Hybrid lethality in interspecific hybrids between Nicotiana tabacum and N. suaveolens: evidence that the Q chromosome causes hybrid lethality based on Q-chromosome-specific DNA markers.
Hybrid seedlings from the cross Nicotiana tabacum x N. suaveolens express lethality at 28 degrees C. We carried out a cross between monosomic lines of N. tabacum lacking the Q chromosome and N. suaveolens by test-tube pollination and ovule culture at 28 degrees C. To suppress hybrid lethality, hybrid seedlings obtained were transferred to 36 degrees C immediately after germination and cultured. We determined whether Q-chromosome-specific DNA markers were detected among hybrid seedlings. When hybrid seedlings cultured at 36 degrees C were transferred to 28 degrees C, hybrid seedlings in which Q-chromosome-specific DNA markers were detected expressed hybrid lethality, while hybrid seedlings in which Q-chromosome-specific DNA markers were not detected did not express hybrid lethality. From these results, we concluded that the presence of the Q chromosome of N. tabacum is related to hybrid lethality observed in crosses between N. tabacum and N. suaveolens. This is the first report that clearly demonstrates the relationship between a certain chromosome and hybrid lethality in the genus Nicotiana using chromosome-specific DNA markers. Additionally, we confirmed that the Q chromosome belongs to the S subgenome because Q-chromosome-specific DNA markers were detected only in N. sylvestris.
Tezuka
T
T
School of Agriculture, Ibaraki University, 300-0393 Ami, Ibaraki, Japan.
Marubashi
W
W
D032461:Chromosomes, Plant / Q000235:genetics*; D003433:Crosses, Genetic; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism; D005819:Genetic Markers; D006823:Hybrid Vigor / Q000235:genetics / Q000502:physiology*; D036226:Seedlings / Q000235:genetics; D014026:Nicotiana / Q000145:classification / Q000235:genetics / Q000502:physiology*
D018744:DNA, Plant; D005819:Genetic Markers