Abnormal Chloroplast Development and Growth Inhibition in Rice Thioredoxin m Knock-Down Plants

• Published in: Plant physiology (Bethesda) Vol. 148; no. 2; pp. 808 - 817
• Main Authors: Chi, Yong Hun, Moon, Jeong Chan, Park, Jin Ho, Kim, Ho-Seung, Zulfugarov, Ismayil S, Fanata, Wahyu Indra, Jang, Ho Hee, Lee, Jung Ro, Lee, Young Mee, Kim, Sun Tae, Chung, Yong-Yoon, Lim, Chae Oh, Kim, Jae-Yean, Yun, Dae-Jin, Lee, Choon-Hwan, Lee, Kyun Oh, Lee, Sang Yeol
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01-10-2008; American Society of Plant Physiologists
• Subjects: Bioenergetics and Photosynthesis; Biological and medical sciences; Carotenoids - metabolism; Chlorophyll - metabolism; Chloroplast Thioredoxins - genetics; Chloroplast Thioredoxins - metabolism; Chloroplasts; Chloroplasts - metabolism; Chloroplasts - ultrastructure; Complementary DNA; Disulfides; Dithiothreitol - metabolism; Electrophoresis, Gel, Two-Dimensional; Enzymes; Fundamental and applied biological sciences. Psychology; Genes, Plant; Hydrogen Peroxide - metabolism; Leaves; Oryza - genetics; Oryza - growth & development; Oryza - metabolism; Peroxiredoxins - metabolism; Phenotype; Photosynthesis; Pigments; Plant physiology and development; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; Protein Isoforms - genetics; Protein Isoforms - metabolism; Receptor, Insulin - metabolism; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Rice; RNA Interference; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Plant - genetics; RNA, Plant - metabolism; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Substrate Specificity; Thioredoxin; Transgenic plants; Monocotyledones; Oryza; Plant physiology; Gramineae; Growth; Angiospermae; Herbaceous plant; Spermatophyta; Inhibition; Thioredoxin; Chloroplast
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.108.123547

Plant cells contain several thioredoxin isoforms that are characterized by subcellular localization and substrate specificity. Here, we describe the functional characterization of a rice (Oryza sativa) thioredoxin m isoform (Ostrxm) using a reverse genetics technique. Ostrxm showed green tissue-specific and light-responsive mRNA expression. Ostrxm was localized in chloroplasts of rice mesophyll cells, and the recombinant protein showed dithiothreitol-dependent insulin β-chain reduction activity in vitro. RNA interference (RNAi) of Ostrxm resulted in rice plants with developmental defects, including semidwarfism, pale-green leaves, abnormal chloroplast structure, and reduced carotenoid and chlorophyll content. Ostrxm RNAi plants showed remarkably decreased Fv/Fm values under high irradiance conditions (1,000 μmol m⁻² s⁻¹) with delayed recovery. Two-dimensional electrophoresis and matrix-assisted laser-desorption/ionization time-of-flight analysis showed that the levels of several chloroplast proteins critical for photosynthesis and biogenesis were significantly decreased in Ostrxm RNAi plants. Furthermore, 2-Cys peroxiredoxin, a known target of thioredoxin, was present in oxidized forms, and hydrogen peroxide levels were increased in Ostrxm RNAi plants. The pleiotropic effects of Ostrxm RNAi suggest that Ostrxm plays an important role in the redox regulation of chloroplast target proteins involved in diverse physiological functions.