Overexpression of acetylcholinesterase gene in rice results in enhancement of shoot gravitropism.
Acetylcholine (ACh), a known neurotransmitter in animals and acetylcholinesterase (AChE) exists widely in plants, although its role in plant signal transduction is unclear. We previously reported AChE in Zea mays L. might be related to gravitropism based on pharmacological study using an AChE inhibitor. Here we clearly demonstrate plant AChE play an important role as a positive regulator in the gravity response of plants based on a genetic study. First, the gene encoding a second component of the ACh-mediated signal transduction system, AChE was cloned from rice, Oryza sativa L. ssp. Japonica cv. Nipponbare. The rice AChE shared high homology with maize, siratro and Salicornia AChEs. Similar to animal and other plant AChEs, the rice AChE hydrolyzed acetylthiocholine and propionylthiocholine, but not butyrylthiocholine. Thus, the rice AChE might be characterized as an AChE (E.C.3.1.1.7). Similar to maize and siratro AChEs, the rice AChE exhibited low sensitivity to the AChE inhibitor, neostigmine bromide, compared with the electric eel AChE. Next, the functionality of rice AChE was proved by overexpression in rice plants. The rice AChE was localized in extracellular spaces of rice plants. Further, the rice AChE mRNA and its activity were mainly detected during early developmental stages (2 d-10 d after sowing). Finally, by comparing AChE up-regulated plants with wild-type, we found that AChE overexpression causes an enhanced gravitropic response. This result clearly suggests that the function of the rice AChE relate to positive regulation of gravitropic response in rice seedlings.
Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, Hokkaido, 099-2493, Japan. Electronic address: kosuke2106@gmail.com.
Kosuke
K
Yamamoto
Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, Hokkaido, 099-2493, Japan.
Satoshi
S
Shida
Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, Hokkaido, 099-2493, Japan.
Yoshihiro
Y
Honda
Tropical Agriculture Research Front, Japan International Research Center for Agricultural Sciences, Maezato-Kawarabaru, Ishigaki, Okinawa, 907-0002, Japan.
Mariko
M
Shono
Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
Hiroshi
H
Miyake
Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, Hokkaido, 099-2493, Japan.
Suguru
S
Oguri
Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, Hokkaido, 099-2493, Japan.
Hikaru
H
Sakamoto
Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, Hokkaido, 099-2493, Japan. Electronic address: y-momono@bioindustry.nodai.ac.jp.
Yoshie S
YS
Momonoki
D000110:Acetylcholinesterase / Q000235:genetics / Q000378:metabolism*; D024861:Genetic Enhancement / Q000379:methods*; D018522:Gravitropism / Q000502:physiology*; D012275:Oryza / Q000502:physiology*; D018520:Plant Shoots / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology
D000110:Acetylcholinesterase
ACh; AChE; Acetylcholine; Acetylcholinesterase; Gravitropism; Rice (Oryza sativa)