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Morphogenetic potential of root, leaf, node and internode expiants of 3 cultivated Piper species was investigated to develop a reliable plant regeneration protocol. P. longum (pipli) was the most responsive followed by P. betle (betel vine) and P. nigrum (black pepper). In P. longum the highest number of shoot buds was produced on root expiants followed by node, internode and leaf expiants. In P. betle and P. nigrum adventitious shoot buds differentiated only from internodal and nodal ring regions, respectively. Histological examination in P. longum showed that adventitious shoot buds originate directly from the cortical cells of the root and the internode without an intervening callus phase. Benzyladenine was superior to kinetin for shoot induction and its optimum concentrations for P. longum, P. betle and P. nigrum were 1-2, 10 and 10 μM, respectively. Shoot elongation and rooting were achieved in B5 medium containing 0.5 μM benzyladenine and 1 μM indoleacetic acid, respectively. Regenerated plants were established in soil.

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Citrus indica and C. macroptera are the wild endangered species of Citrus occurring in northeastern India. Surveys were undertaken in this region for ascertaining distribution, studying variability and for collection of germplasm of these two species. C. indica, an endemic species of this region, was collected from the Citrus Gene Sanctuary located in buffer zone of Nokrek Biosphere Reserve in the Garo hills of Meghalaya. In addition, a putative natural hybrid of C. indica and C. limon was collected for the first time from the south Garo hills. C. macroptera had much wider distribution and was collected from Mizoram and Meghalaya states. In Jantia hills of Meghalaya, natural populations of this species are in a highly threatened state. The two species were unevenly distributed all over the explored territory. Morphological characterization of leaves, fruits and seeds indicated the presence of sizable variability within collected accessions of these two Citrus species. Indigenous technical knowledge gathered on the use and socio-economic importance indicated commercial potential for these two species in northeastern India. However, lack of cultivation of these species and clearing of forest cover at an alarming rate has led to an urgent need to adopt complementary conservation strategies to safeguard these species and to ensure their availability for future utilization. A major emphasis on developing methods for their propagation, multiplication and regeneration in in situ and ex situ conditions is required.

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