Fig. 8

RNAi knockdown of chemosensory genes affected M. graminicola chemosensation to volatile organic compounds. In chemotaxis assay, J2s inoculated at the center of a Petri plate containing Pluronic gel. J2 inoculation point is 1.5 cm equidistant from test chemical and its diluent application points. (A) Visual assessment of chemical gradient establishment in the assay plate. 10 µL acid fuchsin dye was pipetted to the chemical/diluent application points. (B) By 40 min, dyes from chemical/diluent sides slowly dispersed to the inoculation point. (C) Photomicrograph depicts selective dispersion of J2s to test chemical side from the inoculation point. (D) Numerous tracks visible towards the test chemical side (isoamyl alcohol used here) from the inoculation point of gfp dsRNA-treated J2s indicating attraction response. (E) Tracks inscribed away from the test chemical side (1-heptanol used here) indicating aversion response. (F) Comparative chemotaxis indices (CI, ranges from − 1.0 to + 1.0) of gfp dsRNA-treated J2s and Mg-odr-7/Mg-tax-4/Mg-tax-4.1/Mg-osm-9/Mg-ocr-2 silenced J2s towards selective volatile compounds. Each bar indicates average CI from three biological and technical replicates ± SE. Asterisks denote significant difference (P < 0.01, paired t-test) in CI of J2s towards test chemicals when compared to the CI of J2s towards water (negative control)