This opportunity is for Caltech students only
Project Title:
Identification and Characterization of Candidate Target Genes of
AP3/PI
Project Description:
Arabidopsis
is a model plant for studying plant development, due to its small size, short life cycle, suitability to genetical studies and ease of transformation. One of the most intensively studied aspects of
Arabidopsisdevelopment is the formation of flowers. Flowers are composed of four concentric whorls, each containing different floral organs (sepals, petals, stamens and carpels, from the outside to the inside). Mutations in genes called 'organ identity genes' cause changes in the identity of organs which form in particular whorls (for example, mutations in the
AP3
and
PI
genes cause development of sepals and carpelloid organs in whorls 2 and 3, respectively, instead of the usual petals and stamens). Several organ identity genes have been cloned and encode transcription factors which presumably are master regulators of distinct sets of genes whose activity (or repression) is required for the formation of each floral organ. Very little is known, however, about which genes are regulated by the products of organ identify genes. The identification of these 'target genes' would be the first step in elucidating how the activity of organ identity genes is translated into the formation of a particular floral organ with its distinctive morphology and cell types.
The products of the organ identity genes
AP3
and
PI
act together and are necessary and sufficient to determine the formation of petals (replaced by sepals in the absence of
AP3
/PI
function) or stamens (replaced by carpels if
AP3
/PI
are inactive). To identify which genes are regulated by
AP3
/PI
, mRNA populations in flower buds with impaired
AP3
/PI
function are being compared with mRNA populations in similar buds shortly after restoration of
AP3
/PI
. Restoration of
AP3
/PI
activity is being achieved using a heatshock-inducible
AP3
transgene. mRNA populations are compared by differential display RT-PCR (see references below). Differentially expressed genes will be cloned, characterized and their function studied in transgenic plants.
The SURF student is expected to join the effort in the identification and characterization of candidate target genes of
AP3
/PI
. The nature of the work is experimental, involving basic molecular biology techniques (cloning, PCR, DNA sequencing) and some more advanced or specific techniques (differential display, RNAse protection assays, plant transformation). If necessary, instruction on these techniques will be given.
Background Information:
Literature references or articles that may provide more information on the project:
Weigel, D. and Meyerowitz, E.M. (1994),
Cell
78: 203-209 (review of
Arabidopsis
flower development)
Jack, T., Brockman, L.L. and Meyerowitz, E.M. (1992)
Cell
68: 683-687 (AP3
characterization)
Jack, T., Fox, G.L. and Meyerowitz, E.M. (1994)
Cell
76: 703-716 (AP3
characterization)
Goto, K. and Meyerowitz, E.M. (1994)
Genes & Development
8: 1548-1560 (PI
characterization)
Liang, P. and Pardee, A.B. (1992)
Science
257: 967-971 (differential display)
Liang, P. and Pardee, A.B. (1995)
Current Opinion in Immunology
7: 274-280 (differential display)
Requirements (skills, specific coursework, academic major, year in school, etc.):
Knowledge of Genetics and Molecular Biology, both practical and theoretical, is desirable.
Research Sponsor Name: Robert Sablowski
E-Mail: sablowskir@starbase1.caltech.edu
Division: Biology
Telephone: 395-6895
Address: 156-29
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