--Rodney G. Winkler and Michael Freeling

Seedlings that are low or null for ADH1, in contrast to normal seedlings, do not germinate under partially anaerobic conditions. The Freeling lab has utilized this behavior to select revertants of transposon-induced mutants of Adh1 (C.-H. Chen, M. Freeling, Maydica 31:93-108, 1986). Adh1-3F1124 is a novel mutant that has a Mu3 insertion that duplicates the TATA box and has been used in a number of selections for revertants (B. Kloeckener-Gruissem, M. Freeling, MNL 1989). Under the conditions used Adh1-3F1124, which has 6% of the ADH1 activity of the 3F progenitor, does not germinate, although revertants with approximately 30% or greater activity do germinate. Although this selection has yielded a number of revertants, most of the germinating seedlings show no detectable ADH1 by starch gel analysis. Preliminary experiments eliminated the possibility that these mutants are simple ADH2 overproducers. In the simplest terms the phenotypes of the 25 mutants being analyzed are: anaerobic germination positive (unlike the progenitor), less than 6% ADH1 activity by starch gel analysis in both the dry scutellum and submerged root, normal levels of ADH1 in pollen (like the progenitor). In situ analysis of the dry scutellum is also consistent with most of these derivatives being lower in ADH1 than the progenitor. Several of the derivatives are still mutable, yielding full ADH1 revertants. Currently these derivatives are being analyzed at the molecular level to understand their altered pattern of expression. One of these, Adh1-3F1124d104, has been shown to delete all but approximately 600bp of the Mu3 insertion.

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