Identification of genomic factors responsible for hybrid lethality in hybrids between Nicotiana nudicaulis Watson and N. tabacum L.

概要

論文の詳細を見る
Hybrid lethality was expressed in seedlings from crosses between Nicotiana nudicaulis and N. tabacum at 28°C. To clarify the subgenome responsible for this phenotype, we crossed N. nudicaulis with the two progenitors of N. tabacum (SSTT), N. sylvestris (SS) and N. tomentosiformis (TT). Seedlings of N. nudicaulis×N. tomentosiformis did not show any lethal symptoms, and these hybrid seedlings subsequently grew to maturity. On the other hand, in the cross N. sylvestris×N. nudicaulis, all seedlings cultured at 28°C died immediately after germination, and others cultured at 34°C and 36°C were nonviable or abnormal; only one hybrid plant survived. These findings suggest that the S subgenome in N. tabacum is responsible for the lethality occurring in hybrids between N. nudicaulis and N. tabacum. Furthermore, to determine whether the Q chromosome induces this hybrid lethality, we crossed a monosomic line of N. tabacum lacking the Q chromosome with N. nudicaulis. Subsequently, we determined the presence or absence of the Q-chromosome-specific DNA marker in hybrid seedlings. Hybrid seedlings both possessing and lacking the Q chromosome showed hybrid lethality when seedlings cultured at 34°C were transferred to 28°C. From these results, we concluded that the Q chromosome is not responsible for the hybrid lethality observed in crosses of N. nudicaulis×N. tabacum.