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 its success. In this study, therefore, we focused on root knot nematode PolA1, 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 PolA1 gene showed significant reduction in nematode fecundity and multiplication compared to wild type plants in both T0 and T1 generations. T0 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 PolA1 transcript expression in nematodes feeding on roots of transgenic plants provided evidence of HIGS. Taken together, our results show that PolA1 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.
Highlights
Plant parasitic nematodes are among the most significant constraints to sustainable agriculture and achievement of food security [1]
We focused on root knot nematode PolA1, 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
Production of Meloidogyne incognita-specific (MiS) small interfering RNAs (siRNAs) in the transgenic plants coupled with significant reduction of PolA1 transcript expression in nematodes feeding on roots of transgenic plants provided evidence of host induced gene silencing (HIGS)
Summary
Plant parasitic nematodes are among the most significant constraints to sustainable agriculture and achievement of food security [1]. With the complete sequencing of the Meloidogyne incognita genome, the past decade has proven the possibility of engineering nematode resistance in plants via molecular-based strategies like host induced gene silencing [6] [7] [8] [9]. This strategy involves the engineering of suitable host plants to express double stranded RNA (dsRNA) of an essential nematode gene in planta. In HIGS, expression of nematode-specific dsRNA in plants generates siRNAs which are ingested by the nematodes during feeding and mediate silencing of the target nematode gene with possible conferment of plant protection [11]
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