Fig. 3: Exogenous application of Austropuccinia psidii-specific double-stranded RNA (dsRNA) cures myrtle rust infection at 24 h and 6 days post-infection.
From: Double-stranded RNA prevents and cures infection by rust fungi
Syzygium jambos trees (n = 6) were infected with A. psidii urediniospore inocula and treated with a nuclease-free H2O (negative control), a non-specific dsRNA control (GFP dsRNA), or beta-tubulin (β-TUB), or transcription elongation factor (EF1-a) A. psidii-specific dsRNAs at a concentration of 100 ng/μL at 24 h, 6 days, and 14 days post-infection. a Photo comparison shows S. jambos plants inoculated with A. psidii and treated with A. psidii-specific dsRNA 24 h post-infection (hpi) or 6 days post-infection (dpi). Plants were photographed two weeks post-inoculation (wpi). b Boxplots with superimposed scatter of diseased tissue as mean (n = 6) percent (%) coverage of leaf. Each biological replicate includes all young (susceptible) growth in the disease assessment (usually four to eight leaves). Disease was measured automatically using the Leaf Doctor application57 at 2 wpi. EF1-a and β-TUB dsRNAs significantly reduced diseased portions of leaves, as compared to –dsRNA and GFP controls. c Photo comparison shows S. jambos plants inoculated with A. psidii and treated with A. psidii-specific dsRNA 24 h, 6 days, or 14 days post-infection. Plants were photographed 6 wpi. d Boxplots with superimposed scatter of mean (n = 6) qualitative plant health. Plants were assessed according to the qualitative plant health scale (Table 1), developed in this study. EF1-a and β-TUB dsRNAs significantly increased qualitative plant health, as compared to -dsRNA and GFP controls. Significance in all boxplots is represented by asterisks (* = <0.05, ** = <0.01, *** = <0.001 (Welch’s t-test)). Bars represent standard error of the mean. Figures (b) and (d) were made in R 4.0.359.
