We will take advantage of the established genetic system of moss
in which transformation and homologous recombination can be reproducibly
utilized to apply a random (e.g. insertional mutagenesis) and targeted
approach (RNAi and homologous recombination) to identify genes involved
in: 1). the establishment and/or realignment of a polar axis. Our focus will
be on genes whose products have certain characteristics of surface or
secreted proteins (e.g. arabinogalactan proteins) and/or whose products are
involved with actin dynamics (e.g. ARP2/3 complex).
2). the ABA signaling pathway. Our focus will be on genes in moss that are
similar to those in the ABA/desiccation response pathways in seed plants
(e.g. abi1), and in the promoters of those genes in moss that are
differentially regulated when ABA/drought treatment is applied
An example of this approach is shown in
(Figs. 5 and
in which a knock-out
of the p20 protein of the ARP 2/3 complex results in a phenotype in which
elongation of certain filamentous cells results in a more compact and
restricted colony morphology. We have also developed an RNAi strategy [
Pl.Physiol. 133:470-74 (2003) ] in which we use tissue bombardment to view
any altered phenotype in tissue that is silenced, using silenced GFP as an
One of our approaches to study the ABA/desiccation pathway(s) is a
comparative one to determine the evolution of the ABA pathway and its
relationship to desiccation tolerance in moss and to seed development in
Arabidopsis. Agilent microarrays for moss and Arabidopsis are being
utilized to characterize this gene regulatory network. For example, in
expression microarray data from moss protonemal cells treated
with ABA for two hours results in a number of genes being increased (red)
or reduced (green), while thousands remain unchanged (blue). Over 20,000
60-mers are displayed on the chip representing the contigs defined by the
dataset (~80,000 ESTs) from the Hasebe lab in Japan (moss.nibb.ac.jp)
In 2005 the full moss genome will be sequenced as part of the Community
Sequencing Program at the Department of Energy.
Current Research Topics
Control and Identification of Gene Regulatory Networks Involved in Stress
Responses (Drought and Redox Homeostaesis) in Arabidopsis and
Chemical Inducers of Gene Expression (Arabidopsis).
Genes and Gene Complexes Involved in Orienting Polar Growth in Response to
Gravity and Light (Physcomitrella).
Role of the Transcriptional Regulator ABI3 in ABA Signaling: A Comparative
Functional Approach (Physcomitrella and Arabidopsis).
The Physcomitrella Genome: Evolutionary and Genomic Studies.