2010年，区永祥博士来到华南植物园并成立了植物基因工程中心。2012年，植物基因工程中心并入新成立的分子生物分析及遗传改良中心。
The PGEC was formed in 2010 upon the arrival of David Ow. In 2012, the PGEC was merged into the newly formed Molecular Analysis & Genetic Improvement Center(MAGIC).
研究方向 Research
特异性位点的基因叠加
在许多作物中，转基因性状都是先转入可以转化的实验室品系中，然后再导入优良的栽培品系。对于二倍体，或者以二倍体形式遗传的多倍体植物来说，获得n个独立分离（假定无遗传连锁）的位点的纯合子的几率为(1/4)n。再加育种者还需将n个非转基因性状导入同一品种，获得纯合子的几率为(1/4)n+x，增加了优良品系改良的难度。为了减少转基因分离位点数目，一个选择是可以事先在体外叠加多个基因性状一次性导入基因组，但也意味着每增加一个新的性状，以前已经通过审定的性状需要同新性状一起重新审定。另一选择就是绕过实验品系，直接导入栽培品系，但许多优良的栽培品系转化难，直接将优良性状导入是不现实的。再加因每一个独立转化获得的栽培品系也被认为是独立的转化事件，从而需要通过独立的审核检验。针对上述两种解决方案存在的缺点，我们将致力于研发一套全新的重组酶介导的转化操作系统。候黎丽博士及其同事运用重组酶系统，目前已经在烟草中实现了两轮基因叠加和筛选标记的删除，叠加的转基因具有精确的结构和可靠的表达。
Hou, L., Yau, Y-Y, Wei, J., Han, Z., Dong, Z., Ow, D.W. 2014. An open source system for in planta gene stacking by Bxb1 and Cre recombinases. Mol. Plant 7:1756-1765.
目前将这一系统的运用拓展到水稻，已在水稻染色体上成功筛选到多个精确目标位点，李如玉副研究员及其同事利用基因枪转化的方法进行了特异性位点的整合，表明了基因可以在目标位点高效整合。
Li, R., Han, Z., Hou, L., Kaur, G., Qian, Y., Ow, D.W. 2016. Method for biolistic site-specific integration in rice and tobacco catalyzed by Bxb1 integrase. Methods Mol Biol. 1469: 15-30
(Chromosome and Genomic Engineering in Plants, Ed. M. Murata), Humana Press, (Book Chapter).
陈伟强博士进一步研发了一套与体内叠加系统兼容的重组酶介导的体外基因叠加方法。
Chen, W., Ow, D.W. 2016. Protocol for in vitro stacked molecules compatible with in vivo recombinase mediated gene stacking. Methods Mol Biol. 1469: 31-47
(Chromosome and Genomic Engineering in Plants, Ed. M. Murata), Humana Press, (Book Chapter).
接下来我们将利用获得的目标系，建立水稻定点叠加转化服务平台，将不同基因转入水稻基因组同一位置，更精确比较分析转基因的表达。
区永祥研究员最近发表了一篇综述，关于重组酶介导的基因叠加的历史进展。
Ow, D.W. 2016. The long road to recombinase-mediated plant transformation. Plant Biotechnology Journal 14:441-117.
Site-specific gene stacking
In many crop species, transgenic traits are introduced into transformable varieties before introgressing them out to elite field cultivars. For diploids or polyploids that behave as diploids, the ‘n’ number of unlinked transgenic loci can be assorted as homozygous into a single genome at a probability of (1/4)n. However, along with the ‘x’ number of other nontransgenic traits that breeders need to assemble into the same genome, the (1/4)n+x probability for a ‘breeding stack’ makes line conversion difficult. To minimize the number of segregating transgenic loci, the option of in vitro stacking prior to its introduction into the plant genome would mean the re-engineering and re-deregulating of previously introduced traits each time a new trait is introduced. The option of bypassing introgression by directly transforming field cultivars is also not practical as most field cultivars are difficult to transform. Moreover, each locale-specific cultivar would harbor an independent integration event that requires individual de-regulation. PhD student HOU Lili and colleagues have demonstrated recombinase-mediated gene stacking in tobacco. Through two rounds of integration, followed by deletion of unneeded DNA,precise structure and reproducible expression of the sequentially added traits were found.
Hou, L., Yau, Y-Y, Wei, J., Han, Z., Dong, Z., Ow, D.W. 2014. An open source system for in planta gene stacking by Bxb1 and Cre recombinases. Mol. Plant 7:1756-1765.
To implementing this system in rice, a number of precise target sites in the rice genome were screened. Associate Researcher LI Ruyu and colleagues havedeveloped a biolistic mediated method for site-specific integration and have demonstrated that gene insertion into those target sites works efficiently.
Li, R., Han, Z., Hou, L., Kaur, G., Qian, Y., Ow, D.W. 2016. Method for biolistic site-specific integration in rice and tobacco catalyzed by Bxb1 integrase. Methods Mol Biol. 1469: 15-30
(Chromosome and Genomic Engineering in Plants, Ed. M. Murata), Humana Press, (Book Chapter).
PhD student CHEN Weiqiang further developed a method to stack genes in in vitro that would be compatible with the recombinase-mediated gene stacking system in vivo.
Chen, W., Ow, D.W. 2016. Protocol for in vitro stacked molecules compatible with in vivo recombinase mediated gene stacking. Methods Mol Biol. 1469: 31-47
(Chromosome and Genomic Engineering in Plants, Ed. M. Murata), Humana Press, (Book Chapter).
Soon, we plan to offer this service to the rice community for precise transgene insertions into our target sites, so that the comparison of transgene expression can be drawn from the same genomic location.
A recent review describes the historical development of recombinase mediated gene stacking.
Ow, D.W. 2016. The long road to recombinase-mediated plant transformation.
Plant Biotechnology Journal 14:441-117.
金属和氧化胁迫
环境胁迫导致作物减产，生物胁迫和非生物胁迫都会扰乱细胞代谢平衡，引起细胞内活性氧水平升高，进而导致细胞损伤和死亡。我们实验室的研究兴趣在于，解析植物在应答引起氧化损伤的重金属胁迫过程中的分子机理。
本实验室前期研究发现拟南芥OXS2基因作为一个转录因子调控植物胁迫逃逸。从而响应重金属胁迫和氧化胁迫。贺立龙博士及其同事近期将该研究拓展到玉米，研究发现玉米OXS2家族通过激活一个甲基转移酶样基因，进而提高植物对重金属镉的抗性。
He, L., M., X., Li, Z., Jiao, Z., Li, Y., Ow, D.W. 2016. Maize OXIDATIVE STRESS 2 homologs enhance cadmium tolerance in Arabidopsis through activation of a putative SAM-dependent methyltransferase gene. Plant Physiology 171:1675-1685.
本实验室前期研究发现拟南芥中OXS3蛋白很可能作为一个组蛋白修饰因子，从而响应重金属胁迫和氧化胁迫。王昌虎助理研究员及其同事近期的研究还发现过表达水稻中OXS3基因家族成员，可以显著降低水稻谷粒中的镉含量。由于中国耕地污染问题，导致近年来出现了许多高镉稻米产品。土壤修复等手段不能在短期内有效解决这一问题，因此通过创制低镉累积水稻新种质为保障粮食安全提供了新的解决方案。
Wang, C., Guo, W., Ye, S., Wei, P., Ow, D.W. 2016. Reduction of Cd in rice through expression of OXS3-like gene fragments. Molecular Plant, 9:301-304.
最近何玉梅博士后及其同事还在裂殖酵母中阐明了一条新的镉诱导的二硫化物胁迫调控途径—Oxs1-Pap1途径。该途径在真核细胞中高度保守。来源于人类、老鼠、拟南芥中异源蛋白Oxs1和Pap1蛋白在体外均可发生互作，这些异源蛋白质在裂殖酵母中可提高镉的胁迫性。推测Oxs1参与调控生物体内保守的胁迫调控途径。
He, Y., Chen, Y., Song, W., Zhu, L., Dong, Z., Ow, D.W. 2016. A Pap1-Oxs1 signaling pathway for disulfide stress in Schizosaccharomycespombe. Nucleic Acids Research, doi: 10.1093/nar/gkw818.
Metal and oxidative stress tolerance
Environmental stresses reduce plant productivity. Both abiotic and biotic stresses disrupt normal cellular homeostasis leading to elevated levels of reactive oxygen species that in turn leads to cellular damage and cell death. We have been interested in the molecular mechanisms of plant tolerance to heavy metals, which also leads to oxidative stress.
Previously, we described Arabidopsis Oxidative Stress 2 (OXS2) as a transcription factor for regulating stress escape in response to oxidative and metal stress. Ph.D. student HE Lilong and colleagues have since extended this research to crop species and reported that members of the maize OXS2 family can activate transcription of a gene encoding a putative SAM-dependent methyltransferase, a new factor for enhanced Cd tolerance.
He, L., M., X., Li, Z., Jiao, Z., Li, Y., Ow, D.W. 2016. Maize OXIDATIVE STRESS 2 homologs enhance cadmium tolerance in Arabidopsis through activation of a putative SAM-dependent methyltransferase gene. Plant Physiology 171:1675-1685.
Previously, we described Arabidopsis Oxidative Stress 3 (OXS3) as a putative histone modification factor in response to oxidative and metal stress. Assistant Researcher Wang Changhu and colleagues have shown that overproducing certain rice OXS3 family member proteins can lower the cadmium content in rice grain. Due to soil pollution problems in China, rice with high Cd content has been found in recent years. As this problem cannot be solved easily through soil remediation, the engineering of low cadmium rice may provide a solution to minimize dietary intake of cadmium.
Wang, C., Guo, W., Ye, S., Wei, P., Ow, D.W. 2016. Reduction of Cd in rice through expression of OXS3-like gene fragments. Molecular Plant, 9:301-304.
Most recently, Postdoctoral fellow He Yumei and colleagues elucidated a new cadmium induced disulfide stress pathway in the fission yeast. This new Oxs1-Pap1 regulatory pathway appears evolutionarily conserved, as heterologous (human, mouse and Arabidopsis) Oxs1 and Pap1-homologues can bind interchangeably with each other in vitro, and at least in the fission yeast, heterologous Oxs1 and Pap1-homologues can substitute for S. pombe Oxs1 and Pap1 to enhance stress tolerance.
He, Y., Chen, Y., Song, W., Zhu, L., Dong, Z., Ow, D.W. 2016. A Pap1-Oxs1 signaling pathway for disulfide stress in Schizosaccharomycespombe. Nucleic Acids Research, doi: 10.1093/nar/gkw818.
都市农业
到2040年，中国城市将需要容纳10亿居民，但随着城市扩建和工业化发展，农业用地缩减，土壤退化，因此中国不仅存在城市居民对新鲜食品需求的增长与耕地日渐减少的矛盾，同时还要应对石油资源紧缺引起的粮食运输和包装成本上升的问题。屋顶农业可以弥补城市扩建造成耕种面积减少的现状。就地供应食物可以减少高昂的运输和包装成本。垂直农业生产中，水和营养液在封闭的水培系统中高效循环利用，需水量明显降低，可缓解饮用水不足危机，大大减少甚至避免农药的施用，肥料利用效率达到最大化，可生产无公害的绿色食品。刘亭博士及其同事已验证屋顶农业的可行性，研究表明与市场同类相比，屋顶种植叶菜类蔬菜，可以减少成本，并提高蔬菜品质。
Urban farming
By 2040, Chinese cities will house a billion residents, and the need to provide fresh food for this large population will become a greater challenge. Urban development reduces arable land for traditional agriculture while urban industrialization pushes clean growing areas further away from urban centers. Hence, not only is China facing the prospect of less capacity for food production, but also escalating costs (including environmental costs) for food transport and packaging. Roof top agriculture can reclaim some of the land displaced by urban sprawl. Locally grown vegetables would save otherwise costly handling, packaging and transport that depend on fossil fuel. Water and fertilizers are more efficient in closed hydroponics systems without causing eutrophication of scarce drinking water supplies. Herbicides are not necessary, and pesticides can be substantially reduced. Hydroponically grown vegetables can be healthier than soil-grown counterparts given the high soil pollution near most urban surrounds. PhD student LIU Ting and colleagues experimentally tested roof top farming, and the data show that rooftop grown leafy vegetables can be produced more cost effective and with higher quality than market equivalents.
Liu, T., Yang, M, Han, Z., Ow, D.W. 2016. Rooftop production of leafy vegetables can be profitable and less contaminated than farm grown vegetables. Agronomy for Sustainable Development 36:41 DOI 10.1007/s13593-016-0378-6.
Quartz Magazine (Rooftop hydroponic systems in cities produce vegetables that are cheaper and healthier than rural farms, December 14, 2016).