Production and characterization of Raphanus sativus-Brassica rapa monosomic chromosome addition lines

Breeding of Raphanus sativus-Brassica rapa monosomic chromosome addition li nes (MALs, 2n = 19) was carried out by backcrossing the synthesized amphidi ploid line, Raphanobrassica (R. sativus x B. rapa, 2n = 38, RRAA, line RA89 ) with R. sativus cv. 'Shogoin' (2n = 18, RR). In the first cross of Raphan obrassica x radish, four sesquidiploidal BC1 plants (2n = 28, RRA, RA89-36- 1, RA89-31-1, RA89-31-2, RA89-31-3) were successfully developed. In these p lants, the chromosome configurations of 9II + 10I and 10II + 8I were observ ed frequently at first metaphase (MI) of meiosis in pollen mother cells (PM Cs). The RA 89-36-1 plant produced many seeds in the reciprocal backcrosses with radish. About 50% of the BC2 plants obtained from the cross of RA89-3 6-1 plant x radish were 2n = 19 plants, followed by 2n = 18 plants (24%) an d 2n = 20 plants (19%). In the reciprocal cross, 2n = 19 plants were also d eveloped at the rate of 40%. From analysis of specific morphological traits , 2n = 19 plants were classified into eight types (a-h). When 25 selected p rimers were used in polyacrylamide gel electrophoresis, random amplified po lymorphic DNA (RAPD) markers derived from B. rapa for each type of MAL were detected in numbers between three for e-type and 16 for b-type. RAPD marke rs specific for each type alone were from one (OPE 05-344) for h-type to ni ne for b-type. In the g-type, no marker specific to this type alone was obs erved. However, 19 bands were common between at least two types. These MAL plants exhibited predominantly the chromosome configuration of 9II + 1II at MI of PMCs, pollen and seed fertility being the same level as the radish c v. 'Shogoin'. From the morphological traits and DNA markers, eight differen t MAL types among 10 expected were identified.