To understand mechanisms that regulate cell proliferation associated with organ initiation and the determination of organ size, the function of the AINTEGUMENTA (ANT) transcription factor is being studied. ANT is an important regulator of cell proliferation that is responsible for organ primordia initiation and the determination of mature organ size and shape. 1) ANT is transcribed in meristematic cells that initiate all aerial lateral organ primordia, in marginal meristem cells that contribute to organ width and in meristematic procambium cells that generate the vascular system. 2) The loss-of-function ant mutant phenotype (i.e., no ovule integuments, reduction in floral organ size and number, narrow leaves) is associated with a decrease in cell proliferation. 3) In transgenic plants where ANT is transcribed from the strong 35S promoter, the gain-of-function phenotype (i.e., enlarged leaves, floral organs and ovules) is associated with increased cell proliferation. Thus, ANT provides a unique entry point into the signal transduction pathway(s) that link the control of cell proliferation with organ initiation and the determination of organ size and shape.
To understand how cell proliferation is regulated during organogenesis, the PI will accomplish the following goals: 1) Determine the relationship between patterns of ANT transcription and cell proliferation during organogenesis. 2) Identify genes and sequences that control ANT transcription in meristematic cells. 3) Identify targets of the ANT transcription factor and determine their relationship to the control of cell proliferation and organogenesis. 4) Elucidate the role of an ANT interacting protein on the control of cell proliferation and organogenesis. 5) Obtain additional regulators of organogenesis by identifying mutations that suppress or enhance the phenotype of a weak mutant allele, ant-3. Results from these experiments will provide insight into fundamental mechanisms that control organ initiation and the determination of organ size and shape. They will help to elucidate the signal transduction pathways that control cell proliferation during organogenesis. This information will generate novel methods to modify organ size in crop plants, and thereby increase their productivity and value.
