Differential radiosensitivity among the probable genome donors of bread wheat

Abstract

A study of comparative radiosensitivity was undertaken in T. monococcum, Aegilops speltoides var. ligustica and Aegilops squarrosa which are now known to be the probable donors of the A, B and D genomes respectively of T. aestivum. Two doses of X-rays, 11,000 and 16,000 r, were given and survival, frequency of aberrations per unit length of chromosome and X2 chlorophyll mutation rate were used as indices of radiation sensitivity. By all these three criteria, A. squarrosa was found to be much more radiosensitive than the other two species. Since bread wheat has been found by several authors to be more radiosensitive in comparison with einkorn and emmer wheats, it seems likely that the squarrosa genome might have introduced into bread wheat a physiological state which promotes the incidence of a higher frequency of chromosomal aberrations and viable mutations following treatment with mutagens. The results support the view of Stebbins (1957) that in an allopolyploid plant, differences in genome sensitivity may complicate the analysis of the relationship between polyploidy and radiosensitivity.