Molecular cytogenetics, fertility, and scab resistance of the intergeneric hybrid F1 and BC1 between Triticum aestivum and Roegneria kamoji

The reciprocal intergeneric hybrids between common wheat and Roegneria kamoji were successfully obtained by means of embryo culture. Morphology, chromosome pairing behavior at meiosis, fertility, and resistance to scab of the hybrid F1 and BC1 were studied. The results showed that the morphology of the reciprocal intergeneric hybrids F1 between R. kamoji and T. aestivum cv. Chinese Spring were intermediate type between the two parental species. The chromosome configuration at metaphase I (MI) of pollen mother cell (PMC) in reciprocal F1 was 40.33I + 0.78II + 0.03III and 40.40I + 0.79II, respectively. All of the F1 plants showed complete male sterility, and the seeds of BC1 were obtained by backcrossing with Chinese Spring pollen. The somatic chromosome numbers in BC1 plants of (R. kamoji x Chinese Spring) F1 x Chinese Spring ranged from 55 to 63. Many univalents were observed at MI of PMC, which resulted in the sterility of BC1 plants. Similarly, the chromosome numbers in BC1 plants of (Chinese Spring xR. kamoji) F1 x Chinese Spring also ranged from 55 to 63; however, many bivalents at MI of PMC and fertile pollen were observed resulting in partial fruitfulness in some BC1 plants by self-crossing. A plant (2n=63) with 42 wheat chromosomes and 21 R. kamoji chromosomes was obtained from R. kamoji x Chinese Spring cross, which had a chromosome configuration at MI of 26.40I + 18.30II. Because many univalents existed, this plant showed complete male sterility, and BC1 plants were obtained by back-crossing with Chinese Spring as the pollen parent. The chromosome numbers of BC1 ranged from 40 to 59, which contained less alien chromosomes. Although the morphology of the spike in BC1 plants was similar to that of Chinese Spring, these BC1 plants were still sterile. All F1 and most of the BC1 plants showed high resistance to Fusarium graminearum, which indicated that the resistance to scab from R. kmoji can be transferred into wheat.