Pollen genetic markers for detection of mutagens in the environment.

To utilize and exploit pollen for in situ mutagen monitoring, screening and toxicology, the range of genetic traits in pollen must be identified and analyzed. Traits that can be considered include ornamentation, shape and form, male sterility viability, intraspecific incompatibility, proteins and starch deposition. To be useful for the development of mutagen detection systems proteins should be: (1) activity stainable or immunologically identifiable in the pollen, (2) the products of one to three loci, and (3) gametophytic and nuclear in origin. Several proteins including alcohol dehydrogenase in maize, which meet those criteria will be discussed. The waxy locus in barley and maize which controls starch deposition has been characterized genetically and methods have been developed for pollen screening and mutant detection. At Washington State University a waxy pollen system is being developed in barley for in situ mutagen monitoring. The basis is an improved method for staining and scoring waxy pollen mutants. Specific base substitution, frameshift, and deletion mutant lines are being developed to provide information about the nature of the mutations induced by environmental mutagens. Thirty waxy mutant lines, induced by sodium azide and gamma-rays have been selected and are being characterized for spontaneous and induced reversion frequencies, allelism, karyotype, amylose content, and UDP glucose glucosyltransferase (waxy gene product) activity. Twelve mutant alleles are being mapped by recombinant frequencies.

Ontogeny of the barley plant as related to mutation expression and detection of pollen mutations.

Clustering of mutant pollen grains in a population of normal pollen due to premeiotic mutational events complicates translating mutation frequencies into rates. Embryo ontogeny in barley will be described and used to illustrate the formation of such mutant clusters. The nature of the statistics for mutation frequency will be described from a study of the reversion frequencies of various waxy mutants in barley. Computer analysis by a "jackknife" method of the reversion frequencies of a waxy mutant treated with the mutagen sodium azide showed a significantly higher reversion frequency than untreated material. Problems of the computer analysis suggest a better experimental design for pollen mutation experiments. Preliminary work on computer modeling for pollen development and mutation will be described.