Recipient Organization
UNIV OF CALIFORNIA-SAN DIEGO
9500 GILMAN DRIVE
LA JOLLA,CA 92093
Performing Department
(N/A)
Non Technical Summary
Lateral meristems establish the position and the number of secondary axes of growth in plants, i.e. the branches and flowers. They, therefore, represent a major determinant of overall plant form. We recently isolated the barren stalk1 gene (ba1) of maize, which encodes a regulatory protein that acts very early in the pathway of lateral meristem formation. In maize, this involves the formation of vegetative branches (tillers) and both the male (the tassel) and female (the ear) inflorescences. Furthermore, recent evidence suggests that barren stalk1 was selected during maize improvement and has likely been a target of selection during the domestication of modern maize from its wild relative teosinte, presumably for its effect on maize morphology. Understanding the mechanism of ba1 action in regulating lateral meristem formation is the goal of this project. Through the studies proposed here, we will determine basic functions of the Ba1 protein and obtain further insights
into its role in regulating axillary meristem initiation and development, providing a model for lateral meristem formation that may be relevant to other cultivated grasses as well. Furthermore, these studies will contribute to the understanding of the mechanisms of evolution during the domestication of a cultivated species, and may provide information important to the breeding and engineering of plant architecture for commercial purposes. The information obtained will be important to efforts directed at engineering modern crops for plant architectures that can improve productivity and yield.
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
Our long term objective is to determine the mechanism of action of the barren stalk1 (ba1) gene in regulating axillary meristem development in maize. We intend to define functional aspects of the Ba1 protein including the identification of interacting factors and downstream targets. We will integrate our understanding of ba1 function with other genes affecting maize lateral meristem development and tillering. Finally, we will evaluate the possible contribution of ba1 to phenotypic differences that were important during maize domestication.
Project Methods
We propose to determine basic aspects of Ba1 protein function, including the site of action of Ba1 protein through immunolocalization with a Ba1-specific antibody, and the capacity of Ba1 to bind specific DNA sequences and activate transcription. We will integrate our understanding of ba1 function with other genes affecting maize development by characterizing ba1 expression in well-known maize mutants impaired in inflorescence and flower formation, and determine the sufficiency of ba1 to establish new meristems when misexpressed in developing inflorescences. Additionally, we will determine if Ba1 action is involved in auxin transport or signaling by application of exogenous auxin and perturbation of auxin transport in immature ba1 inflorescences, and through transgenic analysis involving perturbation of localized auxin at the site of ba1 expression. Through two hybrid screens and microarray-based technologies we will attempt to identify and characterize interacting
gene products, putative upstream cis-regulatory factors and downstream targets of Ba1 activity. Finally, we will evaluate the contribution of ba1 in maize domestication by introducing ba1 alleles from teosinte into modern maize, crossing them into ba1 mutants and evaluating the corresponding phenotypes for differences relative to a maize Ba1 control.