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Research Groups > Research Group of Biotechnology for Bioenergy Plants  

Introduction

Cassava (Manihot esculenta Crantz) and sweet potato (Ipomoea batatas) are characterized by high yielding, tolerance to stresses and high starch content, playing an important role in bioenergy development and national food supplies. Research projects on cassava and sweet potato will solve their problems of cultivation and production, and facilitate the promotion of agricultural industrialization. Our group is devoted to scientific researches on construction of genetic transformation system of cassava and sweet potato, discovery and verification of functional genes and molecular breeding. Our goal is to lead the development of genetic engineering of cassava and sweet potato in China, hence promoting their molecular breeding and scientific training for young researchers.

Laboratory web: www.cassavabiotech.org

Research Topic

Our research objectives are to increase our understanding of biological questions related to the production of cassava and sweet potato and to develop biotechnological tools for improvement of their yield, quality, resistances to biotic and abiotic stresses and biomass energy conversion efficiency.
There are five research areas of strategic importance: 
1. Cassava and sweet potato tissue culture and genetic transformation;
2. Engineering of sucrose and starch metabolism;
3. Engineering biotic and abiotic stress tolerance;
4. Mechanistic understanding of mineral nutrient uptake and utilization efficiency;
5. Development of insect- and herbicide-resistant transgenic plants.

Research Achievement

Gene expression profiling of developing cassava storage roots

Mechanisms related to the development of cassava storage roots and starch accumulation remain largely unknown. To evaluate genome-wide expression patterns during tuberization, a 60 mer oligonucleotide microarray representing 20 840 cassava genes was designed to identify differentially expressed transcripts in fibrous roots, developing storage roots and mature storage roots. Using a random variance model and the traditional twofold change method for statistical analysis, 912 and 3 386 upregulated and downregulated genes related to the three developmental phases were identified. Among 25 significantly changed pathways identified, glycolysis/gluconeogenesis was the most evident one. Rate-limiting enzymes were identified from each individual pathway, for example, enolase, L-lactate dehydrogenase and aldehyde dehydrogenase for glycolysis/gluconeogenesis, and ADP-glucose pyrophosphorylase, starch branching enzyme and glucan phosphorylase for sucrose and starch metabolism. This study revealed that dynamic changes in at least 16% of the total transcripts, including transcription factors, oxidoreductases/transferases/hydrolases, hormone-related genes, and effectors of homeostasis (Fig. 1). The reliability of these differentially expressed genes was verified by quantitative real-time reverse transcription-polymerase chain reaction. These studies should facilitate our understanding of the storage root formation and cassava improvement.



Alternation of Starch Property by the Regulation of GBSSI Expression in Transgenic cassava

Cassava starch has wide-range of bioindustrial applications because of its unique property such as low levels of fat, protein, phosphorus etc. To further extend its application potential, development of cassava starch with different amylose/amylopectin ratio is demanding. The amylose is synthesized by granule bound starch synthase I (GBSSI) in plants and down-regulation of GBSSI expression in cassava could result in reduced amylose content. More than 50 transgenic cassava plant lines were produced to express hair-pin dsRNAs homologous to GBSSI conserved region under the control of CaMV 35S or vascular-specific promoter p54/1.0. The plant lines were verified by Southern blot analysis for transgene integration and RT-PCR for GBSSI expression using in vitro plants. Iodine-staining of storage roots and starch granules of several selected transgenic plant lines harvested from field demonstrated a significant reduction of amylose content (Fig. 2). Less than 1% of amylose was detected in lines SS-A8, SS-A9 and SS-B10. Analyses of GBSSI protein level by SDS-PAGE showed the decrease of GBSSI expression among these transgenic lines. Although their starch morphology was not detected significant changes by scanning electron microscopy in comparison with the wildtype’s, the inner crystal structure of starch granules of transgenic lines was different from the untransformed by transmission electron microscopy (Fig. 1), which is further illustrated by the morphology of iodine-starch complex. The alternation of starch property from transgenic lines was also proved using differential scanning calorimeter and X-ray diffraction data. Our study provides a biotechnological tool to improve the starch quality in cassava, hence promoting its industrial utilization.

Team Members

Principal Investigator(PI)
ZHANG Peng, Ph.D., Professor
Tel: 021-57799381
Fax: 021-57799381
Email: zhangpeng@sibs.ac.cn
Address: Shanghai Chenshan Plant Science Research Center, Chinese Academy of Scicences, 3888 Chenhua Road, Songjiang District, Shanghai 201602, China

Present Position
Professor of Shanghai Chenshan Plant Science Research Center and Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Member of the National Key Laboratory of Plant Molecular Genetics; Executive Director of SIBS-ETH Shanghai Center for Cassava Biotechnology; and Scientist of Modern Agro-industry Technology Research System supported by Ministry of Agriculture.

Research Interest
My research group focuses on cassava and sweet potato biotechnology to answer basic scientific questions related to the constraints of their production and to develop technologies for bridging the gap of scientific discoveries and applications, especially related to biofortification and bio-energy.

Recent Publications

  1. Xu J, Duan X, Yang J, Beeching JR, Peng Zhang (2013) . Coupled expression of Cu/Zn-superoxide dismutase and catalase in cassava improves tolerance against cold and drought stresses. Plant Signal Behav 8: e24525
  2. Jia Xu, Xiaoguang Duan, Jun Yang, John R. Beeching, Peng Zhang (2013) Enhanced ROS scavenging by over-production of superoxide dismutase and catalase delays post-harvest physiological deterioration of cassava storage roots. Plant Physiology 161(3)1517-1528.
  3. Xiaoguang Duan, Jia Xu, Erjun Ling, Peng Zhang (2013) Expression of Cry1Aa in cassava improves its insect resistance against Helicoverpa armigera. Plant Molecular Biology (in press)
  4. Fan W, Zhang M, Zhang H, Peng Zhang (2012) Improved Tolerance to Various Abiotic Stresses in Transgenic Sweet Potato (Ipomoea batatas) Expressing Spinach Betaine Aldehyde Dehydrogenase. PLoS ONE 7(5): e37344. doi:10.1371/journal.pone.0037344.
  5. An D, Yang J, Peng Zhang (2012) Transcriptome profiling of low temperature-treated cassava apical shoots showed dynamic responses of tropical plant to cold stress. BMC Genomics 13(64) doi:10.1186/1471-2164-13-64.
  6. Huiping Bi, Peng Zhang (2012) Molecular characterization of two sweepoviruses identified from China and infectivity evaluation of cloned SPLCV-JS in Nicotiana benthamiana. Archives of Virology 157: 441-4

Team members:

WANG Lianjun
Research Assistant
Tel: 021-37792288-915
E-mail:
junlianwang5658391@163.com
LIN Duoqing
Research Assistant
Tel: 021-37792288-915
E-mail:
tclamm@yahoo.cn

Post-Doctor:

YANG Jun
Postdoctor
E-mail: jyang03@sibs.ac.cn

Graduate Students:

Deng Gaifang
Master Student
Email:
demggaifang@sibs.ac.cn

Li Shouli
Master Student
Email:
lishouli@sibs.ac.cn

Liu Xinyan
Master Student
Email:
liuxinyan@sibs.ac.cn

Wang Yanyan
Master Student
Email:
wangyanyan@sibs.ac.cn

Cui Zhanfei
Master Student
Email:
cuizhanfei@sibs.ac.cn

 

 

 
 
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