Results

Breeding the combinations of dominant nuclear male sterile gene Ms2, dwarf gene Rht10 and a blue seed marker: In order to transmit the addition chromosome 4D(Ms2)/4E from dun= wheat 89-2343 into common wheat, the cross between durum wheat 89-2343 and hexaploid wheat 7739-3 was made. In this cross, many male-fertile plants with blue seeds (MFP-BS) were produced. The progenies of these plants were all male fertile and their grains were blue. Progenies of most hybrids produced 50% male fertile and 50% male sterile plants with blue seed (MSP-BS). This suggested that a segment exchange must have taken place between the additional chromosome 4D(Ms2)/ 4E and probably 4D(ms2). The MFP-BS may have AABBDD (ms2ms2)+ 4D(ms2)/4E and the MSP-BS maybe AABBDD (Ms2ms2)+4D(ms2)/4E.

To combine the blue seed marker with Rht10 and Ms2, the dwarf male sterile plants were fertilized with the pollen from selected MFP-BS. Translocation between 4D(Ms2ms2Rht10rht10) and 4D(ms2)/4E was expected but nothing happened in the first three years. Among the 10268 spike lines tested from 1993 to 1997, one wheat line, 97-866, was finally found to have combined RUM, Ms2 and blue seed marker (Fig. 1). Characteristics of the combinations of Ms2,Rht10 and a blue seed marker: The characteristics of combinations of Ms2,Rht10 and a blue seed marker were very similar to those (about 55cm height, loosen in individual plant, blue in grain color and enriched seeds) of the dwarf male sterile parents 4325. Besides, the heading date was 1 to 2 days later than that of their recurrent parent. Stigma was full fertile and had good opening status during flowering. Anther was shriveled, gray and without pollen. Other traits were similar to those of their recurrent parents.
Cytological analysis: The chromosome number in root tips of the combination wheat line 97-866 (based on 10 plants) of Ms2,Rht10 and a blue seed marker, was 2n=43 (Fig. 2A), but that of male fertile line with white seed was 2n=42 (Fig. 2C). At metaphase I of meiosis in the pollen mother cells, chromosome configuration of combination wheat line of Ms2,Rht10 and a blue seed marker was 21"+1' (Fig. 2B), whereas, that of male-fertile line with white seed was 21" (Fig. 2D). This suggests that the combination wheat line 97-866 is still a monosomic addition line. All of the plants with blue seed marker were male sterile and short; the white seed plants were male-fertile and tall when planted in the field.
Inheritance analysis: Experiential data of 97-866 from 1998 to 2000 indicated that the transmission rate of short sterile-plant with blue seed marker was 22.1% (21.2-23.5%), and that of white male-fertile plants was 77.7% (Table 1).

13 new sterile wheat combinations of RUM, Ms2and blue seed marker were derived from the crosses among different common wheat background with dwarf male sterile wheat line 97-866. Experimental data from the 18642 spike lines of thirteen dominant nuclear male sterile lines with blue seed marker were obtained in consecutive 3 years (2001-2003). The variance analysis and multiple comparison results suggested that the transmission ratio for short sterile plant with blue marker was still stable at a mean of 22.1% (14.6-48.2%) (Table 2). This result suggested that the transmission ratio for additional chromosome 4D/4E was very similar during different years but dissimilar significantly among recurrent parent. In most recurrent parents, the transmission ratio for additional chromosome 4D/4E was about 20%. To our interest, the transmission ratio for dwarf male sterile plant with a blue seed marker in genotype 477A is up to 48.2%.