Cytokinins (CKs) regulate plant development and growth via a two-component signaling pathway. By forward genetic screening, we isolated an Arabidopsis mutant named grow fast on cytokinins 1 (gfc1), whose seedlings grew larger aerial parts on MS medium with CK. gfc1 is allelic to a previously reported cutin mutant defective in cuticular ridges (dcr). GFC1/DCR encodes a soluble BAHD acyltransferase (a name based on the first four enzymes characterized in this family: Benzylalcohol O-acetyltransferase, Anthocyanin O-hydroxycinnamoyltransferase, anthranilate N-hydroxycinnamoyl/benzoyltransferase and Deacetylvindoline 4-O-acetyltransferase) with diacylglycerol acyltransferase (DGAT) activity in vitro and is necessary for normal cuticle formation on epidermis in vivo. Here we show that gfc1 was a CK-insensitive mutant, as revealed by its low regeneration frequency in vitro and resistance to CK in adventitious root formation and dark-grown hypocotyl inhibition assays. In addition, gfc1 had de-etiolated phenotypes in darkness and was therefore defective in skotomorphogenesis. The background expression levels of most type-A Arabidopsis Response Regulator (ARR) genes were higher in the gfc1 mutant. The gfc1-associated phenotypes were also observed in the cutin-deficient glycerol-3-phosphate acyltransferase 4/8 (gpat4/8) double mutant [defective in glycerol-3-phosphate (G3P) acyltransferase enzymes GPAT4 and GPAT8, which redundantly catalyze the acylation of G3P by hydroxyl fatty acid (OH-FA)], but not in the cutin-deficient mutant cytochrome p450, family 86, subfamily A, polypeptide 2/aberrant induction of type three 1 (cyp86A2/att1), which affects the biosynthesis of some OH-FAs. Our results indicate that some acyltransferases associated with cutin formation are involved in CK responses and skotomorphogenesis in Arabidopsis.
- MeSH
- acyltransferasy genetika metabolismus MeSH
- Arabidopsis genetika růst a vývoj metabolismus účinky záření MeSH
- cytokininy metabolismus farmakologie MeSH
- fenotyp MeSH
- membránové lipidy biosyntéza MeSH
- meristém účinky léků genetika růst a vývoj účinky záření MeSH
- morfogeneze * účinky léků účinky záření MeSH
- mutace MeSH
- proteiny huseníčku genetika metabolismus MeSH
- regulace genové exprese u rostlin účinky léků účinky záření MeSH
- semenáček účinky léků genetika růst a vývoj účinky záření MeSH
- tma MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Light is one of the most important factor influencing plant growth and development all through their life cycle. One of the well-known light-regulated processes is de-etiolation, i.e. the switch from skotomorphogenesis to photomorphogenesis. The hormones cytokinins (CKs) play an important role during the establishment of photomorphogenesis as exogenous CKs induced photomorphogenesis of dark-grown seedlings. Most of the studies are conducted on the plant model Arabidopsis, but no or few information are available for important crop species, such as tomato (Solanum lycopersicum L.). In our study, we analyzed for the first time the endogenous CKs content in tomato hypocotyls during skotomorphogenesis, photomorphogenesis and de-etiolation. For this purpose, two tomato genotypes were used: cv. Rutgers (wild-type; WT) and its corresponding mutant (7B-1) affected in its responses to blue light (BL). Using physiological and molecular approaches, we identified that the skotomorphogenesis is characterized by an endoreduplication-mediated cell expansion, which is inhibited upon BL exposure as seen by the accumulation of trancripts encoding CycD3, key regulators of the cell cycle. Our study showed for the first time that iP (isopentenyladenine) is the CK accumulated in the tomato hypocotyl upon BL exposure, suggesting its specific role in photomorphogenesis. This result was supported by physiological experiments and gene expression data. We propose a common model to explain the role and the relationship between CKs, namely iP, and endoreduplication during de-etiolation and photomorphogenesis.
- MeSH
- buněčný cyklus účinky léků genetika MeSH
- cyklin D3 genetika metabolismus MeSH
- cytokininy metabolismus MeSH
- endoreduplikace fyziologie účinky záření MeSH
- fylogeneze MeSH
- hypokotyl fyziologie účinky záření MeSH
- isopentenyladenosin metabolismus MeSH
- morfogeneze fyziologie účinky záření MeSH
- ploidie MeSH
- rostlinné proteiny genetika metabolismus MeSH
- semenáček fyziologie účinky záření MeSH
- Solanum lycopersicum fyziologie účinky záření MeSH
- světlo MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
