food security

Chris O'Brien, Jayeni Hiti Bandaralage, Raquel Folgado, Sean Lahmeyer, Alice Hayward, Neena Mitter Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Australia The Huntington Library, Art Collections and Botanical Gardens, San Marino, CA., United States

Australia’s avocado industry is worth over ~$557 million and produces more than 77,000t. The genetic diversity of the avocado genus remains largely unexplored but a vast resource (approximately 90 species/>3000 varieties) for crop improvement. Persea spp. are traditionally restricted to ex-situ conservation due to high heterozygosity and recalcitrance nature of seeds. Field banks are vulnerable to abiotic and biotic stresses. Thus, size of the gene pool, replications and quality are restrained by environmental conditions, space and funding. Cryopreservation is a safe and cost-effective method of germplasm conservation. Preserving shoot-tips enables conservation of exact gene pool of interest. Cryo-protocols that use vitrification solutions usually cause high mortality. Avocado is highly susceptible to osmotic stresses upon vitrification. To date there are no reports of survival/regrowth of in vitro cryopreserved shoot tips. This study aimed to optimize sucrose pre-culture to sustain shoot tip survival/regrowth after cryopreservation. In vitro shoots of cultivar ‘Velvick’ were pre-cultured for 2 weeks on 0.3 M sucrose and 100 mg/L Ascorbic acid containing media to be compared with normal sucrose concentration of 0.09 M. For cryo-treatments shoots were dissected to obtain 1 x 1 mm shoot-tips. When treated with PVS2 and evaluated for survival, pre-cultured shoots displayed higher survival 83%, higher regrowth 73% with vigorous green cultures and appeared morphologically normal. In contrast non-precultured shoots-tips recorded 70% survival, 23% regrowth resulted in stunted yellow-brown and less vigorous cultures. Very interestingly, after liquid nitrogen treatment pre-cultured shoot-tips showed 60% survival while no sucrose treatment lead to 0% survival. The cryo-preserved shoots developed into green proliferating clumps after 8 weeks in culture. This result is the first report of successful survival and proliferation of cryopreserved shoots of avocado and further optimizations may lead to development of a high efficiency cryopreservation protocol of the species.

Date Recorded: 
Tuesday, July 23, 2019

Gayle Volk, USDA ARS National Laboratory for Genetic Resources Preservation, United States

The USDA-ARS National Plant Germplasm System has over 30,000 clonally maintained accessions within its field, screenhouse, greenhouse, and tissue culture collections. These fruit, nut, tuber, and bulb crop collections are usually not duplicated at secondary locations and are vulnerable to bioticabiotic, and climatic threats. Only about 15% of the clonally maintained accessions are currently secured in long-term storage at the National Laboratory for Genetic Resources Preservation (NLGRP) in Fort Collins, Colorado. The labor required to cryopreserve the clonal collections at NLGRP exceeds that which is available, even when reliable, robust cryopreservation methods are available. We have sought to prioritize collection materials for cryopreservation and to identify methods that improve the efficiency of the shoot-tip cryopreservation procedure. In particular, we have used field-, screenhouse-, and growth-chamber harvested plant tissue as source material for shoot tip cryopreservation, rather than relying on in vitro grown cultures. This strategy has been particularly effective for garlic, citrus, and grape cryopreservation efforts. In addition, incorporation of antioxidants and shoot tip micrografting methods have made cryopreservation protocols widely applicable to diverse genetic resources for each crop.

Contributing Author(s): 
Date Recorded: 
Tuesday, July 23, 2019

Bart Panis, Bioversity International, Belgium

More than 800 million people are undernourished and 200 million children under five years of age are underweight. Moreover, the world’s population is expected to reach 10,500 million by 2050. Reliable and sustainable improvements in yield will thus be needed to meet the demands of this growing population. The availability of the largest possible crop diversity is central to food security. Crop collections encompass seed propagated as well as vegetatively propagated crops. Seed is classically stored at -20°C (and sometimes cryopreserved) while vegetatively propagated crops are maintained in the field, stored as in vitro collection under reduced growth conditions or through cryopreservation. Cryopreservation plays an essential role in the safe conservation of plant genetic resources of vegetatively propagated crops like bananas, cassava, potato, yams and sweet potato. Cryopreservation research on these crops already started in the 80ties but it was only with the development of vitrification protocols and more recently with the use of droplet vitrification that a significant portion of such collections are now stored in liquid nitrogen. The droplet vitrification protocol was established because it combines the application of highly concentrated vitrification solutions (often PVS2) with ultra-fast freezing and thawing rates both leading to a lower chance of lethal ice crystal formation. Currently, over 10,000 accessions starting from in vitro cultures are safely preserved for the long term through cryopreservation. More than 80% of these belong to 5 crops; potato, cassava, bananas, mulberry and garlic. Other important cryopreserved collections representing thousands of accessions are those of dormant apple buds. One of the recommendations of an expert group to apply cryopreservation to a wider diversity of vegetatively propagated crops was to establish a collaborative effort among researchers and genebanks that is focused on the specific technical and practical issues.

Date Recorded: 
Monday, July 22, 2019