Author
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Bauchan, Gary |
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HOSSIAN, M - MICS. |
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Submitted to: The Alfalfa Genome Conference
Publication Type: Book / Chapter Publication Acceptance Date: 11/1/1999 Publication Date: N/A Citation: N/A Interpretive Summary: The science of studying alfalfa chromosomes, cytogenetics, has progressed significantly in the past 10 years. Most of the advancements which have been made are due to the development and utilization of image analysis and molecular cytogenetic techniques. Studies have shown that there are different landmarks (C- and N-bands) on the chromosomes which can be used d to identify the individual chromosomes of alfalfa. This is important for determining which agronomically important genes are located on each chromosome. Once this is accomplished genes can be isolated and manipulated for the improvement of alfalfa. Investigations into the chromosomes of the nine germplasm sources of U.S. alfalfa varieties have shown that these techniques can be used to characterize the nondormant and dormant types of alfalfa. The implications and applications of molecular cytogenetic approaches such as chromosome banding of meiotic chromosomes, in situ hybridization, and fluorescent tagging methods on the genetic manipulation and chromosome engineering for the improvement of alfalfa are discussed. Technical Abstract: Alfalfa cytogenetics has progressed significantly in the past 10 years. Most of the advancements which have been made are due to the development and utilization of image analysis and molecular cytogenetic techniques including Giemsa banding and in situ hybridization. Chromosome studies with c- and n-banding on the species in the Medicago sativa complex namely M. sativa ssp. coerulea, ssp. sativa, and ssp. falcata have been conducted and standardized karyotypes have been constructed. Tetraploid ssp. sativa banding patterns demonstrated a typical autotetraploid pattern with four chromosomes per set showing similar banding patterns. Investigations into the chromosome banding of the nine germplasm sources for the alfalfa in the US have determined that the non-dormant types have more heterochromatic DNA than the dormant types. Polymorphisms for the number, location, and intensity of the chromosomal bands exist within and d between accessions studied. The implication and applications of molecula cytogenetic approaches such as chromosome banding of meiotic chromosomes, in situ hybridization, and fluorescent tagging methods on the genetic manipulation and chromosomes engineering for the improvement of alfalfa are discussed. |
