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Late blight (Phytophthora infestans), characterized by small water-soaked areas that rapidly enlarge to form purple-brown, oily appearing blotches, is the most destructive fungal disease that continues to stymie worldwide tomato production. Severe outbreaks have been recorded in tomato-growing areas throughout the world in recent years, and the vast majority of commercial tomato cultivars are extremely vulnerable to the late blight infection. The aim of this study was to screen the wild tomato Solanum habrochaites accessions LA1223, LA1353, LA1718, LA1777, LA2156, LA2167, and LA2556 under natural disease pressure conditions to find a possible source of resistance to late blight and also characterized these accessions for various morphological characters. Three S. habrochaites accessions (LA1777, LA2167, and LA2556) were resistant and superior to the susceptible check. With a PDI of 22.29, LA 1777 was shown to have the highest resistance, and as such, it may be used as a donor for late blight resistant tomato pre-breeding programmes in the near future. The success of high crossability (percentage) of some hybrid combinations using LA1777 as a male parent, such as LA3846 × LA1777 (77.77), LA2377 × LA1777 (62.50), and LA3317 × LA1777 (60.00), is encouraging for the development of pre-breeding genetic stocks as well as for the discovery of novel alleles in wild tomato populations. The morphological characterization of seven wild tomato accessions mainly confirms the guidelines of the International Plant Genetic Resources Institute. These accessions and their interspecific crosses showed wide variability in phenotypic and reproductive characters for plant height, flower color, exserted stigma, leaf margin, flowering time, fruit set, and other economic traits that will facilitate breeders in the development of superior tomato cultivars and F1 hybrids resistant to biotic stresses, as well as differentiate these S. habrochaites accessions for their potential use in genetic enhancement of cultivated tomatoes. [ABSTRACT FROM AUTHOR]

Late blight (Phytophthora infestans) is a serious disease of potatoes. The aim of this study was to screen wild potato species and identify differentially expressed genes (DEGs) associated with late blight resistance. Wild potato species such as PIN45 (Solanum pinnatisectum), CPH62 (Solanum cardiophyllum), JAM07 (Solanum jamesii), MCD24 (Solanum microdontum), PLD47 (Solanum polyadenium), and cv. Kufri Bahar (control) were tested by artificial inoculation of P. infestans under controlled conditions. Transcriptomes of the leaf tissues (96 h post-inoculation) were sequenced using the Illumina platform. Statistically significant (p < 0.05) DEGs were analyzed in wild species by comparison with the control, and upregulated (>2 log2 fold change, FC) and downregulated (<-2 log2 FC) genes were identified. DEGs were functionally characterized with Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Selected genes were validated by real-time PCR analysis to confirm RNA-seq results. We identified some upregulated genes associated with late blight resistance in wild species such as cytochrome P450, proline-rich protein, MYB transcription factor MYB139, ankyrin repeat-containing protein, and LRR receptor-like serine/threonine-protein kinase in PIN45; glucosyltransferase, fructose-bisphosphate aldolase, and phytophthora-inhibited protease 1 in CPH62; steroid binding protein and cysteine proteinase 3 in JAM07; glycinerich cell wall structural protein 1 and RING finger protein in MCD24; and cysteine proteinase 3 and major latex protein in PLD47. On the other hand, downregulated genes in these species were snakin-2 and WRKY transcription factor 3 in PIN45; lichenase and phenylalanine ammonia-lyase 1 in CPH62; metallothionein and LRR receptor-like serine/threonine-protein kinase in JAM07; UDP-glucoronosyl/UDP-glucosyl transferase family protein and steroid binding protein in MCD24; and cytoplasmic small heat shock protein class I and phosphatase PLD47. Our study identified highly resistant wild potato species and underlying genes such as disease resistance, stress response, phytohormones, and transcription factors (e.g., MYB, WRKY, AP2/ERF, and AN1) associated with late blight resistance in wild potato 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.

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 (Phytophthora infestans) is a serious disease of potatoes. The aim of this study was to screen wild potato species and identify differentially expressed genes (DEGs) associated with late blight resistance. Wild potato species such as PIN45 (Solanum pinnatisectum), CPH62 (Solanum cardiophyllum), JAM07 (Solanum jamesii), MCD24 (Solanum microdontum), PLD47 (Solanum polyadenium), and cv. Kufri Bahar (control) were tested by artificial inoculation of P. infestans under controlled conditions. Transcriptomes of the leaf tissues (96 h post-inoculation) were sequenced using the Illumina platform. Statistically significant (p < 0.05) DEGs were analyzed in wild species by comparison with the control, and upregulated (>2 log2 fold change, FC) and downregulated (

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]

Background. Yield stability is a necessary trait for sustainable potato production under climate change. Potato breeding is based on crosses between parental lines selected for a set of important traits: productivity, structural yield components, and resistance to abiotic and biotic stresses. Data on plant responses to environmental conditions allows breeders to conduct informed selection of plant forms for crossing. The objective of this work was to characterize interspecific potato hybrids in terms of their productivity, yield plasticity and stability in the Central Region of European Russia.Materials and methods. For seven years (2014–2020), 19 hybrids and cv. ‘Favorit’ (reference) were assessed for productivity, number of tubers per plant, mean tuber weight, marketability, and resistance to late blight. Growing conditions were characterized using the hydrothermal coefficient. Environmental sustainability was determined by calculating the parameters of plasticity (bI) and stability (σ2) according to N. P. Sklyarova and V. A. Zharova.Results. Positive and negative anomalies in heat or moisture supply were observed during the test years. The maximum productivity was obtained in 2016, with heavy rainfall and higher temperatures; the minimum, in the hot and dry 2018. For productivity, the effect sizes of the factors “variety” and “year” were 29% and 38%, respectively. Hybrids with yield levels close to cv. ‘Favorit’ were identified: 117-2, 122-29, 99-6-5, 99-1-3, 99-6-6, and 34-5-2003. ‘Favorit’ is an intensive-type cultivar, with low yield stability. Hybrid 135-2-2006, also of the intensive type, had a stable yield, but developed medium-sized tubers and was less productive than other accessions. Hybrid 117-2 is of the extensive type, with medium stability, while hybrids 8-3-2004 and 135-5-2005 demonstrated high environmental plasticity and yield stability.

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.

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]

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.

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]

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China 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.)

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.)

A new double cropping potato variety, ‘Gangseon’, was bred by the Highland Agriculture Research Institute, National Institute of Crop Science (NICS), RDA, Korea, in 2016. ‘Gangseon’ was obtained from the cross between ‘Daegwan1-83’ and ‘Chubaek’ in 2006. Seedling and line selection was performed from 2008 to 2009, and preliminary and advanced yield trials were carried out with ‘Gangseon’ from 2010 to 2013 in Gangneung city. The regional yield trials were conducted in Gangneung, Muan, and Jeju from 2014 to 2016. ‘Gangseon’ has light purple flowers, green narrow leaflets and petioles with medium anthocyanin coloration, round tubers with yellow russet skin, and yellow flesh. The dormancy of ‘Gangseon’ stored in 20 ℃ was 60-70 days after harvesting, which is longer than those of ‘Dejima’ and ‘Chubaek’, but shorter than that of ‘Superior’. The average yields of tubers in the spring and fall seasons were 36.6 and 21.2 ton⋅ha-1, respectively, in the regional yield trials. It is susceptible to common scab and potato virus Y, but has high resistance to potato leaf roll virus, potato virus X, early blight, and late blight. The dry matter contents were 22.1% in spring and 19.8% in autumn. The adaptation area of ‘Gangseon’ is the southern coastal area, including Jeju Island, Korea. The plant variety protection right of ‘Gangseon’ was registered in April 2020, and its grant number is 8081. [ABSTRACT FROM AUTHOR]

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]

The RB gene, which was cloned from the wild potato species Solanum bulbocastanum, confers a high level of broad spectrum resistance to various strains of Phytophthora infestans, the causal agent of potato late blight. The level of RB-mediated resistance is correlated with the amount of RB transcripts in transgenic potato lines containing RB gene(s) driven by its native promoter. To assess whether the level of RB-mediated resistance can be further enhanced by overexpression of the RB gene, multiple transgenic potato lines containing RB gene(s) driven by the cauliflower mosaic virus (CaMV) 35S promoter were developed. Surprisingly, all 35S::RB transgenic lines with one or several copies of the RB gene showed a similar level of late blight resistance. In parallel, a statistically similar amount of RB transcript was observed among all resistant transgenic lines with different copy numbers of the RB gene. In addition, the levels of RB gene transcription in the 35S::RB transgenic potato lines were the same or lower than in transgenic lines containing the RB gene driven by its native promoter. Thus, developing transgenic potato lines using RB with the native promoter will be the best approach to deploy this gene for combating late blight. [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]

Although development of potato cultivars resistant to late blight has long been one of the primary goals of potato breeding programs, several different methods of field resistance evaluation have been used by potato breeders. Recently, within the EucaBlight network (www.euroblight.net), common methods of late blight evaluation have been agreed on, and these methods are currently highly recommended for use by all those interested in evaluating the resistance of the potato to late blight. Here, we describe a method of evaluating potato resistance in field conditions routinely used at Młochów Research Center, which is compliant with recommendations of the EucaBlight protocol. [ABSTRACT FROM AUTHOR]

The Avr avirulence gene of Phytophthora infestans and R gene of the potato are the genetic components of the gene-for-gene interaction resulting in host plant resistance. This effector-triggered immunity has been recently exploited to generate extreme resistance to late blight in potato by genetic engineering. The choice of the R genes, their number forming a R gene stack, and the pathogen Avr gene diversity will likely determine how long this extreme resistance will last. Here, we report on a comparative study on the Rpi-vnt1.1 gene which originated from Solanum venturii, and was introduced in the potato variety 'Desiree' by genetic transformation, and the Avr-vnt1 gene from two isolates of the EC-1 lineage of P. infestans. EC-1 was reported previously as not expressing the Avr-vnt1 gene and, therefore, being virulent on Rpi-vnt1.1 transgenic plants. Unexpectedly, whole-plant resistance assays identified 5 out of 52 transgenic events as resistant to two isolates of P. infestans, POX067 and POX109, belonging to the EC-1 lineage. We demonstrated that in both isolates, the Avr-vnt1.1 gene was expressed at a low level. Expression of the Rpi-vnt1.1 gene was shown to be rapidly increased by two-fold and subsequently to have steady state expression for at least 5 days after the inoculation. The Rpi-vnt1.1 gene in addition to other R genes as a stack in farmers' preferred varieties will confer extreme resistance to late blight disease and rotations of plants with different R-gene-stack in time is likely to last longer than plants with single R gene. [ABSTRACT FROM AUTHOR]

The EU regulation on organic farming does not allow the use of genetically modified organisms (GMOs) which are subject to Directive 2001/18/EC. Mutagenesis using irradiation or chemicals is genetic modification, but the organisms obtained through these techniques are not subject to the provisions of the GMO directive. Such mutants can therefore be used in organic agriculture. Derived from its basic principles, organic farming can only use natural substances to control disease and crops should be resilient, which, in the case of disease resistance, means that durable (horizontal) resistance is preferred to vertical (single gene) resistance. Cisgenesis can achieve such a durable resistance by introducing multiple resistance genes in one step. These multiple-resistant plants only contain natural genes that can also be introduced by breeding. In case cisgenic plants are not subject to the provisions of the GMO legislation, they can even be legally used in organic agriculture. In case they are not exempted from the GMO regulation, the question is: why obstruct a cisgenic potato crop that can hardly be distinguished from a potato crop that is the result of conventional breeding? Among the reasons why organic agriculture does not allow the use of GMOs it is mentioned that genetic engineering is unpredictable, it causes genome disruption and it is unnatural. However, our knowledge of plant genome evolution and breeding has increased dramatically. We now know that breeding is more unpredictable and causes more genome disruption than genetic engineering. Recent field trials have shown the efficacy of cisgenic late blight-resistant potatoes carrying multiple resistance genes. Large-scale growing of such durably resistant potatoes would not only be environmentally beneficial by it would strongly reducing the need for fungicide sprays in conventional potato cultivation and it would also reduce the disease pressure in organic potato cultivation. [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]

The Rpi- blb2 gene ( R gene) from the Mexican wild potato species, Solanum bulbocastanum, was introduced into the potato variety Desiree by agro-infection in order to confer resistance to late blight which is still the most important disease of the potato worldwide. A total of 148 putative transgenic events was obtained by selection based on hygromycin resistance of which 127 appeared to contain the Rpi- blb2 gene. To rapidly identify the highly resistant transgenic events, we used an in vitro assay with one isolate of Phytophthora infestans and a whole-plant assay with two isolates. Nine transgenic events were highly resistant to both isolates and four of these contained single copy T-DNA and did not contain backbone vector sequences. The transcript abundance of Rpi- blb2 was low in infected and uninfected leaves and did not correlate with the resistance level determined in whole plants. We proceeded with high dose inoculation of whole plants of three highly and moderately resistant transgenic events, which resulted in lesions with low levels of sporulation in a few cases. Reinfection was not successful in any of the cases. Hence our results show that a high level of resistance to LB, including extreme resistance, can be obtained through the Rpi- blb2 gene and that heavy inoculation did not readily increase virulence in our test conditions. These transgenic events will be used for either multi-line deployment or R gene stacking by conventional breeding in order to release late blight resistant varieties which will need limited fungicide use, if any. [ABSTRACT FROM AUTHOR]

Solanum nigrum is a wild non-tuber-bearing species that serves as an excellent resource in potato breeding due to its resistance potential against biotic and abiotic stresses. However, sexual hybrids between S. nigrum and S. tuberosum are difficult to produce because these species are highly incompatible. Therefore, somatic hybridization is used to introduce various traits from this wild species into potato. After somatic hybridization, it is essential to select fusion products often the aid of molecular markers. In this study, we obtained the chloroplast genome sequence of S. nigrum by next-generation sequencing technology and compared it with those of four other Solanaceae species to develop specific markers for S. nigrum. The chloroplast genome has a total sequence length of 155,432 bp. Its size, gene content, order and orientation are similar to those of the four other Solanaceae species, but there are some structural variations at repeat and junction areas. Phylogenic analysis revealed that S. nigrum is located in the same clade as Nicotiana tabacum and S. tuberosum is the least closely related species. After detailed comparisons of the chloroplast genome sequences of the five Solanaceae species, we identified 76 InDels (Insertion/Deletions), including 47 insertions and 29 deletions in the intergenic and intragenic regions. Based on these InDels, we developed seven markers for discriminating S. nigrum from other Solanum species. The results obtained in this study can be used to select somatic fusion products and accelerate breeding using S. nigrum. [ABSTRACT FROM AUTHOR]

Solanum cardiophyllum Lindl. (PI 341233) (2 n = 2 x = 24, 1EBN) is a diploid wild potato species highly resistant to late blight, the most serious disease of potato. However, it poses a problem of sexual incompatibility with common potato. So to circumvent this problem, in this study, we developed interspecific potato somatic hybrids between cultivated S. tuberosum dihaploid C-13 and wild species S. cardiophyllum via protoplast fusion. Out of 26 regenerants, only 4 were confirmed as true somatic hybrids containing both parental genomes based on molecular markers and phenotypes. Somatic hybrids were identified by RAPD, ISSR, SSR, AFLP and cytoplasm (chloroplast and mitochondrial genomes) type molecular markers. Intermediate phenotypes of somatic hybrids were confirmed by leaf, flower and tuber traits. Late blight resistance of the hybrids was assessed by challenge inoculation of P. infestans under controlled conditions. Somatic hybrids were found tetraploid by flow cytometry, exhibited high pollen stainability by acetocarmine staining and formed berries and viable seeds after crossing with a common potato variety. Somatic hybrids possessed diverse cytoplasm types (W/α, W/γ and T/β) as assessed by chloroplast and mitochondrial genome-specific markers. Further, cluster analysis based on the Jaccard's coefficient of molecular profiles generated by all above markers showed genetic distinctness in somatic hybrids and parents. Taken together, these interspecific somatic hybrids with diverse cytoplasm background have potential to be employed in potato breeding programmes to widen the cultivated gene pool through conventional and molecular methods. [ABSTRACT FROM AUTHOR]

The late blight disease can be managed by introduction of resistance ( R) genes from the wild Solanum species into the cultivated potato. The R genes are mostly comprised of the nucleotide binding site-leucine rich repeat (NBS-LRR) domains and share nucleotide sequence homology in the crop species. In this study, we used potato R gene-specific primers to amplify homologous genes from wild species. A total of 39 wild species were tested for late blight resistance by challenge inoculation of Phytophthora infestans under controlled conditions. Of these, only 15 species were highly resistant (HR) and these were PCR (polymerase chain reaction) amplified by 53 primers representing 21 R genes of potato. Further, only single, distinct, and reproducible gene fragments were cloned and sequenced. Following sequence processing and analysis, 17 non-redundant sequences of RB-homologous genes were identified with uninterrupted open reading frames (ORFs) and nucleotide sequence homologies to known late blight R genes. Finally, 17 RB-homologous gene fragments amplified by the primers of the RB gene were isolated from 11 wild species. The isolation and characterization of 17 RB-homologous gene fragments from wild potato species may serve as an important genomic resource for the novel gene discovery in late blight resistance breeding programs. [ABSTRACT FROM AUTHOR]

The aim of this study was to increase marker density in a previously identified late blight resistance QTL in a diploid potato population. SSR markers from the reference potato genome sequence were located by e-PCR in the QTL region in the chromosome 9 genetic map of the diploid potato population B3C1HP, and utilized to identify more candidate genes locating between the SSR markers. After verified by PCR and genetic mapping, two SSR markers and two DM candidate genes were mapped in the QTL peak in the maternal genetic map of B3C1HP. The new markers narrowed down the average 2-LOD support interval from 2.6 to 1.4 cM. The new markers on the LOD peak are valuable for fine mapping and positional cloning of the alleles in late blight resistance QTL. This study proves that combination of SSR and e-PCR is an effective way to develop markers in target QTL region. [ABSTRACT FROM AUTHOR]

Background: Various wild species germplasm has been used in European potato breeding since the first introduction of potato (Solanum tuberosum L.) to Europe. As the plant cytoplasmic genome including chloroplast and mitochondrial genomes is transmitted only through the maternal parent, cytoplasmic markers are useful tools in breeding programs to determine cytoplasmic genome types and to trace maternal ancestors. The potato cytoplasmic genome can be distinguished into six distinct types (M, P, A, W, T, and D). Male sterility was found in genotypes with S. demissum-derived D-type cytoplasm and S. stoloniferum-derived W/γ-type cytoplasm. These wild species were frequently used to incorporate superior pathogen resistance genes. As a result, the percentage of these two types is increasing unintentionally in the European germplasm pool. Other than cytoplasmic male sterility, little is known about effects of the cytoplasmic genome on complex agronomic traits in potato. Result: The cytoplasm types of 1,217 European potato cultivars and breeding clones were determined with type specific DNA markers. Most frequent were T- (59.4 %), D- (27.4 %), and W- (12.2 %) type cytoplasm, while A- (0.7 %) and M-type cytoplasm (0.3 %) was rare and P-type cytoplasm was absent. When comparing varieties with breeding clones, the former showed a relatively higher frequency of T-type and lower frequency of D- and W-type cytoplasm. Correlation analysis of cytoplasm types and agronomic data showed that W/γ-type cytoplasm was correlated with increased tuber starch content and later plant maturity. Correlation with quantitative resistance to late blight was observed for D-type and M-type cytoplasm. Both cytoplasm types had a positive effect on resistance. Conclusion: This study revealed and quantified the cytoplasmic diversity in the European potato germplasm pool. Knowledge of cytoplasm type is important for maintaining genetic diversity and managing the male sterility problem in breeding programs. This is the first comprehensive study to show correlations of distinct cytoplasmic genomes with complex agronomic traits in potato. Correlations particularly with tuber starch content and resistance to late blight provided new knowledge on cytoplasmic effects on these important traits, which can be exploited for genetic improvement of potato. [ABSTRACT FROM AUTHOR]

Ethylene response factors (ERFs) are unique to the plant kingdom and play crucial roles in plant response to various biotic and abiotic stresses. We show here that a potato StERF3, which contains an ERF-associated amphiphilic repression (EAR) motif in its C-terminal region, negatively regulates resistance to Phytophthora infestans and salt tolerance in potato. The StERF3 promoter responds to induction by salicylic acid, ABA ethylene and NaCl, as well as P. infestans, the causal agent of potato late blight disease. StERF3 could bind to the GCC box element of the HIS3 promoter and activate transcription of HIS3 in yeast cells. Importantly, silencing of StERF3 in potato produced an enhanced foliage resistance to P. infestans and elevated plant tolerance to NaCl stress accompanied by the activation of defense-related genes (PRI, NPR1 and WRKY1). In contrast, StERF3-overexpressing plants showed reduced expression of these defense-related genes and enhanced susceptibility to P. infestans, suggesting that StERF3 functions as a negative regulator of downstream defense- and/or stressrelated genes in potato. StERF3 is localized to the nucleus. Interestingly, yeast two-hybrid assay and a bimolecular fluorescence complementation (BiFC) test clarified that StERF3 could interact with other proteins in the cytoplasm which may lead to its re-localization between the nucleus and cytoplasm, revealing a novel means of StERF3 regulation. Taken together, these data provide new insights into the mechanism underlying how StERF3 negatively regulates late blight resistance and abiotic tolerance in potato and may have a potential use in engineering late blight resistance in potato. [ABSTRACT FROM AUTHOR]

Late blight, caused by Phytophthora infestans , is a destructive disease of potato. Defender is the only cultivar in the U.S. with foliar and tuber resistance to this disease. However, this cultivar exhibits susceptibility to infection by Potato virus S (PVS) and severe symptoms appeared on leaves after infection with PVS. PVS is widespread in potato fields in the U.S. To investigate potential interactions between P. infestans and PVS, detached leaves of Defender and Ranger Russet (susceptible to late blight), that were either PVS-infected or non-infected, were inoculated with P. infestans BF-05. The amount of sporulation and the extent of lesion expansion on inoculated leaves were measured to estimate late blight severity. When inoculated with P. infestans only, as expected, Defender exhibited discrete, relatively small, dark purple to black hypersensitive reaction-like spots and on an average had twenty times fewer sporangia compared to Ranger Russet. However, in Defender plants infected with PVS, lesion expansion and sporulation increased significantly compared to PVS-free Defender. The increased severity of late blight in PVS-infected Defender suggests that PVS negatively impacts late blight resistance in this cultivar. This study demonstrates that late blight resistance in cultivars to be released should be screened for PVS susceptibility. [ABSTRACT FROM AUTHOR]

Essentially all plant species exhibit heritable genetic variation for resistance to a variety of plant diseases caused by fungi, bacteria, oomycetes or viruses. Disease losses in crop monocultures are already significant, and would be greater but for applications of disease-controlling agrichemicals. For sustainable intensification of crop production, we argue that disease control should as far as possible be achieved using genetics rather than using costly recurrent chemical sprays. The latter imply CO2 emissions from diesel fuel and potential soil compaction from tractor journeys. Great progress has been made in the past 25 years in our understanding of the molecular basis of plant disease resistance mechanisms, and of how pathogens circumvent them. These insights can inform more sophisticated approaches to elevating disease resistance in crops that help us tip the evolutionary balance in favour of the crop and away from the pathogen.We illustrate this theme with an account of a genetically modified (GM) blight-resistant potato trial in Norwich, using the Rpi-vnt1.1 gene isolated from a wild relative of potato, Solanum venturii, and introduced by GM methods into the potato variety Desiree. [ABSTRACT FROM AUTHOR]

Several quantitative trait loci (QTL) for resistance to late blight have been reported in diploid potatoes. The diploid wild potato species Solanum chacoense possesses a high degree of horizontal resistance to late blight. In the present study, we report on QTL mapping for late blight resistance in a diploid mapping population of 126 F of Solanum spegazzinii (susceptible) × S. chacoense (resistant). The area under the disease progress curve (AUDPC) values for late blight resistance using the 'whole plant in vitro assay' and the 'detached leaf assay' on the mapping population displayed quantitative variation. Out of 64 AFLP primer-pairs combinations and SSR markers, a total of 209 significant AFLP loci were placed onto the 12 linkage group of potato covering a total map length of 6548.1 cM. QTL analysis based on the AUDPC dataset of the 'whole plant in vitro assay' using the interval-mapping option identified two QTL (LOD > 2.5) located on linkage groups IX and X, which explained 14.70 and 3.40% variation, respectively. The present study revealed the presence of potential new genetic loci in the diploid potato family contributing to quantitative resistance against late blight. [ABSTRACT FROM AUTHOR]

Highlights: [•] Evaluation of reaction of Ph-3 gene at ‘L3708’ to a Korean isolate of Phytophthora infestans. [•] Identify Ph-3 candidate gene/s by screening linked TG591 and TG328 tomato markers. [•] 4 tandem duplicated Ph-3 homologs of CC-NBS-LRR class identified as candidate gene. [•] Developed SCAR markers set able to distinguish each copy of the Ph-3 gene homolog. [•] Ph-3 locus also confers resistance to the Korean isolate of the pathogen. [ABSTRACT FROM AUTHOR]

The deliberate release of any genetically modified (GM) organism in the European Union requires an environmental risk assessment (ERA) prior to commercialisation, including impact assessment on nontarget organisms. We report from two expert workshops where a newly developed selection procedure for identification of ecologically relevant testing organisms was applied to the case of a GM potato with increased resistance to late blight, planned for cultivation in southern Scandinavia. Species known to contribute to important ecological functions in the receiving environment were selected in a stepwise procedure, to arrive at a practical number of ecologically relevant species that are likely to be exposed to the transgene and suitable for experimental testing. Four ecological functional categories were identified: herbivory and disease transmission, natural enemies, ecological soil processes and pollination. Among these, relevant nontarget species were identified for herbivores and soil living pathogens, natural enemies and decomposers/beneficial soil organisms. Out of a total of 16 herbivores, 17 soil-living pathogens, 49 natural enemies and 14 decomposers/beneficial soil organisms in the initial lists, 8 herbivores, 10 soil-living pathogens, 15 natural enemies and 11 decomposers/beneficial soil organisms were identified as possible testing organisms, based on ecological criteria. These findings are highly relevant for determining the scope and structure of an ERA of this type of GM potato. The selection procedure could not be completed because of insufficient information about tissue- and developmental stage-specific expression levels of the transgenic products for this particular GM potato. Thus, the case study illustrates some of the difficulties and knowledge gaps that limit the relevance and quality of ERA of GM plants. [ABSTRACT FROM AUTHOR]