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Chromosomal Polymorphism as Detected by C-Banding Patterns in Chilean Alfalfa Germplasm

Bauchan, Gary R., Campbell, T. Austin, Hossain, M. Azhar
Crop science 2002 v.42 no.4 pp. 1291
Medicago sativa, genetic polymorphism, cytogenetic analysis, detection, germplasm, tetraploidy, satellite DNA, Chile
A cytogenetic investigation was conducted on the tetraploid alfalfa [ subsp. (L.) L. & L.] Chilean germplasm source PI 536534 using the combined techniques of C-banding and image analysis. Cluster and multiple correspondence analyses were utilized to compare the C-banding patterns of the Chilean germplasm source and the previously published African germplasm source. Cytogenetic analyses revealed polymorphisms for heterochromatic DNA in the 19 plants observed in detail. Abundant variability in the number, intensity, and location of constitutive heterochromatic DNA was noted; however, this variability was not sufficient to preclude recognition of homologous chromosomes. Five out of the 50 plants studied were aneuploids (2 = 4 + 1 = 33 or 2 = 4 − 1 = 31) because of the presence or absence of a chromosome with a satellite. The Chilean karyotype resembled the reference tetraploid African alfalfa karyotype; however, a reduction in the total amount of heterochromatic DNA was observed. Cluster analysis and multiple correspondence analysis based on all eight alfalfa genome chromosomes yielded no clear separation of Chilean and African germplasms. However, the analysis of C-banding patterns of Homolog 1 of Chromosome 8 in Chilean and African germplasms was effective in separating the two germplasm sources with the exception of two individuals from each germplasm source which clustered together.