Elimination of citrus tristeza closterovirus (ctv) and production of certified citrus plants through shoot-tip micrografting

Kinnow mandarin (Citrus reticulata) and Musambi sweet orange (C. sinensis) are the predominant citrus fruits cultivated in Pakistan. Citrus species are highly vulnerable to many types of pathogens. Among the viruses, Citrus tristeza virus (CTV) is the most devastating which can cause the death of millions of citrus trees if once established. CTV is a graft-transmissible and can be inadvertently propagated through infected budwood. The production of certified and CTV-free citrus plants could be helpful to restrict the widespread of CTV. The study was designed to optimize the micrografting technique for the propagation of CTV free Kinnow mandarin and Musambi sweet orange plants under aseptic conditions. The MS medium supplemented with 5 mgL^-1 BA was found better for successful micrografting of both citrus cultivars on rough lemon seedlings. The survival rate of micrografted citrus plantlets was 88% when transferred to soil. The ELISA results showed that more that 90% Kinnow and Musambi plants either grafted on rough lemon or sour orange rootstock were found free from CTV. The foundation block of mandarin and sweet orange free from CTV was successfully established using shoot-tip micrografting technique.