Phytosanitary

The in vitro genebank of the International Potato Center (CIP) holds 4,486 accessions of potato, 5,574 sweetpotato, and 1,431 Andean roots and tuber crops (ARTCs). Currently, 67% of the in vitro potato accessions and 64% sweetpotato accessions are bacterial and fungal contaminants and are certified as virus-free. While the important diseases and their detection methods are well established for potato and sweetpotato, the ARTC’s have little information on diseases which infects them. Current research has begun to find efficient methods for diagnosing viruses in ARTCs.

Virus elimination

CIP’s virus elimination procedure was originally developed inhouse with help from collaborators and has continuously evolved into an effective but relatively slow, low throughput process that never-the-less can be applied to a wide range of accessions and types of virus. Starting in 2008, methodologies for producing pathogen-tested free materials were improved and certified by the International Standard ISO/IEC 17025:2005.

The virus elimination process for potato and sweetpotato includes the following steps: (a) Initial health status testing by serological, molecular, and bioindexing (5 months); (b) Accessions found to be infected with viruses are subjected to thermotherapy (incubation of in vitro plants at 32-34 for potato and 35-37ºC for sweetpotato (~1 month), followed by meristem isolation (0.2-0.35mm meristems), and complete plant recovery (2-6 months); (c) Final health status testing (step a) is repeated to confirm that the resulting plants are virus-free ( ~ 5 months) .

Excision of potato meristems after undergoing 30 days thermotherapy (32-34ºC).

List of viruses tested by CIP

Crop Virus Acronym Detection Method *
Potato Potato virus T PVT NASH
Potato spindle tuber viroid PSTVd NASH
Potato virus X PVX DAS-ELISA
Potato virus Y PVY DAS-ELISA
Potato leaf roll virus PLRV DAS-ELISA
Potato virus S PVS DAS-ELISA
Andean potato mottle virus APMV DAS-ELISA
Andean potato latent virus APLV DAS-ELISA
Potato yellowing virus PYV DAS-ELISA
Arracacha virus B- Oca strain AVB-O DAS-ELISA
Sweetpotato Sweet potato feathery mottle virus SPFMV NCM-ELISA
Sweet potato mild mottle virus SPMMV NCM-ELISA
Sweet potato caulimo-like virus SPCV NCM-ELISA
Sweet potato chlorotic fleck virus SPCFV NCM-ELISA
Sweet potato C6 virus SPC6V NCM-ELISA
Sweet potato mild speckling virus SPMSV NCM-ELISA
Sweet potato chlorotic stunt virus SPCSV NCM-ELISA
Sweet potato latent virus SPLV NCM-ELISA
Cucumber mosaic virus CMV NCM-ELISA
Sweet potato virus G SPVG NCM-ELISA
Begomovirus - PCR
* NASH: Nucleic Acid Hybrisation detection, DAS-ELISA: double-antibody sandwich method of the enzyme-linked immunosorbent assay, NCM-ELISA: immuno-enzymatic test that uses nitrocellulose membranes.

Bacteria elimination

Bacterial contamination is only an issue for sweetpotato germplasm with about ~3% (182 accessions) of the collection infected. The bacterial contamination in sweetpotato appears to be endogenous and involves a suite of bacteria.  Infection seems to be connected to the origin of the host plant as virtually all sweetpotato derived from African countries contain some type of bacterial infection. Although it is intriguing to speculate a beneficial effect of such endogenous bacteria in sweetpotato, no evidence of any beneficial effect has been reported. In potato, the incidence of bacterial contamination is less than 1% and therefore is a minor issue.

Bacteria cleaning: (A) Plants with bacteria (Note red coloration at medium surface (arrow). (B) Bacteria free plants.

Protocols

  • Genebank - Pathogen elimination of potato
  • Genebank - Pathogen elimination of sweetpotato

Please contact the supervisor/Genebank Leader to get more information.

0

Conserving Biodiversity for the Future

https://cipotato.org/genebankcip/wp-content/uploads/sites/3/2017/05/SO-6-Conserving-Diversity-for-the-Future-Eng-20171.pdf
By : admin | Apr 27, 2017

Related Links

Contact

Brenda Zea
Phytosanitary Specialist
b.zea@cgiar.org