Cryopreservation of shoot tips of recalcitrant and tropical species: Advances and strategies.

Kaempferia galanga L. (Family Zingiberaceae) is an endangered medicinal plant with potent medicinal activities. The leaves, rhizome and root tubers of the plant possess a number of medicinal applications. The plant is economically important and is over exploited to the extent that there is always scarcity of propagating material (rhizomes) which is the consumable part too. As it is vegetatively propagated, its conservation via conventional and non-conventional means is very much crucial. The present review provides broad information of K. galanga throwing light on its current status, economic value, agronomy, ethnobotany, phytochemistry, pharmacology and conservation strategies

https://www.plantsjournal.com/archives/2016/vol4issue3/PartD/4-3-8-414.pdf

A comprehensive review of Kaempferia galanga L. (Zingiberaceae): A high sought medicinal plant in Tropical Asia

Rapid strides have been made in plant biotechnology, including plant tissue culture and conservation techniques. The newly acquired knowledge is now being commonly applied in collection, exchange, multiplication and short- to long-term conservation of genetic resources of crops, especially horticultural crops. Several protocols for in vitro conservation and/or cryopreservation are reported in both temperate and tropical species of fruits, spices, tubers and ornamental and medicinal species. Techniques for rapid multiplication and production of plant material using tissue culture methods are important prerequisites for a successful programme on in vitro conservation and cryopreservation. In case of clones to be maintained under conservation, monitoring genetic stability becomes an integral activity to ensure avoidance of somaclonal variation. In vitro conservation of horticultural germplasm has been successfully applied by means of in vitro slow growth storage in several national and international gene banks/laboratories. Cryopreservation of germplasm (normally using liquid nitrogen, −196 °C) is currently advocated as the safest and cost-effective long-term strategy for conservation of horticultural genetic resources. Although large-scale, routine application of cryopreservation is still limited to a few laboratories, there are an ever-increasing number of publications reporting successful protocols in many horticultural species. This has been possible due to advances in development of more ‘generic’ new-age cryopreservation protocols like droplet-vitrification.

In Vitro Conservation and Cryopreservation of Clonally Propagated Horticultural Species

Tissue culture comprises several techniques for the mass propagation of selected genotypes. In the case of palms, the most promising and efficient micropropagation technique is somatic embryogenesis. Ever since somatic embryogenesis was first induced in oil palm several decades ago, 19 palm species have been induced to develop somatic embryos from several types of explants. Optimization of somatic embryo multiplication protocols has been the central focus of research, but embryo maturation and conversion remains poorly-studied in many palm species. This review summarizes the advances made in both the study and optimization of palm somatic embryogenesis (SE) protocols. Explant choice and inoculation method, media components, culture method, histology of early somatic embryogenesis, gene expression, biochemical changes, embryo maturation and conversion, and acclimatization of regenerated plantlets are presented and critically discussed.

Palm (Arecaceae) somatic embryogenesis

Cryopreservation of oil palm (Elaeis guineensis Jacq.).

Shoot tips from the established in vitro shoot cultures of Kaempferia galanga L., an endangered medicinal plant were successfully cryopreserved using the vitrification procedure. Effect of concentration of sucrose for preculture, vitrification treatment with PVS2(Plant vitrification solution 2) and recovery medium on cryopreservation of shoot tip meristems has been analyzed. Overnight preculturing of the dissected shoot tips in MS medium containing 0.4 M sucrose, osmoprotection with loading solution for 20 minutes, dehydration with PVS2 for 20 minutes at 0 oC were found to be optimum among the various treatments tested. The cryoprotected shoot tips upon rapid freezing in LN (liquid nitrogen) followed by rapid thawing produced 50-60% survival and 30-40% regeneration rates. Incorporation of GA3 (giberellic acid) in the post-thaw culture medium was essential to induce shoot emergence in the initial phase. Subculturing of the recovered shoot tips in MS medium supplemented with 1.0 mgl -1 BA (6-benzyl adenine) and 0.5 mgl -1 NAA (α-naphthaleneacetic acid) resulted plantlet production. The regenerated shoots grew to mature plants were free of any morphogenetic variation upon field transfer.

/pdf/shoot-tip-cryopreservation-by-vitrification-in-kaempferia-nvyytp7fab.pdf

Shoot tip cryopreservation by vitrification in Kaempferia galanga L. An endangered, overexploited medicinal plant in Tropical Asia

Zygotic embryos excised from immature green fruits of the rattan palm, Calamus thwaitesii and cultured for 16 weeks under optimum culture conditions in Murashige and Skoog (MS) medium supplemented with 31.67 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 35.23 μM 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) produced mixed (compact and friable) calli at 70 and 92 % rates. The semi-friable part of the callus (~500 mg) separated and subcultured in medium containing 2.22 μM 6-benzyladenine and 1.07 μM α-naphthalene acetic acid produced groups of 10.37 ± 0.60–21.52 ± 0.48 discrete globular embryoids of varied size in 6–8 weeks. Calli raised in presence of 2,4,5-T were relatively more prolific, friable and embryogenic than those induced by 2,4-D. Embryoids (2.0–3.0 mm) isolated and cultured in basal medium germinated into plantlets at 65 % efficiency while the immature (0.5–2.0 mm) ones produced calloid structures. Approximately 15 % of the in vitro plantlets raised from the 2,4-D-induced embryogenic calli produced secondary immature embryoids on the sheath and lamina parts of leaves which were isolated and cultured in basal medium developed into rooted plantlets at 62 % rate in 12–16 weeks. The continued growth of the embryo-derived callus through successive subcultures together with differentiation of embryoids into plantlets, and the formation of immature embryoids on in vitro plantlets in MS basal nutrient medium reports for the first time a reliable method of producing at least 116 plants from a single embryo in a year. Rooted plantlets treated with 50 % glycerin survived at 78 % rate after hardening and 82.7 % of the hardened plants reintroduced into forest segments showed uniform growth free of morphological abnormalities after 3 years of observation. In addition to embryogenesis, cryopreservation of the zygotic embryos through simple drying and encapsulation–dehydration methods resulting 60–70 % recovery rates also offers another option for long-term conservation and sustainable utilization of this plant genetic resource.

/pdf/utilization-of-zygotic-embryos-of-an-economic-rattan-palm-g14vko3mc0.pdf

Utilization of zygotic embryos of an economic rattan palm Calamus thwaitesii Becc. (Arecaceae) for somaplant regeneration and cryobanking

https://wwmw.academicjournals.org/article/article1380716913_Preetha et al.pdf

T. S. Preetha

Papers

Shoot tip cryopreservation by vitrification in Kaempferia galanga L. An endangered, overexploited medicinal plant in Tropical Asia

Utilization of zygotic embryos of an economic rattan palm Calamus thwaitesii Becc. (Arecaceae) for somaplant regeneration and cryobanking

Effect of plant growth regulators on high frequency in vitro multiplication of a vulnerable woody medicinal climber Embelia ribes Burm. f.