2012 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.
Certified mini tubers or tissue culture grown plants of cultivars Alturas, Blazer Russet, Ranger Russet, Russet Burbank, Premier Russet, Russet Norkotah, Yukon Gem, and Yukon Gold were grown and inoculated with two isolates each of PVY strains PVY-O, PVY-N:O, and PVY-NTN. Tubers on infected plants were harvested, stored, and planted in the Hermiston screenhouse in spring 2011, adressing objective 1.B. Percent and date of emergence were recorded. Plants were tested for PVY by ELISA and mosaic symptoms were recorded. Results showed that the emergence of PVY infected Alturas tubers was significantly reduced compared to healthy tubers and other cultivars. Foliar symptoms varied by virus strains and even between different isolates of the same strain. Cultivars Alturas, Yukon Gem, Ranger Russet and Yukon Gold tended to produce more tubers with necrosis symptoms than the other cultivars.
Progress was also made on objective 1.A. A field trial was conducted with 80 breeding lines or cultivars and their phytonutrient and agronomic characteristics were analyzed. A majority of the genotypes examined were yellow flesh potatoes, about 15 had red or purple flesh and 4 white flesh. The rationale for selecting this type of flesh color distribution is that our previous work found that color flesh potatoes tend to have higher amounts of phytonutrients than white flesh potatoes. Although red and purple potatoes tend to have the highest amount of antioxidants we focused mostly on yellow potatoes because these are expected to have greater market appeal than red/purple potatoes. Vines were killed from 68-88 days after planting and were timed to give potatoes of the desired size. Dry matter content of these tubers ranged from 13.2 to 21.3% and is influenced by genetics and management. The dry matter content will greatly influence taste and likely many of the genotypes that fall outside the desired dry matter range could be improved by tailored management. When expressed on the basis of tubers yielded per seed piece, yield ranged from 4 to 27.4 tubers/seed piece. Over a 5-fold range was observed in phenolic concentrations, from 3.2 mg/g DW to around 17 mg/g DW. These are excellent values relative to mainstream mature potatoes, which typically range from around 1.5-3.5 mg/g DW. The red and purple flesh genotypes had the highest amounts of phenolics, but numerous yellow lines had superior amounts of phenolics. Some genotypes had exceptionally high amounts of anthocyanins. Only trace amounts of anthocyanins were detected in tubers with lightly colored skin, while Purple Pelisse contained 16mg/g DW. Carotenoids were also evaluated and the top performers have several times higher amounts of carotenoids than Yukon Gold.
We selected advanced germplasm based on high yield in the face of heavy disease pressure. A close correlation of high yield is the disease severity index based on ability to detect black dot in sterilely excised stem disks. We selected materials for powdery scab resistance based on yield of large size tubers. An early harvest detected degree of root galling. Root galling was correlated to yield in some years but not in others. We selected additional clones with resistance to corky ringspot disease in field screening. Resistance in PA99N82-4 has held up in two seasons of testing. This clone also cleans up the field to a certain extent and is also early dying resistant. Numerous crosses were made and tuberling families were planted and selected in the Klamath Basin. Twelve hill plots were selected in the Klamath Basin. The project was monitored through meetings, email and phone conversations.
This research is related to objective 1 of the related in-house project, "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".