SECTORING PATTERNS OF SPONTANEOUS AND INDUCED SOMATIC PINK MUTATIONS IN THE STAMEN HAIRS AND PETALS OF MUTABLE AND STABLE CLONES OF TRADESCANTIA

The sectoring patterns of spontaneous and radiation- and EMS-induced s omatic pink mutations were analyzed in the stamen hairs and petals of Tradescantia clones heterozygous for flower color (blue/pink). Spontan eous pink mutations were analyzed using clone KU 20 (a highly mutable clone especially at lower temperature) grown outdoors and clones KU 27 and BNL 02 (stable clones) grown under controlled environmental condi tions, while induced pink mutations were analyzed using clones KU 27 a nd BNL 02 grown under the controlled environments. As for spontaneous mutations in the stamen hairs, the ratio of the number of single inter stitial pink mutant events against that of single terminal pink mutant events was somewhat larger than 1 in all the three clones examined, i ndicating that somewhat more interstitial pink mutant events occur spo ntaneously than terminal pink mutant events. After treatments with X r ays, gamma rays or EMS, however, the ratio increased to about 3 in the two clones examined, showing much more frequent inductions of interst itial pink mutant events than terminal pink mutant events by these mut agens. The daily changes of the sectoring patterns of radiation- and E MS-induced terminal pink mutant events in the stamen hairs showed a go od accordance with the pattern of the stamen-hair development. Multipl e pink mutant sectors in the same hairs were observed at much higher f requencies than expected from independent occurrences, especially in c ases of spontaneous mutations in the mutable clone and of radiation-in duced mutations in the two stable clones, suggesting the involvement o f somatic recombinations. The sectoring patterns of radiation- and EMS -induced somatic pink mutations in the petals also showed daily change s which reflected the pattern of the flower-petal development.