Radiation-inducedalcohol dehydrogenasemutants in maize following allyl alcohol selection of pollen

Abstract

SUMMABYThe alcohol dehydrogenase-1 gene in maize presents advantages for mutational analysis. Foremost among these is the ability to chemically select ADH-negative and ADH-low gametophytes owing to their resistance to allyl alcohol vapour. Immature tassels were irradiated with either 220 kV X-rays or 400 MeV/amu accelerated neon-ions; spontaneous mutants were also selected and recovered. RBE for neon-20 was about 5. A total of 70 presumptive mutants were placed into one of four classes on the basis of allozyme profiles following electrophoresis and ADH staining: (A) dysfunction, (B) underproducer, (C) overproducer, and (D) wp-Adh2 gene. Mutants have been recovered and confirmed in the first three classes. These include two male-transmissible deletion-type lesions induced by X-rays, five underproducer transpositions and one overproducer transposition induced by neon-20. Certain of the neoninduced alleles are unstable in their expression. All 70 mutants are chromosomal aberrations; no intragenic lesions were recovered although our experimental design would have preferentially recovered them if they had occurred.The Discussion considers the mutagenic action of ionizing radiation, and especially the well-documented differences between maize and Drosophila data. In particular, the effect of these chromosome derangements on the 'programmable' component(s) of the Adhl cistron is discussed.

A mutational analysis of the alcohol dehydrogenase system in barley

“…Mutants deficient in ADH activity have been isolated by the use of chemical selective techniques in yeast (Megnet, 1967), Drosophila (Sofer and Hatkoff, 1972) and maize (Schwartz and Osterman, 1976;Cheng and Freeling, 1976;Freeling, 1977;Freeling and Cheng, 1978). A method has also been devised for the biochemical selection of haploid maize embryos utilising the ability of Adh 1 null mutant haploid embryos to survive exposure to levels of allyl alcohol which kill diploid (Adh 1+ /Adh 1 null) embryos (Dhaliwal and King, 1979).…”

Mutant alleles that are altered in quantitative, organ‐specific behavior

“…No complete or near-complete reversions have been noted. Adhl-FkF/ Adhl-S scutella are normally very stable in their allozyme profile; in a control experiment in which 4,000 individuals were analyzed, no aberrant ratios were discovered [12].…”

“…Following 400 MeV/ amu accelerated neonlo+ irradiation to an immature tassel carrying Adhl-S and ally1 alcohol selection of mature pollen, several F, kernels displayed underexpression of the S allele in the FkF/S hybrids. One such kernel, designated FkF/Sl951, was backcrossed to the FkF parent; only one allele displaying low-expression behavior transmitted in 75 attempts [12]. This derivative, designated Sl95Ia, proved stable in backcrosses and self-pollinations; the low-expression behavior segregated with Adhl-S allozyme in every case of 82, proving reasonably close linkage and arguing strongly for cis action of the quantitative site with the coding sequences.…”

Maize Adh1 as a Monitor of Environmental Mutagens

“…The gene is composed of a structural gene component, containing the information for the primary structure of the polypeptide and adjacent cis-acting regulatory gene component(s). There is sound but limited evidence that pointmutagens do not induce detectable mutants in cisacting regions of the gene (17, 15), although such regulatory variants certainly occur spontaneously, and are probably induced by certain types of chromosomal breakage events (15,18,19). There is sound but limited evidence that pointmutagens do not induce detectable mutants in cisacting regions of the gene (17, 15), although such regulatory variants certainly occur spontaneously, and are probably induced by certain types of chromosomal breakage events (15,18,19).…”