Toxic and genetic factors limiting the increase of mutation frequency after treatment by alkylating nitroso- compounds and x- rays on arabidopsis seeds

Abstract

The high M1 sterility is the factor limiting the increase of the mutation frequency after treatment with nitrosamides like N-methyl-N′-nitro-N-nitrosoguanidine, N-methyl-N-nitrosourea, N-methyl-N-nitrosourethane and N-ethyl-N-nitrosourethane, whereas for ethylvinylnitrosamine-treatment the limiting factor is the toxic action on the M1 seed germination. The decrease of mutation frequency at high dimethylnitrosamine doses is explained by the inhibition of enzymes or enzyme-like system which hydroxylate nitrosaminesin vivo and thus enable the production of a mutagenic alkylating intermediate. The increase of mutation frequency after treatment with X-rays is limited both by the decreased M1 survival and M1 fertility.