Programmed cell death in barley aleurone cells is not directly stimulated by reactive oxygen species produced in response to gibberellin.
The cereal aleurone layer is a secretory tissue that produces enzymes to hydrolyze the starchy endosperm during germination. We recently demonstrated that reactive oxygen species (ROS), produced in response to gibberellins (GA), promoted GAMyb expression, which induces α-amylase expression in barley aleurone cells. On the other hand, ROS levels increase during programmed cell death (PCD) in barley aleurone cells, and GAMyb is involved in PCD of these cells. In this study, we investigated whether the ROS produced in response to GA regulate PCD directly by using mutants of Slender1 (SLN1), a DELLA protein that negatively regulates GA signaling. The wild-type, the sln1c mutant (which exhibits gibberellin-type signaling even in the absence of GA), and the Sln1d mutant (which is gibberellin-insensitive with respect to α-amylase production) all produced ROS in response to GA, suggesting that ROS production in aleurone cells in response to GA is independent of GA signaling through this DELLA protein. Exogenous GA promoted PCD in the wild-type. PCD in sln1c was induced even without exogenous GA (and so without induction of ROS), whereas PCD in Sln1d was not induced in the presence of exogenous GA, even though the ROS content increased significantly in response to GA. These results suggest that PCD in barley aleurone cells is not directly stimulated by ROS produced in response to GA but is regulated by GA signaling through DELLA protein.
Crop Science Laboratory, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
Nozomi
N
Aoki
Crop Science Laboratory, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan. Electronic address: yushi@agr.kyushu-u.ac.jp.
Yushi
Y
Ishibashi
Crop Science Laboratory, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
Kyohei
K
Kai
Crop Science Laboratory, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
Reisa
R
Tomokiyo
Faculty of Agriculture, Miyazaki University, 1-1 Gakuenkibanadai-nishi, Miyazaki, Japan.
Takashi
T
Yuasa
Crop Science Laboratory, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
Mari
M
Iwaya-Inoue
D017209:Apoptosis / Q000502:physiology*; D056625:Endosperm / Q000166:cytology / Q000378:metabolism; D018525:Germination / Q000187:drug effects; D005875:Gibberellins / Q000494:pharmacology*; D001467:Hordeum / Q000166:cytology / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction
D005875:Gibberellins; D010940:Plant Proteins; D017382:Reactive Oxygen Species
Aleurone cells; DELLA protein; Gibberellin signaling; Programmed cell death; Reactive oxygen species