基于ISSR与ITS-RFLP的花生白绢病菌遗传多样性分析

本研究利用简单重复序列区间（Inter Simple Sequence Repeat,ISSR）和ITS-RFLP技术,对采自我国12个省市的39个花生白绢病菌菌株进行遗传多样性分析。结果表明：从筛选出的17条ISSR引物共扩增出269条DNA谱带,其中多态性谱带266条,平均多态性百分率为98.9%,UPGMA聚类分析将这些菌株分为4个类群。限制性内切酶AluⅠ、RsaⅠ、HpaⅡ和MboⅠ作用内部转录间隔区（Internal Transcribed Spacer,ITS）PCR扩增产物产生的谱带,利用ITS-RFLP分析遗传多样性,将39个菌株划分为7个组群。ISSR和ITS-RFLP的结果均表明花生白绢病菌存在较高的遗传变异,但其遗传相似性与地理来源无明显相关。     

甘蓝型油菜胚胎离体培养体系的建立及其在油脂合成积累研究中的应用

为便于体外研究甘蓝型油菜的胚胎发育和种子油脂积累规律,以春油菜862的胚胎为材料,构建胚胎离 体培养体系,通过综合比对基础培养基类型、蔗糖浓度、琼脂浓度,确定含蔗糖8%和琼脂0.6%的B5培养基作为胚 胎离体培养和胚胎胚性生长的最佳体外培养体系,并用于研究种子油脂的积累和变化。在体系中分别加入甘蓝型 油菜的角果皮和叶片提取物,调查对胚胎油脂积累的影响,发现含有角果皮提取物和叶片提取物的培养基均能提 高胚胎油脂积累效率,且角果皮提取物对胚胎油脂积累的效率显著高于叶片提取物,源于高油材料的角果皮、叶片 提取物对胚胎油脂的积累效率显著高于低油材料。     

Isolation and Characterization of the Diatom Phaeodactylum Δ5-Elongase Gene for Transgenic LC-PUFA Production in Pichia pastoris

The diatom Phaeodactylum tricornutum can accumulate eicosapentaenoic acid (EPA) up to 30% of the total fatty acids. This species has been targeted for isolating gene encoding desaturases and elongases for long-chain polyunsaturated fatty acid (LC-PUFA) metabolic engineering. Here we first report the cloning and characterization of Δ5-elongase gene in P. tricornutum. A full-length cDNA sequence, designated PhtELO5, was shown to contain a 1110 bp open reading frame encoding a 369 amino acid polypeptide. The putative protein contains seven transmembrane regions and two elongase characteristic motifs of FLHXYHH and MYSYY, the latter being typical for microalgal Δ5-elongases. Phylogenetic analysis indicated that PhtELO5 belongs to the ELO5 group, tightly clustered with the counterpart of Thalassiosira pseudonana. Heterologous expression of PhtELO5 in Pichia pastoris confirmed that it encodes a specific Δ5-elongase capable of elongating arachidonic acid and eicosapentaenoic acid. Co-expression of PhtELO5 and IsFAD4 (a ∆4-desaturase from Isochrysis sphaerica) demonstrated that the high-efficiency biosynthetic pathway of docosahexaenoic acid was assembled in the transgenic yeast. Substrate competition revealed that PhtELO5 exhibited higher activity towards n-3 PUFA than n-6 PUFA. It is hypothesized that Phaeodactylum ELO5 may preferentially participate in biosynthesis of transgenic LC-PUFA via a n-3 pathway in the yeast host.     

In situ measurements of winter wheat diurnal changes in photosynthesis and environmental factors reveal new insight into photosynthesis improvement by super-high-yield cultivation

In past 30 years, the wheat yield per unit area of China has increased by 79%. The super-high-yield(SH) cultivation played an important role in improving the wheat photosynthesis and yield. In order to find the ecophysiological mechanism underneath the high photosynthesis of SH cultivation, in situ diurnal changes in the photosynthetic gas exchange and chlorophyll(Chl) a fluorescence of field-grown wheat plants during the grain-filling stage and environmental factors were investigated. During the late grain-filling stage at 24 days after anthesis(DAA), the diurnal changes in net CO_2 assimilation rate were higher under SH treatment than under high-yield(H) treatment. From 8 to 24 DAA, the actual quantum yield of photosystem II(PSII) electron transport in the light-adapted state(ΦPSII) in the flag leaves at noon under SH treatment were significantly higher than those under H treatment. The leaf temperature, soil temperature and soil moisture were better suited for higher rates of leaf photosynthesis under SH treatment than those under H treatment at noon. Such diurnal changes in environmental factors in wheat fields could be one of the mechanisms for the higher biomass and yield under SH cultivation than those under H cultivation. ΦPSII and CO_2 exchange rate in wheat flag leaves under SH and H treatments had a linear correlation which could provide new insight to evaluate the wheat photosynthesis performance under different conditions.     

Research status of soybean symbiosis nitrogen fixation

Soybean (Glycine max) is one of the most important economic legume crops with largest planting area, and is also an important oil crop, as well as food and feed material. Soybean-rhizobia symbiosis plays important roles in plant cultivation and fertilizer application. However, there are many problems in agricultural application of soybean symbiotic nitrogen fixation. In this review, we summarized three restriction factors (host specificity, low nitrogen fixation efficiency and abiotic stress) and discussed research progresses of these factors. Clarification of host specific mechanism will help to select and apply rhizobia inoculants. Both maintaining high nitrogenase activity and delaying nodule senescence can improve the efficiency of symbiotic nitrogen fixation. Abiotic stress-tolerant rhizobia can improve the abiotic stress tolerance of soybean. Breeding stress tolerant genotypes of soybean and rhizobia, obtaining correlated genes are the common strategies to improve soybean symbiotic nitrogen fixation under extreme conditions. Regulatory mechanisms of these restriction factors are still poorly understood and needs further clarification.     

Evaluation of seed vigor in soybean germplasms from different eco-regions

Seed vigor plays an essential role in soybean production. Soybean seed is sensitive to environment and easy to get seed deterioration. Generally soybean seed vigor can be maintained for less than one year and have to be multiplied every year. Varieties with good seed vigor are essential for maintaining planting population and stable yield. In this research, 419 germplasms from three eco-regions, South China, Huanghuai region and Northeast China, were evaluated for seed vigor by assessing germination ratio, germination potential and germination index. About 34.8% of tested germplasm had germination ratio equal or more than 85%, suggested by the national soybean seed quality standard of China. Only 9 from 82 tested cultivars met the seed standard. Seed germination ratio distribution had obvious regional feature. Landraces performed better seed vigor than cultivars. Germplasms from South China had stronger seed vigor compared to those from Huanghuai and Northeast regions. Seed vigor has no significant relationship with maturity and 100-seed weight. Totally 21 germplasms with strong seed vigor, favor maturation and seed size were identified and can be used in future breeding program.     

芝麻细胞色素P450超家族的成员鉴定及SiCYP703A2的功能验证

细胞色素P450(CYP450)超家族广泛参与初生和次生代谢物质的生物合成,其中CYP703家族基因参与拟南芥、水稻等的花药发育.本研究利用生物信息学方法,从芝麻基因组中鉴定出303个CYP450基因,发现它们分为9个家族簇(clan),43个基因家族,随机分布于16个连锁群中.CYP703家族是71 Clan的成员之...     

BvGLP1过表达增强了转基因小麦对根腐病的抗性

类萌发素蛋白(germin-like protein, GLP)是一类含有cupins结构域的糖蛋白, 在植物基础抗性等方面起着重要作用。本研究人工合成了甜菜GLP基因BvGLP1, 并利用基因重组技术构建了受韧皮部特异表达启动子RSS1P驱动的BvGLP1基因单子叶植物表达载体pA20-RSS1P::BvGLP1。通过基因枪介导法将其转入小麦品种扬麦18中, 对转基因扬麦18的T₀至T₃代植株中BvGLP1进行了PCR、半定量RT-PCR和荧光定量QPCR检测, 并对转基因小麦进行根腐病和纹枯病抗性鉴定。结果表明, BvGLP1已转入转基因小麦扬麦18, 并能在转基因小麦中遗传、转录表达; 5个转BvGLP1基因小麦株系的根腐病抗性比受体品种扬麦18有显著提高, 说明BvGLP1过表达增强了转基因小麦对根腐病的抗性。     

四种油料作物中的细菌型PEPC基因的鉴定及在发育种子中的表达

鉴定和获取了四种油料作物（油菜、大豆、花生和芝麻）中的细菌型PEPC基因,分析了所编码蛋白的保守结构域（BOX I-IV）和蛋白作用功能位点。基因包括甘蓝型油菜的Bna10093361、Bna1009749和Bna10093360,大豆的Glyma10g34970.1, Glyma01g22840.1和Glyma02g14500.1,芝麻的SIN1018296和花生的AhPPC5。这8个基因含有19～21个内含子,内部插入一个约350～600bp的高度变异区,编码的蛋白在C端形成R/KNTG结构域,在N端缺乏磷酸化作用位点。在种子发育的不同时期,油菜中仅Bna10093360表达,但其表达量不到油菜BnActin表达量的0.1%;大豆中Glyma10g34970.1表达量最高（接近大豆GlymaActin的2%）,Glyma02g14500.1次之;花生AhPPC5表达量为花生AhActin的32%～175%,在种子不同发育时期表达量为早期>中期>晚期;芝麻SIN1018296表达量为芝麻SINActin的3%～18%,在种子发育时期的表达趋势和花生AhPPC5相似。8个基因种子中的表达模式差异明显,说明细菌型PEPC基因可能存在着广泛的功能分化。