ARS | Publication request: Long-term preservation of Pycnanthemum genetic resources

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 24, 2012
Publication Date: June 3, 2012
Citation: Jenderek, M.M., Holman, G.E., Ellis, D.D., Reed, B.M. 2012. Long-term preservation of Pycnanthemum genetic resources. Meeting Abstract. In Vitro Biology Meeting, Bellevue, WA, June 3-7, 2012.

Technical Abstract: Plants of Pycnanthemum Michx. (Mountain mint; Lamiaceae) are native to North America. They naturally grow in prairies, forest edges, pastures and along roadsides. Their flowers provide abundant nectar for honey bees, wasps, butterflies and other insects. Mountain mint leaves are very scented and pungent making them usable as spices. The plants also contain fragrant oils that are used in pharmaceutical and cosmetic industries. Some species have ornamental value and are sold in nurseries. The genus has over 20 different species. The National Plant Germplasm System (USDA, ARS) has 120 different accessions of Mountain mint and several of them are maintained vegetatively as tissue culture. Our study investigated the possibility of placing 27 different in vitro accessions (12 species) in long-term storage to avoid periodic subculturing. Shoot tips were isolated from three-week old cultures, cold hardened for two additional weeks (22oC/8 hr light and -1oC/16 hr dark). The shoot tips consisted of basal stem tissue, 1-2 young leaf bases and 1-2 leaf primordia. The cryopreservation followed an encapsulation-dehydration protocol. After 24 hours of storage in liquid nitrogen, the encapsulated shoot tips were warmed to 20-25oC and plated on a recovery medium (MS+BA 0.5 mg/L and IBA and 0.1 mg/L). After two weeks, the shoot tips were transferred to a growth medium (MS without growth regulators) for another three weeks. For 23 accessions, the post cryo viability (culture with developed leaves and roots) was 60 to 100%. The viability for the remaining four accessions was 40 to 50%. The encapsulation-dehydration cryopreservation method proved adequate for long-term preservation of the 27 Pycnanthemum germplasm accessions.