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United States Department of Agriculture

Agricultural Research Service

Research Project: Developing Potatoes with Superior Disease Resistance and Phytonutrients

Location: Vegetable and Forage Crops Production Research

2013 Annual Report

1a.Objectives (from AD-416):
1. Define and Select Resistance to Powdery Scab and Black Dot in Potato. a) Evaluate genetic materials for resistance to powdery scab, emphasizing resistance to root colonization and impairment by the fungus. b) Screen advanced breeding lines and germplasm for black dot resistance emphasizing establishment of screening protocols. Define the triggering factors that result in damaging outbreaks of black dot. c) Evaluate resistance to combined inoculation with black dot and powdery scab. 2. Determining foliar and tuber symptoms and yield impact due to planting seed infected by different Potato Virus Y strains in eight different potato cultivars. a) Determine the foliar and tuber symptoms produced and yield loss in eight different cultivars when seed infected with three PVY strain are planted. 3. Develop high-phytonutrient Washington potatoes. a) Plant breeding lines or cultivars to assess their potential to produce high-phytonutrient potatoes. b) Analyze phytonutrient content of new potatoes grown. c) Select three genotypes that will be harvested at the new potato stage and at full maturity. d) Conduct taste tests of new potato lines that merit additional testing – namely those lines that perform well in terms of yields and phytonutrient content. e) Use some of the same seed from 3-5 varieties grown in Eastern Washington and plant them in Western Washington. Plants will be grown to maturity and small and large tubers harvest from the same plant and analyzed for phytonutrient content. The results will be compared to the levels seen in baby potatoes from young plants. 4. Breed for Resistance to Columbia Root-Knot Nematode and Corky Ringspot Disease (Toward Pesticide-Reduced Potato Production). a) Identify a molecular marker for tuber resistance to CRKN. b) Screen advanced breeding lines and germplasm for CRKN and CRS resistance in the field and in the greenhouse. c) Make crosses, produce tuber families and select new materials with resistance and improved horticultural and culinary traits.

1b.Approach (from AD-416):
Analyze phytonutrients in developmentally young potatoes (baby potatoes) using LCMS and GCMS. Evaluate phytonutrients in over 80 cultivars and breeding lines grown in the same field. Other key traits that will influence market success will be measured, including taste, appearance and yield of small tubers. Screen germplasm in the field and greenhouse for Powdery Scab and Black Dot resistance. Use field inoculation and greenhouse inoculation methods. Determine the relationship of field and greenhouse studies. Search for molecular markers associated with resistance. Use polymerase chain reaction methodology to screen segregating progeny. Tissue samples will be tested in this laboratory by reverse transcription polymerase chain reaction (RT-PCR) for strains of PVY. Documents Trust with Washington State Potato Commission. Log 41804.

3.Progress Report:

This project contributes to in-house project Objective 1: "Identify superior germplasm for potato disease and pest resistance, phytonutrients, minerals and vitamins, using high-throughput methods to determine the extent of natural variation in diverse potato germplasm of select phytonutrients/metabolites. These traits will be incorporated into the cultivated breeding pool using traditional breeding and molecular approaches"; Objective 2: "Determine host resistance options, epidemiological parameters and develop diagnostic tests for emerging pests and pathogens of potato"; and Objective 3: "Elucidate genetic, molecular and biochemical factors governing host disease resistance and accumulation of select phytonutrients and vitamins". To determine the impact of macro and micronutrients to enhance potato resistance to Verticillium wilt in the potato cultivar Norkotah, replicated greenhouse trials assessing 13 treatments were conducted. Plant vigor, height, disease severity and foliar micro and macro-nutrient content were determined at plant senescence for the various treatments. In-furrow applications of phosphorus had the greatest effect on improving height and vigor of Russet Norkotah plants in the presence of the Verticillium. Although disease pressure was low, continuing research on phosphorus nutrition should be considered as part of an integrated approach to managing verticillium wilt in Russet Norkotah.

We identified high antioxidant red and purple potatoes, but because consumers purchase more white potatoes it is desirable to have high-antioxidant white potatoes. Chlorogenic acid (CGA) and ascorbic acid are the two primary antioxidants in white potatoes. Even though it is a colorless compound, chlorogenic acid is present in much lower amounts in white potatoes than colored potatoes. Screening numerous white flesh lines showed all white lines screened so far (over 100) have low CGA. To have any likelihood of finding a high antioxidant white line it will be necessary to screen larger numbers of genotypes. For such screening to be possible faster screening methods must be developed. We are exploring whether potato juice could be measured instead of freeze-dried samples. We tested juice over 100 TriState breeding lines and measured total phenolics, antioxidants, polyphenol oxidase activity and pH (pH is possibly a quick way to assess sugars) and are working to validate the method.

We are examining transcription factors (proteins that regulate gene expression) to try to identify which are most important in tubers for controlling antioxidants, and identified one in particular, StAN1, that appears to play the major role in regulating the accumulation of tuber phenolics (ie antioxidants). Eventually these findings could make it easier to produce high phenolic potatoes and also manipulate flesh and skin color—for example white potatoes with redder skin that is even more visually appealing to consumers.

Three trials were planted in 2013 to screen for resistance in powdery scab and black dot infested fields. The highest yielding genotypes included new breeding lines, POR08BDPS6-1 and POR08BD1-3, which possesses a heavy russet and a high percentage of the largest tuber classes. Development of new varieties with resistance to black dot and powdery scab could reduce the cost of production by 25 %.

Last Modified: 7/31/2014
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