Genetics and mapping of a new anthracnose resistance locus in Andean common bean Paloma

Background: The Andean cultivar Paloma is resistant to Mesoamerican and Andean races of Colletotrichum lindemuthianum, the fungal pathogen that causes the destructive anthracnose disease in common bean. Remarkably, Paloma is resistant to Mesoamerican races 2047 and 3481, which are among the most virulent races of the anthracnose pathogen. Most genes conferring anthracnose resistance in common bean are overcome by these races. The genetic mapping and the relationship between the resistant Co-Pa gene of Paloma and previously characterized anthracnose resistance genes can be a great contribution for breeding programs. Results: The inheritance of resistance studies for Paloma was performed in F2 population from the cross Paloma (resistant) × Cornell 49–242 (susceptible) inoculated with race 2047, and in F2 and F2:3 generations from the cross Paloma (resistant) × PI 207262 (susceptible) inoculated with race 3481. The results of these studies demonstrated that a single dominant gene confers the resistance in Paloma. Allelism tests performed with multiple races of C. lindemuthianum showed that the resistance gene in Paloma, provisionally named Co-Pa, is independent from the anthracnose resistance genes Co-1, Co-2, Co-3, Co-4, Co-5, Co-6, Co-12, Co-13, Co-14, Co-15 and Co-16. Bulk segregant analysis using the SNP chip BARCBean6K_3 positioned the approximate location of Co-Pa in the lower arm of chromosome Pv01. Further mapping analysis located the Co-Pa gene at a 390 kb region of Pv01 flanked by SNP markers SS82 and SS83 at a distance of 1.3 and 2.1 cM, respectively. Conclusions: The results presented here showed that Paloma cultivar has a new dominant gene conferring resistance to anthracnose, which is independent from those genes previously described. The linkage between the Co-Pa gene and the SS82 and SS83 SNP markers will be extremely important for marker-assisted introgression of the gene into elite cultivars in order to enhance resistance.EEA SaltaFil: Castro, Sandra Aparecida de Lima. Universidade Estadual de Maringá. Departamento de Agronomia; BrasilFil: Gonçalves-Vidigal, Maria Celeste. Universidade Estadual de Maringá. Departamento de Agronomia; BrasilFil: Gilio, Thiago Alexandre Santana. Universidade Estadual de Maringá. Departamento de Agronomia; BrasilFil: Lacanallo, Giselly Figueiredo. Universidade Estadual de Maringá. Departamento de Agronomia; BrasilFil: Valentini, Giseli. Universidade Estadual de Maringá. Departamento de Agronomia; BrasilFil: Martins, Vanusa da Silva Ramos. Universidade Estadual de Maringá. Departamento de Agronomia; BrasilFil: Qijian, Song. United States Department of Agriculture. Agricultural Research Service. Soybean Genomics and Improvement Laboratory; Estados UnidosFil: Galvan, Marta Zulema. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; ArgentinaFil: Hurtado-Gonzales, Oscar P. United States Department of Agriculture. Agricultural Research Service. Soybean Genomics and Improvement Laboratory; Estados UnidosFil: Pastor-Corrales, Marcial Antonio. United States Department of Agriculture. Agricultural Research Service. Soybean Genomics and Improvement Laboratory; Estados Unido

RESISTANT REACTION OF ANDEAN COMMON BEAN LANDRACE G19833, REFERENCE GENOME, TO 13 RACES OF \u3ci\u3eUROMYCES APPENDICULATUS\u3c/i\u3e SUGGESTS BROAD SPECTRUM RUST RESISTANCE

INTRODUCTION- The Andean common bean landrace G19833 (Chaucha Chuga) was recently used to obtain the first reference genome of Phaseolus vulgaris (Schmutz et al, 2014). A large quantity of sequence information is available for this landrace which includes BAC libraries, cDNA libraries, SNP databases, gene expression profiles from various tissues (RNAseq), etc. Additionally, G19833 has been used to generate RIL populations for mapping traits such as phosphorous acquisition, agronomic performance, and disease resistance. G19833 has also been reported as resistant to the anthracnose, angular leaf spot, and Ascochyta blight pathogens and susceptible to the bean golden mosaic and bean common mosaic, viruses (Reviewed by Broughton et al, 2003). However, little is known about the reaction of G19833 to the bean rust pathogen. We report here the reaction of G19833 to a set of 13 races of the rust pathogen, 10 Mesoamerican and three Andean. Together, these races overcome all known rust resistance genes in common bean. Rust resistance in the under-utilized Andean beans lags behind that of Mesoamerican beans. The objective of this study was to determine the spectrum of resistance of Andean G19833 to 13 different virulent races of the bean rust pathogen. MATERIALS AND METHODS - All disease evaluations were conducted under greenhouse conditions using published methodologies (Stavely, 1983). Landrace G19833 was inoculated with races 15-1 (41), 6-10 (44), 15-3 (47), 22-6 (49), 31-1 (53), 31-7 (58), 31-22 (67), 21-0 (72), 73 (6-15), 84 (37-1), 85 (6-31), 102 (29-0), and 108 (22-52). Rust resistance controls included Pinto 114, Aurora (Ur-3), Mexico 235 (Ur-3+), Early Gallatin (Ur-4), Mexico 309 (Ur-5), Golden Gate Wax (Ur-6), Great Northern 1140 (Ur-7), Pompadour Checa 50 (Ur-9/Ur-12), PI181996 (Ur-11), Redlands Pioneer (Ur-13), Ouro Negro (Ur-14), PI260418 (Ur-Unnamed), and PI310762 (Ur-Unnamed), and Compuesto Negro de Chimaltenango, CNC (Ur-Unnamed). Rust phenotypic evaluations were conducted twelve days after inoculations

FINE MAPPING THE BROAD SPECTRUM ANTHRACNOSE RESISTANCE GENE IN AMENDOIM CAVALO

INTRODUCTION: The Andean common bean landrace Amendoim Cavalo (AC) is resistant to races 2, 7, 9, 19, 23, 39, 55, 65, 73, 89, 1545, 2047 and 3481 of Colletotrichum lindemuthianum (Nanami et al, 2014). None of the common bean anthracnose resistance genes known to date, were resistant to all 13 races mentioned above, to which AC was resistant. The resistance in AC is conferred by a single and dominant gene (Co-AC) that is independent of the other known genes (Nanami et al., 2014 and Gilio et al, 2016). The AC locus has been located in the lower arm of chromosome Pv01 of common bean (Gilio et al., 2016). The objective of this study was to use fine mapping to locate the position Co-AC locus in the common bean genome

Thermotherapy Followed by Shoot Tip Cryotherapy Eradicates Latent Viruses and Apple Hammerhead Viroid from In Vitro Apple Rootstocks

Virus and viroid-free apple rootstocks are necessary for large-scale nursery propagation of apple (Malus domestica) trees. Apple stem grooving virus (ASGV) and Apple chlorotic leaf spot virus (ACLSV) are among the most serious apple viruses that are prevalent in most apple growing regions. In addition to these viruses, a new infectious agent named Apple hammerhead viroid (AHVd) has been identified. We investigated whether thermotherapy or cryotherapy alone or a combination of both could effectively eradicate ACLSV, ASGV, and AHVd from in vitro cultures of four apple rootstocks developed in the Cornell-Geneva apple rootstock breeding program (CG 2034, CG 4213, CG 5257, and CG 6006). For thermotherapy treatments, in vitro plants were treated for four weeks at 36 °C (day) and 32 °C (night). Plant vitrification solution 2 (PVS2) and cryotherapy treatments included a shoot tip preculture in 2 M glycerol + 0.8 M sucrose for one day followed by exposure to PVS2 for 60 or 75 min at 22 °C, either without or with liquid nitrogen (LN, cryotherapy) exposure. Combinations of thermotherapy and PVS2/cryotherapy treatments were also performed. Following treatments, shoot tips were warmed, recovered on growth medium, transferred to the greenhouse, grown, placed in dormancy inducing conditions, and then grown again prior to sampling leaves for the presence of viruses and viroids. Overall, thermotherapy combined with cryotherapy treatment resulted in the highest percentage of virus- and viroid-free plants, suggesting great potential for producing virus- and viroid-free planting materials for the apple industry. Furthermore, it could also be a valuable tool to support the global exchange of apple germplasm

Fine Mapping of Ur-3, a Historically Important Rust Resistance Locus in Common Bean

Bean rust, caused by Uromyces appendiculatus, is a devastating disease of common bean (Phaseolus vulgaris) in the Americas and Africa. The historically important Ur-3 gene confers resistance to many races of the highly variable bean rust pathogen that overcome other rust resistance genes. Existing molecular markers tagging Ur-3 for use in marker-assisted selection produce false results. Here, we describe the fine mapping of the Ur-3 locus for the development of highly accurate markers linked to Ur-3. An F2 population from the cross Pinto 114 (susceptible) × Aurora (resistant with Ur-3) was evaluated for its reaction to four different races of U. appendiculatus. A bulked segregant analysis using the SNP chip BARCBEAN6K_3 placed the approximate location of Ur-3 in the lower arm of chromosome Pv11. Specific SSR and SNP markers and haplotype analysis of 18 sequenced bean varieties positioned Ur-3 in a 46.5 kb genomic region from 46.96 to 47.01 Mb on Pv11. We discovered in this region the SS68 KASP marker that was tightly linked to Ur-3. Validation of SS68 on a panel of 130 diverse common bean cultivars containing all known rust resistance genes revealed that SS68 was highly accurate and produced no false results. The SS68 marker will be of great value in pyramiding Ur-3 with other rust resistance genes. It will also significantly reduce time and labor associated with the current phenotypic detection of Ur-3. This is the first utilization of fine mapping to discover markers linked to rust resistance in common bean

HTS-Based Diagnostics of Sugarcane Viruses: Seasonal Variation and Its Implications for Accurate Detection

Rapid global germplasm trade has increased concern about the spread of plant pathogens and pests across borders that could become established, affecting agriculture and environment systems. Viral pathogens are of particular concern due to their difficulty to control once established. A comprehensive diagnostic platform that accurately detects both known and unknown virus species, as well as unreported variants, is playing a pivotal role across plant germplasm quarantine programs. Here we propose the addition of high-throughput sequencing (HTS) from total RNA to the routine quarantine diagnostic workflow of sugarcane viruses. We evaluated the impact of sequencing depth needed for the HTS-based identification of seven regulated sugarcane RNA/DNA viruses across two different growing seasons (spring and fall). Our HTS analysis revealed that viral normalized read counts (RPKM) was up to 23-times higher in spring than in the fall season for six out of the seven viruses. Random read subsampling analyses suggested that the minimum number of reads required for reliable detection of RNA viruses was 0.5 million, with a viral genome coverage of at least 92%. Using an HTS-based total RNA metagenomics approach, we identified all targeted viruses independent of the time of the year, highlighting that higher sequencing depth is needed for the identification of DNA viruses

Fine mapping of an anthracnose-resistance locus in Andean common bean cultivar Amendoim Cavalo.

Anthracnose, caused by the fungal pathogen Colletotrichum lindemuthianum, is one of the world's most destructive diseases of common bean. The use of resistant cultivars is the most cost-effective strategy to manage this disease; however, durable resistance is difficult to achieve due to the vast virulence diversity of the anthracnose pathogen. Finding new genes with broad-spectrum resistance increases the prospect of designing an effective anthracnose-management strategy. Genetic analysis confirmed the presence of a single, dominant anthracnose-resistance locus in AC, which we provisionally named Co-AC. Bulk segregant analysis and genetic mapping of two F2 populations from the crosses AC × PI207262 and AC × G 2333 were used to determine the position of the Co-AC locus in a 631 Kbp genomic region flanked by the SNP markers SS56 and SS92 on the lower arm of chromosome Pv01. By genotyping 77 F3 plants from the AC × PI207262 cross using nine additional markers, we fine-mapped the Co-AC locus to a significantly smaller genomic region (9.4 Kbp) flanked by the SNP markers SS102 and SS165. This 9.4 Kbp region harbors three predicted genes based on the common bean reference genome, notably including the gene model Phvul.001G244300, which encodes Clathrin heavy chain 1, a protein that supports specific stomatal regulation functions and might play a role in plant defense signaling. Because the Co-AC resistance locus is linked in cis, it can be selected with great efficiency using molecular markers. These results will be very useful for breeding programs aimed at developing bean cultivars with anthracnose resistance using marker-assisted selection. This study revealed the broad-spectrum resistance of AC to C. lindemuthianum and the existence of the Co-AC anthracnose-resistance locus. Fine mapping positioned this locus in a small genomic region on the lower end of chromosome Pv01 that contained three candidate genes for the Co-AC locus

Looking beyond Virus Detection in RNA Sequencing Data: Lessons Learned from a Community-Based Effort to Detect Cellular Plant Pathogens and Pests.

peer reviewedHigh-throughput sequencing (HTS), more specifically RNA sequencing of plant tissues, has become an indispensable tool for plant virologists to detect and identify plant viruses. During the data analysis step, plant virologists typically compare the obtained sequences to reference virus databases. In this way, they are neglecting sequences without homologies to viruses, which usually represent the majority of sequencing reads. We hypothesized that traces of other pathogens might be detected in this unused sequence data. In the present study, our goal was to investigate whether total RNA-seq data, as generated for plant virus detection, is also suitable for the detection of other plant pathogens and pests. As proof of concept, we first analyzed RNA-seq datasets of plant materials with confirmed infections by cellular pathogens in order to check whether these non-viral pathogens could be easily detected in the data. Next, we set up a community effort to re-analyze existing Illumina RNA-seq datasets used for virus detection to check for the potential presence of non-viral pathogens or pests. In total, 101 datasets from 15 participants derived from 51 different plant species were re-analyzed, of which 37 were selected for subsequent in-depth analyses. In 29 of the 37 selected samples (78%), we found convincing traces of non-viral plant pathogens or pests. The organisms most frequently detected in this way were fungi (15/37 datasets), followed by insects (13/37) and mites (9/37). The presence of some of the detected pathogens was confirmed by independent (q)PCRs analyses. After communicating the results, 6 out of the 15 participants indicated that they were unaware of the possible presence of these pathogens in their sample(s). All participants indicated that they would broaden the scope of their bioinformatic analyses in future studies and thus check for the presence of non-viral pathogens. In conclusion, we show that it is possible to detect non-viral pathogens or pests from total RNA-seq datasets, in this case primarily fungi, insects, and mites. With this study, we hope to raise awareness among plant virologists that their data might be useful for fellow plant pathologists in other disciplines (mycology, entomology, bacteriology) as well.Plant Health Bioinformatics Networ

Correction: Haegeman et al. Looking beyond Virus Detection in RNA Sequencing Data: Lessons Learned from a Community-Based Effort to Detect Cellular Plant Pathogens and Pests. <i>Plants</i> 2023, <i>12</i>, 2139

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