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

Fusarium Oxysporum F. Sp. Radicis-Lycopersici – the Cause of Fusarium Crown and Root Rot in Tomato Cultivation

Fusarium oxysporum f. sp. radicis-lycopersici (FORL) leading to fusarium crown and root rot is one of the most destructive soilborne diseases of tomatoes occurring in greenhouse and field crops. Physiological races of FORL were not defined but nine vegetative compatibility groups (VGCs) were identified. Infection followed by wounds and natural holes and infection is not systemic. The optimum soil temperature for pathogen development is 18°C. Infection may cause plants to wilt and die completely or infection may lower fruit quality. Fusarium oxysporum f. sp. radicis-lycopersici has the ability to produce a specific enzyme, tomatinase, which breaks down α-tomatine and protects the pathogen. In contrast tomato also has a defence system which consists of the enzymes chitinase and β-1, 3-glucanase. Tomato resistance to Fusarium oxysporum f. sp. radicis-lycopersici is determined by a single dominant gene Frl, localized on the long arm of chromosome 9. It was introduced to cultivars from Licopersicum peruvianum (L.) Mill

Effect of the fungus Trichoderma harzianum on the growth and yield of melon (Cucumis melo)

The influence of Trichoderma harzianum TRS 59 on melons ‘Melba’, was investigated in the greenhouse experiment in 2016–2019. Seeds were sown in end of April or in early May and transplanted to containers 8 dm3 (2 plants per each) in June. Fruits were harvested in August and September. In 2016–2017, T. harzianum applied each year to the substrate increased insignificantly the yield by 16% and 17% and the fruit mass by 3% and 9%, comparing with control. In 2019, yield decreased by 19% and fruit mass by 12% comparing with control. Intensive feeding of the cotton aphid (Aphis gossypii) reduced the vigor of plants in 2019. The concentration of vitamin C decreased in 2018, extract and dry mass of fruits decreased, especially in the treatment with T. harzianum

The use of DNA markers in the selection of carrot lines with cytoplasmic male sterility trait

Cytoplasmic male sterility (CMS) is a maternally inherited trait in which a plant is unable to produce functional pollen. It occurs in many plants, including carrots. The expression of this trait depends on environmental conditions, especially temperature – therefore, DNA markers become an excellent tool for selecting carrot genotypes with this feature. In this study, we used seventeen DNA markers available in the literature, linked with various mitochondrial DNA sequences that are associated with the CMS trait. Their amplification was tested on male sterile and male fertile plants. Only five markers – A321/392, I214/401/435, K751, N795, O790 – correctly identified the tested genotypes. They can be used as selection tools in carrot breeding programs

Exceptionally preserved lacustrine ostracods from the Middle Miocene of Antarctica : implications for high-latitude palaeoenvironment at 77 degrees south

A newly discovered Konservat-Lagerstätte from the Middle Miocene of the western Olympus Range, Dry Valleys, Antarctica, yields cypridoidean ostracods complete with preserved body and appendages. This is the first record of three-dimensionally fossilized animal soft tissues from the continent. The ostracods are preserved in goethite, secondary after pyrite, representing a novel mode of exceptional preservation. They signal a high-latitude (greater than 77°south) lake setting (Palaeolake Boreas) viable for benthic animal colonization prior to 14Myr ago. Their presence supports the notion of warmer, tundra-like environmental conditions persisting in the Dry Valleys until the Middle Miocene