J Integr Plant Biol. ›› 2020, Vol. 62 ›› Issue (6): 832-846.DOI: 10.1111/jipb.12848

Special Issue: Crop yield

• Metabolism and Biochemistry • Previous Articles     Next Articles

Production of very-high-amylose cassava by post-transcriptional silencing of branching enzyme genes

Wenzhi Zhou1†, Shanshan Zhao1,2†, Shutao He1,3, Qiuxiang Ma1,3, Xinlu Lu1, Xiaomeng Hao1,3, Hongxia Wang1, Jun Yang1,2 and Peng Zhang1,3*   

  1. 1National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, the Chinese Academy of Sciences, Shanghai 200032, China
    2Shanghai Key Laboratory of Plant Functional Genomics and Resources, Shanghai Chenshan Plant Science Research Center, Shanghai Chenshan Botanical Garden, the Chinese Academy of Sciences, Shanghai 201602, China
    3University of Chinese Academy of Sciences, Beijing 100049, China

    These authors contributed equally to this work.
    Email: Peng Zhan(zhangpeng@sibs.ac.cn)
  • Received:2019-05-06 Accepted:2019-05-30 Online:2019-06-10 Published:2020-06-01


High amylose starch can be produced by plants deficient in the function of branching enzymes (BEs). Here we report the production of transgenic cassava (Manihot esculenta Crantz) with starches containing up to 50% amylose due to the constitutive expression of hair‐pin dsRNAs targeting the BE1 or BE2 genes. All BE1‐RNAi plant lines (BE1i) and BE2‐RNAi plant lines (BE2i) were grown up in the field, but with reduced total biomass production. Considerably high amylose content in the storage roots of BE2i plant lines was achieved. Storage starch granules of BE1i and BE2i plants had similar morphology as wild type (WT), however, the size of BE1i starch granules were bigger than that of WT. Comparisons of amylograms and thermograms of all three sources of storage starches revealed dramatic changes to the pasting properties and a higher melting temperature for BE2i starches. Glucan chain length distribution analysis showed a slight increase in chains of DP>36 in BE1i lines and a dramatic increase in glucan chains between DP 10‐20 and DP>40 in BE2i lines. Furthermore, BE2i starches displayed a B‐type X‐ray diffraction pattern instead of the A‐type pattern found in BE1i and WT starches. Therefore, cassava BE1 and BE2 function differently in storage root starch biosynthesis.

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