Wild potato species (genus Solanum, section Petota) represent a tremendously diverse gene pool which is traditionally utilized as a source of diverse traits for potato breeding. Abiotic and biotic stress tolerance and resistance belong to the most frequently utilized traits of wild species in potato breeding programs. This review provides an introduction to the taxonomy, centre of diversity, genetic characteristics, evolution and important tolerance and resistance traits of wild potatoes and their use for potato breeding. The review has been written for readers who are interested in the problems of finding and utilization of new resistance genes from the wild genetic resources.

Late blight of potato (Solanum tuberosum L.), incited by Phytophthora infestans (Mont.) de Bary, is a devastating disease affecting tuber yield and storage. Recent work has isolated a resistance gene, RB, from the wild species Solanum bulbocastanum Dun. Earlier work in Toluca, Mexico, observed significant levels of field resistance under intense disease pressure in a somatic hybrid containing RB. In this study, five transgenic RB lines were recovered from the late blight susceptible line MSE149-5Y, from the Michigan State University (MSU) potato breeding program. Transgenic lines were molecularly characterized for the RB transgene, RB transcript, and insertion number of the kanamycin resistance gene NPTII. Transgenic lines and the parent line were evaluated for resistance in field and laboratory tests. Molecular characterization alone did not predict which lines were resistant. Three of the RB transformed MSE149-5Y lines showed increased resistance under field conditions at MSU and increased resistance in detached leaf evaluations using multiple isolates individually (US-1, US-1.7, US-8, US-10, and US-14). Transfer of RB into late blight susceptible and resistant lines could provide increased protection to potato late blight. The use of the RB gene for transformation in this way creates a partially cisgenic event in potato because the gene's native promoter and terminator are used. This type of transformation provides a chance to generate greater public acceptance of engineered approaches to trait introgression in food crops.

'Seohong' was bred within the potato breeding program of National Institute of Highland Agriculture (NIHA). It was originated from a cross made in 1997 between 'Jashim' as a female and 93K65-1 as a male parent. Seohong was evaluated as a seedling number 97S05-1 for tuber characteristics, growth and yielding ability from 2001 to 2002, and than this clone was renamed as Daegwan 1-82. This clone was evaluated in the regional yield trial and the disease resistance in the five locations for three years. Finally, this clone was named as 'Seohong' and registered a new recommended potato cultivar in 2006.

Potato late blight, caused by the oomycete Phytophthora infestans, has a long history as a major problem in potato cultivation. Host resistance was introduced and overcome and a new, more versatile and aggressive, pathogen population was introduced into the Netherlands an Europe leading to a situation in which potato late blight is almost exclusively controlled through an intensive use of fungicides. A growing societal concern about the chemical inputs into the food production chain, has inspired two research programmes specifically targeted at potato late blight: the Umbrella Plan Phytophthora (P. infestans biology, ecology and late blight management) and DuRPh, Healthy potato production: development of durable Phytophthora resistance applying GMO methods The Umbrella plan Phytophthora was initialised in 2003 aiming to reduce the environmental impact of late blight control by 75% within 10 years. In a unique management structure the program is funded by the Dutch Ministry of Agriculture, Nature and Food Quality but management is in the hands of the Dutch potato industry. Research within the umbrella plan is structured in 3 themes and a toolbox in which results are evaluated for their practical value. The MasterPlan Phytophthora, a growers initiative, then communicates the results to the Dutch potato growers. This integrated approach has already yielded a significant reduction of the environmental impact due to late blight control. DuRPh, initialised in 2006, is using GMO methodology to detect, clone and marker free transfer major resistance genes to existing varieties. Societal benefits comprise reduced costs of control, an improved environment and a boost to fundamental research. The cisgene approach using only potato genes combined with marker free transformation may contribute to public acceptance of GMO food. The program serves as a proof of principle for the application of GMO techniques and their results for breeding and disease control purposes. Examples of some of the questions studied are: How can the detection efficiency of major (R-) genes in wild species, subsequent isolation and stacking of these genes in existing varieties be improved? How do we develop adequate resistance management strategies for the temporal and spatial deployment of major genes? How to study societal resistance and acceptance mechanisms regarding this specific GMO (marker free and cisgene) approach? The programme integrates related projects, is pre-competitive and its results will be published. Co-operation with the Dutch breeding industry will be sought actively as well as EU FP7 co-funding. | v | ok | Myynti MTT Tietopalvelut 31600 Jokioinen

Worldwide, a variety of pathogens negatively affect potato production, resulting in an estimated 22% annual yield reduction. Wild Solanum species represent a unique gene pool where all the traits necessary to improve the cultivated potato can be found. Therefore, breeding efforts for improved disease resistance and research aimed at characterizing wild germplasm have been extensively made. In this paper, sources of resistance to Phytophthora infestans, Erwinia carotovora subsp. carotovora, Fusarium solani and Globodera spp. have been investigated in several clones of two Solanum species originating from Central Mexico (S. bulbocastanum and S. cardiophyllum). Interestingly, we found sources of combined resistance to late blight and bacterial soft rot. This is an important finding considering that the development of resistant potato varieties has been hindered by the scarcity of resistant germplasm. In addition, we explored molecular differences within and between the two species generating AFLP fingerprints. By means of six primer pair combinations, we found 13 and 16 putative species-specific AFLP markers for S. bulbocastanum and S. cardiophyllum, respectively, and a bounty of markers useful for mapping, MAS, and cloning purposes. The phenotypic and molecular information associated to S. bulbocastanum and S. cardiophyllum for designing strategies of assisted selection are discussed.

An accurate greenhouse screening method has not been developed previously to identify host response to sheath blight disease caused by Rhizoctonia solani Kühn that causes significant economic losses in rice yield worldwide. The unavailability of a robust screening system in the greenhouse has made it difficult to quantify disease reactions to R. solani, and has hampered studies on the genetics of resistance and plant breeding efforts to improve resistance. In an effort to develop a standardized laboratory micro-chamber screening method to quantify resistance to R. solani in rice, five rice cultivars, representing a wide range of observed disease reactions under field conditions, were examined in a blind inoculation test at three locations (Arkansas, Texas, and Colombia). Rice seedlings were inoculated at the three- to four-leaf stage with potato dextrose agar plugs containing mycelium and then covered with a 2- or 3-liter transparent plastic bottle for maintaining high humidity after inoculation. Two cultivars, Jasmine 85 and Lemont, that consistently have shown the highest and lowest levels of resistance, respectively, in previous field and greenhouse studies, were used as standards. Concurrent field experiments in Arkansas and Texas also were performed to compare the greenhouse disease ratings with those observed under field conditions. Overall, the relative disease ratings of the seven test cultivars were consistent between test locations and with field evaluations. Thus, the micro-chamber screening method can be used as an effective approach to accurately quantify resistance to the sheath blight pathogen under controlled greenhouse conditions and should help expedite the selection process to improve resistance to this important pathogen.

Demand for the potato, the fourth most consumed food crop in the world, is steadily increasing. In order to meet the rising demands on the industry, researchers and breeders have been working to better all aspects of potato production, including improvements to the tuber itself. This review will highlight the potential for genomics-assisted advancements, paying particular attention to the genomics tools and resources that are available, and the translation of this information into potato improvements. Immense amounts of genomic data have been generated from expressed sequence tag library construction, molecular linkage maps and microarray expression analyses. This information is helping to clarify the genetic components underlying many of the traits that are important for the continued success of the potato, including increased yields, processing quality traits and disease/pest resistance. Natural genetic resources, such as wild potato varieties and germplasm collections contain valuable genetic variation that, when combined with genomics-assisted breeding techniques such as marker-assisted selection and polymorphism identification, hold great potential for future improvements. With the continued integration of genomics tools and information with rapidly developing technologies such as proteomics and metabolomics, improvements to potato health and quality characteristics will be achieved in an expedited manner with full knowledge and understanding of the genetics involved. Moreover, as the technology advances, the potential exists for the production of potatoes with improved environmental and economic impacts, thus ensuring the sustainability of the industry for future generations.

In the Andean region, the Preduza project and its partners combined breeding for durable disease resistance using locally adapted cultivars and farmer participatory methods. The approach taken resembles participatory variety selection (PVS). Farmers participated in the selection of advanced materials, rather than finished cultivars. This paper describes this approach and reports experiences with farmers-breeders collaboration. As breeders involved farmers as participants, they learned more about the most important criteria of male and female farmers for preferred cultivars in the marginal environments of Andean cropping systems. This approach encouraged the use of locally adapted cultivars (often landraces), made the breeders less dependent on foreign materials, and has resulted in selection and development of new wheat, barley, common bean, quinoa, potato and maize cultivars. Breeding programmes based on crossing locally adapted cultivars followed by selection by the breeders in the early phases of the breeding programmes and by participatory selection with the farmers in the more advanced stages of the breeding programmes appeared successful. It became clear that breeders must be well acquainted with the farmer preferences such as the requirements for specific agronomic, storage, processing and marketing traits. Over a period of five years the centralized formal breeding approach predominantly based on material produced by the international institutes was replaced by decentralized breeding approaches based largely on local germplasm with extensive farmer participation.

This experiment was carried out to investigate whether and how much field resistance to late blight, caused by Phytophthora infestans, is present in the local cultivated potato germplasm. In total 36 entries were compared in a field experiment in an area highly conducive to late blight development. Of the 36 cultivars 32 were local cultivars belonging to five Solanum species, S. tuberosum (1 accession), S. andigena (18), S. juzepczukii (2), S. stenotomum (9) and S. ajanhuiri (2). The other four cultivars were derived from breeding programmes, one being the Dutch cultivar Alpha used as a highly susceptible control. The 36 cultivars were planted according to a simple 6 x 6 lattice design with three replicates. Each replicate was divided in six incomplete blocks each with six cultivars. The disease severity was assessed weekly during 9 weeks starting 48 days after planting. The area under the disease progress curve (AUDPC) was used as a measure of the field resistance. Nine isolates from surrounding potato fields were tested for their virulence to the resistance genes R1-R11 using 22 differential cultivars. The components of the field resistance of 19 of these cultivars were compared in the greenhouse using a local isolate with virulence to all known R-genes, except to R9. The nine isolates represented seven races with a race complexity varying from 7 to 10 virulence factors. All isolates carried virulence against R1, R2, R3, R7, R10 and R11, while virulence against R9 was absent. The AUDPC among the 32 local cultivars ranged from very large, significantly larger than that of 'Alpha' to very small. The AUDPC from S. stenotomum accessions ranged from very large to intermediate, those from S. andigena accessions from large to very small. Especially among the S. andigena accessions interesting levels of field resistance were found. Four components of field resistance were assessed, latency period (LP), lesion size (LS), lesion growth rate (LGR) and relative sporulation area (RSA). All four showed a considerable variation among the cultivars. The LP ranged from 3[fraction one-half] to 6 days. The LS ranged from 225 mm² to 20 mm². The LGR varied about six-fold, the RSA more than 10-fold. The components tended to vary in association with one another. LP and LGR were well associated with each other and had a significant correlation with the AUDPC.