title: Step-by-step acquisition of the gibberellin-DELLA growth-regulatory mechanism during land-plant evolution.
abstract: Angiosperms (flowering plants) evolved relatively recently and are substantially diverged from early land plants (bryophytes, lycophytes, and others [1]). The phytohormone gibberellin (GA) adaptively regulates angiosperm growth via the GA-DELLA signaling mechanism [2-7]. GA binds to GA receptors (GID1s), thus stimulating interactions between GID1s and the growth-repressing DELLAs [8-12]. Subsequent 26S proteasome-mediated destruction of the DELLAs promotes growth [13-17]. Here we outline the evolution of the GA-DELLA mechanism. We show that the interaction between GID1 and DELLA components from Selaginella kraussiana (a lycophyte) is GA stimulated. In contrast, GID1-like (GLP1) and DELLA components from Physcomitrella patens (a bryophyte) do not interact, suggesting that GA-stimulated GID1-DELLA interactions arose in the land-plant lineage after the bryophyte divergence ( approximately 430 million years ago [1]). We further show that a DELLA-deficient P. patens mutant strain lacks the derepressed growth characteristic of DELLA-deficient angiosperms, and that both S. kraussiana and P. patens lack detectable growth responses to GA. These observations indicate that early land-plant DELLAs do not repress growth in situ. However, S. kraussiana and P. patens DELLAs function as growth-repressors when expressed in the angiosperm Arabidopsis thaliana. We conclude that the GA-DELLA growth-regulatory mechanism arose during land-plant evolution and via independent stepwise recruitment of GA-stimulated GID1-DELLA interaction and DELLA growth-repression functions.
authors.affiliation: John Innes Centre, Norwich Research Park, Colney, Norwich, United Kingdom.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Yasumura
authors.forename: Matilda
authors.initials: M
authors.lastname: Crumpton-Taylor
authors.forename: Sara
authors.initials: S
authors.lastname: Fuentes
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Harberd
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D005075:Biological Evolution; D019068:Bryopsida / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D005875:Gibberellins / Q000378:metabolism*; D008969:Molecular Sequence Data; D063245:Plant Development; D010937:Plant Growth Regulators / Q000378:metabolism*; D010944:Plants / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D032503:Selaginellaceae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C512225:GID1a protein, Arabidopsis; D005875:Gibberellins; D010937:Plant Growth Regulators; D011956:Receptors, Cell Surface; D014157:Transcription Factors