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.

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Conserving Biodiversity for the Future

http://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