Arm Ratio Index Research Articles

Karyological Characteristics of Lilium ledebourii Boiss and Lilium longiflorum Thunb.

The karyological characteristics of two Lilium species were investigated by aceto-ferric-hematoxylin staining. Chromosome characteristics, including the number and length of the chromosomes, length of their long and short arms, length of the total set of chromosomes, the arm ratio index and relative lengths of chromosome, were measured based on averages for five different metaphase cells. Both species are diploid (2n=2x=24). The karyotype of Lilium ledebourii consisted of 1 pair of metacentric, 4 pairs of submetacentric, 3 pairs of acrocentric and 4 pairs of subtelocentric chromosomes. The karyotype of Lilium longiflorum was comprised of 1 pair of metacentric, 4 pairs of acrocentric and 7 pairs of subtelocentric chromosomes. Chromosomes 5 and 7 in Lilium ledebourii and chromosomes 6 in Lilium longiflorum had a satellite. Karyotypes were classified as 3A by Stebbins classification.

English

  In this study karyotype and chromosome characteristics of the nine accessions ofAegilops crassa species obtained from gene bank of Seed and Plant Improvement Research Institute (SPII) of Iran and one accession collected by authors were inspected. Aceto-iron-hematoxilin staining method was used to stain chromosomes. For each accession, chromosome characteristics including long and short arms, chromosome lengths, arm ratio index and relative chromosome lengths were measured using micro measure 3.3 software. Results revealed that all of the studied accessions were tetraploid (2n = 4x = 28) and consisted of 13 pairs of metacentric and one pair of submetacentric chromosomes, of which two pairs were satellite chromosomes. Karyotype formula for these accessions were 13 m + 1 sm. Arm ratio index value of chromosomes ranged from 1.11 in chromosome number 6 to 1.77 in chromosome number 12. The B chromosomes were not seen in any of the accessions. Karyological characteristics of theseaccessions were similar to each other. However, some differences were observed between the accessions in some chromosome characteristics.   Key words: Aegilops Crassa, karyotype, aceto-iron-hematoxilin staining, satellite chromosome.

Karyotype and C-banding Patterns of Mitotic Chromosomes in Heteranthelium piliferum

The C-banded karyotype of Heteranthelium piliferum species was studied in a natural population from northwest of Iran using aceto-iron-hematoxilin staining and C-banding technique. Chromosome measurements including long arm, short arm and chromosome lengths, arm ratio index, relative chromosome length, heterochromatin percent per chromosome and per chromosome set were made. It was revealed that the karyotype of this species is symmetric and consists of 7 pairs of metacentric chromosomes. Arm ratio index values ranged from 1.01 in chromosome G to 1.44 in chromosome D. One of the chromosomes had a satellite located on the end of its long arm (chromosome G). The Q genome of this species like A, B, D, S, M and M, genomes in diploid species of Aegilops-Trticum group, H genome in Hordeum, E genome in Agropyron and R genome in Secale has metacentric or sub-metacentric chromosomes.

Comparative Study of Chromosome Morphology and C-banding Patterns in Several Genotypes of Lens culinaris

Karyotype and C-banding patterns of mitotic chromosomes in 10 cultivars and landraces of lentil were studied. Aceto-iron-hematoxilin staining and Giemsa C-banding techniques were used to staining choromosomes and banding patterns analysis, respectively. Chromosome characteristics including long arm, short arm and chromosome lengths, total length of chromosome set, arm ratio index, relative chromosome length, the width and position of each band, heterochromatin percent per chromosome and per chromosome set were measured using Micromeasure software. The results of this study revealed that the genome of this species consisted of four pairs of metacentric and three pairs of submetacentric chromosomes. Chromosome 4 had a secondary constriction near centromeric region of its long arm. Arm ratio index of chromosomes ranged from 1.24 in chromosome 3 to 2.38 in chromosomes 6. Each chromosome, having a distinctive banding pattern, was recognizable. Karyological characteristics and banding patterns of all materials studied were similar to each other, however, some polymorph C-bands were observed on chromosome arms.