CHASE domain-containing receptors play an essential role in the cytokinin response of the moss Physcomitrella patens

0459220 - ÚEB 2017 RIV GB eng J - Journal Article
von Schwartzenberg, K. - Lindner, A.C. - Gruhn, N. - Šimura, Jan - Novák, Ondřej - Strnad, Miroslav - Gonneau, M. - Nogue, F. - Heyl, A.
CHASE domain-containing receptors play an essential role in the cytokinin response of the moss Physcomitrella patens.
Journal of Experimental Botany. Roč. 67, č. 3 (2016), s. 667-679. ISSN 0022-0957. E-ISSN 1460-2431
R&D Projects: GA MŠMT(CZ) LO1204
Institutional support: RVO:61389030
Keywords : cytokinin * Bryophyte * cytokinin receptor
Subject RIV: EB - Genetics ; Molecular Biology
Impact factor: 5.830, year: 2016

While the molecular basis for cytokinin action is quite well understood in flowering plants, little is known about the cytokinin signal transduction in early diverging land plants. The genome of the bryophyte Physcomitrella patens ( Hedw.) B.S. encodes three classical cytokinin receptors, the CHASE domain-containing histidine kinases, CHK1, CHK2, and CHK3. In a complementation assay with protoplasts of receptor-deficient Arabidopsis thaliana as well as in cytokinin binding assays, we found evidence that CHK1 and CHK2 receptors can function in cytokinin perception. Using gene targeting, we generated a collection of CHK knockout mutants comprising single (Delta chk1, Delta chk2, Delta chk3), double (Delta chk1,2, Delta chk1,3, Delta chk2,3), and triple (Delta chk1,2,3) mutants. Mutants were characterized for their cytokinin response and differentiation capacities. While the wild type did not grow on high doses of cytokinin (1 mu M benzyladenine), the Delta chk1,2,3 mutant exhibited normal protonema growth. Bud induction assays showed that all three cytokinin receptors contribute to the triggering of budding, albeit to different extents. Furthermore, while the triple mutant showed no response in this bioassay, the remaining mutants displayed budding responses in a diverse manner to different types and concentrations of cytokinins. Determination of cytokinin levels in mutants showed no drastic changes for any of the cytokinins; thus, in contrast to Arabidopsis, revealing only small impacts of cytokinin signaling on homeostasis. In summary, our study provides a first insight into the molecular action of cytokinin in an early diverging land plant and demonstrates that CHK receptors play an essential role in bud induction and gametophore development.
Permanent Link: http://hdl.handle.net/11104/0259449