First Report of Columbia Root-Knot Nematode (\u3ci\u3eMeloidogyne chitwoodi\u3c/i\u3e) in Potato in Turkey

Columbia root-knot nematode, Meloidogyne chitwoodi Golden et al., was identified from potatoes, Solanum tuberosum L., collected from Nigde Province, Turkey in September 2006. Seed potatoes are the most likely source for this introduction. The nematode is currently found to be infecting potatoes grown in the Netherlands, Portugal, Belgium, Germany, the United States, Mexico, South Africa, and Argentina. M. chitwoodi acquired a quarantine status in Europe (1) because of its potential to become established worldwide and its high damage probability. Some countries prohibit import of both seed and table stock potatoes originating in states known to harbor M. chitwoodi. Lesions on the potatoes had discrete brown coloration with white central spots in the outer 1 cm of the tuber flesh

First Report of Columbia Root-Knot Nematode (\u3ci\u3eMeloidogyne chitwoodi\u3c/i\u3e) in Potato in Turkey

Columbia root-knot nematode, Meloidogyne chitwoodi Golden et al., was identified from potatoes, Solanum tuberosum L., collected from Nigde Province, Turkey in September 2006. Seed potatoes are the most likely source for this introduction. The nematode is currently found to be infecting potatoes grown in the Netherlands, Portugal, Belgium, Germany, the United States, Mexico, South Africa, and Argentina. M. chitwoodi acquired a quarantine status in Europe (1) because of its potential to become established worldwide and its high damage probability. Some countries prohibit import of both seed and table stock potatoes originating in states known to harbor M. chitwoodi. Lesions on the potatoes had discrete brown coloration with white central spots in the outer 1 cm of the tuber flesh

Mapping of the gene in tomato conferring resistance to root-knot nematodes at high soil temperature

Root-knot nematodes (RKNs, Meloidogyne spp.) can cause severe yield losses in tomatoes. The Mi-1.2 gene in tomato confers resistance to the Meloidogyne species M. incognita, M. arenaria and M. javanica, which are prevalent in tomato growing areas. However, this resistance breaks down at high soil temperatures (>28°C). Therefore, it is imperative that new resistance sources are identified and incorporated into commercial breeding programmes. We identified a tomato line, MT12, that does not have Mi-1.2 but provides resistance to M. incognita at 32°C soil temperature. An F2 mapping population was generated by crossing the resistant line with a susceptible line, MT17; the segregation ratio showed that the resistance is conferred by a single dominant gene, designated RRKN1 (Resistance to Root-Knot Nematode 1). The RRKN1 gene was mapped using 111 Kompetitive Allele Specific PCR (KASP) markers and characterized. Linkage analysis showed that RRKN1 is located on chromosome 6 and flanking markers placed the locus within a 270 kb interval. These newly developed markers can help pyramiding R-genes and generating new tomato varieties resistant to RKNs at high soil temperature

Pyramiding multiple genes for resistance to PVY, TSWV and PMMoV in pepper using molecular markers

Pepper (Capsicum annuum L.) is one of the most important vegetables cultivated worldwide. Many pests and pathogens cause economic yield losses in pepper. Potato virus Y (PVY), Tomato spotted wilt virus (TSWV) and Pepper mild mottle virus (PMMoV) are considered among the most destructive viruses affecting pepper in the world. Because chemical treatments have limited success for managing PVY, TSWV and PMMoV, resistant varieties are considered to be the most effective means of controlling these viruses. In this study, resistance genes to these viruses were successfully transferred to the superior sweet Charleston pepper line 'Y-CAR' using molecular markers and biological assays. As a result, a new line which is resistant to PVY, TSWV and PMMoV was developed. The results also showed the applicability of a pyramiding strategy for breeding multiple virus resistance in pepper. © Verlag Eugen Ulmer KG, Stuttgart.Scientific and Technological Research Council of Turkey, TEYDEP foundation (3080171

Genomic-Assisted Marker Development Suitable for CsCvy-1 Selection in Cucumber Breeding

Cucumber is a widely grown vegetable crop plant and a host to many different plant pathogens. Cucumber vein yellowing virus (CVYV) causes economic losses on cucumber crops in Mediterranean countries and in some part of India such as West Bengal and in African countries such as Sudan. CVYV is an RNA potyvirus transmitted mechanically and by whitefly (Bemisia tabaci) in a semipersistent manner. Control of this virus is heavily dependent on the management of the insect vector and breeding virus-resistant lines. DNA markers have been used widely in conventional plant breeding programs via marker-assisted selection (MAS). However, very few resistance sources against CVYV in cucumber exist, and also the lack of tightly linked molecular markers to these sources restricts the rapid generation of resistant lines. In this work, we used genomics coupled with the bulked segregant analysis method and generated the MAS-friendly Kompetitive allele specific PCR (KASP) markers suitable for CsCvy-1 selection in cucumber breeding using a segregating F2 mapping population and commercial plant lines. Variant analysis was performed to generate single-nucleotide polymorphism (SNP)-based markers for mapping the population and genotyping the commercial lines. We fine-mapped the region by generating new markers down to 101 kb with eight genes. We provided SNP data for this interval, which could be useful for breeding programs and cloning the candidate genes

Identifying Molecular Markers Suitable For Frl Selection in Tomato Breeding

Modern plant breeding heavily relies on the use of molecular markers. In recent years, next generation sequencing (NGS) emerged as a powerful technology to discover DNA sequence polymorphisms and generate molecular markers very rapidly and cost effectively, accelerating the plant breeding programmes. A single dominant locus, Frl, in tomato provides resistance to the fungal pathogen Fusarium oxysporum f. sp. radicis-lycopersici (FORL), causative agent of Fusarium crown and root rot. In this study, we describe the generation of molecular markers associated with the Frl locus. An F2 mapping population between an FORL resistant and a susceptible cultivar was generated. NGS technology was then used to sequence the genomes of a susceptible and a resistant parent as well the genomes of bulked resistant and susceptible F2 lines. We zoomed into the Frl locus and mapped the locus to a 900 kb interval on chromosome 9. Polymorphic single-nucleotide polymorphisms (SNPs) within the interval were identified and markers co-segregating with the resistant phenotype were generated. Some of these markers were tested successfully with commercial tomato varieties indicating that they can be used for marker-assisted selection in large-scale breeding programmes

Development and evaluation of robust molecular markers linked to disease resistance in tomato for distinctness, uniformity and stability testing

Molecular markers linked to phenotypically important traits are of great interest especially when traits are difficult and/or costly to be observed. In tomato where a strong focus on resistance breeding has led to the introgression of several resistance genes, resistance traits have become important characteristics in distinctness, uniformity and stability (DUS) testing for Plant Breeders Rights (PBR) applications. Evaluation of disease traits in biological assays is not always straightforward because assays are often influenced by environmental factors, and difficulties in scoring exist. In this study, we describe the development and/or evaluation of molecular marker assays for the Verticillium genes Ve1 and Ve2, the tomato mosaic virusTm1 (linked marker), the tomato mosaic virus Tm2 and Tm22 genes, the Meloidogyne incognita Mi1-2 gene, the Fusarium I (linked marker) and I2 loci, which are obligatory traits in PBR testing. The marker assays were evaluated for their robustness in a ring test and then evaluated in a set of varieties. Although in general, results between biological assays and marker assays gave highly correlated results, marker assays showed an advantage over biological tests in that the results were clearer, i.e., homozygote/heterozygote presence of the resistance gene can be detected and heterogeneity in seed lots can be identified readily. Within the UPOV framework for granting of PBR, the markers have the potential to fulfil the requirements needed for implementation in DUS testing of candidate varieties and could complement or may be an alternative to the pathogenesis tests that are carried out at present

The screening of F2 plants for the root-knot nematode resistance gene, Mi by PCR in tomato

Root-knot nematodes are major pests of field and vegetable crops in Turkey and worldwide. They cause damage to many economically important horticultural crops like potato, cotton and tomato. Tomato is one of the crops in which genetic resistance has been especially effective against root-knot nematodes. In the 1940s the root-knot nematode resistance gene (MI) was introgressed into the cultivated tomato from the wild species Lycopersicon peruvianum. Today, many commercial tomato varieties carry the Mi gene, which has been mapped. This gene confers resistance to Meloidogyne incognita, M. javanica and M. arenaria. The short arm of chromosome 6 and many markers linked to Mi have also been identified. The Mi gene has been isolated, cloned and sequenced. In this study, plants were infected with M. incognita race 2 and resistant and susceptible lines were determined. According to nematode resistance assays, the root-gall index was determined as > 2 and ? 2 for susceptible and resistant plants, and reproduction factors were 0 and > 1 for resistant and susceptible plants, respectively. In conjunction with traditional screening Mi gene specific primers were used to differentiate between resistant and susceptible plants with a 1.6 kb DNA band being detected in resistant plants but absent in susceptible plants. The data showed a clear correlation between traditional screening and the use of markers and support the possibilities of using marker assisted selection for M. incognita resistance breeding. © TÜBITAK