DR. Chun-Ming Liu's group established a new technology for studying peptide hormones
Figure: Establishment of the antagonistic peptide technology. A, Constructs made for two-dimensional substitutions of CLV3. B, Among 43 individual plants transformed with CLV3Thr6 examined, 30 showed a multi-carpel clv3-like phenotype. C, Inflorescences of wildtype, CLV3Thr6 transgenic, and clv3-2 plants. Compared to the wildtype (left), inflorescences in CLV3Thr6 transgenic plants (middle) had supernumerary flowers, as observed in clv3-2 mutants (right). Bars = 3 mm. D, Schematic model of the antagonistic peptide technology.
In recent years, peptide hormones have been recognized as important signal molecules in plants. Genetic characterization of such peptides is challenging since they are usually encoded by highly redundant small genes. As a proof-of-concept, Dr. Chun-Ming Liu's group used the well-characterized stem cell-restricting CLV3 peptide to develop an antagonistic peptide technology in Arabidopsis. Ala scanning showed that transgenic plant carrying the full-length CLV3 with the conserved Gly residue in its peptide-coding region replaced by Ala exhibited a dominant-negative clv3 phenotype, with enlarged shoot apical meristems and increased numbers of floral organs. The second dimensional amino acid (AA) substitutions were then performed, to replace the Gly residue, one at a time, with other 18 possible AA. Examinations of transgenic plants showed that a Gly to Thr substitution gave the strongest antagonistic effect, in which over 70% of transgenic lines showed the clv3-like phenotype. They also demonstrated that the antagonistic peptide technology is applicable to in vitro treatments and to other CLV3/ESR (CLE) peptides, which provides a powerful tool for functional dissection of widely existed CLE genes in plants. The paper has recently been accepted by [Plant Physiology] as a "Breakthrough Technology".