Shoot Chimeras After Exposure to Mercurial Compounds

Abstract

1. Six methods of application of phenylmercuric hydroxide (PMOH) and phenylmercuric nitrate (PMN) to the shoot apex of two dicotyledons (Coleus blumei and Raphanus sativus) and three monocotyledons (Zea mays, Anacharis canadensis, and Ruppia maritima) subsequently produced somatic changes in tissue. The concentrations were higher and the time of exposure usually longer than those tolerated by roots. 2. Seedlings of maize and radish treated when 1 or 2 days old became dwarfed and hypertrophied. Sectors of giant epidermal cells and increased lignification appeared within 1 month after treatment in maize leaves. 3. Chlorophyll sectors occurred in radish cotyledons (xantha) and in maize leaves and husks (albino and virescent) 3-7 weeks after seedling treatment. Ruppia produced a small albino lateral after PMOH treatment, and another appeared in Anacharis after HgCl2 treatment. 4. Pollen sterility appeared in radish and Coleus, sometimes with aborted microspores remaining in tetrads. 5. Alteration in leaf form appeared in maize and in Anacharis. 6. Dwarfed internodes occurred in maize treated at the 10-leaf stage and in an Anacharis shoot with filiform leaves. 7. Some of these changes resemble those produced by X-rays in plants and were probably chimeras (mosaic somatic mutations). This indicates that these chemicals which are known to cause chromosome breaks are also mutagenic.