title: Effectiveness of combining resistance to Thielaviopsis basicola and Tomato spotted wilt virus in haploid tobacco genotypes.
abstract: Black root rot (BRR) caused by Thielaviopsis basicola as well as Tomato spotted wilt virus (TSWV) are the most serious problems in tobacco growing regions. We crossed the breeding line WGL 3 carrying BRR resistance derived from N.glauca with the line PW-834 the resistance of which to TSWV was transferred from cultivar Polalta. Anthers obtained from F(1) hybrid plants were cultured to induce haploids combining resistance to Th. basicola and TSWV. Flow cytometry analysis revealed 242 haploids and 2 spontaneous doubled haploids among regenerants. All haploids were cloned and then evaluated for BRR as well as TSWV resistance. The presence of pathogens was detected by microscopic evaluation of roots or using DAS-ELISA test. Microscopic assessment showed that, 132 haploids had no symptoms of Th. basicola which, together with the absence of symptoms in the F(1) hybrids, indicated a dominant monogenic mode of inheritance. At the same time only 30 haploids demonstrated resistance to TSWV. SCAR markers associated with TSWV resistance gene detection was applied. The results indicate that small proportion of TSWV-resistant haploids is probably due to the influence of deleterious genes flanking the resistance factor that reduced vitality of gametophytes. Altogether, 24 haploids showed multiple resistance to Th. basicola and TSWV.
authors.affiliation: Department of Plant Breeding and Biotechnology, Institute of Soil Science and Plant Cultivation, State Research Institute , ul. Czartoryskich 8, PL-24-100 Pulawy, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Trojak-Goluch
authors.forename: Dorota
authors.initials: D
authors.lastname: Laskowska
authors.forename: Monika
authors.initials: M
authors.lastname: Agacka
authors.forename: Diana
authors.initials: D
authors.lastname: Czarnecka
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kawka
authors.forename: Anna
authors.initials: A
authors.lastname: Czubacka
keywords: Nicotiana tabacum; SCAR markers; Tomato spotted wilt virus; black root rot; multiple resistance