Submitted to: Journal of Crop Improvement
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/21/2007
Publication Date: 3/3/2008
Citation: Sakhanokho, H.F., Kelley, R., Rajasekaran, K. 2008. First Report of Plant Regeneration via Somatic Embryogenesis from Shoot Apex-derived Callus of Hedychium muluense. Journal of Crop Improvement. 21:191-200. Interpretive Summary: The genus Hedychium consists of about 50 species and is one of the most popular genera of the Zingiberaceae family because of its attractive foliage, diverse and showy flowers, and sweet fragrance. Hedychium species are widely cultivated for their perfume essences, and the aerial stems constitute a useful raw material for manufacturing paper. In addition, the essential oils of some Hedychium species have been found to have antimicrobial activity against both Gram-positive and Gram-negative bacteria. The main limitation to using most Hedychium cultivars as potted plants is that they grow too tall, easily reaching two meters. H. muluense is one the few dwarf Hedychium species. Therefore, it has the potential to play an important role in the development of dwarf Hedychium cultivars using either conventional or molecular breeding. Tools of genetic engineering have been used to develop improved ornamental cultivars, but this requires a dependable in vitro regeneration system, preferably based on somatic embryogenesis. Despite their potential ornamental, medicinal, and industrial values, very little molecular work has been done in Hedychium species. The regeneration system available in the literature is generally based on rhizome meristem tissue culture. No report on regeneration based on somatic embryogenesis is available in any Hedychium species. Therefore, the purpose of the present study was to establish an in vitro regeneration system based on somatic embryogenesis system for H. muluense using shoot apex-derived callus, which was successfully achieved. The protocol developed here could be used for the regeneration of other Hedychium species. These results also pave the way for the transformation (genetic engineering) of this dwarf Hedychium species.
Technical Abstract: Plants were successfully regenerated via somatic embryogenesis from shoot apex-derived callus of Hedychium muluense R.M. Smith, an important monocotyledonous ornamental ginger plant. Callus was induced on a modified Murashige and Skoog (MS) medium supplemented with 9.05 µM 2-4, D and 4.6µM kinetin. Friable callus was selectively transferred into a liquid medium consisting of MS basal salts and Gamborg’s vitamins and supplemented with 0.6 µM thidiazuron (TDZ) and 8.9 µM 6-benzylaminopurine (BA) and shaken for four weeks. The cultures were then transferred to three Hedychium embryo development media (HEDM) of varying strengths and referred to as HEDM, 1/2 HEDM and1/4 HEDM. All three media contained both 0.6 µM TDZ and 8.9 µM BA. Somatic embryo production was higher in full strength HEDM, which produced an average of 103 somatic embryos/explants, half of which could be converted into shoots within a month. Regenerated shoots were readily rooted on a medium supplemented with 0.6 µM 3-indoleacetic acid (IAA) and acclimatized before transfer to the greenhouse.