| I. Research Notes The meiotic analysis and morphological characters of the hybrid Triticum aestivum L. var. delfii Korn. x Aegilops triaristata Willd. Murat OZGEN University of Ankara, Faculty of Agriculture Department of Field Crops, Ankara, Turkey A crossing program was organized to transfer genes for resistance to stripe rust (Puccinia striiformis West.) from Aegilops triaristata (2n=28) to Triticum aestivum var. delfii (2n=42). Crosses between these two species were made in the spring of 1980, under field conditions. In all, 712 florets from 28 spikes of T. aestivum var. delfii were pollinated with pollen of Ae. triaristata. Emasculating and crossing techniques were detailed in the previous study of OZGEN (1983a). 114 seeds were obtained from the crosses and chromosome numbers were determined by examining root tips under the microscope. Hybrids were found to be pentaploid (2n=35) (Fig.1). Only 86 of the 114 seeds germinated under laboratory condition. Seedlings were transplanted into the field and 57 F1 plants were obtained. The F1 plants were intermediate with respect to most of the morphological characters, but dominance was observed for some of the characters. The ears of the hybrid plants looked more like wheat than Ae. triaristata (Fig. 2). Some characteristics of the parents and hybrids are given in Table 1. It has long been known that there are some genes which cause sterility by affecting meiosis or it's resulting gametes in the interspecific hybrids (STEBBINS 1958). The characteristics and numbers of chromosomes of parents may also be causes of sterility (KIHARA & YAMASHITA 1956). The hybrid plants had non dehiscent anthers. The seed-setting was rather poor : only 50 seeds were obtained from 2763 spikes of 57 plants, with free pollination. Meiotic behaviour of the F1 hybrids was analyzed at the first metaphase stage and chromosome pairing was observed (Table 2 and 3). This showed that the number of bivalents varied between zero and ten, and most of them were of the rod type (Fig.3), but there also were some ring types. As pointed out by DEWEY (1982), chromosome pairing shows the level of relationship between parents. Chromosome pairing in T. aestivum var. erythroleucon x Ae. biuncialis hybrids (OZGEN 1984), were similar to chromosome pairing in T. aestivum var. delfii x Ae. triaristata hybrids. Chromosome pairing in the F1 hybrids of T. aestivum var. delfii x Ae. triaristata were found to be higher than for T. durum var. hordeiforme x Ae. umbellulata's F1 hybrids (OZGEN 1983b). As indicated by this study, to transfer genes from Ae. triaristata to T. aestivum var. delfii is easier than to transfer genes from Ae. umbellulata to T. durum var. hordeiforme. Literature Cited DEWEY, D.R. 1982. Genomic and phylogenetic relationships among North American perennial Triticeae. Grasses and Grasslands : Systematics and Ecology. Ed. J.R. Estes, R.J. Tyrl and J.N. Brunken. Univ. of Oklahoma Press. p. 51-87. KIHARA, H. & K. YAMASHITA 1956. Wheat and its relatives. Wheat Inform. Serv. 4 : 16-23. OZGEN, M. 1983a. Hybrid seed set in wheat x Aegilops crosses. Wheat Inform. Serv. 56 : 9-11. OZGEN, M. 1983b. Morphological characters and meiotic associations in a T. durum desf. var. hordeiforme Korn. x Ae. umbellulata Zhuk. hybrid. Wheat Inform. Serv. 57 : 1-3. OZGEN, M. 1984. Morphological characters and meiotic associations in a T. aestivum L. var. erythroleucon Korn. x Ae. biuncialis Vis. hybrid. Wheat Inform. Serv. 58 : 1-3. STEBBINS, E.R. 1958. The inviability, weakness and sterility of interspecific hybrids. Advences in Genetics 2 : 147-215. |