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Kang J.,Peking University | Zhang H.,Peking University | Sun T.,Peking University | Shi Y.,Peking University | And 7 more authors.
New Phytologist | Year: 2013

We used a monophyletic group of four natural populations of Arabidopsis thaliana expanded from a single ancestor along the Yangtze River c. 90 000 yr ago to study the molecular mechanism of the divergence in their freezing tolerance, in order to gain an insight into the genetic basis of their local adaption to low temperatures. Freezing tolerance assays, measurements of metabolites in the raffinose biosynthesis pathway and transactivation-activity assays of variation in forms of cold-responsive transcription factors were conducted on the four populations. Quantitative trait locus mapping was adopted with F2 populations of the most- and least freezing-tolerant populations. The degree of freezing tolerance among the four populations was negatively correlated with the lowest monthly average temperature of January in their native habitats, and positively correlated to the expression level of some cold-regulated genes. We identified a major locus harboring three cold-responsive transcription factor genes CBF1-3, and found a nucleotide insertion in CBF2 in all populations except SXcgx, which generated a dysfunctional CBF2 protein. The CBF2 in SXcgx experienced a stronger natural selection in the cooler environment after CBF3 lost its response to low temperature, which possibly reflects a local adaptation of these populations during the expansion from a common ancestor. © 2013 The Authors © 2013 New Phytologist Trust. Source

Chen Y.,China Agricultural University | Chen Z.,China Agricultural University | Chen Z.,Peking University | Kang J.,Peking University | And 4 more authors.
Plant Molecular Biology Reporter | Year: 2013

Low temperature affects plant growth and crop productivity. The CBF genes are a class of transcription factors that play important roles in cold response. Here we report that AtMYB14 participates in freezing tolerance in Arabidopsis by affecting expression of CBF genes. The AtMYB14 gene was down-regulated by cold treatment. AtMYB14 encodes a nuclear protein that functions as an R2R3-MYB transcription activator. Knock-down of AtMYB14 by artificial microRNA increased the tolerance to freezing stress. Both the CBF genes and the downstream genes were induced to a much higher level in AtMYB14 knock-down plants than in wild type under cold treatment. Our results suggest that AtMYB14 plays an important role in the plant response to cold stress. © 2012 The Author(s). Source

Yang Y.,Tsinghua University | Li L.,Tsinghua University | Qu L.-J.,Tsinghua University | Qu L.-J.,The National Plant Gene Research Center Beijing
Journal of Integrative Plant Biology | Year: 2016

The Mediator complex is an important component of the eukaryotic transcriptional machinery. As an essential link between transcription factors and RNA polymerase II, the Mediator complex transduces diverse signals to genes involved in different pathways. The plant Mediator complex was recently purified and comprises conserved and specific subunits. It functions in concert with transcription factors to modulate various responses. In this review, we summarize the recent advances in understanding the plant Mediator complex and its diverse roles in plant growth, development, defense, non-coding RNA production, response to abiotic stresses, flowering, genomic stability and metabolic homeostasis. In addition, the transcription factors interacting with the Mediator complex are also highlighted. © 2016 Institute of Botany, Chinese Academy of Sciences. Source

Han L.,China Agricultural University | Qin G.,Peking University | Kang D.,China Agricultural University | Chen Z.,China Agricultural University | And 5 more authors.
Journal of Genetics and Genomics | Year: 2010

Complex I (the NADH:ubiquinone oxidoreductase) of the mitochondrial respiratory chain is a complicated, multi-subunit, membrane-bound assembly and contains more than 40 different proteins in higher plants. In this paper, we characterize the Arabidopsis homologue (designated as AtCIB22) of the B22 subunit of eukaryotic mitochondrial Complex I. AtCIB22 is a single-copy gene and is highly conserved throughout eukaryotes. AtCIB22 protein is located in mitochondria and the AtCIB22 gene is widely expressed in different tissues. Mutant Arabidopsis plants with a disrupted AtCIB22 gene display pleiotropic phenotypes including shorter roots, smaller plants and delayed flowering. Stress analysis indicates that the AtCIB22 mutants' seed germination and early seedling growth are severely inhibited by sucrose deprivation stress but more tolerant to ethanol stress. Molecular analysis reveals that in moderate knockdown AtCIB22 mutants, genes including cell redox proteins and stress related proteins are significantly up-regulated, and that in severe knockdown AtCIB22 mutants, the alternative respiratory pathways including NDA1, NDB2, AOX1a and AtPUMP1 are remarkably elevated. These data demonstrate that AtCIB22 is essential for plant development and mitochondrial electron transport chains in Arabidopsis. Our findings also enhance our understanding about the physiological role of Complex I in plants. © 2010 Institute of Genetics and Developmental Biology and the Genetics Society of China. Source

Luo Y.,Peking University | Qin G.,Peking University | Zhang J.,Peking University | Liang Y.,Peking University | And 9 more authors.
Plant Cell | Year: 2011

In animal cells, myo-inositol is an important regulatory molecule in several physiological and biochemical processes, including signal transduction and membrane biogenesis. However, the fundamental biological functions of myo-inositol are still far from clear in plants. Here, we report the genetic characterization of three Arabidopsis thaliana genes encoding D-myo-inositol-3-phosphate synthase (MIPS), which catalyzes the rate-limiting step in de novo synthesis of myo-inositol. Each of the three MIPS genes rescued the yeast ino1 mutant, which is defective in yeast MIPS gene INO1, and they had different dynamic expression patterns during Arabidopsis embryo development. Although single mips mutants showed no obvious phenotypes, the mips1 mips2 double mutant and the mips1 mips2 mips3 triple mutant were embryo lethal, whereas the mips1 mips3 and mips1 mips2+/2 double mutants had abnormal embryos. The mips phenotypes resembled those of auxin mutants. Indeed, the double and triple mips mutants displayed abnormal expression patterns of DR5:green fluorescent protein, an auxin-responsive fusion protein, and they had altered PIN1 subcellular localization. Also, membrane trafficking was affected in mips1 mips3. Interestingly, overexpression of PHOSPHATIDYLINOSITOL SYNTHASE2, which converts myo-inositol to membrane phosphatidylinositol (PtdIns), largely rescued the cotyledon and endomembrane defects in mips1 mips3. We conclude that myo-inositol serves as the main substrate for synthesizing PtdIns and phosphatidylinositides, which are essential for endomembrane structure and trafficking and thus for auxin-regulated embryogenesis. © 2011 American Society of Plant Biologists. Source

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