The chromosomes of three species of Chloranthus, C. japonicus, C. serratus, and C. spinulosa were investigated by fluorescent banding method. The chromosome number of 2n=30 and the karyotypes observed in three species were supported previous studies. The karyotype of C. japonicus was different from that of the other two species according to the symmetry of chromosomes. To reveal mechanism of this karyotype variation a fluorescent banding using DAPI was adapted to the chromosomes of the three species. In C. japonicus having long metacentric chromosomes had ten bright DAPI-bands at the short arms of the subetelocentric chromosomes and numerous DAPI-bands were also observed at the terminal and proximal regions in the long metacentric and short chromosomes. The chromosomes of C. serratus and C. spinulosa showed a homogeneous DAPI fluorescence and were not stained differentially as a DAPI-band. An addition or generation of the AT-rich DAPI segments might cause karyotype change from asymmetric to symmetric long chromosomes in Chloranthus species. This result is discussed with taxonomical and molecular phylogenetic treatments.
Mutation can be beneficially utilized for tailoring crop plants. Chemical mutagen become one of important tools in crop improvement. Each mutagen has its important role as positive or negative effects on crops. Cytological abnormalities during meiosis has also been regarded one of the dependable parameters for estimating mutagenic sensitivity of a species. Studies undertaken in M1 and M2 generations on pink flower and white flower strains of Catharanthus roseus showed EMS elicit various chromosomal aberration in meiosis. Different types of meiotic abnormalities such as fragments, univalents, stickiness and unorientation of bivalents could be observed at metaphase I and bridges, laggards, unequal separation, unorientation of bivalents and stickiness could be seen at anaphase I. Meiotic abnormalities increased along with the increase in concentration in mutagens. The percentage of meiotic abnormalities was recorded maximum in M1 generation as compared to M2 generation. Contrary to pink, white flower strain exhibited maximum meiotic abnormalities and pollen sterility and hence, more sensitive to EMS. The highest pollen fertility was recorded in 0.2% concentration of EMS in pink flower strain of C. roseus.
Among the mangrove members grown in Okinawa Prefecture, Japan, Sonneratia alba Sm. placed in the family Sonneratiaceae has a specific character of yellowish green colored calyx, while the same species grown in Pan Yi River, Phang-naga, Thailand has the same species but have reddish colored calyx. To pinpoint whether they belong to different species, we conducted molecular phylogenetic study on the genus Sonneratia using DNA sequence information of chloroplast ribosomal protein L9 gene (rpL9) and nuclear cysteine proteinase inhibitor gene (cpi). Our results show that S. alba, S. apetala, S. griffithii, S. ovate, and S. caseolaris are distinct species, but S. lanceolata is a form of S. caseolaris. Sonneratia apetala is very closely related to S. griffithii and S. caseolaris is a diverse species showing considerable genetic differentiation. The Japanese populations or Thai populations of S. alba do not form a monophyletic lineage, suggesting that these populations belong to the same species. Natural hybridizations between S. alba and S. grifithii in Thailand were confirmed again and the hybrid is suggested to be given a name S. ×albo-griffithii. Either rpL9 or cpi or both can serve as DNA barcodes of Sonneratia.
Somatic chromosomes of seven taxa of Asian haploxylon pines, Pinus armandii var. amamiana, P. armandii var. armandii, P. parviflora, P. pumila, P. x hakkodensis, P. koraiensis and P. bungeana, and a American species of P. edulis were observed by a fluorescent banding method using chromomycin A3 (CMA) and 4’,6-diamidino-2-phenylindole (DAPI). The chromosome number of all taxa was 2n=24 and their karyotypes were composed of 22 long metacentric chromosomes and two short heterobrachial chromosomes as previous reports. CMA-bands appeared at the interstitial region and not at the proximal region of metacentric chromosomes. Interstitial CMA-bands were observed on 16-18 long metacentric chromosomes in chromosome complement of most species excepting for P. bungeana having six interstitial CMA-bands. The short chromosomes of most species have an interstitial CMA-band on their long arms and that of P. edulis had a proximal CMA-band. Clear proximal CMA- or DAPI-bands appeared in most species of subgenus Pinus were not observed in species of subgenus Strobus examined. DAPI-dots appeared at centromeric regions of all chromosomes and many thin DAPI-bands did at interstitial regions as appeared in the species of subgenus Pinus. The karyotype analysis combined with CMA- and DABI-bandings was useful for identification of each homologous chromosome and for chromosomal relationship among species in haploxylon pines.