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United States Department of Agriculture

Agricultural Research Service

Research Project: SELECTION OF POTATO GERMPLASM RESISTANT TO PURPLE TOP PHYTOPLASMA AND LATE BLIGHT IN THE TOLUCA VALLEY OF MEXICO

Location: Vegetable and Forage Crops Production Research

2009 Annual Report


1a.Objectives (from AD-416)
Select potato germplasm resistant to two pathogens, a leafhopper vectored phytoplasma which causes purple top and an oomycete that incites late blight.


1b.Approach (from AD-416)
Tuber families will be sent to PICTIPAPA from various sources in the the US. These will be planted out in field plots in Metepec, Mexico under the supervision of Hector Lozoya Saldana. Obvservations on foliar damage due to Phytophthora infestans and Purple Top Phytoplasma will be recorded. At harvest, selection will be based on field notes and tuber yield and type. Tubers will be retained during the off-season and re-planted the following growing season. Documents SCA with Universidad Autonoma Chapingo.


3.Progress Report

A wide genetic diversity of Phytophthora infestans (Mont) De Bary, the potato late blight pathogen, is present in the highlands of central México. Chapingo, in the State of México, is reported to be the second location with the most variation of the oomycete, after the Toluca Valley. In order to assess the genetic resistance of potato clones to P. infestans, in the summer of 2008, one hundred clones each of 25 families (2,500 clones total) from the ARS-USDA Potato Breeding Program at Aberdeen, Idaho, were planted under rainfed conditions at the University of Chapingo Experiment Station, and exposed to natural infection by late blight without fungicides. Susceptible cv. Alpha reached complete foliar infection five weeks after the epidemic onset. Thirty to 60 clones from eight families showed late infection, but all of them died to the disease later. Genetic variability of P. infestans was detected, and two genotypes resembled the US-11 type: A1; 86/100/111; 100/100, and A1; 86/100/122; 100/100 (mating type; glucose-phosphate-isomerase, GPI; and peptidase, PEP). These results support the idea that Chapingo may also be considered a “hot spot” for evaluation of potato clones for genetic resistance to the disease in addition to the Toluca Valley. Oversight of the Specific Cooperative Agreement was carried out by telephone conversations, in-person meetings, and sharing of data by email between the ADODR and the lead researcher.


Last Modified: 4/17/2014
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