Importance of the rice TCD9 encoding α subunit of chaperonin protein 60 (Cpn60α) for the chloroplast development during the early leaf stage

• Published in: Plant science (Limerick) 2014-02, Vol.215-216, p.172-179
• Main Authors: Jiang, Quan, Mei, Jie, Gong, Xiao-Di, Xu, Jian-Long, Zhang, Jian-Hui, Teng, Sheng, Lin, Dong-Zhi, Dong, Yan-Jun
• Format: Article
• Language: English
• Subjects: Chaperonin 60 - genetics; Chaperonin 60 - metabolism; Chloroplast development; Chloroplasts - genetics; Chloroplasts - metabolism; Cpn60α protein; Genes, Chloroplast; Genes, Plant; Map-based cloning; Mutation; Oryza - genetics; Oryza - growth & development; Oryza - metabolism; Phenotype; Plant Development - genetics; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant Proteins - genetics; Plant Proteins - metabolism; Protein Subunits - genetics; Protein Subunits - metabolism; Rice (Oryza sativa L.); Seedlings - genetics; Seedlings - growth & development; Seedlings - metabolism; Subcellular localization; Temperature; Thermo-sensitive
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2013.11.003

•The abnormal phenotype of the rice albino mutant (tcd9) seedlings at low temperature was controlled by a single recessive nuclear gene (tcd9).•The TCD9 encoding α submit of Cpn60 protein (Cpn60α) localized in chloroplasts.•All expressions for chloroplast development genes in mutant were seriously affected at 20°C, but some of them recovered to normal levels at 32°C.•The rice Cpn60α protein TCD9 plays a crucial role in chloroplast development at early leaf stage of rice. The chloroplast development governs plant growth and metabolism. This study characterized a novel rice thermo-sensitive chloroplast development 9 (tcd9) mutant, which exhibited the albino phenotype before the 3-leaf stage grown below 24°C whereas displayed normal green at over 28°C or even at 20°C after 5-leaf stage. The obvious decrease in Chl levels, abnormal chloroplasts with few thylakoid lamella and abnormal thylakoids were observed for the albino mutant seedlings at low temperature, but the mutant was apparently normal green at high temperature, suggesting the thermo-sensitivity of albino phenotype. Genetic analysis showed that the albino phenotype was controlled by a single recessive nuclear gene (tcd9). The map-based cloning and molecular complementation tests revealed that the mutation of TCD9 encoding α subunit of Cpn60 protein (Cpn60α), localized in chloroplasts, was responsible for albino phenotype. In addition, TCD9 exhibited the high expression in all tested tissues, especially in young leaves. The transcriptional analysis indicated that all expression levels of the studied genes related to chloroplast development in tcd9 mutant were seriously affected in the albino seedlings at 20°C, whereas some of them recovered into normal levels in green-seedlings at 32°C. Our observations suggest that the nuclear-encoded Cpn60α protein TCD9 plays a crucial role in chloroplast development at early leaf stage of rice.