Somatic crossing over in Glycine max (L). Merrill: Possible potentiation of the recombinogenic effect of caffeine by 5-fluorodeoxyuridine and cytosine-β-?-arabinofuranoside

Abstract

The leaves of variety T219 of Glycine max (soybean) exhibit yellow, dark green and twin or double spots on the two simple leaves and the first compound leaf of heterozygous Y 11 y 11 plants. These spots mimic the phenotypes controlled by Y 11 y 11 , Y 11 Y 11 and Y 11 Y 11 − y 11 y 11 genotypes. It has been argued that p recombination is responsible for the origin of twin spots. At least some of the single spots appear due to failure of one of the components of the double spots. Treatment of seeds with caffeine solutions increases the frequency of all types of spots, particularly those of doubles. 5-Fluorodeoxyuridine (FUdR) and cytosine-β- D -aranibofuranoside (CA), both inhibitors of DNA synthesis, cause potentiation of the effects of caffeine by increasing all three types of spots. Since the relative frequencies of the different types of spots do not differ much in caffeine plus FUdR (or CA) treated materials from those observed in case of caffeine treatment alone, it is suggested that (1) the increase in the frequency of spots in caffeine plus FUdR (or CA) treated material is not due simply to additive effect of the two chemical, and (2) there is true synergism between caffeine and FUdR (or CA) which somehow leads to enhancement of the phenomenon of compementary reunions.