| Aegilops juvenalis On the basis of the morphological analysis, this species was classified in the section Vertebrata, which involves 2 tetraploid species, Ae. crassa and ventricosa, and a diploid species, squarrosa. The genome constitutions of these species are McrD, MvD and D, respectively. Ae. juvenalis has the basic characteristics morphologically represented by D and M genomes. By further investigations, however, it has become clear that the upper margin of the empty glumes of Ae. crassa and ventricosa is truncate-bidentate with a slight notch, while that of Ae. juvenalis is truncate-polydentate with slight notches. Which is the characteristics represented by the Cu genome of a diploid species Ae. umbellulata. This indicates that Aegilops juvenalis involves Cu in addition to D and M genomes. Dr. McGinnis and Helnyk has proposed the genome constitution of this species for CuDS, but we do think that the glume characteristics indicate the existence of M genome ratber than S genome. We have also the cytological evidences. The high frequencies of pairings have been observed in the respective hybrids of Ae. juvenalis with 4x and 6x Ae. crassa, and an amphiploid CuCuDD. From these data, both morphological and cytological, we have concluded that Ae. jnveualis has the genomes D Mj, which are closely related to DMcr in Ae. crassa, and Cu. If we may add a few words, the fact that Ae. juvenalis has been found only in the restricted regions in Turkestan in U.S.S.R. and Iraq would suggest that the area where the piesent species was originated, but speculatively. Aegilops triaristata According to Eig (1929) the species Ae. triaristata is widely distributed from Pyrenees through France, Italy, Greece, Crimea, Transcaucasia, Asia Minor, Tripoli, Cyrenaica, Tunis, Algeria to Morrocco. The genome constitution of the 4x species of Ae. triaristata has already been established as CuCuMtMt by the senior author in 1947. Morphologically, 4x and 6x forms are very similar in general, but through the careful investigations a difference was found in the number of undeveloped sterile top spikelets between these two forms. Namely, in 6x from the spikelets are fertile from the base to top of an ear, while in 4x form 1 or 2 top spikelets are not well developed and sterile. Similar relation is seen in the diploid analyzers. For instance, Ae. comosa or Ae. uniaristata has fertile spikelets on the top of an ear, while Ae. umbellulata has a few sterile ones. From these analytical data, it will be suggested that M genome should be involved in 6x form of Ae. triaristata in addition to CuMt genomes of the tetraploid form. For this consideration we have also the favorable genome analytical evidenccs. The cytological analyses have been carried out for the various hybrids of the 6x form of Ae. triaristata. From the former and present data we can extract the following pairing relations between the genomes in M-group. This is based on the assumption that the chromosomes in Cu of Ae. triaristata pair completely with those of the other parents. Based on these data, it will be concluded that the third genome of 6x triaristata will be the one in closer relation to M, especially Mu. Consequently the genome constitution of the 6x triaristata has been established for CuMt1Mt2. The centre of the distribution of the tetraploid species, with the genome constitution CuM is in Asia Minor. The place where 6x form was originated could be, though speculative, Balcan Peninsula, including Greece, where is the centre of the diploid analyzer Ae. umbellulata. |
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