1a. Objectives (from AD-416):
The primary objective of this research project is to develop and release potato varieties and germplasm with improved disease and pest resistances, enhanced processing and nutritional characteristics, and a reduced need for production inputs such as water and nitrogen. Research focuses on the development of potato varieties important for the irrigated production of the western U.S., with an emphasis on varieties with long tubers and russet skin. This market class of potato comprised 85% of potato production in the western states of Colorado, Idaho, Oregon, and Washington in 2010 (National Agricultural Statistics Service, Potatoes 2010 Summary, September 2011) and is used for the production of frozen potato products such as French fries, as well as for fresh consumption as baking potatoes. The targets for resistance breeding will be the major diseases and pests that detrimentally impact potato production in the western United States, as well as newly emerging pest and disease threats. Several of the diseases and pests that plague western potato production are problematic for all U.S. potato producers. Therefore, potato germplasm and varieties with enhanced resistance originating from our program also will benefit potato producers outside the western United States. Over the next 5 years, the research objectives of our program are: Objective 1: Develop enhanced potato germplasm and varieties for the most important market classes for the western United States, with emphasis on recurrent and emerging disease and pest resistance (late blight, Potato mop top virus, Potato leafroll virus, Potato virus Y, emerging cyst nematodes, and Zebra Chip), reduced sugar and acrylamide accumulation, reduced production inputs (nitrogen and water), and enhanced nutritional qualities (vitamin C and protein). Objective 2: Devise marker-assisted selection (MAS) protocols to accelerate breeding for resistance to recurrent and emerging pathogens and pests (Potato virus Y, Potato leafroll virus, and potato cyst nematode) that impact the western United States. Objective 3: Characterize foliar and tuber responses of potato varieties to infection by newly identified strains of Potato virus Y (PVY), and identify new sources of resistance to these new strains.
1b. Approach (from AD-416):
As this project’s research is non-hypothesis driven, no hypotheses are presented in the approach. Experimental approaches to be used include hybridization of breeding clones of species and their enhanced progeny from ARS collaborators with adapted parental material from our program using a modified backcross method to minimize inbreeding depression. Progenies synthesized will be screened for trait(s) of interest for genetic enhancement, as well as for acceptable agronomic characteristics to identify superior breeding clones having the desired traits of the wild species with better adaptation and agronomic characteristics. Seed amounts are adequate by the end of the 2nd field season to allow field evaluation of promising progenies in a randomized completed block design (RCB) relative to industry standards, with the number of replicates and locations of trials increasing in subsequent field years as a breeding clone advances in the project. Data analysis over years and locations consists of a mixed model ANOVA with repeated measures with fixed effects being clone, year, and their interaction. Random effects would be location, clone x location, block within location, and clone x block within location. The latter interaction would be the experimental unit for which the correlation structure across years would be incorporated in the model. Breeding clones with enhanced traits will be released as new varieties, or alternatively as germplasm for breeding if industry requirements for a new variety are not fully met. Marker assisted selection also will be utilized to accelerate breeding for resistances to viruses and nematodes that impact the western United States. Newly-released potato varieties and advanced breeding lines will also be assayed to determine susceptibility to potato tuber necrotic ringspot disease caused by Potato virus Y (PVY) strains. PVY strain isolates of the O, NTN, and N:O groups will be used to characterize foliar and tuber symptoms in North American cultivars and advanced breeding lines in U.S. potato breeding programs. These experiments will be conducted in a greenhouse secured to prevent aphid entry to eliminate cross-contamination from outside sources and the release of the PVY strains used in the research. Breeding efforts include the “stacking” or “pyramiding” of an assemblage of desirable traits into a variety that proves acceptable to the potato industry. However, if the trait in question proves recalcitrant for effectively combining with other desired traits into an improved potato variety, then the following approaches would be taken: 1. The enhanced breeding clone would be released by the project as germplasm for use as parental material by other potato breeding programs. 2. Continued hybridization by this project of the enhanced breeding clone with potato varieties to obtain commercially-acceptable progeny having the desired multiple genetic enhancements. The number of progenies evaluated from these hybridizations would also be increased to improve the probability of success in identifying superior selections having the desired multiple traits.
3. Progress Report:
This report documents progress for Project Number 5366-21000-032-00D, which started in March 2013 and continues research from Project Number 5366-21000-026-00D, entitled “Development of Potato Varieties and Germplasm with Improved Resistances, Production Efficiencies, and Tuber Qualities for the Western U.S.”. Thousands of potato breeding clones were planted, maintained, and harvested at multiple sites for seed increase and in trials for evaluation of their merit for continued advancement in the project for release as new potato varieties. In addition, forty-three progenies from the hybridization of Rio Grande Russet x Premier Russet were grown in a replicated field trial along with their respective parents as a component of the Specialty Crop Research Initiative (SCRI) grant for reducing acrylamide in processed potato products. This population had previously been characterized using molecular markers with field and processing data collected from the trial being used for identifying molecular markers important in the formation of acrylamide that can aid in the breeding of lower-acrylamide potato varieties suitable for the processing industry, with research contributing to Objective 2 of the project. This project also contributed advanced breeding clones and varieties for the National Fry Processing Trial (NFPT) which seeks to identify processing varieties having low acrylamide that could be rapidly adopted by the U.S. potato processing industry, and also oversaw a NFPT trial site for the last three years. Data from the NFPT was used by industry in identifying two low- acrylamide breeding clones from our project (A02507-2LB and A02138-2) for the rapid multiplication of seed to allow larger, commercial evaluations at fry processing plants in 2015. This research contributes to Objective 1 of the project. As part of the SCRI Zebra Chip (ZC) Research initiative, potato germplasm from this project was identified as having resistance to ZC disease and its insect vector. This is notable in that potato varieties currently utilized by industry have shown no or little resistance to ZC, with further evaluations of this germplasm being conducted in 2013 in collaboration with researchers in Washington and California. This research contributes to project objective 1. Our project also manages a trial site in Idaho that is screening U.S. germplasm for resistance to PVY in collaboration with researchers in New York and Wisconsin. In addition, our work to screen for PVY resistance in intra-genetically modified lines from collaborators in Michigan continues with additional trials planted and harvested in 2013. This research contributes to project objective 3.