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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]

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 (

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]

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]

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]

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]

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]

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]

As the cultivated potatoes are not resistant to late blight caused by Phytophthora infestans, wild Solanum species are considered to be great resources for achieving durable resistance. This study reports newly identified resistance loci derived from Solanum venturii. Two mapping populations from the same accession, but different genotypes were used. Three specific loci segregated in the first population based on the isolates used for the resistance assay. One has already been mapped on the same region of chromosome 9, whereas the other two were localized below the first locus. In the second population, two specific resistance loci segregated and their genetic positions were also expected to be on the south from other genes clustered on chromosome 9. The resistance loci identified in this study could be different and isolate-specific. These results, together with markers developed using sequences of previously cloned resistance genes and integrated genetic maps of different late blight resistance loci, indicate that there are two resistance gene clusters on the long arm of chromosome 9. [ABSTRACT FROM AUTHOR]

A coiled coil-nucleotide binding site-leucine-rich repeat gene RB/Rpi-blb1 isolated from Solanum bulbocastanum confers broad-spectrum resistance to Phytophthora infestans and is currently employed in potato breeding for durable late blight (LB) resistance. RB homologues were reported in several Solanum species; some of them retained defence function. Here, we report additional evidence on RB-like sequences in 21 Solanum species of the section Petota. The panel of Solanum species was screened with three RB-related PCR markers. RB-like sequences were found in every tested Solanum accession, suggesting universal distribution of RB structural homologues among Solanum genomes, while locus-specific RB-629 was found only in 15 species. Phylogenetic analysis of RB-629 sequences suggested a highly conservative pattern of polymorphisms that was neither species- nor series-specific. Apparently, duplication and evolution of RB-like loci preceded Solanum speciation. Marker presence and particular haplotypes were not immediately associated with high LB resistance. [ABSTRACT FROM AUTHOR]

The RB gene from wild potato Solanum bulbocastanum imparts broad-spectrum late blight resistance to cultivated potato. To explore marker associations and haplotype frequencies near RB, we developed, optimized, validated, and employed a set of markers specific to the haplotype associated with the RB resistance allele. Our markers, developed using a mismatch amplification mutation assay (MAMA)-PCR approach, have single nucleotide polymorphism-level sensitivity. MAMA markers were validated via linkage mapping and applied to a collection of 60 S. bulbocastanum genotypes representing the geographic distribution of the species. Considerable marker disassociation within a 100 kb region encompassing RB was revealed. Physical distance between markers was not an effective predictor of marker disassociation. Applied to a collection of four S. bulbocastanum genotypes of known RB allelic status, a set of six MAMA markers accurately predicted the presence of the RB allele. Implications for marker aided genotype selection and association mapping in wild potato species are explored. [ABSTRACT FROM AUTHOR]

For breeding potato varieties resistant to late blight, identification of resistance genes to Phytophthora infestans ( Rpi genes) is essential. Introduction of Rpi genes from wild Solanum species into cultivated potato is likely to be a good method to achieve durable resistance to P. infestans. In this study, we identified two Rpi genes ( Rpi-ber1 and Rpi-ber2) derived from two different accessions of Solanum berthaultii. These two genes are closely linked on the long arm of chromosome 10. There are similarities between the predicted genetic locations of the previously identified Rpi-ber and Rpi-ber1, which given the common origin of these genes, may indicate that they are the same. However, the genetic positions of Rpi-ber1 and Rpi-ber2 are different. Rpi-ber1 is positioned between CT214 and TG63, whereas Rpi-ber2 is located below both of these two markers. In addition, the sequences of four linked markers to both R genes showed different polymorphisms indicating the two Rpi genes could be transmitted from different haplotypes (chromosomes). [ABSTRACT FROM AUTHOR]

Abstract: Plant pathogenesis-related proteins are toxic to invading pathogens. Among them, the subfamily PR-1 represents low-molecular weight proteins of unknown biochemical function. Here, we describe the cloning and isolation of two PR-1 genes (PR-1b1 (GenBank accession no. SPH493450) and PR-1b2 (SPH493451)) that encode predicted basic proteins. We isolated them from Solanum phureja, a native Andean potato with horizontal resistance to late blight, caused by the oomycete Phytophthora infestans. We demonstrate that the PR-1 genes belong to a small multigene family with an estimated copy number of 4–6 with one of them located on chromosome IX as determined by genetic mapping. The expression of PR-1 genes was different in late blight resistant and susceptible genotypes. Therefore, we propose that both PR-1 genes may play a role in horizontal late blight resistance of S. phureja. [Copyright &y& Elsevier]

The morphological, cytological and molecular analyses of the plants regenerated after PEG-induced fusion between mesophyll protoplasts from the dihaploid potato clone H-8105 and the wild tuberous disease-resistant species S. pinnatisectum, were performed. A single fusion experiment yielded 313 calli, although only two calli produced shoots. From the rooted shoots, two stable clones (PT-01-1 and PT-01-2) exhibiting different vigor and habitat, were developed. The plants of PT-01-1 clone grew slowly in vitro, produced tubers after transfer to soil but did not set flowers. In contrast, the plants of the vigorous clone PT-01-2 produced both tubers and flowers after transfer to soil. The flower and tuber morphology of PT-01-1 and PT-01-2 regenerants was intermediate in comparison to the parental species. Cytological analysis revealed that the PT-01-1 clone was pentaploid and the PT-01-2 clone was tetraploid. The molecular (RAPD) analysis confirmed hybridity of both clones. The preliminary tests on late blight resistance of the hybrids showed no differences with a potato parent. [ABSTRACT FROM AUTHOR]

Copyright of American Potato Journal is the property of Springer Nature 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.)