摘要
Four kinds of mitochondrial plasmid-like DNAs, designated pC1, pC2, pC3 and pC4, were detected in Cucumis sativus Jinyan No. 4. The electron microscopy observation showed that pC4 was linear conformation. Complete sequence of pC4 was cloned into pUC19 with E. coli JM109 as host. Sequence analysis revealed that pC4 was 370 bp long, the shortest one among all the reported mitochondrial plasmid-like DNAs. pC4 was AT rich. It contained terminal direct repeat sequence (35 bp in length)as well as many short direct and inverted repeats. ORFs in pC4 were short. pC4 was found to be homologous to nuclear DNAs, but lack homology with main mitochondrial and chloroplast DNAs. pC4-homologous sequence also occurred in nuclear genome of Jinyan No. 7 which contained no mitochondrial plasmid-like DNAs. The hybridization pattern of Jinyan No. 7 was slightly different from that of Jinyan No. 4. This suggested that pC4 occurred at the forepart of Cucumis sativus species divergence and integrated into the nuclear genome,
Four kinds of mitochondrial plasmid-like DNAs, designated pC1, pC2, pC3 and pC4, were detected inCucumis sativus Jinyan No. 4. The electron microscopy observation showed that pC4 was linear conformation. Complete sequence of pC4 was cloned into pUC19 withE coli JM109 as host. Sequence analysis revealed that pC4 was 370 bp long, the shortest one among all the reported mitochondrial plasmid-like DNAs. pC4 was AT rich. It contained terminal direct repeat sequence (35 bp in length) as well as many short direct and inverted repeats. ORFs in pC4 were short. pC4 was found to be homologous to nuclear DNAs, but lack homology with main mitochondrial and chloroplast DNAs. pC4-homologous sequence also occurred in nuclear genome of Jinyan No. 7 which contained no mitochondrial plasmid-like DNAs. The hybridization pattern of Jinyan No. 7 was slightly different from that of Jinyan No. 4. This suggested that pC4 occurred at the forepart ofCucumis sativus species divergence and integrated into the nuclear genome, and the pC4-homologous sequence in nucleus varied during species diverging.
基金
This work was supported by the National Natural Science Foundation of China (Grant No. 39770414).
