Emission of ent-kaurene, a diterpenoid hydrocarbon precursor for gibberellins, into the headspace from plants.
ent-Kaurene is a tetracyclic hydrocarbon precursor for gibberellins (GAs) in plants and fungi. To address whether fungal GA biosynthesis enzymes function in plants, we generated transgenic Arabidopsis plants overexpressing ent-kaurene synthase (GfCPS/KS) from a GA-producing fungus Gibberella fujikuroi. GfCPS/KS catalyzes a two-step reaction corresponding to ent-copalyl diphosphate synthase (CPS) and ent-kaurene synthase (KS) activities in plants. When GfCPS/KS was overexpressed and targeted to plastids, a range of GA-deficient phenotypes of the ga1-3 and ga2-1 mutants (defective in CPS and KS, respectively) were restored to wild type. Unexpectedly, the transgenic lines overproducing GfCPS/KS emitted the GA precursor ent-kaurene into the headspace besides its accumulation in the plant body. When co-cultivated with the ent-kaurene overproducers in a closed environment, the airborne ent-kaurene was able to fully complement the dwarf phenotype of ga1-3 and ga2-1 mutants, but not that of the ga3-1 mutant (defective in ent-kaurene oxidase). These results suggest that ent-kaurene may be efficiently metabolized into bioactive GAs in Arabidopsis when supplied as a volatile. We also provide evidence that ent-kaurene is released in the headspace of wild-type Chamaecyparis obtusa and Cryptomeria japonica plants, suggesting the occurrence of this hydrocarbon GA precursor as a volatile in nature.
Otsuka
Minoru
M
Course of the Science of Bioresources, United Graduate School of Agricultural Sciences, Iwate University (Yamagata University), Tsuruoka, Yamagata, 997-8555 Japan.
Kenmoku
Hiromichi
H
Ogawa
Mikihiro
M
Okada
Kazunori
K
Mitsuhashi
Wataru
W
Sassa
Takeshi
T
Kamiya
Yuji
Y
Toyomasu
Tomonobu
T
Yamaguchi
Shinjiro
S
D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D017931:DNA Primers; D045786:Diterpenes, Kaurane / Q000378:metabolism*; D005875:Gibberellins / Q000096:biosynthesis*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D045786:Diterpenes, Kaurane; D005875:Gibberellins; C002627:kaurene; D019883:Alkyl and Aryl Transferases; C021459:kaurene synthetase