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Sau3AI "shot gun" cloning and colony hybridization with total genomic probes were used to isolate genome-specific sequences inPhleum species. The total DNA isolated from diploid speciesP. alpinum andP. bertolonii was partially digested withSau3AI and cloned using pUC19 as a vector to anE. coli strain DH5αmcr. A partial genomic DNA library consisting of 3030 colonies for the genome ofP. alpinum and one consisting of 3240 colonies for the genome ofP. bertolonii were constructed. Twelve hundred and thirty colonies from the DNA library ofP. alpinum and 1320 from that ofP. bertolonii were respectively blotted to membrane filters and hybridized to the total genomic probes from these two species. Eight clones specific toP. alpinum and 13 specific toP. bertolonii were isolated through colony hybridization and further dot-blot hybridization. Most of these clones may carry highly or moderately repetitive sequences. Three sequences specific toP. alpinum and 3 specific toP. bertolonii were used as probes to hybridize theEcoRI-digested DNA samples from four species,P. alpinum,P. bertolonii,P. pratense andP. montanum, on Southern blot. The results from these hybridization experiments showed that all 3P. bertolonii-specific probes and 2 of the 3P. alpinum-specific probes hybridized to the DNA ofP. pratense, thus confirming the conclusion of the close relationships between the cultivated timothy and its two wild relatives that was drawn in our previous study using the C-banding technique.

CAI, Q., and BULLEN, M. R. 1991. Characterization of genomes of timothy (Phleurn pratense L.). I. Karyotypes and C-banding patterns in cultivated timothy and two wild relatives. Genome, 34: 52-58. In an attempt to know the phylogeny of timothy (Phleurn pratense), the cultivated species and two wild relatives, Phleurn alpinurn and Phleurn bertolonii, were karyotyped with conventional and Giemsa C-banding methods. In the hexaploid P. pratense (2n = 6x = 42), two sets of seven chromosomes were indistinguishable from each other both in morphology and in banding patterns and the third set of seven was found to be differentiated from them. Two genomes, A and B, were tentatively established. The banded karyotype in diploid P. alpinurn (2n = 2x = 14) was close to the A genome, which was tetraploid in P. pratense, and the karyotype in P. bertolonii (2n = 2x = 14) was analogous to the B genome in P. pratense, which suggests these species were the genome donors of P. pratense. CAI, Q., et BULLEN, M. R. 1991. Characterization of genomes of timothy (Phleurn pratense L.). I. Karyotypesand C-banding patterns in cultivated timothy and two wild relatives. Genome, 34 : 52-58. Dans le but de connaitre la phylogenese du Phleurn pratense, la Fleole des pres, les caryotypes Giemsa de l'espece cultivee et deux especes sauvages, Phleurn alpinurn et Phleurn bertolonii ont ete examines. Les bandes C obtenues ainsi que la longueur et les rapports des bras des chromosomes ont conduit a l'identification des genomes de ces especes. En ce qui concerne l'espece hexaploi'de P. pratense (2n = 6x = 42), on a trouve que deux groupes de sept chromosomes etaient identiques tandis qu'un troisieme groupe de sept chromosomes etait different des deux premiers, sur la base de la morphologie et de la distribution des bandes C. Le caryotype de l'espece diploi'de P. alpinurn (2x = 2x = 14) est proche de genome A (tetraploi'de chez P. pratense) tandis que le caryotype de P. bertolonii (2n = 2x = 14) ressemble au genome B de P. pratense.