target nematode gene is critical to it s success. In this study, therefore, we focused on root knot nematode PolA 1, an essential single copy nuclear gene encoding the largest subunit of RNA polymerase I enzyme and evaluated its effectiveness as a target in conferring nematode resistance on Agrobacterium - mediated transformed tobacco plants. Transgenic tobacco expressing Meloidogyne incognita -specific ( MiS ) dsRNA of PolA 1 gene showed significant reduction in nematode fecundity and multiplication compared to wild type plants in both T 0 and T 1 generations. T 0 plants showed varying degrees of agronomic vigorover WT plants possibly due to varying levels of processed siRNA. However, production of MiS siRNAs in the transgenic plants coupled with significant reduction of PolA 1 transcript expression in nematodes feeding on roots of transgenic plants provided evidence of HIGS. Taken together, our results show that PolA 1 is a potentially effective target for HIGS-mediated reduction of root knot nematode damage on transgenic tobacco. Given the homology of our target sequence among Meloidogyne species, this protection could be broad range against other root knot nematodes aside M. incognita .