Genome assembly of primitive cultivated potato Solanum stenotomum provides insights into potato evolution

Genetic diversity is the raw material for germplasm enhancement. Landraces and wild species relatives of potato, which contain a rich gene pool of valuable agronomic traits, can provide insights into the genetic diversity behind the adaptability of the common potato. The diploid plant, Solanum stenotomum (Sst), is believed to have an ancestral relationship with modern potato cultivars and be a potential source of resistance against disease. Sequencing of the Sst genome generated an assembly of 852.85 Mb (N50 scaffold size, 3.7 Mb). Pseudomolecule construction anchored 788.75 Mb of the assembly onto 12 pseudochromosomes, with an anchor rate of 92.4%. Genome annotation yielded 41,914 high-confidence protein-coding gene models and comparative analyses with closely related Solanaceae species identified 358 Sst-specific gene families, 885 gene families with expansion along the Sst lineage, and 149 genes experiencing accelerated rates of protein sequence evolution in Sst, the functions of which were mainly associated with defense responses, particularly against bacterial and fungal infection. Insights into the Sst genome and the genomic variation of cultivated potato taxa are valuable in elaborating the impact of potato evolution in early landrace diploid and facilitate modern potato breeding.

Organic production of native potato landrace “pintaboca” (Solanum stenotomum Juz. & Bukasov) in Bolivia: experimenting planting times and cultivation strategies

In the municipality of Colomi, in the highlands of Bolivia, market pressure leads small scale farmers to substitute their native landraces with commercial potato varieties. Organic cultivation might offer a channel for selling native potatoes to an emerging industry of coloured native potato crisps. Nevertheless, as the area is endemic for late blight (Phytophthora infestans), adequate cultivation practices that allow organic production must be defined. The present experiment compared four cultivation strategies (two organic, which included the use of beneficial microoorganisms applied in the soil and through foliar spray, one conventional, which included cymoxanil and mancozeb based fungicides and a control with the same soil treatment as the organic strategies but no foliar spray) and two planting dates (early and main season planting) on a native potato landrace locally known as ‘pintabocaʼ (Solanum stenotomum). Our results showed that early planting resulted in significantly higher yields, although the area under disease progress curve (AUDPC) of late blight did not differ significantly between planting dates. The lower yields in the plot planted during the main season were mainly due to the combined incidence of early and late blight. There was no significant difference in yields and quality of the tubers cultivated with conventional, organic or control treatment, with the exception that the largest tuber size category was produced only in the conventional treatment. We conclude that farmers in Colomi who want to shift to organic cultivation of the landrace ʻpintabocaʼ at altitudes around 3,300 m a.s.l. could benefit from practicing early planting, although additional trials covering several seasons are needed to confirm our results.

Asociaciones de marcadores moleculares con la resistencia a enfermedades, caracteres morfológicos y agronómicos en familias diploides de papa (Solanum tuberosum L.)

<p>Quince familias de papa (840 genotipos) provenientes de cruzas inter-específicas entre especies de Solanum stenotomum, S. goniocalyx y S. phureja fueron genotipadas, con el objetivo de asociar seis marcadores moleculares (GP94, HC, Nl25, Gro 1-4, RYSC3 y CP60) con genes mayores de resistencia para tizón tardío (Phytophthora infestans), verruga (Synchytrium endobioticum), nematodo - quiste (Globodera pallida y G. rostochiensis) y virus PVY y PVX. Los resultados mostraron que cinco de los marcadores aplicados fueron polimórficos y amplificaron en más del 80% de las familias. El marcador RYSC3 que co-localiza con el gen Ry no amplificó en ninguna de las familias evaluadas. La familia 8 amplificó la banda para tres marcadores (CP60, GP94 y NL25) en la totalidad de sus clones. La prueba de χsup2 se utilizó para determinar el ajuste de las proporciones de segregación de cada familia para cada marcador y genotipar los progenitores. Nueve caracteres agronómicos y morfológicos fueron evaluados en la cosecha. Mediante agrupamiento cluster fueron seleccionados 107 clones con resistencia a PVX, P. infestans, G. rostochiensis y S. endobioticum, alto rendimiento y volumen de tubérculos, elevado número de tubérculos y ojos superficiales. Sobre la base de estos resultados, aspectos prácticos para la aplicación eficiente de la selección asistida por marcadores moleculares son discutidos en este artículo.</p>

Orange Flesh Trait in Potato: Inheritance and Carotenoid Content

Potatoes with orange flesh were found in cultivated diploid (2n = 24) potato populations derived from Solanum stenotomum Juz. et Buk. and S.phureja Juz. et Buk. The orange flesh trait was found to be controlled by an allele at the Y- locus designated Or. Or is dominant over Y and y, which control yellow and white flesh, respectively. In a comparison of white and orange flesh segregants from crosses, the orange was associated with large amounts of zeaxanthin, a xanthophyll previously not reported as a constituent of potato flesh carotenoids. The combined total of lutein and zeaxanthin was four times higher than the highest carotenoid composition previously reported for potato, this is about one-sixth the total carotenoid content of carrot with standard carotenoid levels, although lutein and zeaxanthin do not possess provitamin A activity.