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Development of Anther-Derived Dihaploids to Combine Disease Resistance in Maryland Tobacco

Dep. of Agronomy, Univ of Maryland, College Park, MD 20742

^* Corresponding author.

Anther culture can reduce the amount of time required to develop completely homozygous lines of tobacco (Nicotiana tabacum L.). The objectives of this study were to determine the value of anther culture in combining resistance to three diseases in dihaploid lines of Maryland tobacco and to evaluate the agronomic performance of these lines relative to the parent cultivars. ‘MD 609’, which is resistant to black shank (Phytophthora parasitica var. nicotianae), was crossed with ‘MD 341’, which is resistant to tobacco mosaic virus (TMV) and wildfire (Pseudomonas syringae pv. tabaci). Anthers from the F₁ were cultured to produce approximately 2000 haploid plantlets. The haploids were screened for resistance to TMV and wildfire, and midveins from 315 resistant plants were cultured to generate 133 dihaploids. These 133 dihaploids were then screened for black shank resistance, and 16 (12%) had levels of resistance similar to MD 609. In a 2-yr field study involving 24 dihaploids, the average dihaploid was inferior to the midparent mean for price and quality index, had longer internodes, and flowered 6% later. These results indicate that whenever possible, screening for desired traits should be conducted at the haploid level to maximize efficiency. Although reduced yields were frequently observed with the dihaploids, certain lines with desirable levels of disease resistance equaled, and occasionally exceeded, the midparent value for yield and other agronomically important traits.

Received for publication April 30, 1993.