Felix M. Navarro

Identification and Selection for Tuber Calcium, Internal Quality and Pitted Scab in Segregating ‘Atlantic’ x ‘Superior’ Reciprocal Tetraploid Populations

Developing chipping cultivars with improved tuber quality and disease resistance is a major interest for breeders and the potato industry. A popular chipping cultivar ‘Atlantic’, is desired for its high yield and gravity. However, this cultivar suffers from poor internal tuber quality and high scab susceptibility. On the contrary, cultivar ‘Superior’ is known to have excellent tuber internal quality and moderately scab resistance. In addition, this cultivar is known to have high tuber calcium as compared to ‘Atlantic’. The present study intended to generate populations that can be suitable for the genetic study of tuber calcium, internal quality, common scab, and other commercially important traits such as yield, specific gravity and chip quality at the tetraploid level. Two populations obtained by reciprocally crossing the cultivars ‘Atlantic’ and ‘Superior’ were evaluated during 2009 to 2012 at Hancock, Wisconsin. Significant genotype effects and moderately low to high broad-sense heritabilities were identified for all traits evaluated indicating that the observed phenotypic variation has an important genetic component. In addition, the parents differed significantly for all traits across trials, and most genotypes performed in between the two parents but some genotypes were more extreme than the parents. Furthermore, evidence of reciprocal effects was found for some traits. In addition to learning about the genetics of these important traits we were able to identify some genotypes that combined the commercially desired traits of the two cultivars.ResumenEs de gran interés para fitomejoradores y para la industria de la papa el desarrollar variedades de freído con calidad de tubérculo mejorada y resistencia a enfermedades. Una variedad de freído popular, “Atlantic”, es deseable por su alto rendimiento y gravedad. No obstante, esta variedad sufre de pobre calidad interna de tubérculo y de alta susceptibilidad a la roña. Por el contrario, la variedad “Superior” se sabe que tiene excelente calidad interna de tubérculo y resistencia moderada a la roña. Además, esta variedad se sabe que tiene alto contenido de calcio en el tubérculo al compararla con “Atlantic”. El presente estudio pretendió generar poblaciones que pueden ser deseables para el estudio genético de calcio en el tubérculo, calidad interna, resistencia a la roña común, y otras características económicamente importantes como el rendimiento, gravedad específica, y calidad de freído a nivel tetraploide. Durante el 2009 al 2012, se evaluaron dos poblaciones obtenidas mediante cruzas recíprocas con “Atlantic” y “Superior” en Hancock, Wisconsin. Se identificaron efectos significativos de genotipo y heredabilidades de moderadamente bajas a altas en un amplio sentido para todos los caracteres evaluados, indicando que la variación fenotípica observada tiene un componente genético importante. Además, los progenitores difirieron significativamente para todos los caracteres en todos los ensayos, y la mayoría de los genotipos se comportaron dentro de la amplitud de los dos progenitores, pero algunos genotipos estuvieron más allá de los extremos de los padres. Aún más, se encontró evidencia de efectos recíprocos para algunos caracteres. Además de aprender sobre la genética de estos caracteres importantes, fuimos capaces de identificar algunos genotipos que combinaron los caracteres deseados comerciales de las dos variedades.

Megachip — a new potato variety for chipping

Abstract‘MegaChip’ is a medium-late variety for chipping, with round-oval tubers of white tan skin and white flesh. MegaChip has consistently shown good to high yield potential. The tubers bulk early and produce a good size distribution for chipping. The specific gravity is consistently high and is close to the solid content of ‘Atlantic’. MegaChip has longer dormancy than ‘Snowden’ and Atlantic and stores well. It produces high quality chips that have an excellent color both from the field and after storage at 7.2 to 10 C. MegaChip showed a high level of resistance to common scab at most locations in North Central Regional trials and is moderately resistant to foliar early blight, powdery scab, pink rot, dry rot and soft rot. MegaChip is also fairly resistant to shatter bruise.Resumen‘MegaChip’ es una variedad para hojuelas medianamente tardía, con tubérculos redondos a ovales, de piel bronceada y pulpa blanca. MegaChip ha mostrado siempre un potencial de rendimiento bueno a alto. Los tubérculos son de crecimiento precoz y de una buena distribución de tamaño como para hojuelas. La gravedad específica es consistentemente alta y cercana al contenido de sólidos de ‘Atlantic’. MegaChip tiene mayor periodo de dormancia que ‘Snowden’ y Atlantic y se almacena bien. Produce hojuelas de alta calidad que tienen un excelente color de tubérculos recién cosechados y después de almacena dos de 7.2 a 10 C. MegaChip muestra un alto nivel de resistencia a sarna común en la mayoría de pruebas Regionales de Norte Centro y es moderadamente resistente al tizón temprano del follaje, sarna polvorienta, pudrición rosada, pudrición seca y pudrición blanda. MegaChip es tambien medianamente resistente a magulladuras por golpe.

Freedom Russet—A Dual Purpose Russet Potato Cultivar with Resistance to Common Scab and Good Fry Quality

Freedom Russet was developed from a cross between ND14-1, a parent with scab resistance, and W1005rus, a parent with good processing quality. It is a mid-season cultivar and can be used for dual purposes for both fresh market and processing. The tubers of Freedom Russet are oblong-long with medium-dark russet skin, and have an attractive appearance. Freedom Russet tubers have better external and internal qualities than Russet Burbank tubers. The total and US No. 1 yield of Freedom Russet is equal to or higher than Russet Burbank in most environments. The specific gravity of Freedom Russet is similar or 1–3 unit less than Russet Burbank. Freedom Russet produced better fry color than Russet Burbank when processed after storage at 10, 8.9, and 7.2°C. It showed similar susceptibility to both early blight and late blight compared to Russet Burbank. Freedom Russet is resistant to common scab and moderately resistant to powdery scab. It is similarly susceptible to soft rot and pink rot as Russet Burbank, and clearly expresses bacterial ring rot symptoms. Freedom Russet is tolerant to Verticillium wilt and showed better yield potential than Russet Burbank under early dying pressure.

Genetic variance partitioning and Genome-Wide prediction with allele dosage information in autotetraploid Potato

As one of the world’s most important food crops, the potato (Solanum tuberosum L.) has spurred innovation in autotetraploid genetics, including in the use of SNP arrays to determine allele dosage at thousands of markers. By combining genotype and pedigree information with phenotype data for economically important traits, the objectives of this study were to (1) partition the genetic variance into additive vs. nonadditive components, and (2) determine the accuracy of genome-wide prediction. Between 2012 and 2017, a training population of 571 clones was evaluated for total yield, specific gravity, and chip fry color. Genomic covariance matrices for additive (G), digenic dominant (D), and additive × additive epistatic (G#G) effects were calculated using 3895 markers, and the numerator relationship matrix (A) was calculated from a 13-generation pedigree. Based on model fit and prediction accuracy, mixed model analysis with G was superior to A for yield and fry color but not specific gravity. The amount of additive genetic variance captured by markers was 20% of the total genetic variance for specific gravity, compared to 45% for yield and fry color. Within the training population, including nonadditive effects improved accuracy and/or bias for all three traits when predicting total genotypic value. When six F1 populations were used for validation, prediction accuracy ranged from 0.06 to 0.63 and was consistently lower (0.13 on average) without allele dosage information. We conclude that genome-wide prediction is feasible in potato and that it will improve selection for breeding value given the substantial amount of nonadditive genetic variance in elite germplasm.