Genetic behavior of somatic hybrids in the genus Nicotiana: N. otophora + N. tabacum and N. sylvestris + N. tabacum.

Somatic hybrids have been produced between N. tabacum and two closely related species in the genus Nicotiana, N. otophora and N. sylvestris, to evaluate interclonal variation and genetic behavior of these hybrids. As with the previously reported N. nesophila+ N. tabacum somatic hybrids, we have detected variation for morphological and isoenzyme characters between somatic hybrid clones, despite stability of chromosome number. One clone of N. sylvestris+N. tabacum was marked by variation in leaf spot frequency. The inheritance of this unstable trait was monitored through two sexual generations. Transmission of the Su gene marker was monitored in self-fertilized and back-crossed progeny of the N. sylvestris+N. tabacum somatic hybrids. Segregation ratios were similar to those previously reported for amphiploid N. sylvestris x N. tabacum sexual hybrids.