Production and cytogenetics of hybrids of Ogura CMS Brassica campestris var. purpuraria x Raphanus sativus x Brassica napus]

Crosses of Ogura CMS Brassica campestris var. purpuraria x Raphanus sativus x Brassica napus were made and four hybrids were produced. One plant (PRN-1) was mosaic with yellow and milk white flowers and some flowers had both yellow and white petals. The others (PRN-2, -3, -4) had white flowers. PRN-4 had degenerated anthers, the other three had three to six anthers and could produce some pollens, but the pollens of PRN-2 were unstainable by I2-KI solution. PRN-2 had four normal honey glands, PRN-1 and PRN-3 had two, and PRN-4 had none. PRN-2 had normal leaf color and the other three showed different degrees of chlorophyll deficiency at low temperature. The chromosome number of PRN-1 was 2n = 38 and had the mean chromosome paring configuration of 14.67 I + 10.07 II + 1.06 III, and its chromosome set constitution might be AACR. This chromosome constitution may be due to the fertilization of female gamete of n = 19 (AR) with male gamete of n = 19 (AC) from B. napus. The occurrence of mosaic flower color in this plant may be attributed to the chromosome abnormalities caused by wide hybridization, such as chromosome deficiency and the formation of chromosome fragments and chromosome bridges. The chromosome number of PRN-2 was 2n = 35 and the mean chromosome paring configuration was 13.89 I + 8.33 II + 1.33 III + 0.11 IV. The chromosome number of PRN-3 was 2n = 33 and the mean chromosome paring configuration was 14.00 I + 7.82 II + 1.00 III + 0.09 IV. The chromosome number of PRN-4 was not determined as there was no pollen mother cell formation. Chromosome bridges and laggards were observed in PRN-1-3. Some seeds were harvested from PRN-1-3 but none was harvested from PRN-4 when backcrossed with B. napus. It seems possible for us to overcome the chlorophyll deficiency and honey gland abnormality and restore the male fertility in Ogura CMS by introduction of the nucleus of R. sativus into this cytoplasmic male sterile line.