中文摘要：

【目的】甘蓝（Brassica oleracea L.）是世界上最广泛种植的蔬菜作物之一,其种植已由春、秋两季种植转变为四季栽培,因此,研究甘蓝对光温的反应能力是品种改良的重要基础。光敏色素是植物最重要的一类光受体,主要响应远红光和红光的变化,其中,光敏色素B是红光的最主要受体,与光形态建成、避荫性以及生物产量等性状密切相关。克隆甘蓝的光敏色素B基因（Bo PHYB）,在拟南芥中验证异源基因Bo PHYB在光形态建成和避荫性反应中的作用,丰富植物光敏色素基因功能研究,评价光敏色素在甘蓝品种改良中应用的潜在价值。【方法】利用RT-PCR的方法克隆、测序验证得到甘蓝自交不亲和系12C的Bo PHYB编码区c DNA序列;利用生物信息学软件分析其编码的氨基酸序列及结构域,并与其他植物的光敏色素B进行序列比对,分析它们之间的同源关系;构建其35S启动子驱动的植物表达载体p JIM19-Myc-Bo PHYB,通过农杆菌介导法转化拟南芥野生型Col-0和phy B-9突变体,并获得纯合转基因株系;比较Bo PHYB与拟南芥光敏色素B（At PHYB-GFP）的转基因株系在不同光质下的下胚轴伸长和成株期的表型,验证其在光形态建成和避荫性反应中的作用。【结果】从甘蓝中克隆了Bo PHYB的编码区c DNA序列,该基因编码区含有3 507个核苷酸,编码具有1 168个氨基酸残基、分子量为128.9 k D的蛋白质;与拟南芥和白菜的phy B结构域类似,Bophy B包含1个GAF结构域、2个PAS结构域、1个His KA结构域和1个HATPase_c结构域;氨基酸序列同源性分析发现,Bophy B与拟南芥以及白菜的phy B同源性最高,与小麦、玉米、水稻等单子叶植物的同源性较低;与At PHYB-GFP类似,在红光和白光下不但Myc-Bo PHYB能互补phy B-9极端黄化的表型,而且转基因株系均表现为下胚轴加剧缩短;长日照和短日照下成株期转基因导致植株矮化、叶片深绿和叶柄缩短。【?

英文摘要：

【Objective】Cabbage（Brassica oleracea L.） is one of the most widely grown vegetable crops in the world. Cabbage is grown in spring and fall,however varieties need to be made suitable for cultivation all the year round. Study on the response of cabbage phytochromes to light and temperature is an important basis for crop improvement with respect to extending growth periods. Phytochromes of interest here are the red/far-red reversible photoreceptors. Among them,phy B is an essential red light receptor that predominantly mediates seedling photomorphogenesis and shade-avoidance response. The objective of this study was to isolate the phytochrome B gene in cabbage（i.e.,Bo PHYB）,to explore its functions on seedling de-etiolation and shade avoidance by ectopic expression in Arabidopsis,and evaluate its potential in cabbage breeding. 【Method】The c DNA sequence of Bo PHYB was isolated from leaves of a self incompatible line 12 C. Bioinformatic analyses were employed to predict its function domains and to build a phylognetic relationship tree among plant phy B homologs. The p JIM19-Myc-Bo PHYB binary construct was electroporated into the Agrobacterium tumefaciens strain GV3101 and then introduced into Arabidopsis thaliana（both of the wild type and phy B-9 mutant） via a floral dip method. Transgenic plants were selected on germination plates containing 50 mg·m L-1 kanamycin for Myc-Bo PHYB. Homozygous T3 or T4 transgenic plants were used for testing the seedling hypocotyl elongation and shade avoidance responses. 【Result】The reading frame of Bo PHYB possesses 3 507 bp and encodes 1 168 amino acid residues（128.9 k D） deduced from the DNA sequence. Similar to both phy B protein of Arabidopsis thaliana（i.e.,Atphy B） and Brassica rapa（i.e.,Brphy B）,Bophy B contains one GAF domain,two PAS domains,one His KA domain,and one HATPase_c domain. Phylogenetic analysis indicated that Bophy B belongs to the same branch as Brphy B and Atphy B,while showing low similarity to phy B proteins from monocotyle