Arabinan Metabolism during Seed Development and Germination in Arabidopsis

Arabinans are found in the pectic network of many cell walls, where, along with galactan, they are present as side chains of Rhamnogalacturonan I. Whilst arabinans have been reported to be abundant polymers in the cell walls of seeds from a range of plant species, their proposed role as a storage reserve has not been thoroughly investigated. In the cell walls of Arabidopsis seeds, arabinose accounts for approximately 40% of the monosaccharide composition of non- cellulosic polysaccharides of embryos. Arabinose levels decline to -15% during seedling establishment, indicating that cell wall arabinans may be mobilized during germination. Immunolocalization of arabinan in embryos, seeds, and seedlings reveals that arabinans accumulate in developing and mature embryos, but disappear during germination and seedling establishment. Experiments using 14C-arabinose show that it is readily incorporated and metabolized in growing seedlings, indicating an active catabolic pathway for this sugar. We found that depleting arabinans in seeds using a fungal arabinanase causes delayed seedling growth, lending support to the hypothesis that these polymers may help fuel early seedling growth.     

铵减弱拟南芥主根向地性及其相关作用途径

向地性是决定植物根系空间构型的主要因素之一,对植物锚定和水分养分吸收至关重要。除了重力,根系向地性还受土壤环境因子影响。本文采用琼脂培养方法,研究了铵对拟南芥主根向地性反应的影响及相关作用途径。结果表明：短期内,不同浓度（NH4）2SO4均显著抑制主根向地性弯曲,但随着时间的延长,根尖向地性角度逐渐变小。而等（NH4）2SO4浓度的NaCl对主根向地性抑制效应较小,不同浓度的甘露醇不阻碍主根向地性弯曲。纽织化学染色结果显示铵处理12h以内,Col-0根尖没有淀粉体的快速降解过程,并且铵对淀粉体缺失突变体pgm—1主根向地性的影响同Col-0相似。铵处理部分恢复生长素转运载体突变体auxl-22和eir1-1主根向地性缺失。这些结果表明,铵对拟南芥主根向地性的影响独立于根尖淀粉体参与的重力感应途径。     

AhAO2转基因拟南芥植株抗旱生理分析

目的:研究AhAO2基因对拟南芥抗旱生理的影响.方法:以转AhAO2基因拟南芥(AO2 -1 -4、AO2 -3 -7、AO2 -8 -1)为实验材料,通过植物根长、相对含水量、气孔开度和抗氧化酶比活力指标的综合评定,分析超表达AhAO2基因对拟南芥抗旱生理的影响.结果:在PEG胁迫下,AO2 -1 -4、AO2 -3 -7、AO2 -8 -1植株体内相对含水量分别比野生型高2.1％、1.3％和1.6％;超表达植株AO2 -1 -4、AO2 -3 -7、AO2 -8 -1抗氧化酶POD酶比活力较野生型提高73.1％、66.2％和74.4％,SOD酶比活力较野生型提高64.6％、80.5％和43.1％.而野生型的气孔开度在正常生长和PEG胁迫的条件下均低于超表达拟南芥株系.AhAO2转基因植株可能通过提高抗氧化酶活性提升了抗旱能力.     

CRISPR/Cas9介导靶向敲除拟南芥BRI1突变体的鉴定

以拟南芥(Arabidopsis thaliana)油菜素内酯受体BRI1为目的基因,利用CRISPR/Cas9基因编辑技术定向编辑拟南芥BRI1,以期获得更多BRI1的突变体,为后续BRI1功能的进一步深入研究奠定基础。通过筛选转基因植株,对编辑后的BRI1进行测序分析,结果显示该突变体中BRI1基因序列由于新碱基的插入导致提前终止。同BRI1强突变体bri1-710一样,相比于野生型对照均对BL处理不敏感,但相比于bri1-710,该突变体植株较大,暗示BRI1 N端可能在BR信号途径中有重要作用。因此该研究可为后续进一步研究拟南芥及其他同源物种的BRI1功能提供可靠的参考依据。     

拟南芥WUSCHEL基因在转基因烟草中的超表达(英文)

The Arabidopsis WUSCIHIEL (WUS） gene plays a key role in the specification of the stem cellsin the shoot apical meristem (SAM). A cDNA of WUShas been amplified with the RT-PCR approach fromArabidopsis. The plant overexpression vector was constructed. It was driven by a dual enhanced CaMV35Spromoter. The construct was transformed into tobacco (Nicotiana tabacum L.) via Agrobacterium mediation.Dramatic phenotypic changes appeared in the WUS overexpression transgenic plants. Aberrant celldivisions and ectopic organogenesis could be found in almost every aerial parts of the transgenic tobaccoexcept the meristems and the inner two floral whorls. The data showed a highly conserved function of WUSin tobacco, and suggested that WUS is involved in organogenesis. The leaves were malformed, whichstrongly matched those only described previously for plants grown in the presence of polar auxin transportinhibitors. It suggested a possible function of WUS in leaf development. These results provide usefulinformation for functional analysis of WUS and important biotechnological implication as well.     

拟南芥PRRs基因在红光和蓝光信号转导中的作用初探

以拟南芥为材料,在红光和蓝光下对PRRs(pseudo-response regulators)突变体prr5p、rr7、prr9和toc1及其野生型的下胚轴表型进行比较观察,并采用实时定量PCR方法对突变体中光信号通路相关基因ZTL(zeitlupe)和CO(constans)的节律表达进行分析.结果表明:在红光下,prr5和toc1的下胚轴长度比野生型显著增长,在蓝光下,prr7p、rr9和toc1较野生型短,表明突变体降低了拟南芥对红光的敏感性,却增强了对蓝光的敏感性.红光和蓝光下,PRRs突变体中ZTL和CO的mRNA节律表达与野生型明显不同,其中红光下prr5和prr7、蓝光下prr5和toc1中的ZTLmRNA的表达显著下降且节律消失;红光下prr7和prr9以及蓝光下prr5突变体中的COmRNA表现基本无节律.因此推测,PRRs与ZTL的相互作用很可能在红光和蓝光信号转导途径中发挥作用,且PRRs基因极有可能参与了红光和蓝光对CO的调控.     

拟南芥HyPRP蛋白AZI1在大肠杆菌中的表达及其抗真菌活性分析

AZI1(AZELAIC ACID INDUCED 1)基因位于拟南芥4号染色体上,编码产物是脂质转移蛋白(lipid transfer protein, LTP)家族的一个成员。该基因在系统获得抗性(systemic acquired resistance, SAR)中具有重要功能,名称来自它可以被壬二酸(azelaic acid, AzA)诱导。已有的研究结果显示,在拟南芥中由AzA和甘油-3-磷酸(glycerol-3-phosphate, G3P)诱导的SAR反应需要AZI1和DIR1,这两个脂质转移蛋白有助于G3P的积累。为了确定AZI1蛋白是否具有抗真菌活性,本工作构建了原核表达载体pET28a-AZI1,利用大肠杆菌BL21(DE3)受体细胞制备了没有信号肽的AZI1重组蛋白。Western免疫印迹分析发现通过半乳糖苷类似物IPTG诱导表达的AZI1重组蛋白主要以包涵体的形式存在。体外抑菌实验以及激光共聚焦显微观察结果表明,用镍离子亲和层析树脂纯化的AZI1重组蛋白对灰霉菌、赤霉菌、棉花枯萎病菌和酿酒酵母细胞的生长/分裂均具有抑制作用。     

生长素调控植物重力反应的分子机理研究

重力反应是植物对环境的一种适应现象。生长素参与植物环境适应与发育调控的过程,重力反应过程的核心之一是在重力反应器官形成生长素的浓度梯度,诱导下游基因的差异表达。生长素的合成、代谢、极性运输及信号转导在此过程中发挥了关键作用。该文以拟南芥和水稻的研究为基础,综述了近几年对生长素调控植株重力反应的分子机理的研究进展,并对该领域未来的研究进行展望。     

过表达AhAREB1影响GA代谢调控拟南芥的株型

与野生型相比,过表达AhAREB1的拟南芥植株茎节间的生长受抑制,花序轴短和分枝数多。普遍认为植株的矮化可能与植物体内促进生长的激素作用的异常有关。本文测定了过表达AhAREB1植株体内激素GA3、IAA和ABA含量,并通过外施ABA、IAA和GA3观察植株表型变化及检测相关基因表达,研究AhAREB1在植物株型方面的作用。结果表明,与野生型植株相比,过表达AhAREB1拟南芥植株内源ABA、IAA和GA含量均升高,外施GA3可使植株的表型恢复至野生型水平,推测AhAREB1通过影响GA代谢失活及降低其生理活性水平而引起株型矮化。