Ocimum basilicum is widely distributed in the tropical and subtropical regions of the world, with greatest variability in Africa and India. It is valued in many countries for its culinary, medicinal, industrial and re...Ocimum basilicum is widely distributed in the tropical and subtropical regions of the world, with greatest variability in Africa and India. It is valued in many countries for its culinary, medicinal, industrial and religious importance. Although cytogenetic entries on the plant have been made in other geographical locations of the world, in Nigeria, such entries, prior to this report, have been limited if not completely unavailable. In this analysis, axillary buds, obtained from growing plants, were used to conduct mitotic study. Results from this study showed chromosome counts of 2n = 48 and 60, thus bringing to light the existence of chromosome number variation and the possibility of polyploidy at different levels in the plant species in this agro-ecological zone. This research has, therefore, established that at least there are two cytotypes in the population of Ocimum basilicum growing in the humid forest vegetation zone of Nigeria. Analysis of the two cytotypes revealed asymmetrical karyotypes, indicative of advancement in the evolutionary trend of the plant species.展开更多
Abstract: Seven hundred and fourteen individuals of the Scilla sinensis (Louriro) Merrill complex were sampled from 21 populations at 19 localities in 10 provinces and two cities of China and investigated cytologicall...Abstract: Seven hundred and fourteen individuals of the Scilla sinensis (Louriro) Merrill complex were sampled from 21 populations at 19 localities in 10 provinces and two cities of China and investigated cytologically in order to test its cytotype composition and cytogeographical variation still further. Five cytotypes were found (i.e. AA (2n = 16), BB (2n = 18), AABB (2n = 34), AAA (2n = 24), and AABB+9 (2n = 43)). Until now, nine of the 12 cytotypes have been identified on the continent, which indicates that it is an important place for the cytotypic differentiation of the complex. The cytotype AABB+9 is a new record on the continent. AAA was recorded for the second time in this complex. The majority of populations are composed of only one cytotype (AA, BB, or AABB), whereas another four populations consist of more than two cytotypes involving AA, BB, AAA, AABB, and AABB+9. The distribution of BB covers the entire region south to Huai River, whereas AA populations are distributed in Taiwan, Fujian, Hong Kong, and Guangdong and are isolated from its major distribution. The appearance of AABB+9 is possibly evidence for the degeneration of the subglobular bulb type of AABB and the fact that AAA and AAAA exist in the interior border regions of the range of this complex probably suggests that drought is a major factor promoting plant polyploidization. In addition, the mean numbers of B chromosomes per individual, the percentage of individuals with the B chromosome in each population, and the correlation coefficients between the latter and their latitude/longitude were calculated. Generally speaking, the B chromosome number is higher in BB populations compared with AA populations and there is a prominent tendency that the B chromosome content in either AA or BB populations correlates with the latitude and longitude of the populations.展开更多
The localization of 18S ribosomal RNA genes （rDNA） by fluorescence in situ hybridization （FISH） had been performed for some species of Paeonla. However, the pattern of 18S rDNA loci among populations Is Indistinct...The localization of 18S ribosomal RNA genes （rDNA） by fluorescence in situ hybridization （FISH） had been performed for some species of Paeonla. However, the pattern of 18S rDNA loci among populations Is Indistinct. In the present study, we localized 18S rDNA loci on meiotic or mitotic chromosomes of six populations of Paeonla obovata Maxim. （Paeonlaceae）. Different numbers of rDNA loci were found with different diploid （2n=10） populations, namely eight （Lushl and Mt. JIuhua populations）, 10 （Mt. Talbal population）, and seven （Mt. Guandl population）, whereas tetraplold （2n=20） populations were all found with 16 loci. Aii rDNA loci were mapped near teiomeres of mitotic chromosomes and there was no chromosome with two loci. The present results show that molecular cytological polymorphlsm exists among P. obovata diploid populations, Indicating that structural variations occurred frequently during the evolutionary history of this species, accompanied with differentiation among populations.展开更多
文摘Ocimum basilicum is widely distributed in the tropical and subtropical regions of the world, with greatest variability in Africa and India. It is valued in many countries for its culinary, medicinal, industrial and religious importance. Although cytogenetic entries on the plant have been made in other geographical locations of the world, in Nigeria, such entries, prior to this report, have been limited if not completely unavailable. In this analysis, axillary buds, obtained from growing plants, were used to conduct mitotic study. Results from this study showed chromosome counts of 2n = 48 and 60, thus bringing to light the existence of chromosome number variation and the possibility of polyploidy at different levels in the plant species in this agro-ecological zone. This research has, therefore, established that at least there are two cytotypes in the population of Ocimum basilicum growing in the humid forest vegetation zone of Nigeria. Analysis of the two cytotypes revealed asymmetrical karyotypes, indicative of advancement in the evolutionary trend of the plant species.
文摘Abstract: Seven hundred and fourteen individuals of the Scilla sinensis (Louriro) Merrill complex were sampled from 21 populations at 19 localities in 10 provinces and two cities of China and investigated cytologically in order to test its cytotype composition and cytogeographical variation still further. Five cytotypes were found (i.e. AA (2n = 16), BB (2n = 18), AABB (2n = 34), AAA (2n = 24), and AABB+9 (2n = 43)). Until now, nine of the 12 cytotypes have been identified on the continent, which indicates that it is an important place for the cytotypic differentiation of the complex. The cytotype AABB+9 is a new record on the continent. AAA was recorded for the second time in this complex. The majority of populations are composed of only one cytotype (AA, BB, or AABB), whereas another four populations consist of more than two cytotypes involving AA, BB, AAA, AABB, and AABB+9. The distribution of BB covers the entire region south to Huai River, whereas AA populations are distributed in Taiwan, Fujian, Hong Kong, and Guangdong and are isolated from its major distribution. The appearance of AABB+9 is possibly evidence for the degeneration of the subglobular bulb type of AABB and the fact that AAA and AAAA exist in the interior border regions of the range of this complex probably suggests that drought is a major factor promoting plant polyploidization. In addition, the mean numbers of B chromosomes per individual, the percentage of individuals with the B chromosome in each population, and the correlation coefficients between the latter and their latitude/longitude were calculated. Generally speaking, the B chromosome number is higher in BB populations compared with AA populations and there is a prominent tendency that the B chromosome content in either AA or BB populations correlates with the latitude and longitude of the populations.
基金Supported by the National Natural Science Foundation of China （39928003）.
文摘The localization of 18S ribosomal RNA genes （rDNA） by fluorescence in situ hybridization （FISH） had been performed for some species of Paeonla. However, the pattern of 18S rDNA loci among populations Is Indistinct. In the present study, we localized 18S rDNA loci on meiotic or mitotic chromosomes of six populations of Paeonla obovata Maxim. （Paeonlaceae）. Different numbers of rDNA loci were found with different diploid （2n=10） populations, namely eight （Lushl and Mt. JIuhua populations）, 10 （Mt. Talbal population）, and seven （Mt. Guandl population）, whereas tetraplold （2n=20） populations were all found with 16 loci. Aii rDNA loci were mapped near teiomeres of mitotic chromosomes and there was no chromosome with two loci. The present results show that molecular cytological polymorphlsm exists among P. obovata diploid populations, Indicating that structural variations occurred frequently during the evolutionary history of this species, accompanied with differentiation among populations.
