The “in vitro conservation” is a biotechnological method that uses a combination of plant tissue culture techniques through which vegetative propagules (ie. stem cutting, shoot, meristem) of clonal crop are cultured aseptically in a medium of specific chemical composition, incubated in controlled environment, and maintained growing under healthy and safe conditions. Currently, it is considered the most efficient method for conserving and distributing genetic resources of clonal crops.
The CIP’s genebank uses this technology for conserving the global genetic resources collections of potato, sweetpotato and six clonal Andean root and tuber crops (ARTCs) (achira, arracacha, mashua, oca, ulluco, and yacon). These collections comprise over 13,000 accessions maintained “in vitro” constituting the largest “In vitro Genebank” in the world. Over 11,000 accessions are landraces and varieties held in trust under the International Treaty for Plant Genetic Resources For Food and Agriculture (ITPGRFA), and additionally about 2,000 accessions of CIP-derived breeding research materials (breeding lines) are conserved.
The CIP Genebank initiated in vitro cultures more than 45 years ago and has extensive expertise in developing and applying diverse technologies for the introduction to in vitro of vegetative propagules, safe in vitro conservation, pathogen elimination, cryopreservation and ensuring these genetic resources are available for immediate distribution and use. Germplasm accessions are incorporated to the in vitro collections by two ways, one is taking tissue samples from in vivo plants which are subjected to disinfection and aseptic culture until to get plantlets successfully growing in vitro; the second way is by receiving in vitro cultures transferred from other in vitro genebank, these cultures follow strict quarantine rules before its establishment in the CIP’s collections. All the materials held in the CIP’s In vitro Genebank are the primary source of germplasm for the most Genebank activities as characterization, genetic identity, DNA extractions, pathogen elimination, cryopreservation, safety back-ups, and distribution to breeders, farmers, and researchers within CIP and worldwide. All procedures for the in vitro conservation and distribution are carried out under strict quality control measures ensuring the genetic integrity and health of each accession maintained.
The in vitro conservation methods developed by CIP’s genebank use treatments for reducing plantlet growth, such as osmotic stress and low temperature for storing viable plantlets in a medium-term-storage (MTS), period where transferring is not needed as often. CIP’s potato method uses low temperature (6-8°C) and culture medium containing sorbitol as an osmotic agent; by this, the need for fresh transferring is prolonged from once every 6-8 weeks to two years. This is currently the most robust method for conserving potato collections and is used by most potato genebanks worldwide. The sweetpotato method includes incubation at 19-21°C with a MTS period averaging one year. Regarding the ARTCs, a similar method than potato is applied to oca, ulluco and mashua; however, the germplasm has a shorter tolerance to the low temperature and thus must be regenerated more frequently. MTS is 1 year in oca, 1.5 year in ulluco and mashua. The other root collections (yacon, arracacha, and achira) are conserved by short-term methods with renewals occurring every 4-8 months. Research is required for developing improved MTS methods for these crops. Maintenance of the collections implies continues monitory of the viability of each accession. When plantlets viability declines, cultures require subculturing by isolating and transferring healthy shoots onto fresh media for re-growing (see protocols for in vitro conservation of potato and sweetpotato, and for ARTCs). In the CIP’s In vitro genebank all procedures are constantly evolving and improving.
CIP Genebank promotes the use of this germplasm under the International Treaty for Plant Genetic Resources for Food and Agriculture (ITPGRFA) and therefore each distribution is subjected to the terms and conditions of the Standard Material Transfer Agreement (SMTA).