Somatic Hybrids Between Nicotiana repanda and N. tabacum Show Resistance to Tobacco Mosaic Virus and Meloidogyne arenaria

Abstract

Crop improvement in cultivated tobacco (Nicotiana tabacum L.) has a long history of utilization of wild germplasm as a source of disease resistance genes. Genes for resistance have been obtained from several wild Nicotiana species and N. tabacum accessions. These include tobacco mosaic virus (TMV) and powdery mildew resistance from N. glutinosa, wildfire and black shank resistance from N. longiflora, black shank resistance from N. plumbaginifolia, black root rot and blue mold resistance from N. debneyi, blue mold resistance from N. goodspeedii and N. velutina, root knot nematode resistance from N. tomentosa and N. megalosiphon, fusarium wilt and bacterial wilt resistance from the N. tabacum accession 448A, and black root rot, black shank, powdery mildew, and root knot nematode resistance from other N. tabacum accessions (Burk and Heggestad 1966; Lucas 1975; Stavely 1979). One wild species which has not been used successfully as a source of disease-resistance genes is N. repanda (Fig. 1). N. repanda has been reported to be resistant to more tobacco diseases and pathogens than any other Nicotiana species (Table 1). To date, no cultivars are available carrying disease-resistance genes derived from this species. Two species of root knot nematodes, Meloidogyne arenaria and M. javanica, are an increasingly prevalent problem on tobacco in the southeastern United States, and N. repanda has a high level of resistance to both of them. Current cultivars lack resistance to these nematode species, and the development of cultivars containing resistance genes from N. repanda would be highly desirable.