In Vitro Laticifer Identification in Young Shoot-Derived Callus of Hevea brasiliensis Muell. Arg.

In vitro laticifer in young shoot-derived callus of Hevea brasiliensis Muell. Arg. (RRIM600 cultivar) was examined histologically and histochemically. Calluses were induced on a 2,4-D (1 mgL -l ) supplemented Murashige and Skoog (MS) culture medium containing different strengths of MS-micronutrients (quarter (¼), half (½) and full) and kinetin (0, 1 and 2 mgL -1 ). The highest percentage of callus induction (52.78 ± 5.01 %) exhibiting hard and compact calluses was achieved using ½-strength MS-micronutrients without kinetin. Friable calluses were obtained on full-strength MS-micronutrients supplemented with 1 mgL -1 kinetin. Histological details indicated that calluses initiated from the sub-epidermal layers. One-month-old calluses presented thick cell wall laticifers which were mainly randomly arranged and located in separately and aggregately. All in vitro laticifers in the callus were non-elongated which were different from those in the stem. Some callus cells exhibited secondary wall thickening which had structural features similar to those of the vessel.