Histochemical and immunohistochemical identification of laticifer cells in callus cultures derived from anthers of Hevea brasiliensis

Laticifers are highly specialized cells present in over 20 plant families. They are well defined in planta. In vitro development of laticifers was also observed in some plants, but uncertain in the callus cultures of rubber tree, one of the most economically important latex producing plants. In the present study, we provide evidence that laticifer cells present in the callus cultures of rubber tree by histochemical and immunohistochemical studies. They present in the callus mainly as separate non-elongated form, a novel morphology different from the morphology of laticifer cells in planta, excluding their origin from explants. The occurring frequency of laticifer cells in the callus was genotype-dependent and negatively correlated with the somatic embryogenetic ability, suggesting that the presence of laticifer cells in the callus inhibit somatic embryogenesis in tissue culture of rubber tree. The genotypes PR107, RRIM600, Reyan8-79, and Reyan7-33-97 with lower embryogenetic ability compared to Haiken 2 had more laticifer cells, and laticifer clusters were only observed in these genotypes.