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Materials and methods

Plant material
The investigated varieties of Ae. caudata L. var. typica and var. polyathera Boiss. were collected from a natural population located between the villages Kassandrino and Scioni, Chalkidiki, Greece where the two varieties grow sympatrically. Voucher specimens of the plant material are kept at the Department of Botany, Aristotelian University of Thessaloniki, Greece.

Techniques
Cytological studies were carried out on cells from root tips. The C-banding technique used was described by Teoh and Hutchinson (1983). The C-banding patterns of Ae. caudata var. typica and var. polyathera were established from 17 and 13 seedlings, respectively. Each seedling came from an original seed collected from a different mother plant.

Band expression
The size of the C-bands varied from very small to large. The very small did not occur in all chromosomes, but only in less contracted chromosomes. The intensity of the staining varied among different preparations as well as within the same preparation. Bands, which were weak in intensely stained metaphases, were usually absent in weakly stained metaphases. For these reasons, the expression of each band was classified into three classes in the diagram shown in Fig. 3 according to the frequency of its appearance. The bands on each chromosome arm were numbered from centromere to telomere.

Measurements
The C-banding pattern of each plant was established from at least 10 complete metaphases. Complete and well- spread metaphase plates were drawn after magnification. The length of chromosomes and the width and position of each band were also calculated and are expressed in the diagrams. The total percentage of heterochromatin for each chromosome variant and karyotype was estimated. The centromere position was calculated by the arm ratio = S:L (S:short arm, L:long arm). The nomenclature followed Levan et al. (1965). The identification of homologous chromosomes was based m similarities of C-banding patterns and the position of the centromeres.


Results

Karyotype analysis of the two varieties of Ae. caudata studied indicated that the chromosome complement of both varieties was similar to that described by Karataglis (1975). Chromosome complement of each variety contains two satellited (SAT₁, SAT₂), one submetacentric (SM) and four subtelocentric (ST₁, ST₂, ST₃ and ST₄) chromosomes. (Fig.1, Fig.2, Fig.3 and Table 1).

All chromosomes of both varieties had at least one centromeric band and a variable number of intercalary bands. In addition, six out of the seven chromosomes of the haploid set had at least　one terminal band. The position and the width of these bands for each individual chromosome are given in Table 2.

The C-banding pattern of each individual chromosome of the variety typica is described below separately (Fig.1a,b , Fig.2a , Fig.3a).

SAT₁: Both arms are characterized by the presence of five bands. On the short arm, one of them is centromeric, two intercalary, one terminal and the other is located besides the secondary constriction. The long arm has one terminal and four intercalary bands.

SAT₂: This chromosome is polymorphic with two variants. On the long arm of variant A three intercalary bands are situated between the terminal and the centromeric bands. The short arm of the same variant has two large bands which very often observed as a single band, and one band besides the secondary constriction which is absent from the variant B. The variant A is the most heavily banded chromosome of the complement.

SM: This chromosome has two variants and the polymorphism concerns both the position and the width of the L ₂ band. Other two intercalary bands are also present on the long arm. The short arm has one terminal, one intercalary and one centromeric band.

ST₁: On the short arm one intercalary and one terminal band were observed. The long arm is characterized by one centromeric and five intercalary bands.

ST₂: This chromosome is the most heavily banded of all the ST chromosomes. The short arm has two interealary bands while on the long arm there were one centromeric, and six intercalary bands.

ST₃: This chromosome has two centromeric bands with the largest one on the side of the long arm. In addition, the short arm has a very small terminal band. The long arm has four intercalary bands.

ST₄: One centromeric band is observed on the short, arm. The long arm has one terminal and three intercalary bands. Two of the intetcalary bands are located very close to each other and often they fuse into a single band.

It is worth to be mentioned that in all the 17 plants studied from var. typica the chromosome pair SAT₂ was found to be homozygous, either AA (3 plants) or BB (14 plants). In contrast the chromosome pair SM in all plants was found to be heterozygous (AB).

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