Homeotic Transformation of Ovules into Carpel-like Structures in XXXX .

@entity958 @entity62089 @entity30387
Ovules are specialized reproductive organs that develop within the carpels of higher plants. In @entity958 , mutations in two genes, @entity62089 ( @entity62089 ) and @entity30387 ( @entity30387 ), disrupt ovule development. In @entity62089 ovules, the inner integument fails to form, the outer integument develops abnormally, and the embryo sac arrests at a late stage of megagametogenesis. During later stages of ovule development, cells of the outer integument of a @entity62089 ovule sometimes develop into a carpel-like structure with stigmatic papillae and second-order ovules. The frequency of carpel-like structures was highest when plants were grown under conditions that normally induced flowering and was correlated with ectopic expression in the ovule of AGAMOUS (AG), an organ-identity gene required for carpel formation. Together, these results suggested that @entity62089 negatively regulates AG late in ovule development. Likewise, mutants homozygous for the strong @entity30387 allele @entity30387 -6 sometimes displayed structures with carpel-like features in place of ovules. However, such abnormal @entity30387 ovules are much less ovulelike in morphology and form earlier than the @entity62089 carpel-like structures. Because one role of the @entity30387 gene is to negatively regulate AG expression early in flower development, it is possible that @entity30387 works in a similar manner in the ovule. A novel ovule phenotype observed in @entity62089 / @entity30387 -6 double mutants suggested that @entity62089 and @entity30387 genes function independently during ovule development.
