Abstract: [Objective] There are many bamboo species with different chromosome numbers. The study was aimed to analyze the karyotype characteristics and genome sizes of different bamboo species, to estimate their evolutionary order according to the karyotype information, and to reveal the relationship between the genome size and chromosome numbers. [Method] Traditional squash technique and flow cytometry were used to study the karyotype and genome size of the four bamboo species, i.e. the monopodial bamboo species of Phyllostachys praecox cv. Prevernalis and P. vivax f. aureocaulis, mixed monopodial and sympodial bamboo species Sasa pygmea, and sympodial bamboo species Bambusa gibboides. [Result] The karyotype parameters of these four bamboos were as follows: The karyotype formula of P. praecox cv. Prevernalis was 2n=48=40m+6sm+2st,and the range of relative chromosome length was from 2.464% to 6.269%, the proportion of chromosomes whose arm ratio larger than 2 was 12.5%, the ratio of chromosome length (Longest/Shortest) and the karyotype asymmetry index were 2.554 and 60.107, respectively. The karyotype was 2B type. As for P. vivax f. aureocaulis, its karyotype formula was 2n=48=24m+16sm+8st,the range of relative chromosome length was from 2.185% to 9.091%, the proportion of chromosomes whose arm ratio larger than 2 was 29.17%, the ratio of chromosome length(Longest/Shortest) and asymmetry index were 4.161 and 64.49, respectively. Its karyotype belonged to 2C type. The karyotype formula of S. pygmea was 2n=48=28m+18sm+2st, the range of relative chromosome length was from 2.080% to 7.881%, the proportion of chromosomes whose arm ratio larger than 2 was 20.83%, the ratio of chromosome length(Longest/Shortest) and asymmetry index were 3.789 and 61.505, respectively. Its karyotype belonged to 2B type. However, the karyotype formula of B. gibboides was different from the above three bamboo species, its karyotype formula was 2n=69=40m+25sm+4st, and the range of relative chromosome length was from 1.790% to 4.382%, the proportion of chromosomes whose arm ratio larger than 2 was 28.57%, the ratio of chromosome length(Longest/Shortest) and asymmetry index were 2.448 and 64.076, respectively. Its karyotype belonged to 2B type. The genome sizes of P. praecox cv. Prevernalis, P. vivax f. aureocaulis, S. pygmea, and B. gibboides were (3.71±0.10) pg, (3.93±0.85) pg, (4.67±0.52) pg and (2.92±0.38) pg, respectively. [Conclusion] The evolutionary order of these four bamboo species was probably P. praecox cv. Prevernalis, S. pygmea, B. gibboides, and P. vivax f. aureocaulis. The genome size of S. pygmea was the largest among these four different bamboo species. However, the genome size of B. gibboides was the smallest although its chromosome number was the largest among these bamboos. The genome size did not positively correlate with the chromosome number of these bamboos.

Key words: bamboo, chromosome, karyotype, genome size, evolutionary order