Morphological and chemical characteristics of doubled haploids of flue-cured tobacco combining resistance to Thielaviopsis basicola and TSWV

Thielaviopsis basicola and Tomato spotted wilt virus (TSWV) are the most important problems in a moderate climate zone. Previously obtained doubled haploids (DH) of F₁ hybrids of the flue-cured line WGL3 resistant to Th. basicola and the dark-cured line PW-834 carrying RTSW-al gene provided the research material. Biological tests and SCAR markers linked with TSWV were applied to confirm resistance of DH. Lines combining resistance to TSWV and Th. basicola were evaluated for morphological and chemical characteristics. Most of DH were significantly shorter than parents but two lines, 31/A/2 and 31/B/3, were close to the flue-cured WGL3. Usually DH possessed fewer leaves while one of them 31/B/3, exceeded parental forms. The doubled haploids flowered later than their parents. The most negative effect was reduced area of mid-position leaves of DH. It might be explained by a recombination during microsporogenesis in F₁, however the influence of ‘Polalta’-derived RTSW-al gene cannot be excluded. Extensive line to line variation for nicotine and sugars content was not associated with the genes for TSWV and Th. basicola resistance. Biological tests and field performance of DH revealed potential to overcome the negative effect of coupling between the RSTV-al gene and genes responsible for the morphological deformations.