In vitro conservation
The CIP genebank is one of the largest (if not the largest) in vitro genebank world. This global germplasm collection comprising the widest genetic diversity of cultivated potato, sweetpotatoes and Andean Root and Tuber Crops (ARTCs) (achira, ahipa, arracacha, oca, maca, mashua, mauka, ulluco, and yacon). Together these collections comprise over 11,000 accessions in tissue culture held in trust under the International Treaty for Plant Genetic Resources For Food and Agriculture (ITPGRFA) (Table 1), plus in addition to ~4,500 CIP-derived research materials (breeding lines Link to breeding materials website).
The CIP Genebank initiated in vitro cultures more than 40 years ago and have extensive expertise in the research for developing and assaying tissue culture technologies for these crops. In vitro cultures are initiated from and maintained sterily as identical replicates (clones of plantlets) of the original mother plant. They are periodically renewed (transferred) to maintain optimal viability and to ensure that phytosanitary clean germplasm is available for immediate distribution and use. These in vitro accessions are the primary source of germplasm for characterization, genetic identity, DNA extractions, pathogen elimination, cryopreservation, safety back-up, and distribution to breeders, farmers, and researchers within CIP and worldwide (Link to protocols and Fig. 1).
The in vitro conservation methods developed by CIP’s Genebank apply treatments reducing plantlets’ growth, such as osmotic stress and low temperature for storage. The aim is to keep viable plantlets in a medium-term-storage (MTS) period. CIP’s potato method is quite efficient, by using low temperature (6-8°C) and culture medium containing sorbitol as an osmotic agent, the MTS is two years. This is currently the most robust method for conserving potato collections and is used by most potato Genebanks worldwide. A similar method is applied to the other tuber crops; however, the germplasm has a shorter tolerance and must be regenerated more frequently. MTS is 1 year in oca, 1.5 year in ulluco and mashua. The Sweetpotato method includes incubation at 19-21°C with a MTS period of one year. 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 yacon, arracacha, and achira. The cultures require renewal when plantlets viability declines. Plantlets are sub-cultured by isolating and transferring healthy shoots onto fresh media for re-growing (see Annex 1, operational procedures for in vitro conservation of potato, sweetpotato, and ARTCS, and related documents). CIP’s In vitro Genebank is constantly evolving and improving.