Abstract: Cytogenetic research in Medicago sativa subsp. sativa L., the cultivated tetraploid alfalfa (2n=4x=32), has lagged behind other crops mostly due to the small size and the uniform morphology of its chromosomes. However, in the last decades the development of molecular cytogenetic techniques based on in situ hybridization largely contributed to overcoming these limitations. The purpose of this study was to extend our knowledge on the chromosome structure of alfalfa by using a combination of GISH (Genomic In Situ Hybridization) and FISH (Fluorescent In Situ Hybridization) techniques. The results of self-GISH (sGISH) suggested that a substantial part of the repetitive fraction of the genome of subsp. sativa is constituted by tandem repeats typical of satellite DNA. The coincidence of sGISH and C-banding patterns supported this assumption. The FISH mapping of the Arabidopsis-type TTTAGGG telomeric repeats demonstrated, for the first time, that the alfalfa telomeres consist of this type of sequences and revealed a massive presence of interstitial telomeric repeat (ITRs). In the light of this finding M. sativa appears a suitable material for studying the origin and function of such extra telomeric repeats. To further exploit this result investigations will be extended to the diploid subspp. coerulea and falcata in order to explore possible connections between the distribution of ITRs, the ploidy level and the evolutionary pathway of the taxa.

Insight into the chromosome structure of the cultivated tetraploid alfalfa (Medicago sativa subsp. sativa L.) by a combined use of GISH and FISH techniques

Falistocco
2020

Abstract

Abstract: Cytogenetic research in Medicago sativa subsp. sativa L., the cultivated tetraploid alfalfa (2n=4x=32), has lagged behind other crops mostly due to the small size and the uniform morphology of its chromosomes. However, in the last decades the development of molecular cytogenetic techniques based on in situ hybridization largely contributed to overcoming these limitations. The purpose of this study was to extend our knowledge on the chromosome structure of alfalfa by using a combination of GISH (Genomic In Situ Hybridization) and FISH (Fluorescent In Situ Hybridization) techniques. The results of self-GISH (sGISH) suggested that a substantial part of the repetitive fraction of the genome of subsp. sativa is constituted by tandem repeats typical of satellite DNA. The coincidence of sGISH and C-banding patterns supported this assumption. The FISH mapping of the Arabidopsis-type TTTAGGG telomeric repeats demonstrated, for the first time, that the alfalfa telomeres consist of this type of sequences and revealed a massive presence of interstitial telomeric repeat (ITRs). In the light of this finding M. sativa appears a suitable material for studying the origin and function of such extra telomeric repeats. To further exploit this result investigations will be extended to the diploid subspp. coerulea and falcata in order to explore possible connections between the distribution of ITRs, the ploidy level and the evolutionary pathway of the taxa.
2020
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11391/1479373
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