Synthetic seed production of Polygonatum verticillatum All. a threatened medicinal herb growing in Kashmir Himalaya

Polygonatum verticillatum , is an IUCN Red List-assessed Vulnerable medicinal plant exploited for its bioactive compounds. The species is declining rapidly in its natural habitat because of unregulated and intensive collection, highlighting the urgent need for its conservation. Encapsulation is an alternative approach for conservation and germplasm storage. During the present study, an encapsulation protocol was established to obtain artificial seeds of P. verticillatum. Buds excised from in vitro raised rhizomes were encapsulated in calcium chloride and sodium alginate complexing solution. Best bead formation was achieved with 3% sodium alginate, 3% sucrose and 125 mM CaCl 2 .2H 2 O solution. The encapsulated buds exhibited the best growth and conversion frequency on MS medium supplemented with kinetin (2.0 mg L − 1 ) and 6-benzylaminopurine (1.0 mg L − 1 ) after 21 ± 0.57 days with 90% germination rate. For shoot multiplication, result was observed on MS medium fortified with kinetin + 6-benzylaminopurine (2.0 mg L − 1 ) on which 16.33 ± 0.88 number of shoots regenerated with 5.2 ± 0.11 cm length within 13.66 ± 0.33 days. Among the two different temperature regimes (4 ℃ and 25 ℃), storage of artificial seeds at 25 ℃ showed the maximum frequency of conversion (70%) after 20 days of storage. Besides in vitro synthetic seed germination, successful conversion of encapsulated rhizome buds in in vivo conditions was obtained in soil: vermicompost in the ratio of 1:1 with 40% culture response within 32 days. Extended period of storage time and storage temperature, however, decreased the conversion frequency. Application of this protocol, demonstrated here for short-term storage of up to 30 days, would help in reducing collection pressure on natural populations and provides a promising basis for short- to medium-term germplasm exchange of elite genotypes of P. verticillatum , with cryopreservation and long-term storage remaining a goal for future work.