Cytogenetic and Physiological Analyses of Antarctic Hair Grass, Deschampsia antarctica Desv.

CARDONE S, SAWATANI P, GARCIA A.M., GONZALEZ G, POGGIO L, JOHN U.P, AND G.E. SCHRAUF

Bueno Aires, Argentina

Simposio; The 6th International Symposium on the Molecular Breeding of Forage and Turf; 2010

Molecular Breeding of Forage and Turf - MBFT

Deschampsia antarctica, is the only grass species to have colonized one ofthe most inhospitable environments on earth, Antarctica. In order to understand how its biology and evolution have contributed to this unique ability we have undettaken karyotypic analysis of D. antarctica, and comparative genomic and physiological studies relative to D. caespitosa These included c1assical and molecular cytogenetic (genomic in situ hybridisation, GISH), and electrolyte leakage experil1lents to quantify cellular dal1lage by freezing. The karyotype of D. anfarctica collectcd near Jubany Station on King George Island in the l1laritime Antarctic is reported. This spccies exhibits a chromosol1le number of 2n = 2x = 26, with a karyotypic fonnula: 10m + 6S111 + Sst + 2t. The nucleolar organizer region is locatcd on the short arm of one of lhe submetacentric pairs forming a temlinal satellite. Aneusomaty, a phenol1lenon already repOlted in the genus, was detected in metapbase plates. Also, differences in relative nuclear DNA content from f10w cytometry analysis were found. Reciprocal GISH hybridizations with labelled genomic DNA revealed differences in the intensity of hybridization signal between D. antarctica and D. caespitosa. Moreover, when visualized with DAPI stai ning, chromosol1les of D. caespitosa showed a higher nUl1lber of heterochromatic bands than those of D. antarctica. Most of these heterochromatic bands do not hybridizc with DNA of D. antarctica. Electrolyte leakage tests revealed that D. antarclica experiences less cellular damage when exposed to freezing temperatures than D. caespitosa, This provides evidence of the evolutionary development of freezing tolerance l1lechanisms in D. antarctica that have allowed it to colonize the Antarctic continent.