Anaerobic tolerant null: a mutant that allows Adh1 nulls to survive anaerobic treatment.

Anaerobic tolerant null (ATN) is a recessive factor that allows alcohol dehydrogenase-1 (ADH1) null individuals of Zea mays L. to survive 24 h of anaerobic conditions. ADH1 null lines that do not possess this factor survive only a few hours of anoxia. We studied ADH activity levels in protein extracts from the primary root tissue of ATN. ADH levels were similar in ATN and other ADH1 null lines, suggesting that ADH activity does not account for differences in the ability of ATN to survive anaerobic treatment. The ATN survival trait segregated as a single recessive locus in crosses between ATN and double null (Adh1-S5657, Adh2-33). We also made crosses between ATN and 1s2p, an inbred line with ADH1 activity that carries an electrophoretic mutation of Adh2, to determine whether atn increases the number of survivors over that which would be expected from the segregation of Adh1 alone and to use the Adh2P allele to study the cosegregation of Adh2 and atn. The observed number of survivors in that cross exceeded the expected number of survivors by a margin consistent with a single recessive gene adding to the ADH+ survivors. Extracts from the primary root or scutellum of induced F2 seedlings from the above crosses were assayed for ADH activity by native polyacrylamide gel electrophoresis (PAGE) and simultaneously scored for survival to determine whether Adh2 and atn were segregating independently. We screened the (ATN x 1s2p)F2 progeny for ADH1 activity by staining root tips with an ADH-specific stain to select Adh1 null individuals prior to gel assay. Atn was found to be assorting independently of Adh1 and Adh2 in both crosses.