October 24, 2014 at 5:15 pm

PBIO Colloquium: ‘Conservation of Protein Function across Land Plants,’ Oct. 24

The Environmental & Plant Biology Colloquium Series presents Dr. Ralph S. Quatrano on “Conservation of protein function across land plants: What has the moss system revealed about the roles of the proteins ABI3 and DEK1 in desiccation tolerance and cell polarity?” on Friday, Oct. 24, at 11:50 a.m. in Porter Hall 104.

Dr. Ralph Quatrano

Quatrano is Dean of Engineering and Applied Science and Spencer T. Olin Professor of Biology at Washington University in St. Louis.

Abstract: It is becoming clear that with the increasing number of plant genomes being sequenced, we are finding proteins in non-vascular plants that are similar to those in seed plants. More recently, comparative functional studies have elucidated that a few of these proteins in non-seed plants may exhibit more ancient functional mechanisms, which are related to their role in seed plants. The moss Physcomitrella patens is an excellent model system that can be used for functional comparisons across the plant kingdom, since its genome is well annotated (https://cosmoss.org/), and one can apply efficient gene transfer/insertion technology to test specific gene function from different origins. Two such genes from P. patens will be discussed: defective kernel-1 (dek1) and abscisic acid insensitive 3 (abi3).

Our recent studies on cellular morphogenesis have focused on DEK1, a highly conserved trans-membrane protein found as a signal copy gene in all plants surveyed in the green plant lineage (Liang et al.). It is also required for early seed development, since when absent, the aleurone layer does not form due to an aberrant cell division pattern. Deletion of this gene in P. patens, which lacks seeds, leads to the mis-orientation of cell divisions leading to the lack of a proper meristem and three-dimensional growth of the bud (Perroud et al.). Further evidence will be presented in the seminar. We are now attempting to identify proteins that complex with the cytoplasmic domain and/or the outer loop of DEK1, and their role in controlling the direction, duration and distribution of cell divisions.

Our second major area of research is centered on the gene networks that control desiccation tolerance in seeds. The phytohormone abscisic acid (ABA) and the highly conserved regulatory protein ABI3 are both required for seeds to tolerate desiccation (Yotsui et al.). Both ABA and ABI3 are found in moss, and as in seeds, are both required for desiccation tolerance in P. patens (Khandelwal et al.). Our working hypothesis is that gene regulatory pathways that include both ABA and ABI3 originally evolved for cellular protection from water deficits but independently have been used to provide desiccation tolerance in vegetative tissues of bryophytes and in angiosperm seeds.

Selected Publications

Khandelwal, A., Cho, S. H., Marella, H., Sakata, Y., Perroud, P-F., Pan, A. and Quatrano, R.S. (2010). Role of ABA and ABI3 in desiccation tolerance. Science, 327: 546.

Yotsui, I., Saruhashi, M., Kawato, T., Taji, T., Hayashi, T., Quatrano, R. and Sakata, Y. (2013). ABI3 regulates ABA-responsive gene expression by interacting with the NF-Y complex in Physcomitrella patens. New Phytologist, 199: 101-109.

Liang, Z., Demko, V., Wilson, R., Johnson, K., Rafi, A., Perroud, P-F., Quatrano, R.S., Sen, Z., Shalchian-Tabrizi, K., Otegui, M., Olsen, O-A. and Johansen, W. (2013). The catalytic domain CysPc of the DEK1 calpain is functionally conserved in land plants. Plant Journal, 75: 742-754.

Perroud, P-F., Demko, V., Johansen, W., Wilson,R, Olsen, O-A. and Quatrano, R.S. (2014). Defective Kernel 1 (DEK1) is required for three-dimensional growth in Physcomitrella patens. New Phytologist, 203: 794-804.

Demko, V., Perroud, P-F., Johansen, W., Delwiche, C., Cooper, E., Remme, P., Ako, A., Kugler, K., Mayer, K., Quatrano, R., and Olsen, O-A. (2014). Genetic analysis of DEK1 Loop function in three-dimensional body patterning in Physcomitrella patens. Plant Physiology. In Press.