Either soluble or plastidic expression of recombinant protoporphyrinogen oxidase modulates tetrapyrrole biosynthesis and photosynthetic efficiency in transgenic rice.
Protoporphyrinogen oxidase (Protox) is the last shared enzyme of the porphyrin pathway. As a continuation of our previous work in which the transgenic rice plants expressing the Bacillus subtilis Protox in the cytoplasm or the plastid showed resistance to diphenyl ether herbicide, this study was undertaken to identify the effects of tertapyrrole biosynthesis in these transgenic rice plants. The transgenic plants either targeted into plastids or expressed in cytoplasm showed higher Protox activity than wild-type plants did. Photosynthetic activity, measured as a quantum yield of photosystem II, was slightly higher in transgenic plants than in wild-type plants, but chlorophyll contents were not significantly different between transgenic and wild-type plants. As for porphyrin biosynthesis, both cytoplasm-expressed and plastid-targeted transgenic plants showed increased synthesis of aminolevulinic acid, Mg-Proto IX, and protoheme in comparison to wild-type plants whereas synthesis of protoporphyrin IX was similar for wild-type and transgenic plants. These results indicate that either cytoplasm or plastid expression of B. subtilis Protox in rice can upregulate the porphyrin pathway leading to increase in photosynthetic efficiency in plants.
Jung
Sunyo
S
Scigen Harvest Research Center, Suwon, Korea.
Chung
Jung Sung
JS
Jang
Sun Mi
SM
Guh
Ja Ock
JO
Lee
Hee Jae
HJ
Chon
Sang-Uk
SU
Kim
Kyung-Moon
KM
Ha
Suk Bong
SB
Back
Kyoungwhan
K
D000622:Aminolevulinic Acid / Q000378:metabolism; D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics; D015153:Blotting, Western; D002245:Carbon Dioxide / Q000378:metabolism; D002734:Chlorophyll / Q000096:biosynthesis; D015870:Gene Expression; D005822:Genetic Vectors / Q000235:genetics; D006418:Heme / Q000378:metabolism; D012275:Oryza / Q000235:genetics* / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology*; D030821:Plants, Genetically Modified; D018087:Plastids / Q000235:genetics*; D050768:Protoporphyrinogen Oxidase; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012995:Solubility; D045725:Tetrapyrroles / Q000096:biosynthesis*
D012333:RNA, Messenger; D011994:Recombinant Proteins; D045725:Tetrapyrroles; D002734:Chlorophyll; D002245:Carbon Dioxide; D006418:Heme; D000622:Aminolevulinic Acid; D044925:Oxidoreductases Acting on CH-CH Group Donors; D050768:Protoporphyrinogen Oxidase