MEYEROWITZ, ELLIOT M. Division of Biology 156-29, California Institute of Technology, Pasadena, CA 91125. - Genes, genomes, and plant developmental biology.
A central question in botany is "How do plants grow and
develop?" Without a mechanistic answer, we will not be able to
understand how plants interact with their environments, how they
reproduce, or how they evolve. In the past decade there has been much
learned from developmental genetics, starting with plants mutant in
single genes, and from experiments with these plants to infer the role
of individual gene products in developmental processes. Such studies
have led to an outline of the mechanism of floral induction and some
aspects of flower development, and of cell behavior in root and shoot
apical meristems. This year we will complete the complete genomic
sequence of a plant, the mustard Arabidopsis thaliana. From
this sequence, we can roughly identify the complete list of genes
necessary for all of the cellular and organismal processes of a plant.
This list of parts gives us, for the first time, a view of the total
complexity of a plant and its life processes. It also gives us, based
on earlier work on single genes, a series of testable hypotheses for
the mechanisms by which plant cells communicate with each other, and
learn their positions in developing tissues. One conclusion is that
plants have hundreds of receptor protein kinases of a type not found
in animals, that appear to form a regulatory network for communication
between plant cells that may act to control relative rates of cell
division and differentiation. The Arabidopsis genome
contains, in addition to many genes whose biochemical function can be
inferred from comparison to known genes, over 10,000 genes that code
for proteins that are completely unfamiliar. Thus the genomic
sequence also allows us to quantitate our ignorance; the quantity is
large.
Key words: Arabidopsis thaliana , development, developmental genetics, genomics, meristems