Abstract Detail

Recent Topics Posters

Stafford, Maribeth [1], Philpott, Megan [2], Pence, Valerie [1].

Improving survival rates after cryopreservation due to genetic variation in the exceptional Hawaiian species Melicope mucronulata..

A growing number of plant species are labelled ‘exceptional’, meaning they cannot be preserved using traditional seed banking methods. Instead, ex situ conservation efforts may utilize cryopreservation for long term storage. A major focus of endangered plant conservation is maintaining as much genetic diversity as possible within a species. Issues arise within some exceptional plant species when cryopreservation protocols must be tested and optimized per genotype as opposed to developing one protocol per species, as in the exceptional species Melicope mucronulata, an endemic, critically endangered tree from Hawaii. Genotypes of the species exhibited differing survival rates following cryopreservation ranging from 0% to 60%. Without improved survival in the low surviving genotypes, an unrepresentative ex situ collection could put future restoration populations at a high risk for inbreeding and low diversity. Losing this genetic diversity could also lead to unintentional artificial selection during restoration and reintroduction. Two preculture and two recovery media were tested using a standard droplet vitrification (DV) cryopreservation protocol across all genotypes. This included CREW’s standard two-day preculture (MS salts with 1mg/L BAP, 0.01mg/L NAA, 0.3M mannitol, and 10µM ABA gel medium) and recovery (0.5mg/L BAP gel medium) and a USDA citrus plant one day preculture (½ MS liquid medium) and recovery (Woody Plant salts agar medium). The USDA preculture showed significantly higher survival (p = 0.002) while the USDA recovery medium had a significant negative effect compared to the CREW recovery medium (p = 0.04). M. mucronulata was initially banked using CREW’s DV cryopreservation protocol and those genotypes with survival under 40% were marked for rebanking using the USDA preculture and CREW recovery media. The new protocol increased survival of low surviving genotypes from 1.5% on the CREW protocol to 6.8%, however this is lower than the standard target of 40%. To combat this, over 870 shoot tips of all 17 genotypes were banked, 360 of them with the new protocol on the 10 low surviving genotypes. For plants that show low survival following cryopreservation, banking replicates is often the best route if new protocols do not shift overall survival above the goal of 40%. This work focused on improving protocols for cryopreservation across genotypes in a species and demonstrates the challenge of cryopreservation in species that exhibit survival differences due to genotypic variation.

1 - Cincinnati Zoo and Botanical Garden, CREW, 3400 Vine Street, Cincinnati, OH, 45220, USA
2 - Cincinnati Zoo & Botanical Garden, CREW, 3400 Vine St., Cincinnati, OH, 45220, United States

Keywords:
Hawaiian Islands  
endangered
exceptional
cryopreservation
conservation
ex situ.

Presentation Type: Recent Topics Poster
Session: P1, Recent Topics Posters
Location: Virtual/Virtual
Date: Thursday, July 22nd, 2021
Time: 5:00 PM(EDT)
Number: P1RT012
Abstract ID:1402
Candidate for Awards:None