Rice CYO1, an ortholog of Arabidopsis thaliana cotyledon chloroplast biogenesis factor AtCYO1, is expressed in leaves and involved in photosynthetic performance.
In the dicotyledonous plant Arabidopsis thaliana, the cotyledon chloroplast biogenesis factor AtCYO1 is crucial for the biogenesis of cotyledon chloroplasts. Arabidopsis mutants lacking AtCYO1 have pale cotyledons but develop normal mature leaves. In the monocotyledonous plant Oryza sativa, the gene OsCYO1 has high sequence identity to AtCYO1, but its function is unknown. We examined the role of OsCYO1 in O. sativa. We first confirmed that transformation with OsCYO1 could recover the phenotype of the Arabidopsis cyo1 mutant. Similar to AtCYO1, recombinant OsCYO1 has protein disulfide reductase (PDR) activity, which increased as a function of dieosin glutathione disulfide concentration with an apparent Kmof 3.2μM and Kcatof 0.53min-1. The PDR activity was reduced when NADPH or NADH was used as an electron donor; however, PDR activity was observed with OsCYO1 and glutathione, suggesting that glutathione may serve as a reducing agent for OsCYO1 in vivo. In O. sativa, the OsCYO1 transcript level was higher in leaves compared with the coleoptile, which is the first leaf-like organ that forms during rice embryogenesis. Many OsCYO1 mutant lines defective in RNA interference had green leaves, however, three mutant lines had not only albino coleoptile but also albino leaves. Those having green leaves reduced photosynthetic performance in leaves. Our results demonstrate that OsCYO1 is enzymatically equivalent to AtCYO1 but that the physiological role of OsCYO1 in monocotyledonous plants may differ from that of AtCYO1 in dicotyledonous plants.
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan.
Jun
J
Tominaga
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan.
Haruka
H
Mizutani
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan.
Daisuke
D
Horikawa
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan.
Yasutoshi
Y
Nakahara
Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, 710-0046, Japan.
Tsuneaki
T
Takami
Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama, 710-0046, Japan.
Wataru
W
Sakamoto
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan.
Atsushi
A
Sakamoto
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan. Electronic address: hshimada@hiroshima-u.ac.jp.
Hiroshi
H
Shimada
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D003080:Cold Temperature; D018548:Cotyledon / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D012275:Oryza / Q000378:metabolism*; D010641:Phenotype; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D011490:Protein Disulfide Reductase (Glutathione) / Q000378:metabolism; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D011490:Protein Disulfide Reductase (Glutathione)
CYO1; Coleoptile; Cotyledon; Leaf; Oryza sativa; Pulse amplitude modulation