Karyotype analysis and new chromosome number reports in Achillea species

Abstract

Cytological analyses were performed in nineteen accessions belonging to seven Achillea species. The results indicate that two species, A. filipendulina and A. tenuifolia, are diploid (2n = 2x = 18) and three species, A. bieberstinii, A. pachycephala, and A. aucheri are tetraploid (2n = 4x = 36). For two latter species, the chromosome numbers are new. Two ploidy levels of 2n = 6x = 54 and 2n = 8x = 72 in A. millefolium and two ploidy levels of 2n = 2x = 18 and 2n = 4x = 36 in A. santolina species were found. Cluster analysis based on chromosomal characteristics and karyotype asymmetry indices clustered the studied genotypes into three major groups. The first group included the diploid species (A. filipendulina, A. santolina and A. tenufolia), while the second group comprised tetraploid species (A. santolina, A. aucheri and A. pachycephala). A. millefolium (hexaploid, octaploid) and A. bieberstinii (tetraploid) were classified in the third group. Total form percentage (TF%) in groups 1, 2 and 3 were 42.03, 42.15 and 41.08, respectively. Group 1 possessed the highest average of symmetry index (S% = 70.8). Stebbins classification method grouped all accessions in class A. Moreover, group 1 (diploid level species), had the most symmetric karyotype from point of view of centromere and chromosome length. Therefore, it can be concluded that the genotypes belonging to group 1 are the earliest evolutionary form.

Cytological investigations and new chromosome number reports in yarrow (Achillea millefolium Linnaeus, 1753) accessions from Iran

“…Am1 and Am2 accessions were diploids (2n= 2x= 18) whereas the two other accessions (Am3 and Am4) showed tetraploid (2n= 4x= 36) level ( Figure 1 ). According to previous studies, Farsi et al (2009) and Khaniki (1995) , reported 2 n = 4 x = 36 chromosomes, while Sheidai et al (2009) and Ebrahim et al (2012) reported hexaploid and octoploid cytotypes. In our findings, we have observed a new ploidy level (2n= 2x= 18) for two Iranian accessions of Achillea millefolium (Am3, Am4) that were collected in northern parts of Iran.…”

“…Cluster analysis was done based on karyotypic characteristics (TCL, MCL, MAR and DRL) and karyotype asymmetry (TF% and S%) ( Figure 2 ) and agrees with Ebrahim et al (2012) . The results of cluster analyses divided the four accessions in two groups ( Figure 2 ); based on ploidy levels.…”

“…Three cytological studies have been reported in Iran and showed the following ploidy levels: tetraploid 2n= 4x= 36, hexaploid 2n= 6x= 54 and octoploid 2n= 8x= 72 (Farsi et al 2000, Ebrahim et al 2012, Sheidai et al 2009). The aims of this study were (1) to determine the chromosome numbers of four Achillea millefolium accessions and (2) to find any relationship between the karyotype characteristics and asymmetrical index with ploidy levels.…”

“… Achillea millefolium has a high genetic and phenotypic variation in Iran ( Farajpour et al 2012 , Ebrahimi et al 2012 ). The basic chromosome number is often reported in different species of Achillea is x= 9; however, the diversity in chromosome numbers and ploidy levels are frequently occurring in the genus ( Ebrahim et al 2012 ). Polyploid taxa have originated in many clades including 4 x , 6 x and 8 x species, and as a result, several Achillea species show high morphological variability ( Sheidai et al 2009 ).…”

“… Achillea millefolium has been cytologically analyzed extensively in different regions of the world ( Felfoldy 1947 , Mizianty and Frey 1973 , Pireh and Tyrl 1980 , Lavrenko et al 1991 , Guo et al 2012 , Bala and Gupta 2013 ). Three cytological studies have been reported in Iran and showed the following ploidy levels: tetraploid 2n= 4x= 36, hexaploid 2n= 6x= 54 and octoploid 2n= 8x= 72 ( Farsi et al 2000 , Ebrahim et al 2012 , Sheidai et al 2009 ). The aims of this study were (1) to determine the chromosome numbers of four Achillea millefolium accessions and (2) to find any relationship between the karyotype characteristics and asymmetrical index with ploidy levels.…”