| Trisomics in common rye, Secala cereale L.
M. KAMANOI1) and B. C. JENKINS Department of Plant Science, University of Manitoba, Winnipeg, Canada The winter rye variety Petkus, Secale cereale, was utilized in this study. The primary simple trisomics were obtained in the progeny of autotriploids which were derived from the cross between autotetraploids and diploids. Primary simple trisomics appeared in the highest frequency (39.7%), which was higher than that of disomics. The primary in rye show distinctive characteristics in their external morphology due to the extra chromosome as do trisomics reported for many other plants. In order to distinguish the trisomics cytologically, a karyotype analysis was made for each type. It has been observed that Petkus rye has a somewhat different karyotype from that of Dakold analyzed by BHATTACHARYYA and JENKINS (1960). Morphology and karyotypes of the 7 primary trisomics are as follows: Slender The plants is slender with thin, erect stems. The leaf is the shortest among all trisomics. The spike is nearly the same as that of the disomics but is more compact. Few tillers are produced. This type has an extra chromosome I which is the longest one with nearly median primary constriction and with a very small satellite at the end of the short arm. Feeble Plants of this type are very weak in appearance. Various organs. in general, are thin and small, and leaves are extremely narrow. Seedlings of this type are characterized by very narrow thread-like purple leaves and thus are very easily recognized at an early stage. The plant has an extra chomosome II which is slightly shorter than chromosome I; its primary constriction is submedian. Stout This type has thick culms, the longest and widest leaves, and the longest culms of all types. It is particularly notable that it is susceptible to mildew. The plants have a tendency to forming branched spikes, especially the later ones, and in the greenhouse they are about a half month later in heading than the disomics. The extra chromosome in this type is chromosome III with a median constriction; it is shorter than chromosome II and has no satellite. Pseudonormal The trisomics of this type are in appearance very much like the disomics but are somewhat smaller. The characteristic hairy neck is usually absent. Spikes are nearly of the same size as those of disomics but spike density is considerably less. In appearance and growth habit the seedlings are quite similar to those of disomics, and distinguishing them from the latter is difficult but they seem to be somewhat weaker. Chromosome IV, which is triplicated, possesses a secondary constriction in the long arm, and the short arm carries a very small terminal satellite. Semi-stout Trisomics of this type are very similar to Stout having a waxy stem and wide leaves, especially in general appearance and growth habit, but the plants are smaller. They do not show susceptibility to mildew which is one of the most characteristic traits of Stout. The base of the young leaf is purplish making it not too diffcult to distinguish them from Stout in early seedling stages. The extra chromosome V has been observed in root tips. It is very similar to chromosome IV but differs from it in being somewhat shorter. Chromosome V has a longer short arm than chromosome IV. |
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