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Volatile organic compounds (VOCs) play key roles in plant abiotic and biotic stress resistance, but even for widespread crops, there is limited information on variations in the magnitude and composition of constitutive VOC emissions among cultivars with varying stress resistance. The foliage VOC emissions from nine local and commercial potato cultivars (Alouette, Sarme, Kuras, Ando, Anti, Jõgeva Kollane, Teele, 1681-11, and Reet) with medium to late maturities and varying Phytophthora infestans (the causative agent of late blight disease) resistance backgrounds were analyzed to gain an insight into the genetic diversity of constitutive VOC emissions and to test the hypothesis that cultivars more resistant to Phytophthora infestans have greater VOC emissions and different VOC fingerprints. Forty-six VOCs were identified in the emission blends of potato leaves. The majority of the VOCs were sesquiterpenes (50% of the total number of compounds and 0.5–36.9% of the total emissions) and monoterpenes (30.4% of the total number of compounds and 57.8–92.5% of the total VOC emissions). Qualitative differences in leaf volatiles, mainly in sesquiterpenes, were related to the potato genotype background. Among the volatile groups, the monoterpenes α-pinene, β-pinene, Δ3-carene, limonene, and p-cymene, the sesquiterpenes (E)-β-caryophyllene and α-copaene, and green leaf volatile hexanal were the major volatiles in all cultivars. A higher share of VOCs known to have antimicrobial activities was observed. Interestingly, the cultivars were grouped into high and low resistance categories based on the VOC profiles, and the total terpenoid and total constitutive VOC emission scale positively with resistance. To support and expedite advances in breeding for resistance to diseases such as late blight disease, the plant research community must develop a fast and precise approach to measure disease resistance. We conclude that the blend of emitted volatiles is a fast, non-invasive, and promising indicator to identify cultivars resistant to potato late blight disease. [ABSTRACT FROM AUTHOR]

Late blight (LB) caused by the oomycete Phytophthora infestans (Mont.) de Bary is the greatest threat to potato production worldwide. Current potato breeding for LB resistance heavily depends on the introduction of new genes for resistance to P. infestans (Rpi genes). Such genes have been discovered in highly diverse wild, primitive, and cultivated species of tuber-bearing potatoes (Solanum L. section Petota Dumort.) and introgressed into the elite potato cultivars by hybridization and transgenic complementation. Unfortunately, even the most resistant potato varieties have been overcome by LB due to the arrival of new pathogen strains and their rapid evolution. Therefore, novel sources for germplasm enhancement comprising the broad-spectrum Rpi genes are in high demand with breeders who aim to provide durable LB resistance. The Genbank of the N.I. Vavilov Institute of Plant Genetic Resources (VIR) in St. Petersburg harbors one of the world's largest collections of potato and potato relatives. In this study, LB resistance was evaluated in a core selection representing 20 species of seven Petota series according to the Hawkes (1990) classification: Bulbocastana (Rydb.) Hawkes, Demissa Buk., Longipedicellata Buk., Maglia Bitt., Pinnatisecta (Rydb.) Hawkes, Tuberosa (Rydb.) Hawkes (wild and cultivated species), and Yungasensa Corr. LB resistance was assessed in 96 accessions representing 18 species in the laboratory test with detached leaves using a highly virulent and aggressive isolate of P. infestans. The Petota species notably differed in their LB resistance: S. bulbocastanum Dun., S. demissum Lindl., S. cardiophyllum Lindl., and S. berthaultii Hawkes stood out at a high frequency of resistant accessions (7–9 points on a 9-point scale). Well-established specific SCAR markers of ten Rpi genes—Rpi-R1, Rpi-R2/Rpi-blb3, Rpi-R3a, Rpi-R3b, Rpi-R8, Rpi-blb1/Rpi-sto1, Rpi-blb2, and Rpi-vnt1—were used to mine 117 accessions representing 20 species from seven Petota series. In particular, our evidence confirmed the diverse Rpi gene location in two American continents. The structural homologs of the Rpi-R2, Rpi-R3a, Rpi-R3b, and Rpi-R8 genes were found in the North American species other than S. demissum, the species that was the original source of these genes for early potato breeding, and in some cases, in the South American Tuberosa species. The Rpi-blb1/Rpi-sto1 orthologs from S. bulbocastanum and S. stoloniferum Schlechtd et Bché were restricted to genome B in the Mesoamerican series Bulbocastana, Pinnatisecta, and Longipedicellata. The structural homologs of the Rpi-vnt1 gene that were initially identified in the South American species S. venturii Hawkes and Hjert. were reported, for the first time, in the North American series of Petota species. [ABSTRACT FROM AUTHOR]

The breeding of new cultivars is a powerful approach to increase both the quantity and quality of potato harvest per land unit. The aim of this research was to determine using multi-site testing the progress made by the genetic enhancement of potato in Sweden in the last 1.5 decades by comparing advanced breeding clones (T4 upwards) bred in Sweden (Svensk potatisförädling hereafter) versus available released cultivars in Europe and grown in its Nordic Region. The multi-site testing results show that potato breeding based in Scandinavia offers to the growers of the Nordic Region of Europe cultivars for prevailing farming environments and end-user needs rather than relying, as happens today in the market, on foreign cultivars. These cultivars bred elsewhere are not always very suitable for the challenging Nordic agroecosystems, as shown by the results of the multi-site testing herein. Such an approach on relying on foreign cultivars may be advocated for not funding potato breeding in, and for Fennoscandia by those ignoring the results shown by this research. [ABSTRACT FROM AUTHOR]

Bangladesh is in a subtropical monsoon region and extends from 20°34'N to 26°38'N latitude, its agriculture is comprised of several diversified rice-based cropping systems. Potato is an important winter crop across the country. To help increase the sustainability of potato production in Bangladesh, a set of medium-term late blight-resistant potato clones bred in CIP were evaluated for diversification potential at six locations from 2008 to 2013. After seven years of field trials, TCRC, BARI identified two clones, namely CIP 393371.58 (coded LB-6) and CIP 393280.64 (LB-7) which are consistently resistant to Late Blight under field conditions without fungicide and yield as well or better than the predominant commercial varieties (Diamant) in a 90-day cropping window. According to the AUDPC, LB-4, LB-5, LB-6 and LB-7 were moderate to highly resistant to Late Blight. The latter two produced over 30 tons of tubers per hectare. Similar yields were recorded in on-farm trials during 2011-12. These two clones were entered into regional yield trials as a requirement for variety release by the NSB. Based on field performance at on-station and farmers' fields, NSB released BARI Alu-46 (LB-7) in 2013 and BARI Alu-53 (LB-6) in 2014 as the country's two late blight-resistant varieties. [ABSTRACT FROM AUTHOR]

Pyramiding resistance genes (R genes) in potato generally provides improved field resistance against late blight (LB). Potato breeders may implement pyramiding by targeting breeding schemes according to LB genetic profiles. This study interrogated LB resistant elite germplasm for pyramided late blight R genes using DNA-based markers, which were then challenged against contemporary LB races. Five late blight R gene markers were used in this study. LB resistance ratings were determined using detached leaf assay (DLA) and field data from multiple locations and years. The clone J117, found to have the Rpi-blb1/RB gene, showed high resistance against US-23 in the laboratory and field. Several varieties positive for the R3b gene showed at least moderate resistance in the DLA and in the field. While two varieties were found to be pyramided with the R1 and R3b genes and also showed good field resistance, DLA results indicate that the combination is likely non-additive. LB resistance may be broadened by incorporating novel R gene combinations. [ABSTRACT FROM AUTHOR]

Kufri Sangam is a medium maturing, main season high yielding dual purpose potato variety suitable for cultivation in northern plains (for table use) and central plains (for processing and table use). It is a clonal selection from a cross between Kufri Himsona v Kufri Pukhraj. It has compact, vigorous and medium-tall plants. It produces attractive white-cream, ovoid tubers with shallow eyes and cream flesh. It possesses 18-20% tuber dry matter, low reducing sugars (<150mg/100 g fresh weight), mealy texture, very good taste. It produces >90 marketable and >80% processing grade tuber yield and is capable of yielding 35-40 t/ha under optimum agronomical practices. Kufri Sangam yields higher than the presently grown popular table variety Kufri Bahar and processing varieties viz., Kufri Chipsona-3 and Kufri Frysona. Kufri Sangam is moderately resistant to late blight and has excellent keeping quality under country storage conditions with over 10 weeks dormancy period. [ABSTRACT FROM AUTHOR]

Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For two decades, Solanum bulbocastanum Dun. has been challenging potato geneticists with its durable resistance to Phytophthora infestans Mont. de Bary, the causal agent of late blight, the most devastating potato disease. In this study, highly specific SCAR (sequence characterized amplified region) markers for three S. bulbocastanum genes of broad-spectrum resistance to P. infestans,RB/Rpi-blb1,Rpi-blb2 and Rpi-blb3, were employed to screen a vast collection of wild tuber-bearing species from several series of Solanum L. section Petota Dumort. and also potato hybrids and varieties. In S. bulbocastanum and S. stoloniferum Schlechtd. et Bché, the sequences of the markers Rpi-blb1-820 and Rpi-sto1-890, which recognize the LRR and CC regions respectively differed inconsiderably in the orthologous genes RB/Rpi-blb1 and Rpi-sto1. These two markers were tightly linked in diverse wild Solanum genotypes. These markers as well as RB-226, another marker recognizing the LRR region of the Rpi-blb1 gene, were obviously related to high resistance to P. infestans. One more marker recognizing the CC region of the gene, RB-629, was found in much wider range of Solanum genotypes; it was not related to resistance to P. infestans and is therefore considered non-specific. In addition to Rpi-blb1 = Rpi-sto1, the Rpi-blb2 and Rpi-blb3 genes were registered in both S. bulbocastanum and S. stoloniferum accessions. In most cases, three bulbocastanum genes were not linked together. The markers specific for Rpi-blb1 = Rpi-sto1 genes were found in the Solanum series Bulbocastana (Rydb.) Hawkes (genome designation BB) and Longipedicellata Buk. (genome designation AABB) and were absent from five Pinnatisecta Rydb. species also comprising genome B. The marker for Rpi-blb2 was found in the series Bulbocastana and Longipedicellata and also in three accessions of Pinnatisecta, while the Rpi-blb3 gene, the orthologue of widely spread R2 gene for resistance to P. infestans, was present in all three Solanum series. In contrast with Rpi-blb1 = Rpi-sto1, two other functional RB homologues, Rpi-bt1 in S. bulbocastanum and RBver in S. verrucosum Schlechtd. (genome AA), apparently diverged earlier in the evolution of tuber-bearing Solanum species. Our evidence on functional Rpi-blb1 = Rpi-sto1 genes in three Petota series substantiates the assumption that the B genome of tetraploid Longipedicellata evolved from diploid Bulbocastana rather than from diploid Pinnatisecta progenitors. Similar to wild Solanum species, the markers Rpi-blb1-820 and Rpi-sto1-890 were tightly linked in advanced potato hybrids and established varieties bred from S. stoloniferum as the conventional source of bulbocastanum genes for late blight resistance, but did not always match the markers for the Rpi-blb2 and Rpi-blb3 genes and the marker for the Rysto gene as an independent indicator of stoloniferum germplasm. [ABSTRACT FROM AUTHOR]

Eleven wild potato species were characterized by simple sequence repeat (SSR) markers (STU6SNRN and STIIKA), morphological (DUS: distinctness, uniformity and stability) characters and late blight resistance trait. SSR analysis distinguished all the wild species based on molecular profiling. SSR marker STU6SNRN (PIC: 0.92 and alleles: 15) exhibited higher polymorphism than STIIKA (PIC: 0.89 and alleles: 14). The predominant alleles in these species were 175, 178, 184, 190 and 202 bp (STU6SNRN); and 188, 192, 195, 203, 209 and 214 bp (STIIKA). Additionally, morphological characterization based on DUS traits showed phenotypic variations in the species. All species were observed highly resistant to late blight under controlled chamber study. This study suggests that diversity exists among the wild species based on SSR profile, DUS traits and late blight resistance, and could be exploited in future research. Further, SSR profile of these species would be useful in research on identification of trait-specific alleles for late blight resistance, their utilization in biotechnological research, and also in genetic fidelity testing for true-to-type genotypes. [ABSTRACT FROM AUTHOR]

Summary: Considered responsible for one million deaths in Ireland and widespread famine in the European continent during the 1840s, late blight, caused by Phytophthora infestans, remains the most devastating disease of potato (Solanum tuberosum L.) with about 15%–30% annual yield loss in sub‐Saharan Africa, affecting mainly smallholder farmers. We show here that the transfer of three resistance (R) genes from wild relatives [RB, Rpi‐blb2 from Solanum bulbocastanum and Rpi‐vnt1.1 from S. venturii] into potato provided complete resistance in the field over several seasons. We observed that the stacking of the three R genes produced a high frequency of transgenic events with resistance to late blight. In the field, 13 resistant transgenic events with the 3R‐gene stack from the potato varieties 'Desiree' and 'Victoria' grew normally without showing pathogen damage and without any fungicide spray, whereas their non‐transgenic equivalent varieties were rapidly killed. Characteristics of the local pathogen population suggest that the resistance to late blight may be long‐lasting because it has low diversity, and essentially consists of the single lineage, 2_A1, which expresses the cognate avirulence effector genes. Yields of two transgenic events from 'Desiree' and 'Victoria' grown without fungicide to reflect small‐scale farm holders were estimated to be 29 and 45 t/ha respectively. This represents a three to four‐fold increase over the national average. Thus, these late blight resistant potato varieties, which are the farmers' preferred varieties, could be rapidly adopted and bring significant income to smallholder farmers in sub‐Saharan Africa. [ABSTRACT FROM AUTHOR]

Genetic parameters were assessed in 24 potato genotypes for 15 characters related to tuber yield, late blight resistance and keeping quality based field trials conducted during 2015-16 and 2016-17 in winter crop season at Modipuram. High coefficient of variation (genotypic and phenotypic) associated with high heritability and genetic advance were observed for rottage weight loss (%), sprout weight loss (%) and sprouting (%). Tuber yield showed positive association with plant vigour and marketable tuber yield but negative association with tuber dry matter. Thus for selecting varieties for table potatoes, high yielding with moderate tuber dry matter, and for selecting processing potatoes, moderate tuber yield with high tuber dry matter (> 20%) should be considered. The area under disease progress curve (late blight) showed low but significant correlation with detached leaf lesion area (cm2). Keeping quality was dependent on appearance of tubers after storage as it was negatively associated with sprouting (%), sprout weight loss (%) and physiological weight loss (%). Twenty four genotypes could be grouped into six clusters. The grouping of genotypes in clusters indicated that morphological diversity is not related to geographical diversity. Maximum contributions to genetic divergence were of sprouting (%) and sprout weight loss (%) followed by total tubers, tuber dry matter and marketable tuber yield. Though the maximum inter-cluster distances was observed between cluster III and VI, however desirable traits for improvements were available in cluster I and Cluster II. These result would be helpful in selection of superior parents aiming to generate diverse segregating population for effective selection in potato breeding programme. [ABSTRACT FROM AUTHOR]

Elite hybrid progenies of late blight resistant potato somatic hybrids were developed through hybridization with common potato varieties, and also linked ISSR markers were identified with resistant parent/progenies. Previously developed potato somatic hybrids (considered as F1 being protoplast fusion product between Solanum tuberosum dihaploid 'C-13' + S. pinnatisectum) were back-crossed with potato varieties (S. tuberosum) and true potato seed (TPS) were produced. TPS-raised seedlings were advanced to back-cross progenies clones (BC1-C1, BC1-C2, BC1-C3 and BC1-C4) during the five years based on tuber traits in field trials and field resistance to late blight. The BC1-C2 progenies were profiled by ISSR markers and alleles linked to late blight resistant somatic hybrid parent P8 and their progenies (P8 v× Kufri Jyoti) were identified. Eight promising advanced hybrids of BC1-C4 progenies (Kufri Garima v Bulk pollen: MSH/14-7; Kufri Gaurav v P2: MSH/14-129 and -131 for yield enhancement; P8 v Kufri Jyoti: MSH/14-112, -113, -115, -122 and -123 for late blight resistance and dry matter) were identified. This study concludes successful exploitation of interspecific potato somatic hybrids possessing high resistance to late blight and developed promising clones with linked ISSR alleles for genetic fidelity and breeding purposes. This is the first ever report in India towards widening the genetic base of potato by exploitation of interspecific somatic hybrids. [ABSTRACT FROM AUTHOR]

The Estonia potato cultivar Ando has shown elevated field resistance to Phytophthora infestans , even after being widely grown for over 40 years. A comprehensive transcriptional analysis was performed using RNA-seq from plant leaf tissues to gain insight into the mechanisms activated for the defense after infection. Pathogen infection in Ando resulted in about 5927 differentially expressed genes (DEGs) compared to 1161 DEGs in the susceptible cultivar Arielle. The expression levels of genes related to plant disease resistance such as serine/threonine kinase activity, signal transduction, plant-pathogen interaction, endocytosis, autophagy, mitogen-activated protein kinase (MAPK), and others were significantly enriched in the upregulated DEGs in Ando, whereas in the susceptible cultivar, only the pathway related to phenylpropanoid biosynthesis was enriched in the upregulated DEGs. However, in response to infection, photosynthesis was deregulated in Ando. Multi-signaling pathways of the salicylic-jasmonic-ethylene biosynthesis pathway were also activated in response to Phytophthora infestans infection. • Potato cultivar Ando has maintained a long-lasting high-field resistance to Phytophthora infestans. • A comparative transcriptome analysis was performed to gain insights into its resistance mechanism. • Compared to a susceptible cultivar, about a five-fold greater number of differentially expressed genes were found in the highly resistant cultivar Ando. • Several disease-resistant pathways were significantly enriched in Ando and photosynthesis was deregulated. • Multi-signaling pathways of the salicylic-jasmonic-ethylene biosynthesis pathway were also activated in response to P. infestans infection at 72 h post-inoculation. [ABSTRACT FROM AUTHOR]

Kufri Mohan is a medium maturing, main season, high yielding table purpose potato variety suitable for cultivation in Indo-Gangetic plains (northern and eastern). It is a clonal selection from a cross between MS/92-1090 x CP1704. The plants are tall with vigorous and semi-compact canopy and field resistance to late blight. It produces white cream, ovoid tubers with shallow eyes and white flesh. It possesses good keeping quality and moderate tuber dry matter (15-18%). The variety yields 35-40 t/ha and >90% marketable tuber yield under optimum agronomical practices. [ABSTRACT FROM AUTHOR]

Ten tetraploid interspecific potato somatic hybrids developed earlier through protoplast fusion between the dihaploid Solanum tuberosum L. 'C-13' and the diploid wild species Solanum pinnatisectum Dun. were used in this study. Somatic hybrids and standard control cultivars were evaluated for adaptability, tuber traits, late blight resistance and keeping quality attributes (dormancy, sprouting, weight loss and appearance after 75 days of storage) during two successive winter crop seasons (short-days) in the sub-tropical plains of India, where nearly 90% of India's potatoes are grown. Somatic hybrids showed medium to good plant vigour and late to very late plant maturity. Though none of the somatic hybrids produced equal or higher tuber yield than the control cultivars, except clone P7, all other somatic hybrids produced significantly higher marketable and total tuber yield after a 90-day growth than the parent C-13. Most of the somatic hybrids possessed higher tuber dry matter concentration, resistance to late blight and better keeping quality attributes than the control cultivars. Notably, the tubers of somatic hybrids showed a tendency for colour change from white to purple on exposure to sunlight. Breeding potential of somatic hybrids was further assessed by crossing them with commonly grown local potato cultivars for the development of backcross (BC) progenies. In the hybridization programme, berries were formed while somatic hybrids were used either as male or female parents with common cultivars. Our results revealed that the use of bulk pollen of somatic hybrids not only resulted in higher pollination success but also helped to achieve higher numbers of true potato seeds (TPS) per berry. Despite the formation of berries, TPS was absent in 22 crosses using somatic hybrids as a female or male parent which may be due to ovule or embryo abortions. Segregating BC generations were evaluated under the same sub-tropical conditions for further exploitation in potato breeding. Based on our study, the somatic hybrids P4, P8 and P10 can be utilized for the introgression of important characters such as high tuber dry matter concontration, resistance to late blight and excellent keeping quality attributes into the cultivated potato via conventional breeding methods for cultivar development in the sub-tropical plains of India. [ABSTRACT FROM AUTHOR]

Igorota (also known as PO3) is a high yielding potato cultivar with durable resistance to LB ( Phytophthora infestans (Mont.) De Bary), resistance to PVY and PLRV, tolerant to heavy rain and good adaptation to growing conditions in the tropical highlands. Igorota is a result of intercrossing poorly adapted but highly LB resistant Solanum tuberosum ssp. Andigena clones obtained from the International Potato Center (CIP), Lima, Peru in 1986. Igorota is a seedling, selected at La Trindad, Benguet, the Philippines in 1988. Igorota, as second clonal generation rooted cuttings, was grown in an experiment with 46 other entries in 1989 in which it was the highest yielder with 26.5 tons/ha and showed high level of LB resistance. From the 3rd clonal generation, it was also evaluated by farmers, who soon saw its potential. Igorota has excellent vegetative growth, medium maturity in both the wet season and dry seasons. Igorota was officially registered in the Philippines in 1997 and in Vietnam in 2004. At present, Igorota covers around 70 % of the total highland potato production area of 11,000 ha in the Philippines and also 60 % of the total area of 1200 ha in Lamdong, Vietnam. Igorota continues to have durable resistance to LB in extremely high LB pressure environments. Igorota is conducive to rapid multiplication by apical shoot cutting farmer multipliers, who supply the demand for planting material in both countries. [ABSTRACT FROM AUTHOR]

Growing more resistant potato varieties is one of the most effective strategies to control late blight, to protect potato yield and to prevent harming the environment. The main aim of our study was to identify potato varieties with higher resistance to late blight and which were high yielding in Estonian conditions and suitable for organic farming. During the three-year trial, twelve potato varieties were tested at the Jõgeva Plant Breeding Institute (PBI) in 2010-2012. Foliage late blight (Phytophtora infestance (Mont) de Bary) and yield were estimated. First infection of late blight occurred in different times during the trial years. The three-year average infection level indicated that early varieties Arielle', 'Impala' and 'Princess' were more damaged than other varieties in the first estimation. Late varieties 'Ando', 'Anti', 'Juku' and 'Sarme' had higher late blight resistance. Their foliage damage remained less than 30% in the last estimation. The new medium variety 'Teele' had a lower infection rate than other medium varieties and did not significantly differ from late varieties. Based on these data, late varieties, early variety 'Maret' and medium variety 'Teele' can be considered suitable for organic farming. The new variety 'Teele' had the highest three-year average tuber yield (52.8 t ha-1). Varieties 'Impala', 'Princess' and 'Secura' had significantly lower yield. Yield loss of these varieties might have been caused by higher late blight infection during trial years. [ABSTRACT FROM AUTHOR]

New races of Phytophthora infestans rapidly defeat potato late blight (LB) resistance based on Solanum demissum germplasm, and breeders search for new sources of durable LB resistance. We developed and verified six sequence characterized amplified region markers recognizing the race-specific genes R1 and R3 of S. demissum and the broad-spectrum resistance gene RB of S. bulbocastanum and the germplasms of these species and used them to screen 209 accessions of 21 wild Solanum species. In addition to S. demissum, homologues of R1 and R3 were found in several species of series Demissa,Longipedicellata and diploid Tuberosa; R3 homologues were also detected in S. bulbocastanum,S. cardiophyllum and S. ehrenbergii. The RB homologues were found in a wider range of Solanum species. The markers of R1 and R3 genes reliably discerned between germplasms of S. tuberosum ssp. tuberosum and wild sources of LB resistance. Following introgression, the species-specific markers of demissum and bulbocastanum germplasm were rapidly lost, whereas the markers of R1 and R3 genes lasted through several meiotic generations and were maintained at high frequencies in modern potato cultivars. The presence of these markers in demissoid potato cultivars was significantly associated with LB resistance, presuming that both genes contribute to overall defence response. [ABSTRACT FROM AUTHOR]

Copyright of Latvian Journal of Agronomy / Agronomija Vestis is the property of Latvian Journal of Agronomy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction of more durable resistance against Phytophthora infestans causing late blight into the cultivated potato is of importance for sustainable agriculture. We identified a new monogenically inherited resistance locus that is localized on chromosome 4. The resistance is derived from an ABPT clone, which is originally a complex quadruple hybrid in which Solanum acaule, S. bulbocastanum, S. phureja and S. tuberosum were involved. Resistance data of the original resistant accessions of the wild species and analysis of mobility of AFLP markers linked to the resistance locus suggest that the resistance locus is originating from S. bulbocastanum. A population of 1383 genotypes was screened with two AFLP markers flanking the Rpi-abpt locus and 98 recombinants were identified. An accurate high-resolution map was constructed and the Rpi-abpt locus was localized in a 0.5 cM interval. One AFLP marker was found to co-segregate with the Rpi-abpt locus. Its DNA sequence was highly similar with sequences found on a tomato BAC containing several resistance gene analogues on chromosome 4 and its translated protein sequence appeared to be homologous to several disease resistance related proteins. The results indicated that the Rpi-abpt gene is a member of an R gene cluster. [ABSTRACT FROM AUTHOR]