New insights into the role of the maize ameiotic1 locus.
In maize the am1-1 mutant allele results in both the male and female meiocytes undergoing mitosis in place of the meiotic divisions. A second mutant allele am1-praI enables both the male and female meiocytes to proceed to the early zygotene stage of meiotic prophase I before being blocked. Here we report on three new alleles that allow all male meiocytes to undergo mitosis but in female meiocytes approximately one quarter (am1-2), one half (am1-485), or all (am1-489) of them are blocked at an abnormal interphase stage. Previous analysis has shown that am1-praI is dominant to am1-1 in male meiocytes. Cytological analysis of heteroallelic combinations in female meiocytes now indicates a dominance relationship of am1-praI > am1-1 > am1-2/am1-485 > am1-489. The evidence provided by the female phenotypes of the new mutant alleles suggest that, whereas the normal am1 allele is required for the meiocytes to proceed through meiosis, a partially functional allele may be required for their diversion into a mitotic division. The partial or complete blockage of mitosis in female meiocytes carrying the new am1 alleles rules out the possibility that the mitotic division of mutant meiocytes reflects a simple default pathway for cells that cannot initiate meiosis. This locus may have a dual function.
Golubovskaya
I
I
N.I. Vavilov Research Institute of Plant Industry, St. Petersburg, Russia.
Avalkina
N
N
Sheridan
W F
WF
D000483:Alleles; D029681:Arabidopsis Proteins; D017343:Genes, Plant; D008540:Meiosis / Q000235:genetics; D009154:Mutation; D009698:Nucleoproteins; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D003313:Zea mays / Q000235:genetics*
C108559:AML1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D009698:Nucleoproteins; D010940:Plant Proteins