Comparison of different species of cotton for the transmission of CLCuV through whitefly

Most plants have developed some physiological properties that either increase the grip of the insect or inhibit them. In this study, vegetative and floral characteristics of plants, thickness of leaf cross section, number of the mesophyll layer and epicuticular wax of different cotton species namely Gossypium arboreum, its wax mutant GaWM3, G. hirsutum and G. harknessii were characterized, and correlated with detection of CLCuV thorough PCR. Viral particles were detected in all experimental plants other than G. arboreum. Thickness of cross section of the leaves in G. arboreum, its wax mutant 3 (GaWM3) and G. hirsutum was ~200-237 μm as compared to G. harknessii (~350 μm) as it had 2 layers of mesophyll cells. The thickness of the wax layer was found to be maximum in G. arboreum (180 μg cm^-2) and least in its wax mutant (95 μg cm^-2). From the results it was concluded that the thickness of the leaves and presence of single and double layers of the mesophyll had no role in the transmission of CLCuV through whiteflies (Bemisia tabaci Gennadius). Moreover, least number of whiteflies were found on the leaves of G. arboreum which was resistant to CLCuV determined the fact that more epicuticular waxes hindered the attachment and infestation of whiteflies in G. arboreum as compared to susceptible plants, i.e., its wax deficient mutant, G. hirsutum and G. harknessii.