Figure 1.

Selection and Chimerism.

(A) Mandelonitrile (1), the substrate of the HTH homolog mandelonitrile lyase, and nitriles and isothiocyanates (2 and 3) produced by hydrolysis of seed glucosinolates. Nitriles or isothiocyanates and their derivatives could be the toxic and mutagenic compounds that accumulate in Arabidopsis hth mutants (−/−) in the toxic mutator hypothesis.

(B) Rare revertant pollen (+) outcompetes mutant pollen (−) during self-fertilization, resulting in frequent +/− heterozygotes.

(C) Revertant sectors are formed in the seed, meristem, and adult plant body.