Morphological, Anatomical and Tissue Culture Studies on Xylocarpus granatum

Xylocarpus species are important endangered mangrove species in Malaysia. One of the economic
importance of the species, particularly Xylocarpus granatum is for wood carving. Hence, there is an
urgent need to conserve the species. In the present study, some morphological, anatomical and tissue
culture studies were carried out on Xylocarpus granatum. To date, there is no record on detailed
morphological study of the species. Therefore, it is one of the aims of the study to investigate the
morphological characteristics of the species. Anatomical studies on the leaf and primary stem were also
carried out. Scanning electron microscope study revealed the presence of sunken, anomocytic-type
stomata on the abaxial surface of the leaf. Results from anatomical studies showed the presence of
thick cuticle on both abaxial and adaxial surfaces of the leaf. Sunken stomata and thick cuticle are
adaptations of mangrove species to reduce transpiration. Tannin cells were also observed in the leaf
lamina and primary stem and this needs further investigation. Regeneration of this species from tissue
culture had been attempted, however, only callus formation was observed. Formation of callus from
leaf segments, young stems and flower buds were observed after three weeks being cultured on MS
medium supplemented with 2.5mg/l 2,4, Dichlorophenoxyacetic acid (2,4-D). MS medium
supplemented with 10 mg/l 2,4-D and 10mg/l Naphthalene acetic acid (NAA) managed to produce
87.5% callus after 14 days in culture when leaf explants were used. It was observed that more calli
were formed when the cultures were maintained in the dark. At pH 4.0, the cultures seemed to form
faster and more calli were formed. The addition of 0.1g/l sodium chloride (NaCl) to MS medium
produced 70% callus. The callus produced was analysed to see whether they are embryogenic or nonembryogenic.
A few callus cells were found to be in the globular stage of embryogenesis but failed to
develop further. Work is in progress to induce somatic embryogenesis in this species.