The responses of tomato and pepper populations to salinity stress will be the main focus of the work of the second NatGenCrop PhD student, Michael Wittenberg. The first screening was done on tomato at seedling and fruiting stages and resulted in the identification of several lines with improved salt tolerance. In addition, the generated data will be used to look for genes that influence salinity tolerance in this important crop.

The work with tomato and pepper tolerance to biotic stressors is part of the PhD thesis of Gabrielle Adornato. As a result of the first experiment with tomato treated with phytopathogen Botrytis cinerea, several lines showing weaker symptoms on leaves and fruits have been identified and will be studied further.

A new poster with updated data on the selection and work with the target gene SlWRKY46 related to drought stress responses in tomato was presented with a poster at the 6th Balkan Conference on BioSciences, 30-31 October 2025, in Plovdiv by Dr. Nikolay Anachkov. [download] 

Michael Wittenberg from the University of Cape Town in South Africa became the second NatGenCrop PhD student on 28.07.2025. His dissertation will be on the topic “Genetic Basis of Salinity Tolerance in Tomato and Pepper: Implications for Crop Resilience and Sustainability”.

A poster devoted to the identification of target genes related to tomato fruit quality under water stress was presented at the international 21th EUCARPIA Meeting of the Tomato Group, 10-13 June 2025, in Plovdiv by Dr. Nikolay Anachkov. [download]

On 18.02.2025 Gabrielle Adornato from Italy became the first NatGenCrop PhD student. His dissertation topic will be “Genome-Wide Association Study (GWAS) Mapping of Horticultural Traits and Disease Resistance Loci in Pepper and Tomato”.

As a result of the greenhouse screenings of tomato and pepper populations and their responses to drought, several lines that consistently show a drought tolerant phenotype were found. In the later stages of the project, they will be characterized in greater details.

In 2024, the NatGenCrop team repeated the greenhouse characterization of the GWAS and BIL tomato populations in order to collect data on their physiological and biochemical traits under control and water-limited conditions. This was used to verify the results from 2023 and improve the robustness of the data.

Different molecular biology strategies were employed for the functional validation of genes with the highest potential to modulate stress signaling and secondary metabolism, and regulate important agronomical traits during drought.

As a result of a GWAS study on tomato fruits, lists of 10 candidate genes associated with fruit quality, shape and yield traits and 19 other candidate genes linked to primary metabolite traits under low water stress were prepared. The second list includes genes potentially associated with the amounts of important metabolites such as glucose, arginine, histidine, raffinose, glycine, and others.

• The NatGenCrop team cultivated hundreds of tomato and pepper varieties for analysis, both in greenhouses and experimental fields. One panel of genotypes, intended for genome-wide association studies (GWAS), included 180 pepper and 152 tomato lines. In addition, 2 BILs populations (backcrossed inbred lines), comprising 56 tomato lines and 110 pepper lines, were also grown and analyzed in the greenhouse.

• Detailed phenotypic analysis of the plants was carried out in terms of height, diameter, stem thickness, flowering time, weight, yield and fruit size. Other notable traits, such as presence of top rot and other diseases, were also analyzed. Leaves were sampled for metabolic and elemental analysis at the flowering and fruiting stages. Fruit samples were collected as well.

• By the middle of 2023, the core members of the NatGenCrop team, led by Dr. Saleh Alseekh, have already been selected and the work on the experiments for the first year of the project has been initiated.