Variation in leaf color and combine effect of pigments on physiology and resistance to whitefly of pepper (Capsicum annuum L.)

Pigments are important in vegetable kingdom. However, little is known regarding role of their combination in pepper. In this study, three pepper strains were crossed to get F1 pepper plants, and exposed to whitefly attack at 6-8 leaves stage. Populations (M1-M9) differing in leaf color divulged that leaf color inherited to progenies at different extent and intensively showed matrocliny. Furthermore, in purple-colored population, the accumulation of anthocyanin improved the physiology and resistance to whitefly, with increased photosynthetic rate (Pn), Fv/Fm as well as root activity and reduction in superoxide dismutase (SOD), peroxidase (POD), malonaldehyde (MDA) and pest index (PI). Best manifestation of these parameters was observed in M3 population, indicating plant development be related to the optimum combination of anthocyanin and chlorophyll in the investigated leaves. Interestingly, M3 population possessed highest resistance to whitefly, while level of its anthocyanin and chlorophyll was in moderate level. Besides, no significant difference was observed in the expression levels of genes related to carotenoid metabolism in all populations. significant correlation was observed between PI and expression of genes related to pigment, namely CaGLK and CaCHS genes (R2 > 0.8), while the correlation was also found between ANS and GUN4 genes. These results suggested that the combination of anthocyanin and chlorophyll could enhance the resistance of pepper plants against whitefly attack.