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Over 450 potato varieties and landraces are preserved as in vitro cultures by the Plant Biotechnology department of Estonian Crop Research Institute. This collection contains germplasm from various countries as well as old Estonian landraces. These potato accessions are periodically grown in the field for verification; however, this is not always sufficient to validate varieties and, in many cases, the true origin or identity of old landraces is not known. A reliable and cost-effective method for fingerprinting Estonian potato germplasm needed to be implemented. Simple sequence repeat (SSR) markers are known as robust and efficient markers for the identification of tetraploid potato. Here, fingerprinting results are presented for 103 genotypes from the Estonian potato collection using 8 SSR markers. It was shown that as few as three markers were sufficient to yield unique fingerprints for the given set of samples. SSR markers were used to estimate the allele copy number with varying success. Additionally, the reproducibility of four of these markers was assessed in two different laboratories, and repeatable results were observed. It was verified that the putative landrace ‘Kuldkera’ has the same genetic fingerprint as the variety ‘Ando’, whilst an expected clone of ‘Early Rose’ is a completely different genotype. Implementation of genetic fingerprinting and these results is of high importance for further potato genebank management and Estonian breeding programme. more...

This paper reviews plant protection methods for organic cultivation of potatoes. Colorado potato beetle (CPB), the most important insect pest of potatoes worldwide, can be controlled by using the following techniques: organic soil management, lower fertilizer rates, treatment with spinosad, an insecticide based on chemical compounds found in the bacterial species Saccharopolyspora spinosa, no-till soil management, straw mulching and crop rotation. CPB has the ability to evolve resistance to a wide variety of chemicals. Variety choice has a significant effect on tuber losses caused by wireworms. Protection of potatoes against disease damage involves preventive measures, appropriate regulation strategies and optimum spraying techniques such as copper contact fungicides. Planting early in the cropping season and using short vegetation period varieties help to avoid early incidence and high disease severity from potato viruses. Plant growth promoting and biological control bacteria, such as Bacillus spp. and/... more...

Potato, the third largest global food crop after wheat and rice, suffers from the devastating late blight disease, which causes 16% loss of yield globally (Haverkort et al., 2009). Late blight, caused by the plant pathogen Phytophtora infestans (Mont.) de Bary, is one of the most devastating potato diseases worldwide. Two phenotypic expressions of host plant resistance to P. infestans have been described. The distinction between two types of resistance, qualitative (race-specific) and quantitative (field resistance), is controlled by major R genes and minor genes. Factors controlling quantitative resistance to P. infestans have been found on almost every potato chromosome, confirming the truly polygenic nature of this trait (Gebhard and Valkonen, 2001). The most sustainable strategy to protect potato plants from late blight is to breed disease resistance (R) genes into the cultivars (Hansen et al., 2005). Potato breeding is complicated because potato cultivars are highly heterozygous autotetraploid plants (2n = 4x = 4n), they suffer from acute inbreeding depression and introduced R genes are quickly deflated by P. infestans (Fry, 2008). Also, quantitative resistance is thought to result in a more durable resistance under field conditions (Solomon-Blackburn et al., 2007; Fry, 2008). Late blight resistance breeding has been pretty much unsuccessful for more than 150 years (Muller and Black, 1952), and breeding for multigenic resistance, including field resistance, remains a major challenge (Rietman, 2012). more...