Costa, Rita Maria LourençoDonato, Maria Helena Machado TrindadeAmaral, Andreia Vanessa Campos Pusich2021-06-222021-06-222020Amaral, A.V.C.P. - Micropropagation, phenotyping and genotyping of chestnut progenies obtained from controlled crosses. Lisboa: ISA, 2020, 81 p.http://hdl.handle.net/10400.5/21510Mestrado em Biologia dos Recursos Vegetais / Instituto Superior de Agronomia / Faculdade de Ciências. Universidade de LisboaPhytophthora cinnamomi is an oomycete that infects the roots and can cause the death of trees belonging to the Fagaceae family, such as genus Castanea. Ink disease is currently considered the major threat to chestnut trees in Europe, causing a high decrease in nut production, which is the highest income of mountain regions of Trás-os-Montes. Thus, genetic improvement for resistance aiming to developing new chestnut varieties less susceptible to this pathogen is very important for the national economy. The European species, Castanea sativa Mill., is susceptible to Phytophthora cinnamomi, while Asian species are resistant due to coevolution with the pathogen. INIAV initiated in 2006 a breeding program based on controlled crosses, using Asian species, namely Castanea crenata Sieb. & Zucc. (Japanese) and Castanea mollissima Blume (Chinese) as donors of resistance, and the sensitive European species as female progenitor with the objective of obtaining segregating progenies for the resistance character. During this thesis, phenotyping and genotyping of progenies of crosses performed in 2016 was carried out in order to select the most resistant individuals and try to associate resistance with fragment analysis patterns. This phenotyping-genotyping analysis was performed with 16 microsatellites in 47 genotypes and the result was 4 alleles that may be related to resistance. Was also performed the micropropagation of the genotypes SM904, SC55, SC1202 and SC914, already selected with improved resistance during the project on course, where this thesis fits. Calculations for multiplication rate and rooting percentage were made, important for the characterization of the genotypes. Genotype SM904 showed the highest result for both analysis. My work also contributes to one of the objectives of the current research program, which is to obtain new genotypes with improved resistance to Phytophthora cinnamomi to be used as rootstocks compatible for grafting with the national chestnut varieties of nut productionenginfectionpathogenic agentselectionmicropropagationmicrosatellitesmaster thesis203085337