Fig. 6. A mild intracellular immunity in whitefly facilitated its coexistence with TYLCV.

a, b Autophagy agonist rapamycin, autophagy inhibitor 3-MA, apoptosis agonist PAC-1, and apoptosis inhibitor Z-VAD-FMK were fed with 24 h in artificial diet respectively. a The relative protein abundance of TYLCV CP was determined by immunoblotting in viruliferous whitefly, and b the relative quantity of TYLCV DNA per whitefly was determined by qPCR. c–e Effects of agonist and inhibitor combinations on activation of apoptosis and autophagy in viruliferous whitefly, and on viral load and whitefly survival rate. Whiteflies were transferred to acquire virus for 24 h after agonist and/or inhibitor treatment via feeding. c The activation of apoptosis and autophagy in viruliferous whitefly was determined by immunoblotting, and d relative virus DNA was determined by qPCR. Sample sizes (n) for statistical tests indicated in the panels refer to biologically independent whitefly. e Whiteflies (100/replicate for each pharmacological combination treatment) were transferred to virus-infected plants for 48 h prior to survival rate measurement, three independent samples were used for each treatment. f Nonviruliferous whiteflies fed with rapamycin and Z-VAD-FMK were sampled for survival rate measurement, and their prediction bands (95% confidential interval) were generated based on regression result using linear quadratic survival model, five independent samples were used for each treatment. g Viral burden on whitefly survival rate with 24 h treatment of autophagy inhibitor 3-MA. Whiteflies, in groups of 60, was transferred to uninfected plants, and then to TYLCV-infected plants for time periods as indicated. Survival was recorded for survival rate calculation, and determination of TYLCV CP abundance by immunoblotting, three independent samples were used for each treatment. Values in bars or line plots represent mean ± SEM. All data were checked for normality by the Wilk-Shapiro test. Two-sided paired t-test was used to separate the means of normally distributed data, while Mann-Whitney test was used to analyze nonparametric distributed data, no multiple comparisons were performed in each test. h Model of interaction between apoptosis and autophagy in viruliferous whitefly and consequence on survival rate and virus load: TYLCV-induced apoptosis negatively regulated autophagy to maintain a homeostasis in favor of the coexistence of TYLCV within whitefly. This graph was created with BioRender.com.