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Environmental regulation of floral anthocyanin synthesis in Ipomoea purpurea

Authors

  • YINGQING LU,

    1. State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, 20 Nan Xin Cun, Beijing 100093, China
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  • JIN DU,

    1. State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, 20 Nan Xin Cun, Beijing 100093, China
    2. Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
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    • 1

      The authors contributed equally to the study

  • JINGYU TANG,

    1. State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, 20 Nan Xin Cun, Beijing 100093, China
    2. Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
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    • 1

      The authors contributed equally to the study

  • FANG WANG,

    1. State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, 20 Nan Xin Cun, Beijing 100093, China
    2. Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
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    • 1

      The authors contributed equally to the study

  • JIE ZHANG,

    1. Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, 20 Nan Xin Cun, Beijing 100093, China
    2. College of Science, Northwest A&F University, Shaanxi 712100, China
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    • 1

      The authors contributed equally to the study

  • JINXIA HUANG,

    1. State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, 20 Nan Xin Cun, Beijing 100093, China
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  • WEIFENG LIANG,

    1. State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, 20 Nan Xin Cun, Beijing 100093, China
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  • LIANGSHENG WANG

    1. Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, 20 Nan Xin Cun, Beijing 100093, China
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  • Y. Lu is interested in ecological and evolutionary genomics, who designed the experiments, developed the real-time method, participated in data collection, and performed data analysis and writing. As Master students, J. Du worked on the natural variation of anthocyanin content, F. Wang participated in gene sequencing and genotyping, and J. Tang collected data on real-time quantification of gene expression. J. Zhang was a second year PhD student when performed 2006 experiments. W. Liang and J. Huang helped with the earlier planning and sequencing. L. Wang is interested in horticulture of floral colours and applications of secondary compounds, and assisted in both the HPLC and the fieldwork.

Yingqing Lu, Fax: +86 10 62590843; E-mail: yqlu@ibcas.ac.cn

Abstract

Responses of metabolites to environmental fluctuations may play large roles in biological adaptation, yet how these responses initiate in the natural environment and the molecular mechanisms remain unclear. Synthesis of floral anthocyanins, as typical examples of secondary metabolites, is known to respond to the physical environment and therefore an ideal system for understanding the process of the environmental regulation. Here, by simultaneous monitoring of six natural environmental variables and anthocyanin content of daily opening flowers throughout a natural flowering season (∼50 days) of Ipomoea purpurea, we have identified significant and positive correlations of temperature (3-days ago) and ultraviolet (UV) light intensity (5-days ago) with the floral anthocyanin content. We sequenced all known (seven structural and three regulatory) anthocyanin genes in I. purpurea flowers and examined their transcript quantities in the natural environment across eight floral developmental stages (covering 0–96 h before anthesis). The anthocyanin gene expression patterns corroborated with the inferred effects from the time-series data, and further showed that the positive UV effect became negative on transcript levels about 36 h before anthesis. With falling natural temperature, content of the principal anthocyanin declined, whereas that of an alternative anthocyanin with fewer glucose and caffeic acid moieties increased. Our data suggest that environmental regulation of the anthocyanin pathway may account for more than half of the flux variation in the floral limb, and is influenced mainly by daily average temperature and UV light intensity that modulate anthocyanin transcript levels (most likely via myb1) at floral developmental stages.

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