Policy ForumAgriculture

Sustainable Intensification in Agriculture: Premises and Policies

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Science  05 Jul 2013:
Vol. 341, Issue 6141, pp. 33-34
DOI: 10.1126/science.1234485

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  • Why dry regions contribute to increased sweetness in fruits?
    • Qiuyun Liu, Professor, Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals, Sun Yat-sen University
    • Other Contributors:
      • Yanchao Zhou, Student, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
      • Ran He, Student, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
      • Zi-Wei Ye, Student, School of Biological Sciences, the University of Hong Kong, Hong Kong

    Carbohydrate molecules possess hydroxyl groups and aldehyde groups, which are hydrogen bond donors and acceptors that form hydrogen bonds with water molecules or protons. As desert regions are hot and arid, saccharides build up and help to preserve water molecules for plant survival.
    Substantial diurnal temperature amplitude changes also contribute to increased sweetness in fruits. Daytime photosynthesis builds up carbohydrate. Low temperature at night drives a robust Krebs cycle, which generates large amounts of protons that can be absorbed by carbohydrates. Therefore, saccharides build up in plants, and potentially deleterious proton stress is alleviated. This could explain why immature fruits are often sour. The aforementioned theory can be explored and harnessed for the genetic improvement of plants.

    Yanchao Zhou, 1,3 Ran He, 1,3 Zi-Wei Ye, 2,3 Qiuyun Liu 1,*

    1. Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals, Biomedical Center, State Key Laboratory of Biocontrol, Department of Biochemistry, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
    2. School of Biological Sciences, the University of Hong Kong, Hong Kong.
    3. Equal contributions.

    *Correspondence author.
    E-mail address: lsslqy@mail.sysu.edu.cn (Q. Liu)

    ACKNOWLEDGMENT
    Manuscript editing by Ms. Yan Shi, and support from Guangdong Science and...

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    Competing Interests: None declared.
  • Why are starch-rich grain seeds associated with low lysine content of seed proteins?
    • Qiuyun Liu, Professor, Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals, Sun Yat-sen University
    • Other Contributors:
      • Shaoping Weng, Professor, Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals, Sun Yat-sen University
      • Wei Shi, Ph.D, C334, Medicine Building, Tsinghua University, Beijing 100084, China
      • Feng Wang, Professor, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Australia

    Starch harbors oxygen atoms which can form hydrogen bonds with protons. Lysine is positively charged at physiological conditions. Starch-rich and lysine-rich seeds would allow the trapping of protons and chloride ions, leading to the local formation of HCl which damages cells (1-2). The positively charged guanidine group of arginine possesses lone electron pairs and pi electrons, which can attract larger anions than lysine does and render arginine slightly less toxic than lysine. The guanidyl side chain of arginine exhibits a delocalization of the positive charge within the pi-bonded system. Evolutionary selections may have selected grain seeds with poor lysine content to evade stress. Rich-cellulosic material in plants would have somewhat similar effect as starch does since it is also rich in hydrogen bond donors and acceptors.

    Shaoping Weng, 1,4 Wei Shi, 2,4 Feng Wang, 3,4 Qiuyun Liu 1,*
    1. Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals, Biomedical Center, State Key Laboratory of Biocontrol, Department of Biochemistry, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
    2. C334, Medicine Building, Tsinghua University, Beijing 100084, China
    3. Molecular Model Discovery Laboratory, Department of Chemistry and Biotechnology, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Melbourne, Vic. 3122, Australia.
    4. Equal contribution....

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    Competing Interests: None declared.