Spraying of dsRNA Molecules Derived from Phytophthora Infestans, as a Plant Protection Strategies for the Management of Potato Late Blight

Phytophthora. infestans is a well known late blight causing oomycetes pathogen. It evolves and adapts to the host background and new fungicide molecules rapidly within a few years of their release, may be due to the predominance of transposable elements in its genome. Frequent and huge applications of fungicides cause environmental concerns. Here we developed target specific RNA interference based molecules, that are capable of effectively reducing the late blight infection. cDNA microarray expression data was used for the selection of genes involved in the early stage of infection process, sporulation etc. The in vitro synthesis of double stranded RNA molecule, targeting SDH, EF-1α, GPI-HAM344, PLD-3 and HSP-90 encoding genes revealed the reduction in growth, sporulation and symptom expression, which were subsequently assessed by culture bioassay, detached leaf assay and topical application methods. The multiple genes targeted dsRNA nano clay sprayed plants showed enhanced disease resistance (4% disease severity) and least sporulation (<1x103), compared to naked dsRNA spray. Use of nano clay was assumed to be involved in the effective delivery, protection and boosting the action of RNAi in potato plants. A significant difference in the growth, sporulation count, disease severity and reduced expression of the genes and confocal microscopy imaging authenticates the effects of SIGS on late blight disease progression. Our research demonstrated that topical dsRNA nano clay spray under the open-air environment could be an alternative to chemical fungicides and transgenic approaches as a novel plant protection strategy for late blight in an environmentally friendly manner.