Variation of spontaneous mutation frequency in Tradescantia stamen hairs under natural and controlled environmental conditions

Abstract

Considering the lack of information about the variation in spontaneous mutation frequency, especially due to different genotypes and under different environmental conditions, a long-term scoring of spontaneous pink somatic mutations was carried out in the stamen hairs of three different clones of Tradescantia heterozygous for flower and stamen-hair color, keeping them under controlled or natural conditions. One of the clones, KU 20, was found to be highly mutable and also unstable showing about a 23-fold difference in the spontaneous mutation frequency depending upon the environmental condition. The other two clones, KU 7 and KU 9, were rather stable and much less mutable than KU 20. High negative correlations were found between spontaneous mutation frequency and temperature in clone KU 20, i.e., the lower the temperature (in the range of about 18 to 28°C) the higher was spontaneous mutation frequency, and this clone was found to be especially sensitive to temperature variation. A significant (at the 5% level) negative correlation between spontaneous mutation frequency and temperature was also found in KU 7, and a similar, but not significant tendency was observed in KU 9. The spontaneous somatic mutation frequency in older inflorescences of clone KU 20 was significantly lower than that in the younger inflorescences.