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Session I: General remarks on biomass and bioenergy

Status and prospects of the biomass technology development in China
Zhenhong Yuan*
GuangZhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, China
Exploiting the biomass energy is important for inhibiting the global warming, preventing the environmental deterioration, and securing the national energy source. China is a large agricultural country, the annual output of crop straw is 6.5 billion tons, of which 50% can be used for the bioenergy producing, approximately equal to 2.1 billion tons of standard coal. With the strong support for the biomass energy exploitation China has developed a wide range of biomass technologies, including rural biogas, straw gasification system for gas supply, briquette, biomass power generation, biodiesel and fuel ethanol. All these technologies have been applied in industry. Meanwhile, China is also actively developing the next-generation biomass utilization technologies, including the biomass synthetic liquid fuels and cellulose fuel ethanol, so far it has made periodical achievements in this field. In order to develop the biomass energy technologies and industries, the Chinese government has formulated and issued a series of incentive and supportive policies, including the ‘Renewable Energy Law’ and its implementation rules, industrialization taxation and subsidies. Since 1970, the biomass energy has been included in our national ‘Five-year Plan’for priority development. Furthermore, during the ‘12th Five-year’ period, a ‘subject planning’ has been made to focus on the biomass energy science. According to the roadmap of the biomass energy science and technology in China, till 2050, the biomass energy will be used for industrial applications and become one of the important renewable energy.
Keywords: Biomass energy, Technologies, The next-generation 
* E-mail: yuanzh@ms.giec.ac.cn 

Biorefinery of Sweet Sorghum based on ASSF Technology
Shizhong Li*, Jihong Li
MOST-USDA Joint Research Center for Biofuels
Institute of New Energy Technology, Tsinghua University, China
Due to the rapid depletion of fossil fuels and the change of environmental concerns, sustainable and renewable sources of energy are needed to address a range of economic and environmental issues. Bio-ethanol as a liquid fuel has been considered to compensate for the lack of petroleum. However, the high producing cost of cellulosic ethanol hide the implement of commercial production.
Biorefining is defined as the sustainable processing of biomass into a serious of bio-based products, such as food, feed, chemicals, materials and bioenergy. Biorefinery could maximize the value derived from the biomass feedstock by producing multiple products, for example, one or several low-volume, but high-value chemical products, and a low-value, but high-volume liquid transportation fuel. The high-value products increase profitability, the high-volume fuel helps meet energy needs, and the power production helps to lower energy costs and reduce greenhouse gas emissions from traditional power plant facilities. Sweet sorghum as a multiple platform plant can meet the need of biorefinery. It couls supply grain, sugar, cellulose and feed. Furthermore, its tolerance of drought and sterilize allow sweet sorghum to grow on marginal land. Moreover, non-food feedstock was encouraged by China’s government. The soluble sugar in sweet sorghum stalks can be converted into ethanol by a advanced solid-state fermentation technology (ASSF) which was designated by Li’s research team. Ethanol produced during the solid-state fermentation can be separated by distillation of these fermenting stalks. And the residue solid is called SSB which is rich with homocelluloses (70%). Based on ASSF technology, a biorefining process which combined ethanol separation stage after solid-state fermentation and alkaline pretreatment stage of SSB was designed. In our novel process, energy consumption of mechanically squeeze and pretreatment of SSB was avoided. So it is efficient to reduce the cost of ethanol production with sugar crops and implement bio-conversion of all carbohydrates in sweet sorghum stalks. Meanwhile, the recalcitrance of lignocellulose was destructed and the biodegradation of lignocellulose into chemical products is feasible to achieve.
Biogas, feed, cellulosic ethanol are achieved by various technology respectively. So it is considered a promising process to produce ethanol at commercial scale.  
* Email: szli@tsinghua.edu.cn
Producing Diatom for Environment and Profit
Jaw-Kai Wang
Member of National Academy of Engineering (USA)
CEO, Jawkai Bioengineering R&D Center, Shenzhen, China
Among the most promising leading candidates for the production of biofuel are microalgae, particularly diatoms. An outstanding attribute of an open microalgae-based biofuel production system is its ability to simultaneously capture carbon dioxide and other pollutants while producing biofuel. Some diatoms can double their weight in a few hours. An open microalgae production system must be able to successfully confront two major problems: 1) How to control contamination by other species. In an open production system other invasive species will come into the system and the ability to maintain the dominance of a single selected species in the system is essential to the success of an open production system. 2) There are many microorganisms that feed on microalgae and an open microalgae production system must be able to control these microorganisms. In agriculture, these tasks are often taken care of by chemicals, such as herbicides and pesticides. In the cultivation of microalgae, poisonous chemicals cannot be used because, while they may control the undesirable species and microorganisms, they will also kill the microalgae one wishes to cultivate.
To improve the profitability of algae production, integrated production systems are needed to take advantage of the many by-products. Because of its complicated nano-structured shell, diatom frustules are capable of removing heavy metal from high tech industry waste water by adsorption and can be used as a carrier for catalysts. Waste carbon dioxide and waste heat from oil refineries and power plants can be used in lipids and bio-crude productions.
* E-mail: jawkai@gmail.com

Improving plant cell wall properties for biofuel applications
Sascha Gille1, Monique Benz1, Gungyan Xionag1, Alex Schultink2, Amancio Souza1,   Kun Cheng1, Florian Kraemer2, Ben Kuhn2, Moritz Koch1, Markus Pauly1, 2,*
1 Energy Biosciences Institute, USA;
2 Department of Plant and Microbial Biology, UC Berkeley, USA
Lignocellulosics represent the dominant carbon sequestration system on land as their production amount in just 2 days equals the entire annual production of all chemicals combined made by humans. However, lignocellulosics are not merely a carbon storage sink for plants, but they represent sophisticated, highly complex materials that plants produce to benefit their sessile life-styles allowing their survival for up to several millennia as is the case in some tree species. Lignocellulosics consist of a complex aggregate of microcrystalline cellulose microfibrils, crosslinking water-soluble hemicelluloses, and a water repellent polyphenol, lignin.
In order to utilize this renewable resource for biofuels or other commodity chemicals it is desirable to increase the quantity of sugars harbored in this material and reduce the amount of potential inhibiting compounds that might arise during the processing of this material. Such knowledge may also one day lead to bioenergy crops with improved biofuel yield traits.
The presentation focuses on identifying the genetic basis associated with such traits including the mechanism of polysaccharide O-acetylation and increasing hemicellulose content facilitated by forward genetic screens in Arabidopsis and maize.
Keywords: Plant cell walls, hemicelluloses, O-acetylation, maize, Arabidopsis
* E-mail: mpauly69@berkeley.edu

Session II: Biomass synthesis and regulation

Recent advances in chloroplast biotechnology for
 bioenergy applications
Henry Daniell
Department of Molecular Biology & Microbiology, College of Medicine,
University of Central Florida, Orlando FL 32816-2364, USA
Chloroplast transformation has several unique advantages including high levels of expression and transgene containment via maternal inheritance of chloroplast genomes or by harvesting products from vegetative tissues before appearance of reproductive structures. The highest levels of expression in the published literature for engineering agronomic traits or human therapeutic proteins or industrial products were indeed achieved using this concept. In addition, this concept offers a number of other unique advantages including multi-gene engineering, lack of gene silencing or position effects due to site specific transgene integration and minimal or elimination of pleiotropic effects. Chloroplasts are ideal bioreactors for production of biopharmaceuticals, biofuels, industrial enzymes and vaccines.
Biofuel production from lignocellulosic materials is limited by the lack of technology to efficiently and economically release fermentable sugars from the complex multi-polymeric raw materials. Therefore, several biomass hydrolysis enzymes were expressed in tobacco chloroplasts. Chloroplast-derived crude-extract enzyme cocktails yielded more glucose from pine wood or citrus peel than commercial cocktails produced via fermentation and 1000-fold less expensive (Plant Biotech J. 8: 332-350, 2010). One of these enzymes, B-glucosidase, released active hormones from their inactive conjugates stored within chloroplasts, doubled plant biomass and conferred protection against aphids and whiteflies (Plant Physiology – Breakthrough Technologies section, 155: 222-235, 2011). Chloroplasts transformed with the agglutinin gene from Pinellia ternata (pta), a widely cultivated Chinese medicinal herb, conferred broad spectrum resistance to homopteran (sap-sucking), lepidopteran insects as well as anti-bacterialor anti-viral activity (Plant Biotech J. 10: 313-327, 2012). This provides a new option to engineer protection against biotic stress by hyper-expression of a single protein that is naturally present in a medicinal plant.
Expression of the endo-β-mannanase gene for the first time in plants facilitated its characterization for use in enhanced lignocellulosic biomass hydrolysis (PLoS One 6, e29302, 2012). Endo-β-mannanase expression levels reached up to 25 units per gram of leaf (fresh weight). Chloroplast-derived mannanase had higher temperature stability (40 °C to 70 °C) and wider pH optima (pH 3.0 to 7.0) than E.coli enzyme extracts. Plant crude extracts showed 6-7 fold higher enzyme activity than E.coli extracts due to the formation of disulfide bonds in chloroplasts, thereby facilitating their direct utilization in enzyme cocktails without any purification. Chloroplast-derived mannanase when added to the enzyme cocktail containing a combination of different enzymes yielded 20% more glucose equivalents from pinewood than the cocktail without mannanase. Our results demonstrate that chloroplast-derived mannanase is an important component of enzymatic cocktail for woody biomass hydrolysis and should provide a cost-effective solution for its diverse applications in the paper, oil, pharmaceutical, coffee and detergent industries. Recent advances in this field will be presented.
* E-mail: Henry.Daniell@ucf.edu

Transcriptional regulation of secondary wall formation in rice
Baocai Zhang, Debao Huang, Lifeng Liu, Shaogan Wang, Yihua Zhou*
State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology,     Chinese Academy of Sciences, Beijing, 100101, China
Cell wall structure is complex and contains various components, including polysaccharides, lignin and proteins. As the most abundant biomaterial on Earth, secondary walls have a high potential to be used as an important sustainable energy resource. Considering one of the functions of secondary wall for providing mechanical support for plants, researches about rice cell wall are not only of great significance for the improvement of lodging and other agronomic traits, but also will promote the process for successful utilization of cell wall polymers as clean energy.
Secondary cell wall formation is a highly orderly coordinated process, including the synthesis and deposit of cellulose fibrils, hemicelluloses and lignin, in which thousands of genes are involved. The dynamics of gene expression in this process was mainly modulated at transcriptional level. In Arabidopsis, a transcriptional regulatory network, including a battery of NAC and MYB transcription factors, have been identified through forward and reverse genetic studies. However, such regulatory network has rarely been reported in monocot plant rice. As a different cell-wall type from Arabidopsis, it is interesting to investigate whether rice has a distinct regulatory network or master switches to carry on secondary wall biosynthesis. To achieve this, we carried out RNA-seq analyses in three parts of developing rice internodes to reveal the expression profiles and identify the key transcription factors. A dozen of transcription factors were chosen for further studies based on the coexpressing and RNA-seq data. Transgenic plants harboring over-expressing or knock-down constructs have been generated. All those offer us opportunities to evaluate the biochemical and biological functions of the key transcriptional factors in secondary wall synthesis in rice.
Keywords: Rice, Transcription factor, Secondary wall synthesis, Cellulose synthesis
* E-mail: yhzhou@genetics.ac.cn

Development of novel modified starches using transgenic cassava having high amylose or amylopectin
Wenzhi Zhou1, Shanshan Zhao1, Jun Yang2, Peng Zhang1, 2*
1 Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China;
2 Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, Shanghai Chenshan Botanical Garden, 3888 Chenhua Road, Shanghai 201602, China
Starch is an important renewable raw material with an increasing number of industrial applications. As the most important trait in cassava, the starch quality of storage roots has been paid more attention in cassava research and breeding community. Cassava cultivars showing either high amylose or high amylopectin are desirable for cassava starch industries. Several attempts have been made to obtain waxy or high amylose cassava by mutation breeding (Ceballose et al., 2007, 2008) or genetic engineering (Munyikwa et al. 1997; Koehorst-van Putten et al., 2011). The expression of granule-bound starch synthase I (GBSSI) and starch branching enzymes (SBE), two key enzymes in starch biosynthesis, have been successfully down-regulated by RNA interference in transgenic cassava, respectively. Those transgenic cassava lines have been proved to be waxy or high amylose, ranging from 0-75% in amylose content. Compared to wild-type starch, the physico-chemical properties of those starches have been changed significantly, including granule size, paste temperature, viscosity, freeze-thaw stability, starch-iodine chelates stability, rheological properties, etc. The native starches from those transgenic cassava lines were used to develop novel modified starches, including oxidized starch, gelatinized starch, cross-linked starch, esterified starch, etherified starch and so on. Most properties of novel modified starches were totally different from the traditional modified starch; and several types showed a better performance in certain characters when compared with commercial ones. These studies will not only demonstrate the successful production of starch quality improved cassava by transgenic approach but also provide the raw materials for the development of novel modified starches for industrial applications.
Keywords: transgenic cassava, starch biosynthesis, gene expression regulation, modified starch
* E-mail: zhangpeng@sibs.ac.cn

Multiple OsGH9 Family Genes Are Specific for Lignocellulose Crystallinity Modification in Rice
Guosheng Xie1,2,3,, Bo Yang1,2,3, Zhengdan Xu1,2,3, Fengcheng Li1,2,3, Kai Guo1,2,4, Mingliang Zhang1,2,3, Lingqiang Wang1,2,3, Weihua Zou1,2,3, Yanting Wang1,2,3,
 Liangcai Peng1,2,3,4*
1National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, 2Biomass and Bioenergy Research Centre,3College of Plant Science and Technology,         4College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
Plant glycoside hydrolase family 9 (GH9) comprises typical endo-β-1,4-glucanase (EGases, EC3.2.1.4). In this study, we observed a global gene co-expression profiling and conducted a correlation analysis between OsGH9 and OsCESA among 66 tissues in 2 rice varieties. Using distinct rice non-GH9 mutants and wild type, we also performed integrative analyses of gene expression level, cellulase activities and lignocellulose crystallinity in stem tissues. Phylogenetic analysis and gene co-expression comparison revealed GH9 function similarity in Arabidopsis and rice. The data can provide insights into OsGH9 function in plants and offer the potential for genetic manipulation of plant cell walls using novel OsGH9 genes.
Keywords: Rice; GH9 family; cellulase activity assay; lignocellulose crystallinity; plant cell walls
* E-mail: lpeng@mail.hzau.edu.cn

Improvement of biomass and hydrogen photoproduction of Chlamydomonas reinhardtii
Shuangxiu Wu1*, Lili Xu2,3, Rongrong Wang2, Huang Rui2, Liu Xiaolei2, Quanxi Wang2
1 Department of Biology, college of life and environmental science, Shanghai Normal University, Shanghai, 200234, PR China 2 Beijing Institute of Genomics, Chinese Academy of Sciences, Beijng, 100029, PR China 3 Department of environmental science, college of resources and environmental science, East China Normal University, Shanghai, 200062, PR China
Today energy crisis and environmental pollution are the outstanding problems threatening human being’s survival and development. H2 is believed to be the clean and alternative energy because of its high energy content and only burning product of H2O. Especially, the photobiological H2 production technology of direct transformation of solar energy into hydrogen energy by microalgae is the hot topic in the field of renewable bioenergy study at present.
Chlamydomonas reinhardtii was selected to be the model species for the study of biological hydrogen production because of its high hydrogenase activity, easy cultivation, fast growth, clear genetic background and so on. However, the H2ase of C. reinhardtii is easily inactivated by O2, which is the main product of algal photosynthesis and is the main reason for low efficiency of H2 production of C. reinhardtii. Therefore, it is quite necessary and important to decrease the cellular O2 content for improvement of algal H2 yield.
Two strategies were carried out to improve H2 production of C. reinhardtii in our laboratory. One is the mutagenesis of the genome of C. reinhardtii to screen the important genes involved in algal hydrogen production. Another is the hetero-expression of leghemoglobin genes in C. reinhardtii to increase hydrogen yield. Finally, one mutant with about 7-fold hydrogen yield increased was obtained and leghemoglobin improved algal hydrogen production significantly. Rhizobia could also enhance algal hydrogen yield obviously. The molecular mechanism and metabolic pathway of C. reinhardtii were expounded based on above work.
Keywords: Chlamydomonas reinhardtii, hydrogen production, biomass, mutagenesis, leghemoglobin
* E-mail: wushx@big.ac.cn; bowusx@yahoo.com.cn
Regulation of cellulose biosynthesis and deconstruction
by protein phosphorylation
Shaolin Chen1*, Zhiqi Hao2, Chris Somerville1
1 Energy Biosciences Institute, University of California, Berkeley, CA 94720, USA
2 Thermo Fisher Scientific Inc, 355 River Oaks Parkway, San Jose, CA 95134, USA
The great abundance of cellulose places it at the forefront as a primary source of biomass for a renewable energy source, and a variety of efforts are underway to improve cellulose deconstruction for the production of cellulosic biofuels. However, the knowledge of how plant cells make cellulose and how microorganisms degrade cellulose remains very rudimentary. Understanding these processes will help optimize the production of cellulosic biofuels. Protein phosphorylation plays critical roles in regulating cellulose biosynthesis and deconstruction. Cellulose microfibrils are synthesized at the plasma membrane by cellulose synthase (CesA) complexes. The CesA1 and CesA3 components of cellulose synthase complexes are phosphorylated at sites clustered in two hypervariable regions of the proteins. Mutations of the phosphorylated residues to Ala (A) or Glu (E) alter anisotropic cell expansion and bidirectional motility of CesA complexes in the plasma membrane in rapidly expanding hypocotyls. In addition, protein phosphorylation regulates cell wall deconstruction by filamentous fungi. Here we present a mass spectrometry-based quantitative phosphoproteomics approach to identify the signaling pathways that control the expression and production of cell wall degrading enzymes from the filamentous fungus Neurospora crassa.
Keywords: cell wall, biosynthesis, deconstruction, phosphorylation, CesA proteins, kinase
* E-mail: schen1@berkeley.edu

Function Analysis of Xylan Biosynthesis in Arabidopsis
Aimin Wu1, Alan Marchant,2
1 College of Forestry, South China Agricultural University, Guangzhou, Guangdong, 510642, P. R. China.
2 School of Biological Sciences, University of Southampton Boldrewood Campus, Southampton SO16 7PX,
United Kingdom.
The hemicellulose glucuronoxylan (GX) is a major component of plant secondary cell walls and an important resource for bioenergy. However, our understanding of GX synthesis remains limited. Here, we identify and analyze some gene members from GT47 and GT43 family, and define a set of genes comprising IRX9, IRX10, IRX14, and FRA8 that perform the main role in GX synthesis during development. The IRX9-L, IRX10-L, IRX14-L, and F8H genes are able to partially substitute for their respective homologs and normally perform a minor function. Revealing two distinct sets of four genes each differentially contributing to GX biosynthesis. Now we are focusing on gene screening in xylan synthesis pathway and further gene function analysis
Keywords: xylan synthesis, two sets of genes, Arabidopsis
* E-mail: wuaimin@scau.edu.cn

Hemicellulose biosynthesis in grasses
Wei Zeng*, Jizhi Zhou, Lili Song, Andrew Cassin, Monika Doblin and Antony Bacic
ARC centre of Excellence on Plant Cell Walls, School of Botany,The Melbounre UniversityParkville, Vic 3010 Australia
The plant cell wall is the key component of biomass and has various applications in food, paper, feed industries as well as in growing biofuel areas. It is mainly composed of polysaccharides, proteins and phenylpropanoids. In this study, Lolium multiflorum, a popular forage grass was recruited to study plant cell wall biosynthesis. We have initiated Lolium Suspension Cell Culture (SCC) from endosperm to enable sampling from a homogenous tissue type. The Lolium SCC cell walls have around 30% β-(1-3,1-4)-mixed linkage-glucan and 20% heteroxylan, providing an ideal system to study hemicellulose biosynthesis. Total RNA was extracted from the 7-day old Lolium SCC and by taking advantage of the recent development of next-generation sequencing technology, we are able to analyze hundreds of cell wall related genes. GT43 and GT47 genes are cloned and expressed for functional characterization involved in xylan biosynthesis. We are in a position to uncover the processes of cell wall biosynthesis at the transcriptome level and begin to understand gene expression and regulation in the wall degradation and regeneration process.
Keywords: grass, hemicellulose, xylan
* E-mail: zengw@unimelb.edu.au

Function Analysis of Two CCCH Transcription Factors in regulating secondary cell wall formation in Arabidopsis and poplar
Guohua Chai, Zengguang Wang, Yingping Cao, Guang Qi, Li Yu, Yanchong YuRuibo Hu, Gongke Zhou*
Key Laboratory of Biofuels, Chinese Academy of Sciences. Shandong Provincial Key Laboratory of Energy Genetics. Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, PR China
Wood biomass is mainly made of secondary cell walls; hence, elucidation of the molecular mechanisms underlying the transcriptional regulation of secondary wall biosynthesis during wood formation is necessary to design strategies for genetic improvement of wood biomass. Here, we provide direct evidence demonstrating that the two poplar CCCH domain proteins PdC3H17 and PdC3H18 are involved in the coordinated regulation of secondary wall biosynthesis during wood formation, and together, they are master switches regulating a battery of downstream transcription factors. We show that PdC3H17 or PdC3H18 mainly are expressed predominantly in fibers and vessels in stems and their encoded protein are targeted to the cytoplasmic foci and can traffic between the nucleus and cytoplasmic foci. Transgenic Arabidopsis and poplar plants with dominant repression of PdC3H17 or PdC3H18 functions exhibit a drastic reduction in secondary wall thickening in fiber and vessel cells, and those with PdC3H17 or PdC3H18 overexpression result in an increase in secondary cell wall thickening. RT-qPCR showed that PdC3H17 and PdC3H18 overexpressors regulated the biosynthetic pathways of cellulose, xylan, and lignin by activating the expression of a number of transcription factor involved in secondary wall biosynthesis, cell wall modification, and programmed cell death. Our study has uncovered that the CCCH proteins master switches together with a battery of their downstream transcription factors form a transcriptional network controlling secondary wall biosynthesis during wood formation.
Keywords: Wood formation, CCCH transcription factors, Secondary cell wall regulation
* E-mail: zhougk@qibebt.ac.cn

Four GhCESA isoforms specific for high cellulose production that contributes to cell wall dynamics and fiber quality in Gossypium hirsutum and Gossypium barbadense
Ao Li1,2,3, Tao Xia1,2,4, Wen Xu1,2,4, Tingting Chen1,2,4, Xianliang Li1,2,3, Jian Fan1,2,3,
Ruyi Wang1,2,3, Shengqiu Feng1,2,3, Yanting Wang1,2,3, Bingrui Wang3, Liangcai Peng1, 2, 3,4
1National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research, 2Biomass and Bioenergy Research Centre, 3College of Plant Science and Technology,        4College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
Cotton fiber is an excellent model system of cellulose biosynthesis. We initially identified six full-length CESA genes designated as GhCESA5–GhCESA10. GhCESA1, CESA2, CESA7, and CESA8 are essential isoforms for secondary cell wall biosynthesis, whereas CESA3, CESA5, CESA6, CESA9, and CESA10 are associated with primary cell walls. Then, we characterized that CESA8 plays an enhancing role for rapid and massive cellulose accumulation that affects fiber quality in terms of fiber length, cellulose production, and crystallinity. With respect to the specific role of CESA8, a dynamic alteration was observed in cell wall composition and a significant discrepancy between the cotton species during fiber elongation. In addition, we discussed that callose synthesis may be regulated in vivo for massive cellulose production during active secondary cell wall biosynthesis in cotton fibers.
Keywords: Gossypium hirsutum; Gossypium barbadense; Cotton fiber; cellulose; CesA
* E-mail: lpeng@mail.hzau.edu.cn

Global Analysis of Gene Expression Profiles in Developing Physic Nut (Jatropha curcas L.) Seeds
Pingzhi Wu, Huawu Jiang, Guojiang Wu*
Key Laboratory of Plant Resources Conservation and Sustainable Utilization,                 South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, P. R. China.
Physic nut (Jatropha curcas L.) is an oilseed plant species with high potential utility as a biofuel. Further, following recent sequencing of its genome and the availability of expressed sequence tag (EST) libraries it is a valuable model plant for studying carbon assimilation in endosperms of oilseed plants. There have been several transcriptomic analyses of developing physic nut seeds using ESTs, but they have provided limited information on the accumulation of stored resources in the seeds.
We applied next-generation Illumina sequencing technology to analyze global gene expression profiles of developing physic nut seeds 14, 19, 25, 29, 35, 41, and 45 days after pollination (DAP). The acquired profiles reveal the key genes, and their expression timeframes, involved in major metabolic processes including: carbon flow, starch metabolism, and synthesis of storage lipids and proteins in the developing seeds. The main period of storage reserves synthesis in the seeds appears to be 29–41 DAP, and the fatty acid composition of the developing seeds is consistent with relative expression levels of different isoforms of acyl-ACP thioesterase and fatty acid desaturase genes. Several transcription factor genes whose expression coincides with storage reserve deposition correspond to those known to regulate the process in Arabidopsis. The results will facilitate searches for genes that influence de novo lipid synthesis, accumulation and their regulatory networks in developing physic nut seeds, and other oil seeds. Thus, they will be helpful in attempts to modify these plants for efficient biofuel production.
Keywords: Physic nut; transcriptomic analyses; developing seeds; storage reserves synthesis
*Email: wugj@scbg.ac.cn

Session III: Genetic manipulation of Energy Plants

Cell Hydrolysis: Not a Simple Issue ---Talking about a hydrolase from poplar
Liangliang Yu and Laigeng Li*
Laboratory of Synthetic Biology, Institute of Plant Physiology and EcologyShanghai Institutes for Biological SciencesChinese Academy of Sciences, Shanghai 200032, China
Plant endo-1,4-β-glucanase(EGase) family is consisted of α, β and γ groups. EGases from α group and γ group have been reported to regulate cell expansion and cellulose biosynthesis, respectively. However, there is no report on the function of EGases from β group. In this study, we characterized PtiEGase1 which is a member of β group of Populus EGases. PtiEGase1 is found specifically expressed in developing xylem which is undergoing secondary cell wall thickening verified by Promoter-GUS and immunolocalization experiment. The PtiEGase1:GFP protein is localized on the plasma membrane, which is different from secretory α-type EGases but similar to a γ-type EGases, KOR. Over expression of PtiEGase1 in Arabidopsis not only promotes leaf epidermis cell expansion, root elongation, but also increases fiber cell length. One featured phenotype of PtiEGase1 overexpressed Arabidopsis plant is the infertility. Investigation of anatomical structure of the anther reveals that overexpression of PtiEGase1 leads to defect of cell wall thickening of the endothecium cells and further affect the release of pollen. Enzymatic analysis demonstrates that PtiEGase1 catalyzes amorphous cellulose. These results indicate the plasma membrane localized PtiEGase1 plays a role in modulating amorphous cellulose to facilitate secondary wall biopolymers assembly during wood formation.

* E-mail:lgli@sippe.ac.cn