title: Induction of thioredoxin is required for nodule development to reduce reactive oxygen species levels in soybean roots.
abstract: Nodules are formed on legume roots as a result of signaling between symbiotic partners and in response to the activities of numerous genes. We cloned fragments of differentially expressed genes in spot-inoculated soybean (Glycine max) roots. Many of the induced clones were similar to known genes related to oxidative stress, such as thioredoxin and beta-carotene hydroxylase. The deduced amino acid sequences of full-length soybean cDNAs for thioredoxin and beta-carotene hydroxylase were similar to those in other species. In situ RNA hybridization revealed that the thioredoxin gene is expressed on the pericycle of 2-d-old nodules and in the infected cells of mature nodules, suggesting that thioredoxin is involved in nodule development. The thioredoxin promoter was found to contain a sequence resembling an antioxidant responsive element. When a thioredoxin mutant of yeast was transformed with the soybean thioredoxin gene it became hydrogen peroxide tolerant. These observations prompted us to measure reactive oxygen species levels. These were decreased by 3- to 5-fold in 7-d-old and 27-d-old nodules, coincident with increases in the expression of thioredoxin and beta-carotene hydroxylase genes. Hydrogen peroxide-producing regions identified with cerium chloride were found in uninoculated roots and 2-d-old nodules, but not in 7-d-old and 27-d-old nodules. RNA interference-mediated repression of the thioredoxin gene severely impaired nodule development. These data indicate that antioxidants such as thioredoxin are essential to lower reactive oxygen species levels during nodule development.
authors.affiliation: Department of Biological Science, Sookmyung Women's University, Seoul 140-742, Korea.
authors.forename: Mi-Young
authors.initials: MY
authors.lastname: Lee
authors.forename: Ki-Hye
authors.initials: KH
authors.lastname: Shin
authors.forename: Yun-Kyoung
authors.initials: YK
authors.lastname: Kim
authors.forename: Ji-Yeon
authors.initials: JY
authors.lastname: Suh
authors.forename: Young-Yun
authors.initials: YY
authors.lastname: Gu
authors.forename: Mi-Ran
authors.initials: MR
authors.lastname: Kim
authors.forename: Yoon-Sun
authors.initials: YS
authors.lastname: Hur
authors.forename: Ora
authors.initials: O
authors.lastname: Son
authors.forename: Jin-Sun
authors.initials: JS
authors.lastname: Kim
authors.forename: Eunsook
authors.initials: E
authors.lastname: Song
authors.forename: Myeong-Sok
authors.initials: MS
authors.lastname: Lee
authors.forename: Kyoung Hee
authors.initials: KH
authors.lastname: Nam
authors.forename: Keum Hee
authors.initials: KH
authors.lastname: Hwang
authors.forename: Mi-Kyung
authors.initials: MK
authors.lastname: Sung
authors.forename: Ho-Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jong-Yoon
authors.initials: JY
authors.lastname: Chun
authors.forename: Miey
authors.initials: M
authors.lastname: Park
authors.forename: Tae-In
authors.initials: TI
authors.lastname: Ahn
authors.forename: Choo Bong
authors.initials: CB
authors.lastname: Hong
authors.forename: Suk-Ha
authors.initials: SH
authors.lastname: Lee
authors.forename: Hong Jae
authors.initials: HJ
authors.lastname: Park
authors.forename: Jong-Sug
authors.initials: JS
authors.lastname: Park
authors.forename: Desh Pal S
authors.initials: DP
authors.lastname: Verma
authors.forename: Choong-Ill
authors.initials: CI
authors.lastname: Cheon
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D018744:DNA, Plant / Q000235:genetics / Q000302:isolation & purification; D017343:Genes, Plant; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006899:Mixed Function Oxygenases / Q000235:genetics; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000096:biosynthesis* / Q000235:genetics; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013025:Glycine max / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D013559:Symbiosis; D013879:Thioredoxins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D018744:DNA, Plant; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D013879:Thioredoxins; D006861:Hydrogen Peroxide; D006899:Mixed Function Oxygenases; C079232:beta-carotene hydroxylase