In vitro medium-term conservation of Garcinia indica: a tropical recalcitrant seeded fruit tree of India

Garcinia indica (Thouars) Choisy is one of the important fruit species of the Clusiaceae family distributed in the Western Ghats of India in wild and semi-domesticated forms. This is an under-exploited, dioecious tree with high economic potential. Germplasm conservation of this species is limited to in situ or on-farm level only due to the highly recalcitrant nature of its apomictic seeds. As the seeds are sensitive to moisture as well as low-temperature stresses, conservation has so far not been reported from any seed genebank or cryogenebank. The present work aimed to develop a medium-term conservation strategy under in vitro culture conditions. Adventitious in vitro shoots were developed through direct organogenesis in one accession (IC638184) sourced from Konkan region of the Western Ghats of Maharashtra. These shoots were grown on different concentrations of plant growth regulators to increase the subculture duration of the in vitro plants. The effects of growth regulators on multiplication and growth of cultures were investigated in Murashige and Skoog (MS) media with 6-benzylaminopurine (BAP) at six concentrations (4.44, 6.66, 8.88, 17.76, 26.64, and 35.52 mu M) alone and in combination with naphthaleneacetic acid (NAA) at three concentrations (0.53, 2.68, and 5.37 mu M). Cultures raised on MS medium supplemented with 6.66 mu M BAP and 0.53 mu M NAA and incubated at 25 +/- 2 degrees C showed a 36% survival up to 24 mo of culture. Similar results were obtained in three other accessions of G. indica (IC638183, IC638185, and IC638186) collected from the same region. The shoots conserved for 2 yr showed 100% regeneration on fresh multiplication medium and successfully hardened with a survival of 90%. Conservation of germplasm using in vitro medium-term storage was not only cost-effective but also important for the development of cryopreservation protocols for its long-term conservation.