Cyto-Chromosomal Analysis of Developing Wheat Monosomics
作 者 ：Zhang Yu-lan and Sun Rong-iing
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Abstract:In order to achieve the aim of advanced breeding program with the definite direction, it is necessary for us to develop the monosomic lines used for the wheat breeding programs in China. We fixed the wheat ears at appropriate stage in Carnoy’s fluid, and stained with acetocarmine in every generation from the different crosses mentioned above. According to their karyotypes of metaphase 1, the monosomics, normal bodies, monotelosomics, ditelosomics and allotypic bivalents were identified (Plate Ⅰ, 1–8). In the process of developing monosomic lines “Beijing Red No.1”, some monosomic lines such as 5A’s and 4D’s, can be directly proved by their phenotypes, other lines of monosomic 1B, 5B add 6B can also be directly proved to be true by their typical chromosomal morphology. In order to check the accuracy of chromosomal orders of monosomic lines, we tested all 21 monosomic lines of “Beijing Red No.1” by means of telosomic testing. At the same time we tested the origirnal monosomics of “Chinese Spring” as a check. In the F1’s of test crosses, those showing 20 bivalents and one monoelemic (20”+t’) were proved to be right. Whereas those showing 19 bivalents, 1 univalent and 1 allotypic bivalent (19”+1’+1’t’) were proved to be wrong. The karyotypes of F1’s from the test crosses for “Beijing Red No.1” can be verified by compairing with that of the check. During some years, we have examined 500 F1 plants of test crosses for monosomic lines of “Beijing Red No.1”, and some what less plants for monosomic lines of “Chinese Spring”. The number of observed cells usually was 100–200, the least was 40 and the most was 600. As the result, all F1‘s of test crosses showed accurate karyotypes. Besides detemning the F1 karyotypes of test crosses, we also analysed and compared their phenotypes with each other (photograph 9–12). According to the pbenotypes caused by the chang in chromosome number, structure and gene dosage, not only we can check the accuracy of testing result, but also locate the genes controlling some characters on the chromosomes or chromosomal arms.