ibclogo XVI International Botanical Congess


Abstract Number: 4368
Poster No. = 1740


INVESTIGATION ON DEFENSIVE MECHANISMS AND SEED COAT DEVELOPMENT IN MELILOTUS INDICA


Nidhi Gautam, Department of Botany, Daulat Ram College, Universityof Delhi, Delhi-7, India


Histochemical and electron microscopic studies were performed on developing seeds and pods of Melilotus indica all with an objective to elucidate the probable role of long lasting trichomes present on ovary surface and to study the development details of seed coat.he seeds of Melilotus indica All (an important fodder legume) are considered as one of the hardest leguminous seeds, that develop inside single seeded small pods. The young ovary is covered with small, multicelled, uniseriate glandular trichomes that develop from epidermal cells as early as at the embryo-sac stage and persist late up to the dicotyledonous embryo stage at the time when seed coat is hard enough. The mature dry seed is dorsoventrally flat with a complex hilar region. During ontogeny the outer integument modifies gradually into a thick and hard seed coat comprised of outermost macrosclereid layer, a hypodermal osteosclereid layer that is followed by two or three parenchymatous layers. Like other legumes, the macrosclereid layer represents the modified epidermal layer of the outer integument while the cells of hypodermal layer change to osteosclereids imparting additional hardiness to the seed coat. The present investigations suggest that secretory and long lasting ovarion trichomes play an important defensive role against the attack of pathogens and ensure the survival of seed inside the pod. The tight packaging and cuticularization of macrosclereids make the seeds of Melilotus indica hard and impermeable.


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