Inheritance of Tobacco Etch Virus Resistance Found in Nicotiana tabacum Cultivar Havana 307

Abstract

The inheritance of resistance to tobacco etch virus (TEV) found in Nicotiana tabacum cv. Havana 307 (HA 307) was investigated by analysis of disease severity data from sexually derived generations of HA 307 crossed with TEV-susceptible burley tobacco cvs. Kentucky 14 and Jaraiz 1. Parental, F1, F2, and both backcross generations (BC1, BC2) were grown for each cross in randomized complete block designs with three replicates. Evaluations for virus reaction were performed under greenhouse and field conditions. Generation means analysis indicated that additivity (lack of dominance) was the predominant genetic effect with no evidence of epistasis. A simple Mendelian gene model did not fit the data, but control of TEV resistance is postulated to be due to a few genes with additive effects based on the high frequency of resistant genotypes observed in F2 generations. Selection for TEV resistance at the haploid level was effective compared with selection among doubled haploid lines. Therefore, utilization of haploids in a breeding program for TEV resistance should allow development of completely homozygous resistant lines in a short time.