Step-by-step acquisition of the gibberellin-DELLA growth-regulatory mechanism during land-plant evolution.
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.
Yasumura
Yuki
Y
John Innes Centre, Norwich Research Park, Colney, Norwich, United Kingdom.
Crumpton-Taylor
Matilda
M
Fuentes
Sara
S
Harberd
Nicholas P
NP
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*
D029681:Arabidopsis Proteins; C512225:GID1a protein, Arabidopsis; D005875:Gibberellins; D010937:Plant Growth Regulators; D011956:Receptors, Cell Surface; D014157:Transcription Factors