Genomic prediction of morphometric and colorimetric traits in Solanaceous fruits

Selection of high-performance lines with respect to traits of interest is a key step in plant breeding. Genomic prediction allows to determine the genomic estimated breeding values of unseen lines for trait of interest using genetic markers, e.g. single-nucleotide polymorphisms (SNPs), and machine learning approaches, which can therefore shorten breeding cycles, referring to genomic selection (GS). Here, we applied GS approaches in two populations of Solanaceous crops, i.e. tomato and pepper, to predict morphometric and colorimetric traits. The traits were measured by using scoring-based conventional descriptors (CDs) as well as by Tomato Analyzer (TA) tool using the longitudinally and latitudinally cut fruit images. The GS performance was assessed in cross-validations of classification-based and regression-based machine learning models for CD and TA traits, respectively. The results showed the usage of TA traits and tag SNPs provide a powerful combination to predict morphology and color-related traits of Solanaceous fruits. The highest predictability of 0.89 was achieved for fruit width in pepper, with an average predictability of 0.69 over all traits. The multi-trait GS models are of slightly better predictability than single-trait models for some colorimetric traits in pepper. While model validation performs poorly on wild tomato accessions, the usage as many as one accession per wild species in the training set can increase the transferability of models to unseen populations for some traits (e.g. fruit shape for which predictability in unseen scenario increased from zero to 0.6). Overall, GS approaches can assist the selection of high-performance Solanaceous fruits in crop breeding

Pepper Diseases in Balkan Region

One of the most important problems affecting pepper production in the Balkan peninsula is the occurrence of common pathogens causing severe diseases and epidemics resulting in reduced and compromised yield. Phytophthora capsici, Botrytis cinerea, Sclerotinia sclerotiorum, Verticillium dahliae, Fusarium spp., Pseudomonas syringae pv. syringae, Xanthomonas vesicatoria, Pepper mild mottle virus (PMMV), Tobacco mosaic virus (TMV), Cucumber mosaic virus (CMV), Tomato spotted wilt virus (TSWV), Alfalfa mosaic virus (AMV), Potato virus Y (PVY) etc. are among the most devastating and widely distributed pathogens. This region is also characterized with endemic, emerging or newly introduced pathogens threatening pepper production. In the last years new pepper fungal pathogens (Phomopsis capsici and several Colletotrichum spp.) were found in Bulgaria with increasingly frequency. In 2010 a SEE-ERA. NET project started combining the research efforts of seven scientific institutions from five Balkan countries (Albania, Bulgaria, Greece, Macedonia and Serbia). The strategic objectives of the project are: i) to explore Balkan biodiversity of Capsicum spp. in order to extract biotic stress resistant germplasm; ii) to update knowledge about the most economically important and emerging pathogens on Capsicum in the Balkan region and to form pathogen collection; iii) to develop database, concerning the pepper pathogen occurrence in the mentioned regions; iv) to identify areas at differing pathogen risk in the involved Balkan countries and to define risks related to introduction of new pathogen biotypes by trading. Adequate knowledge for pathogens is essential for the management of the diseases, caused by them and for solving problems in sustainable and conventional agriculture. First joint collecting expeditions have been carried out. Pathogens have been isolated, identified and characterized mainly at species level. Collections have been created and properly preserved in related institutes for further investigations concerning the race and strain specificity of the saved pathogens and host-pathogen interaction