Wild Potato Species Research Articles

Genetic characteristics of the diploid offsprings in potato Cooperation 88 induced by diploid donor IVP101

Diploid lines (2n = 2x = 24) derived from tetraploid potato cultivars have been utilized to hybridize with wild diploid potato species, yielding fertile offsprings. Utilizing the pollen of Solanum tuberosum Group Phureja, such as IVP101, IVP35 and IVP48, as an inducer for wide hybridization with tetraploid cultivars represents a common method for producing diploids. In this study, we created a distant hybridization induced population of tetraploid potato cultivar Cooperation 88 (C88) and IVP101, and screened all diploids using flow cytometry and ploidyNGS. We investigated the genetic composition of chloroplast and nuclear genomes in 43 diploid offsprings. We found that all diploid offsprings share the same chloroplast genomic sequence as C88 and no evidence of paternal chloroplast inheritance was found. Used SNP data to calculate the theoretical introgression index of IVP101 with diploid offsprings. The results showed that the inducer’s nuclear genome was involved in the nuclear genome of the diploid offsprings with purple stem trait, indicating that the inducer nuclear genome was not completely eliminated in the nuclear genome during distant hybridization. Furthermore, we conducted a comparative analysis of the chloroplast genomes of the Solanum genus. The results indicated that (1) the chloroplast genome sizes of the 14 Solanum species ranged from 154,289 bp to 155,614 bp, with a total number of genes ranging 128-141, and with ycf1 and rps19 pseudogenes appearing at the IRB/SSC and IRA/LSC boundaries, respectively; (2) eight divergent hotspots distributed in the LSC and SSC regions of the Solanum chloroplast genomes were identified; (3) positive selection was detected in the clpP, rbcL, rps15, and rps4 genes, likely contributing to the adaptation of Solanum species to different habitats. These results reveal the variation and evolutionary characteristics of chloroplast genomes in Solanum plants.

Image-Based Quantitative Analysis of Epidermal Morphology in Wild Potato Leaves.

The epidermal leaf patterns of plants exhibit remarkable diversity in cell shapes, sizes, and arrangements, driven by environmental interactions that lead to significant adaptive changes even among closely related species. The Solanaceae family, known for its high diversity of adaptive epidermal structures, has traditionally been studied using qualitative phenotypic descriptions. To advance this, we developed a workflow combining multi-scale computer vision, image processing, and data analysis to extract digital descriptors for leaf epidermal cell morphology. Applied to nine wild potato species, this workflow quantified key morphological parameters, identifying descriptors for trichomes, stomata, and pavement cells, and revealing interdependencies among these traits. Principal component analysis (PCA) highlighted two main axes, accounting for 45% and 21% of variance, corresponding to features such as guard cell shape, trichome length, stomatal density, and trichome density. These axes aligned well with the historical and geographical origins of the species, separating southern from Central American species, and forming distinct clusters for monophyletic groups. This workflow thus establishes a quantitative foundation for investigating leaf epidermal cell morphology within phylogenetic and geographic contexts.

Haplotype-resolved genome and mapping of freezing tolerance in the wild potato Solanum commersonii.

Solanum commersonii (2n = 2x = 24, 1EBN, Endosperm Balance Number), native to the southern regions of Brazil, Uruguay, and northeastern Argentina, is the first wild potato germplasm collected by botanists and exhibits a remarkable array of traits related to disease resistance and stress tolerance. In this study, we present a high-quality haplotype-resolved genome of S. commersonii. The two identified haplotypes demonstrate chromosome sizes of 706.48 and 711.55Mb, respectively, with corresponding chromosome anchoring rates of 94.2 and 96.9%. Additionally, the contig N50 lengths are documented at 50.87 and 45.16Mb. The gene annotation outcomes indicate that the haplotypes encompasses a gene count of 39 799 and 40 078, respectively. The genome contiguity, completeness, and accuracy assessments collectively indicate that the current assembly has produced a high-quality genome of S. commersonii. Evolutionary analysis revealed significant positive selection acting on certain disease resistance genes, stress response genes, and environmentally adaptive genes during the evolutionary process of S. commersonii. These genes may be related to the formation of diverse and superior germplasm resources in the wild potato species S. commersonii. Furthermore, we utilized a hybrid population of S. commersonii and S. verrucosum to conduct the mapping of potato freezing tolerance genes. By combining BSA-seq analysis with traditional QTL mapping, we successfully mapped the potato freezing tolerance genes to a specific region on Chr07, spanning 1.25Mb, with a phenotypic contribution rate of 18.81%. In short, current research provides a haplotype-resolved reference genome of the diploid wild potato species S. commersonii and establishes a foundation for further cloning and unraveling the mechanisms underlying cold tolerance in potatoes.

Leaf and tuber resistance to <I>Phytophthora infestans</I> and relationship between these traits in wild potato species

Background. Phytophthora infestans (Mont.) de Bary is a well-known serious pathogen that affects a wide range of currently grown potato cultivars. Control of the disease, including the breeding process, is complicated by the fact that leaf resistance to P. infestans is often unrelated to tuber resistance, resulting in the need to identify individual plants with leaf and/or tuber resistance to be used in breeding programs. In view of this, research efforts to identify such sources are quite relevant. The objective was to assess the occurrence of plants with resistance in both organs among different wild species and analyze the relationship between leaf and tuber resistance within them.Material and methods. Assessment of leaf and tuber resistance in 97 accessions belonging to 36 species was carried out under artificial inoculation. Using the data obtained on each individual plant, the connection between leaf and tuber resistance was analyzed by means of the Wilcoxon matched-pairs test and Spearman’s rank-order correlations.Results. The species with more frequent occurrence of plants combining leaf and tuber resistance and the species with the predominance of leaf or tuber resistance were identified. The statistical analysis did not show complete (100%) correlations between leaf and tuber resistance in any of studied species. In some cases, a significant positive or negative correlation between these characters was found. The assessment results for the studied species/accessions can facilitate the search for leaf and/or tuber resistance sources capable of improving potato cultivars susceptible to late blight.

The haplotype-resolved T2T genome assembly of the wild potato species Solanum commersonii provides molecular insights into its freezing tolerance

The haplotype-resolved T2T genome assembly of the wild potato species Solanum commersonii provides molecular insights into its freezing tolerance

The use of <i>in vitro</i> androgenesis for the involvement of interspecific hybrids between <i>Solanum tuberosum</i> L. and wild allotetraploid potato species <i>Solanum stoloniferum</i> Schltdl. et Bouché into breeding

Wild allotetraploid potato species Solanum stoloniferum Schltdl. & Bouché from Mexico is regarded as a valuable source of resistance genes for use in breeding. However, introgression of its resistance genes into breeding material is hampered by a set of reproductive barriers. The genomic difference between S. stoloniferum (genome ААВВ) and S. tuberosum L. (AAAA) is one of them. This makes questionable the possibility of transferring a variety of valuable genes of the wild species localized on the chromosomes of its genome B into the genome of cultivated potatoes. It is proposed to produce tetraploid (4x, AAAB) interspecific hybrids of S. stoloniferum, which are regarded as more promising for homoeological recombination than pentaploid (5x, ААААВ) hybrids commonly used in the introgression schemes. However, the effective ploidy of tetraploid hybrids (3EBN) hinders their backcrossing to cultivated potatoes (4 EBN). For instance, our attempts to involve the tetraploid hybrid of S. stoloniferum IGC16/36.1 obtained by us into hybridization with potato varieties were unsuccessful for a number of years. To solve this problem, we suggested a technique based on the production of 4x plants obtained in anther culture of this hybrid. The present research was aimed at assessing the efficiency of this approach.Thirty-one plants were obtained in anther culture (androgenic clones, androclones) of the hybrid IGC16/36.1 in 2018. Most of them exceeded the initial hybrid in habitus strength and flowering intensity. As a result of crosses made in 2019, 1039 hybrid seeds were obtained from crossing 21 androclones with the ‘Lemhi Russet’ variety (8.7 seeds/pollination), 1017 seeds (7.5 seeds/pollination) from crosses of 23 androclones with the ‘Quarta’ variety, and 716 seeds (12.3 seeds/pollination) from crosses of 11 androclones and a diploid potato line IGC 17n8 capable of producing fertile unreduced (2n) pollen. The hybrid seeds had good germination rate of 70-90%. Among the androclones that gave progeny in crosses with potato varieties, we identified genotypes carrying DNA markers of late blight (LB) resistance genes Rpi-sto1, R2 and R3b, PVY resistance genes Ryadg, Rysto and Rychc, and potato wart disease resistance gene Sen2 (these markers were found in the initial accession of S. stoloniferum PI 205522 and in the IGC 16/36.1 hybrid). Despite the complex nature of inheritance of the analyzed markers in progenies of backcrosses of androclones, a number of isolated hybrids carried several markers, including those of the Rpi-sto1, a broad-spectrum gene for high resistance to late blight. Hybrids with relatively high tuber productivity, features of cultivated potatoes such as regularly shaped tubers with small eyes, and high field resistance to late blight were selected.The prospects for using androclones of the tetraploid interspecific hybrid IGC 16/36.1 for increasing the frequency of homoeologous A/B recombination of chromosomes are discussed.

Characterisation and mapping of a Globodera pallida resistance derived from the wild potato species Solanum spegazzinii

Key messageA new resistance locus acting against the potato cyst nematode Globodera pallida was mapped to chromosome VI in the diploid wild potato species Solanum spegazzinii CPC 7195.The potato cyst nematodes (PCN) Globodera pallida and Globodera rostochiensis are economically important potato pests in almost all regions where potato is grown. One important management strategy involves deployment through introgression breeding into modern cultivars of new sources of naturally occurring resistance from wild potato species. We describe a new source of resistance to G. pallida from wild potato germplasm. The diploid species Solanum spegazzinii Bitter accession CPC 7195 shows resistance to G. pallida pathotypes Pa1 and Pa2/3. A cross and first backcross of S. spegazzinii with Solanum tuberosum Group Phureja cultivar Mayan Gold were performed, and the level of resistance to G. pallida Pa2/3 was determined in progeny clones. Bulk-segregant analysis (BSA) using generic mapping enrichment sequencing (GenSeq) and genotyping-by-sequencing were performed to identify single-nucleotide polymorphisms (SNPs) that are genetically linked to the resistance, using S. tuberosum Group Phureja clone DM1-3 516 R44 as a reference genome. These SNPs were converted into allele-specific PCR assays, and the resistance was mapped to an interval of roughly 118 kb on chromosome VI. This newly identified resistance, which we call Gpa VIlspg, can be used in future efforts to produce modern cultivars with enhanced and broad-spectrum resistances to the major pests and pathogens of potato.

In silico search for and analysis of R gene variation in primitive cultivated potato species.

Pathogen recognition receptors encoded by R genes play a key role in plant protection. Nowadays, R genes are a basis for breeding many crops, including potato. Many potato R genes have been discovered and found suitable for breeding thanks to the studies of a wide variety of wild potato species. The use of primitive cultivated potato species (PCPS) as representatives of the primary gene pool can also be promising in this respect. PCPS are the closest to the early domesticated forms of potato; therefore, their investigation could help understand the evolution of R genes. The present study was aimed at identifying and analyzing R genes in PCPS listed in the open database of NCBI and Solomics DB. In total, the study involved 27 accessions belonging to three species: Solanum phureja Juz. & Bukasov, S. stenotomum Juz. & Bukasov and S. goniocalyx Juz. & Bukasov Materials for the analysis were the sequencing data for the said three species from the PRJNA394943 and PRJCA006011 projects. An in silico search was carried out for sequences homologous to 26 R genes identified in potato species differing in phylogenetic distance from PCPS, namely nightshade (S. americanum), North- (S. bulbocastanum, S. demissum) and South-American (S. venturii, S. berthaultii) wild potato species, as well as the cultivated potato species S. tuberosum and S. andigenum. Homologs of all investigated protein-coding sequences were discovered in PCPS with a relatively high degree of similarity (85-100 %). Homologs of the Rpi-R3b, Rpi-amr3 and Rpi-ber1 genes have been identified in PCPS for the first time. An analysis of polymorphism of nucleotide and amino acid sequences has been carried out for 15 R genes. The differences in frequencies of substitutions in PCPS have been demonstrated by analysis of R genes, the reference sequences of which have been identified in different species. For all the studied NBS-LRR genes, the proportion of substituted amino acids in the LRR domain exceeds this figure for the NBS domain. The potential prospects of using PCPS as sources of resistance to Verticillium wilt have been shown.

An international breeding project using a wild potato relative Solanum commersonii resulted in two new frost-tolerant native potato cultivars for the Andes and the Altiplano.

This breeding project, initiated at the United States Potato Genebank (USPG) in collaboration with Peruvian partners Instituto Nacional de Innovacion Agraria (INIA), International Potato Center, Peru (CIP), and local farmers, sought to enhance cold hardiness and frost tolerance in native potato cultivars in Peru. The Andes and Altiplano are often affected by frost, which causes significant reduction in yield; creating varieties with superior resilience is a critical undertaking. The goal was to transfer outstanding non-acclimated cold tolerance and acclimation capacity found in wild potato species Solanum commersonii (cmm). Breeding families segregating for cold hardiness were created using (a) a somatic hybrid cmm + haploid Solanum tuberosum (tbr) (cv. Superior, US variety from Wisconsin) as male and (b) seven cultivars native to Peru of the species S. tuberosum sbsp. andigenum (adg) as females. All plant materials were part of the USPG germplasm collection. Sexual seeds of each family were sent to Peru for evaluations under the natural conditions of the Andean highlands and Altiplano. The plants were assessed for their response to frost, and genotypes showing exceptional tolerance were selected. Plants were also evaluated for good tuber traits and yield. Initial planting involving ~2,500 seedlings in five locations resulted in selecting 58 genotypes with exceptional frost tolerance, good recovery capacity after frost, and good tuber traits. Over the years, evaluations continued and were expanded to replicated field trials in the harsher conditions of the Altiplano (Puno). All trials confirmed consistency of frost tolerance over time and location, tuber quality, and yield. After 8 years, two advanced clones were considered for cultivar release because of their exceptional frost tolerance and superior field productivity that outyielded many of the established cultivars in the region. In November 2018, a new native cultivar named Wiñay, a Quechua word meaning "to grow" was released in Peru. In 2022, a second cultivar followed with the name Llapanchispaq (meaning "for all of us"). This project evidenced that a multinational and all-encompassing approach to deploy valuable genetic diversity can work and deliver effective results. This is even more significant when outcomes can promote food security and sustainability in very vulnerable regions of the world.

Screening for Resistance Resources against Bacterial Wilt in Wild Potato.

Potato is an important crop, used not only for food production but also for various industrial applications. With the introduction of the potato as a staple food strategy, the potato industry in China has grown rapidly. However, issues related to bacterial wilt, exacerbated by factors such as seed potato transportation and continuous cropping, have become increasingly severe in the primary potato cultivation regions of China, leading to significant economic losses. The extensive genetic diversity of Ralstonia solanacearum (R. solanacearum), which is the pathogen of bacterial wilt, has led to a lack of highly resistant potato genetic resources. There is a need to identify and cultivate potato varieties with enhanced resistance to reduce the adverse impact of this disease on the industry. We screened 55 accessions of nine different wild potato species against the bacterial wilt pathogen R. solanacearum PO2-1, which was isolated from native potato plants and belongs to phylotype II. Three accessions of two species (ACL24-2, PNT880-3, and PNT204-23) were identified with high resistance phenotypes to the tested strains. We found these accessions also showed high resistance to different phylotype strains. Among them, only PNT880-3 was capable of flowering and possessed viable pollen, and it was diploid. Consistent with the high resistance, decreased growth of R. solanacearum was detected in PNT880-3. All these findings in our study reveal that the wild potato PNT880-3 was a valuable resistance source to bacterial wilt with breeding potential.

Wild relatives of potato (Solanum L. sec. Petota) poorly sampled and unprotected in Colombia

AbstractWild potato relatives (Solanum L. sec. Petota) play a vital role in crop improvement, understanding crop evolution, and conserving potato diversity. However, these invaluable resources are often neglected and underutilized and are susceptible to threats such as climate change, urbanization, and agricultural expansion. Little is known about the diversity, conservation status, and distribution of wild potato species in Colombia. To address this gap, we assessed the conservation status of five wild potato relatives conserved in the ex situ Colombian Central Collection. Five species were analyzed for their spatial patterns of biodiversity, conservation status, and conservation gaps. Colombia was found to have six centers of species richness, four areas of endemism, and six biogeographical regions. Of the five native species, only one was classified as adequately conserved for ex situ conservation, while the other four were considered low priority. In contrast, for in situ conservation, three species showed high priority, one was classified as medium priority, and one as low priority. In light of these findings, we propose three conservation strategies: (1) conducting collection missions to increase accessions in the national germplasm bank, prioritizing high‐priority species; (2) identifying and protecting unprotected natural habitats and engaging stakeholders to enhance in situ conservation efforts; and (3) establishing regional community genebanks to ensure localized conservation efforts.

Identification and mapping of Rpi-blb4 in diploid wild potato species Solanum bulbocastanum

More than 170 years after causing the potato famine in Ireland, late blight is still considered one of the most devastating crop diseases. Commercial potato breeding efforts depend on natural sources of resistance to protect crops from the rapidly evolving late blight pathogen, Phytophthora infestans. We have identified and mapped a novel broad-spectrum disease resistance gene effective against P. infestans from the wild, diploid potato species Solanum bulbocastanum. Diagnostic resistance gene enrichment sequencing (dRenSeq) was used to confirm the uniqueness of the identified resistance. RenSeq and GenSeq-based mapping of the resistance, referred to as Rpi-blb4, alongside recombinant screening, positioned the locus responsible for the resistance to potato chromosome 5. The interval spans approximately 2.3 Mb and corresponds to the DM reference genome positions of 11.25 and 13.56 Mb.

Identification of novel late blight resistance source in wild potato species and interspecific somatic hybrids, and their distinctness, uniformity and stability (DUS) characterization

Forty potato genotypes, including wild Solanum species and interspecific somatic hybrids were characterized for late blight resistance and distinctness, uniformity and stability (DUS) descriptors. Thirty-two genotypes (14 wild species + 18 somatic hybrids) were found highly resistant to late blight, whereas 4 were resistant and 1 was moderately resistant compared to the control varieties viz., Kufri Jyoti (susceptible), Kufri Bahar (highly susceptible), and Kufri Girdhari (highly resistant). All wild species were high resistant to late blight. Further, morphological characterization based on 51 DUS descriptors showed phenotypic variation in the genotypes studied. Thus, we identified late blight-resistant potato wild species and somatic hybrids, which could serve as a potential source for late blight resistance breeding.

Screening of wild species and transcriptome profiling to identify differentially regulated genes in response to late blight resistance in potato.

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 (96h 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; glycine-rich 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.

Peculiarities of Transfer of DNA Markers of Wild Allotetraploid Potato Species &lt;i&gt;Solanum stoloniferum&lt;/i&gt; to Backcross Progenies Depending on Their Subgenomic Location and Used Schemes of Introgression

Genomic difference between wild allotetraploid potato species Solanum stoloniferum Schltdl et Bouchet (genome AABB) and S. tuberosum L. (AAAA) is one of the factors hampering its use in breeding. However, there is practically no information on valuable genes of this species located in the subgenome B and on the way of their transfer into the genome A of cultivated potatoes. The objectives of this research were to identify subgenomic location of a set of S. stoloniferum genes using an original approach based on a difference of inheritance of DNA markers of the genes in backcross BC1 of chromosome doubled triploid hybrids (6x, AAAABB) to 4х S. tuberosum dependent on belonging to A or B subgenome; to study their inheritance in BC2 and BC3 in the framework of four introgression schemes and marker assisted selection of the gene Rpi-sto1. The markers of late blight (LB) resistance genes Rpi-sto1, R3b, R2, potato virus Y (PVY) resistance genes Rysto, Ryadg were located on the subgenome B and the marker of PVY resistance gene Rychc – on the subgenome A. We observed an appearance of unexpected sporadic hybrids free of markers in BC1 that may be explained by rare cases of homeological recombination of A and B subgenome chromosomes. The segregation of the markers in BC2 (close to 1 : 1) matched in general to that expected in the case of random transfer of the corresponding chromosomes of the subgenome B. Some promising for breeding hybrids have been selected in BC3 having the marker of the gene Rpi-sto1.

In Vitro Assessment of Salt Stress Tolerance in Wild Potato Species

Proof of concept salt tolerance and plasticity. Wild germplasm may represent a precious source of genetic variability for salt tolerance. This study evaluated the morphological changes occurring under controlled and saline conditions in tuber-bearing S. bulbocastanum, S. commersonii, S. chomatophyllum, S. multidissectum, S. pinnactisectum, S. phureja, and cultivated S. tuberosum. An in vitro screening method was employed. Significant phenotypic variations were observed for all phenotypic traits analyzed at all NaCl levels (0, 40, 60, and 120 mM). In addition, a significant correlation between root plasticity and salt tolerance was found. Further, changes in proline and total phenolic content were assessed to envisage the metabolic adjustments of tolerant clones towards salinity. The most promising sources of tolerance were identified in S. commersonii and S. multidissectum and information obtained is discussed from a breeding perspective.

High regrowth of potato crop wild relative genotypes after cryogenic storage

Potatoes are consumed by millions of people and are the survival food in several countries. Cultivated varieties of potato (Solanum tubersosum L.) are results of selection and crossing of many wild species. Only 8–13% of wild potato species used for food are preserved by either in situ or ex situ methods. The U.S. National Potato Germplasm Collection maintains over 5900 accessions, of which 75% are crop wild relatives (CWR). The objective of the study was to investigate regrowth of cryogenically stored clonal propagules (shoot tips) of selected CWR accessions maintained in the collection. Sixty-nine accessions from 30 Solanum species and six accessions that are not yet assigned to a species were cryopreserved by a droplet vitrification method at the NLGRP. The post cryopreservation regrowth varied from 40 to 100% (average 68%) but was not significantly different between the tested accessions. Regrowth of six accessions tested after 10 years of cryogenic storage was between 35 and 90% (average 66%) and was significantly different from their initial regrowth (average 87%); the largest viability loss was in S. condolleanum; but for the other five accessions the regrowth was between 45 and 90% (average 72%) and suggested at least 10 years of successful storage in LN was possible. Twelve potato wild species cryopreserved in this study were reported in literature as important for developing cultivated varieties for changed weather conditions.

Collecting wild potato species (Solanum sect. Petota) in Peru to enhance genetic representation and fill gaps in ex situ collections.

Crop wild relatives (CWRs) are important sources of novel genes, due to their high variability of response to biotic and abiotic stresses, which can be invaluable for crop genetic improvement programs. Recent studies have shown that CWRs are threatened by several factors, including changes in land-use and climate change. A large proportion of CWRs are underrepresented in genebanks, making it necessary to take action to ensure their long-term ex situ conservation. With this aim, 18 targeted collecting trips were conducted during 2017/2018 in the center of origin of potato (Solanum tuberosum L.), targeting 17 diverse ecological regions of Peru. This was the first comprehensive wild potato collection in Peru in at least 20 years and encompassed most of the unique habitats of potato CWRs in the country. A total of 322 wild potato accessions were collected as seed, tubers, and whole plants for ex situ storage and conservation. They belonged to 36 wild potato species including one accession of S. ayacuchense that was not conserved previously in any genebank. Most accessions required regeneration in the greenhouse prior to long-term conservation as seed. The collected accessions help reduce genetic gaps in ex situ conserved germplasm and will allow further research questions on potato genetic improvement and conservation strategies to be addressed. These potato CWRs are available by request for research, training, and breeding purposes under the terms of the International Treaty for Plant Genetic Resources for Food and Agriculture (ITPGRFA) from the Instituto Nacional de Innovacion Agraria (INIA) and the International Potato Center (CIP) in Lima-Peru.

Recognition of Pep-13/25 MAMPs of Phytophthora localizes to an RLK locus in Solanum microdontum.

Pattern-triggered immunity (PTI) in plants is mediated by cell surface-localized pattern recognition receptors (PRRs) upon perception of microbe-associated molecular pattern (MAMPs). MAMPs are conserved molecules across microbe species, or even kingdoms, and PRRs can confer broad-spectrum disease resistance. Pep-13/25 are well-characterized MAMPs in Phytophthora species, which are renowned devastating oomycete pathogens of potato and other plants, and for which genetic resistance is highly wanted. Pep-13/25 are derived from a 42 kDa transglutaminase GP42, but their cognate PRR has remained unknown. Here, we genetically mapped a novel surface immune receptor that recognizes Pep-25. By using effectoromics screening, we characterized the recognition spectrum of Pep-13/25 in diverse Solanaceae species. Response to Pep-13/25 was predominantly found in potato and related wild tuber-bearing Solanum species. Bulk-segregant RNA sequencing (BSR-Seq) and genetic mapping the response to Pep-25 led to a 0.081 cM region on the top of chromosome 3 in the wild potato species Solanum microdontum subsp. gigantophyllum. Some BAC clones in this region were isolated and sequenced, and we found the Pep-25 receptor locates in a complex receptor-like kinase (RLK) locus. This study is an important step toward the identification of the Pep-13/25 receptor, which can potentially lead to broad application in potato and various other hosts of Phytophthora species.

Convergent evolution of immune receptors underpins distinct elicitin recognition in closely related Solanaceous plants.

Elicitins are a large family of secreted proteins in Phytophthora. Clade 1 elicitins were identified decades ago as potent elicitors of immune responses in Nicotiana species, but the mechanisms underlying elicitin recognition are largely unknown. Here we identified an elicitin receptor in Nicotiana benthamiana that we named REL for Responsive to ELicitins. REL is a receptor-like protein (RLP) with an extracellular leucine-rich repeat (LRR) domain that mediates Phytophthora resistance by binding elicitins. Silencing or knocking out REL in N. benthamiana abolished elicitin-triggered cell death and immune responses. Domain deletion and site-directed mutagenesis revealed that the island domain (ID) located within the LRR domain of REL is crucial for elicitin recognition. In addition, sequence polymorphism in the ID underpins the genetic diversity of REL homologs in various Nicotiana species in elicitin recognition and binding. Remarkably, REL is phylogenetically distant from the elicitin response (ELR) protein, an LRR-RLP that was previously identified in the wild potato species Solanum microdontum and REL and ELR differ in the way they bind and recognize elicitins. Our findings provide insights into the molecular basis of plant innate immunity and highlight a convergent evolution of immune receptors towards perceiving the same elicitor.