Comparative histochemical localization of secondary metabolites in seed-raised and in vitro propagated plants of Excoecaria agallocha Linn. (Euphorbiaceae), the milky mangrove tree of historical significance.
Mangroves synthesize novel secondary chemicals that are poorly understood. Among the euphorbiaceous mangrove species, Excoecaria agallocha Linn. produces novel terpenoids and alkaloids of medicinal importance. We conducted a comparative tissue level histochemical study of E. agallocha L. to determine whether in vitro propagation alters the content of phytochemicals within the plant parts. Transverse sections of the root, stem and leaves of seed-raised saplings and in vitro propagated plants stained with 10% vanillin-perchloric acid revealed accumulation of terpenoids in the cork cambium. Alkaloids were localized using Dragendorf's reagent in the cortex of the root sections as brown layers. Methylene blue staining revealed that seed-raised plants possessed more lignified cells, distinct latex ducts and ellipsoidal guard cells compared to the plants propagated in vitro, which revealed abnormal, circular guard cells. The phytochemical content of E. agallocha propagated by the in vitro method was comparable to the seed-raised plants. Phytochemical studies of the species of E. agallocha propagated in vitro would confirm whether the species could be used for its medicinal compounds.
Satyan
R S
RS
Tissue Culture and Bioprospecting Laboratory, M. S. Swaminathan Research Foundation, 3rd Cross Street, Taramani Institutional Area, Taramani, Chennai 600113, India. satyanoid@gmail.com
Aveek
N
N
Eganathan
P
P
Parida
A
A
D000470:Alkaloids / Q000032:analysis / Q000378:metabolism*; D058506:Cambium / Q000737:chemistry / Q000166:cytology; D019665:Euphorbiaceae / Q000254:growth & development / Q000378:metabolism*; D006651:Histocytochemistry; D008031:Lignin / Q000032:analysis / Q000378:metabolism*; D018515:Plant Leaves / Q000737:chemistry / Q000166:cytology; D012639:Seeds / Q000254:growth & development / Q000378:metabolism*; D013194:Staining and Labeling / Q000379:methods*; D013213:Starch / Q000032:analysis; D013729:Terpenes / Q000032:analysis / Q000378:metabolism*
D000470:Alkaloids; D013729:Terpenes; D013213:Starch; D008031:Lignin