BACKGROUND & AIMS: :Development is a dynamic process occurring at the microscopic scale. The ability to see how it unfolds in detail is invaluable not only for helping us appreciate its full complexity but also to experimentally dissect its mechanisms. The sophistication of experimental approaches and imaging technologies has increased over the past decade at an astounding pace. In this review we highlight and discuss several studies that illustrate the latest advances in the application of live-imaging to dissect plant development.

背景与目标： : 发展是一个在微观尺度上发生的动态过程。了解其详细展开的能力不仅有助于我们理解其全部复杂性，而且还可以通过实验剖析其机制，这是无价的。在过去的十年中，实验方法和成像技术的复杂性以惊人的速度增长。在这篇综述中，我们重点介绍并讨论了几项研究，这些研究说明了活体成像在解剖植物发育中的最新进展。

BACKGROUND & AIMS: Mutagen-induced chromatid aberrations are not randomly distributed along the metaphase chromosomes. In the field bean (Vicia faba), defined late-replicating and transcriptionally inactive heterochromatic regions are preferentially involved. After exposure to the alkylating agent N-methyl-N-nitrosourea (MNU) (10(-3) M, 1 hour), 70% of all aberrations are clustered within 6 segments containing tandemly repeated FokI elements of 59 bp, which comprise approximately 10% of the genome. Using immuno-slot-blot analyses, we have studied the frequency of O6-methylguanine (O6-MeG), a mutagenic lesion important for aberration induction, in total genomic DNA as well as in FokI sequences of the field bean after exposure to MNU. In either case, similar numbers of adducts per nucleotide were found immediately after treatment as well as after 18 hours of recovery, when most adducts were removed and significant amounts of chromatid aberrations were detectable. Peculiarities of long FokI element arrays (e.g., formation of specific tertiary structures), resulting in error-prone recombination repair, rather than preferential formation or delayed repair of O6-MeG are apparently responsible for aberration clustering in these hot spot regions.

背景与目标： 诱变剂诱导的染色单体畸变并非沿中期染色体随机分布。在田间豆 (蚕豆) 中，优先涉及定义的后期复制和转录非活性异色区域。在暴露于烷基化剂N-甲基-N-亚硝基脲 (MNU) (10(-3) M，1小时) 后，所有像差中的70% 聚集在6个片段中，所述片段含有59 bp的连续重复FokI元素，其构成基因组的约10%。使用免疫缝隙印迹分析，我们研究了暴露于MNU后，在总基因组DNA以及田间豆的FokI序列中O6-methylguanine (一种对畸变诱导重要的诱变病变) 的频率 (O6-MeG)。在任何一种情况下，在治疗后以及恢复18小时后立即发现每个核苷酸的加合物数量相似，当时除去了大多数加合物并可检测到大量的染色单体畸变。长FokI元素阵列的特殊性 (例如，形成特定的三级结构)，导致容易出错的重组修复，而不是O6-MeG的优先形成或延迟修复，显然是造成这些热点区域像差聚集的原因。

BACKGROUND & AIMS: :Most high-yielding rice cultivars developed for irrigated conditions, including the widely grown lowland variety IR64, are highly susceptible to drought stress. This limits their adoption in rainfed rice environments where there is a risk of water shortage during the growing season. Mapping studies using lowland-by-upland rice populations have provided limited information about the genetic basis of variation in yield under drought. One approach to simultaneously improve and understand rice drought tolerance is to generate backcross populations, select superior lines in managed stress environments, and then evaluate which features of the selected lines differ from the recurrent parent. This approach was been taken with IR64, using a range of tolerant and susceptible cultivars as donor parents. Yields of the selected lines measured across 13 widely contracting water environments were generally greater than IR64, but genotype-by-environment effects were large. Traits expected to vary between IR64 and selected lines are plant height, because many donors were not semi-dwarf types, and maturity, because selection in a terminal stress environment is expected to favour earliness. In these experiments it was found that some lines that performed better under upland drought were indeed taller than IR64, but that shorter lines with good yield under drought could also be identified. In trials where drought stress developed in previously flooded (lowland) fields, height was not associated with performance. There was little change in maturity with selection. Other notable differences between IR64 and the selected backcross lines were in their responses to applied ABA and ethylene in greenhouse experiments at the vegetative stage and in leaf rolling observed under chronic upland stress in the field. These observations are consistent with the hypothesis that adaptive responses to drought can effectively allow for improved performance across a broad range of water environments. The results indicate that the yield of IR64 under drought can be significantly improved by backcrossing with selection under stress. In target environments where drought is infrequent but significant in certain years, improved IR64 with greater drought tolerance would be a valuable option for farmers.

背景与目标： : 大多数为灌溉条件开发的高产水稻品种，包括广泛种植的低地品种IR64，都极易受到干旱胁迫的影响。这限制了它们在生长季节有缺水风险的雨养水稻环境中的采用。使用低地旱稻种群进行的作图研究提供了有关干旱条件下产量变化的遗传基础的有限信息。同时改善和了解水稻耐旱性的一种方法是生成回交种群，在受管理的胁迫环境中选择优良的品系，然后评估所选品系的哪些特征与轮回亲本不同。IR64采用了这种方法，使用了一系列耐性和易感品种作为供体亲本。在13个广泛收缩的水环境中测得的选定品系的产量通常大于IR64，但基因型对环境的影响很大。预计在IR64和选定品系之间变化的性状是植物高度，因为许多供体不是半矮化类型，而成熟度则是，因为在末端胁迫环境中进行选择有望有利于早熟。在这些实验中，发现某些在高地干旱下表现更好的品系确实比IR64高，但是在干旱下也可以确定产量较高的短品系。在先前被洪水淹没的 (低地) 田地中出现干旱胁迫的试验中，高度与性能无关。选择的成熟度几乎没有变化。IR64与选定的回交系之间的其他显着差异在于它们在营养阶段的温室实验中对ABA和乙烯的响应以及在田间长期高地胁迫下观察到的叶片滚动。这些观察结果与以下假设一致: 对干旱的适应性反应可以有效地改善各种水环境的性能。结果表明，在干旱条件下，通过选择回交可以显着提高IR64的产量。在干旱很少发生但在某些年份很严重的目标环境中，对农民来说，提高IR64的耐旱性将是一个有价值的选择。

BACKGROUND & AIMS: BACKGROUND:Currently, there is little data available regarding the role of gender-specific gene expression on synonymous codon usage (translational selection) in most organisms, and particularly plants. Using gender-specific EST libraries (with > 4000 ESTs) from Zea mays and Triticum aestivum, we assessed whether gender-specific gene expression per se and gender-specific gene expression level are associated with selection on codon usage. RESULTS:We found clear evidence of a greater bias in codon usage for genes expressed in female than in male organs and gametes, based on the variation in GC content at third codon positions and the frequency of species-preferred codons. This finding holds true for both highly and for lowly expressed genes. In addition, we found that highly expressed genes have greater codon bias than lowly expressed genes for both female- and male-specific genes. Moreover, in both species, genes with female-specific expression show a greater usage of species-specific preferred codons for each of the 18 amino acids having synonymous codons. A supplemental analysis of Brassica napus suggests that bias in codon usage could also be higher in genes expressed in male gametophytic tissues than in heterogeneous (flower) tissues. CONCLUSION:This study reports gender-specific bias in codon usage in plants. The findings reported here, based on the analysis of 1,497,876 codons, are not caused either by differences in the biological functions of the genes or by differences in protein lengths, nor are they likely attributable to mutational bias. The data are best explained by gender-specific translational selection. Plausible explanations for these findings and the relevance to these and other organisms are discussed.

背景与目标：

BACKGROUND & AIMS: :The evolution of oxygen transport hemoglobins occurred on at least two independent occasions. The earliest event led to myoglobin and red blood cell hemoglobin in animals. In plants, oxygen transport "leghemoglobins" evolved much more recently. In both events, pentacoordinate heme sites capable of inert oxygen transfer evolved from hexacoordinate hemoglobins that have unrelated functions. High sequence homology between hexacoordinate and pentacoordinate hemoglobins in plants has poised them for potential structural analysis leading to a molecular understanding of this important evolutionary event. However, the lack of a plant hexacoordinate hemoglobin structure in the exogenously ligand-bound form has prevented such comparison. Here we report the crystal structure of the cyanide-bound hexacoordinate hemoglobin from barley. This presents the first opportunity to examine conformational changes in plant hexacoordinate hemoglobins upon exogenous ligand binding, and reveals structural mechanisms for stabilizing the high-energy pentacoordinate heme conformation critical to the evolution of reversible oxygen binding hemoglobins.

背景与目标： : 氧转运血红蛋白的演变至少发生在两个独立的场合。最早的事件导致动物出现肌红蛋白和红细胞血红蛋白。在植物中，氧气运输 “leghe血红蛋白” 是最近进化的。在这两种情况下，能够惰性氧转移的五配位的血红素位点都是由具有无关功能的六配位的血红蛋白进化而来的。植物中六配位和五配位血红蛋白之间的高序列同源性使它们可以进行潜在的结构分析，从而对这一重要的进化事件有了分子理解。然而，由于缺乏外源配体结合形式的植物六配位血红蛋白结构，因此无法进行这种比较。在这里，我们报告了大麦中氰化物结合的六配位血红蛋白的晶体结构。这为研究外源配体结合后植物六配位血红蛋白的构象变化提供了第一个机会，并揭示了稳定对可逆氧结合血红蛋白的进化至关重要的高能五配位血红素构象的结构机制。

BACKGROUND & AIMS: BACKGROUND:The reasons for low adherence to cereal dietary guidelines are not well understood but may be related to knowledge, attitudes, beliefs and perceived barriers. This study aims to assess trends in cereal foods consumption, intention to change and factors associated with intake among Western Australian (WA) adults 18 to 64 years. METHOD:Cross-sectional data from the 1995, 1998, 2001, 2004, 2009, and 2012 Nutrition Monitoring Survey Series involving 7044 adults were pooled. OUTCOME VARIABLES:types and amount of cereals (bread, rice, pasta, and breakfast cereal) eaten the day prior. Attitudes, knowledge, intentions, weight status and sociodemographic characteristics were measured. Descriptive statistics, multiple binary logistic and multinomial logistic regressions assess factors associated with consumption. RESULTS:Bread (78%) was the most commonly consumed cereal food. The proportion eating bread decreased across survey years (Odds Ratio OR = 0.31; 95% Confidence Interval; 0.24-0.40 in 2012 versus 1995), as did the amount (4.1 slices of bread in 1995 to 2.4 in 2012). The odds of consuming whole-grain cereal foods increased since 2009 (OR = 1.27; 1.02-1.58 versus 1995 p < 0.05). The likelihood of trying to eat less cereal food in the past year was greater in 2012 compared to 1995 (Relative Risk Ratio RRR 10.88; 6.81-17.4). Knowledge of cereal recommendations decreased over time (OR = 0.20; 0.15-0.27 in 2012 versus 1995 p < 0.001). Overweight and obese respondents were more likely than healthy weight respondents to have tried to eat less cereals (RRR 1.65; 1.22-2.24 and 1.88; 1.35-2.63 respectively). 'I already eat enough' was the main barrier (75% in 1995 to 84% in 2012 (p < 0.001)). CONCLUSIONS:WA adults are actively reducing the amount of cereal foods they eat and intake is associated with a misperception of adequacy of intake. Nutrition intervention is needed to increase awareness of the health benefits of cereal foods, particularly whole-grains, and to address barriers to incorporating them daily. TRIAL REGISTRATION:Not applicable.

背景与目标：

BACKGROUND & AIMS: :Contents 1314 I. 1315 II. 1316 III. 1322 IV. 1323 V. 1325 VI. 1326 VII. 1326 VIII. 1327 1328 References 1328 SUMMARY: Invasions of alien plants are typically studied as invasions of individual species, yet interactions between plants and symbiotic fungi (mutualists and potential pathogens) affect plant survival, physiological traits, and reproduction and hence invasion success. Studies show that plant-fungal associations are frequently key drivers of plant invasion success and impact, but clear conceptual frameworks and integration across studies are needed to move beyond a series of case studies towards a more predictive understanding. Here, we consider linked plant-fungal invasions from the perspective of plant and fungal origin, simplified to the least complex representations or 'motifs'. By characterizing these interaction motifs, parallels in invasion processes between pathogen and mutualist fungi become clear, although the outcomes are often opposite in effect. These interaction motifs provide hypotheses for fungal-driven dynamics behind observed plant invasion trajectories. In some situations, the effects of plant-fungal interactions are inconsistent or negligible. Variability in when and where different interaction motifs matter may be driven by specificity in the plant-fungal interaction, the size of the effect of the symbiosis (negative to positive) on plants and the dependence (obligate to facultative) of the plant-fungal interaction. Linked plant-fungal invasions can transform communities and ecosystem function, with potential for persistent legacies preventing ecosystem restoration.

背景与目标： : 内容1314 I.1315二.1316三.1322四.1323 V.1325六.1326七.1326八.1327 1328参考文献1328摘要: 外来植物的入侵通常被研究为单个物种的入侵，但是植物与共生真菌 (共生主义者和潜在病原体) 之间的相互作用会影响植物的生存，生理特征和繁殖，从而影响入侵的成功。研究表明，植物与真菌的关联通常是植物入侵成功和影响的关键驱动因素，但是需要明确的概念框架和跨研究的整合才能超越一系列案例研究，从而获得更具预测性的理解。在这里，我们从植物和真菌起源的角度考虑了相关的植物-真菌入侵，简化为最不复杂的表示或 “基序”。通过表征这些相互作用基序，病原体和共生真菌之间的入侵过程中的相似之处变得清晰，尽管结果通常是相反的。这些相互作用基序为观察到的植物入侵轨迹背后的真菌驱动动力学提供了假设。在某些情况下，植物-真菌相互作用的影响是不一致的或可以忽略不计的。不同相互作用基序的时间和地点的变异性可能是由植物-真菌相互作用的特异性，共生对植物的影响 (从负到正) 的大小以及植物-真菌相互作用的依赖性 (专性到兼性) 驱动的。相关的植物真菌入侵可以改变社区和生态系统功能，并有可能导致持久的遗产阻止生态系统恢复。

BACKGROUND & AIMS: :Bryonia, a well-known medicinal plant used mainly in homeopathy as an antiinflammatory, has never been considered an adaptogen. However, much evidence has been accumulated during the last decade indicating that Bryonia roots have adaptogenic properties. This review summarizes the reports (published mainly in Russian) on the chemical composition, the pharmacological and biochemical investigations of the active principles of Bryonia alba roots. It also summarizes reports on clinical trials of a Bryonia extract (tablets prepared from a standardized powder of Bryonia alba root, called "Loshtak" in Armenia) that indicates it is an adaptogenic and restorative drug with immunomodulatory, stress-protective and tonic properties that increase the nonspecific resistance of an organism toward harmful stimuli. The major active components of the Bryonia extract are cucurbitacin glucosides and trihydroxyoctadecadienoic acids (THODA). The biological activities of these compounds are associated with biosynthesis of eicosanoids and corticosteroids, which are important mediators in the immune, endocrine and nervous systems. Clinical trials show that the Bryonia extract was effective in treating workers at the Chernobyl Nuclear reactor who suffered from vegetovessel dystonia and other accompanying illnesses as a result of that facility's well-known accident. It was also effective in preventing radiation-induced disorders and cytostatic side effects in cancer therapy. The use of Bryonia extract in healthy athletes increases their endurance, working capacity and heart rate restoration after physical loading. No side effects caused by Bryonia extract intake were recorded during these trials.

背景与目标： : Bryonia是一种著名的药用植物，主要用于顺势疗法作为抗炎药物，从未被认为是适应原。然而，在过去十年中，已经积累了许多证据，表明Bryonia根具有适应性。这篇综述总结了有关Bryonia alba根的化学成分，药理和生化研究的报告 (主要以俄语发表)。它还总结了Bryonia提取物 (由Bryonia alba根的标准化粉末制成的片剂，在亚美尼亚称为 “Loshtak”) 的临床试验报告，表明它是一种适应性和恢复性药物，具有免疫调节，应激保护和滋补特性，可增加生物体对有害刺激的非特异性抵抗力。Bryonia提取物的主要活性成分是葫芦苷和三羟基十八碳二烯酸 (THODA)。这些化合物的生物活性与类花生酸和皮质类固醇的生物合成有关，后者是免疫，内分泌和神经系统中的重要介质。临床试验表明，Bryonia提取物可有效治疗切尔诺贝利核反应堆的工人，这些工人因该设施的著名事故而患有植物血管张力障碍和其他伴随疾病。在癌症治疗中，它还可有效预防辐射引起的疾病和细胞抑制副作用。在健康运动员中使用Bryonia提取物可提高其耐力，工作能力和身体负荷后的心率恢复。在这些试验中没有记录到由Bryonia提取物摄入引起的副作用。

BACKGROUND & AIMS: :According to the World Bank and FAO, the population grows worldwide and the poorest countries are expected to double their population within the next decades, reaching approximately 7.2 billion in 2015. Moreover, the food and financial crisis together with the global economic recession pushed the number of hungry and undernourished people in the world to unprecedented levels. The substitution of animal proteins by plant proteins in food and feed is a general trend because of the lower cost and better production efficiency. Pathogens and pests can reduce the crop yields up to 30%. In some places, the losses can reach 80% due to climate conditions, proliferation of insects, and fungal diseases. All together, the harvest and postharvest losses vary from 5% to 20% and depending on the commodity can be as high as 50%. Plants have a complex chemical armory for defense composed of low and high molecular mass compounds that can act over a variety of pests and pathogens, from micro-organisms to phytophagous insects or grazing animals. Among them, plant fungitoxic and insecticidal polypeptides represent promising alternatives to increase the supply of plant-derived proteins and tackle the hunger in a global scale.

背景与目标： : 根据世界银行和粮农组织的数据，全世界的人口都在增长，最贫穷的国家预计在未来几十年内人口将翻一番，达到约72亿2015年。此外，粮食和金融危机以及全球经济衰退使世界上饥饿和营养不良的人数达到了前所未有的水平。食品和饲料中植物蛋白替代动物蛋白是大势所趋，因为其成本较低，生产效率较好。病原体和害虫可以降低作物产量高达30%。在某些地方，由于气候条件，昆虫的繁殖和真菌疾病，损失可能达到80%。总而言之，收获和收获后的损失从5% 到20% 不等，根据商品的不同，可能高达50%。植物具有复杂的防御化学武器，由低分子量和高分子量化合物组成，可作用于多种害虫和病原体，从微生物到植食性昆虫或放牧动物。其中，植物真菌毒素和杀虫多肽代表了有希望的替代品，可增加植物衍生蛋白质的供应并在全球范围内解决饥饿问题。

BACKGROUND & AIMS: :Habitat destruction has resulted in the extinction of many plant species from the earth, and many more face extinction. Likely, the annual endemic Mediterranean knapweed (Centaurea tchihatcheffii) growing in the Golbasi district of Ankara, Turkey is facing extinction and needs urgent conservation. Plant tissue culture, a potentially useful technique for ex situ multiplication, was used for the restoration of this ill-fated plant through seed germination, micropropagation from stem nodes, and adventitious shoot regeneration from immature zygotic embryos. The seeds were highly dormant and very difficult to germinate. No results were obtained from the micropropagation of stem nodes. However, immature zygotic embryos showed the highest adventitious shoot regeneration on Murashige and Skoog (MS) medium, containing 1 mg l(-1) kinetin and 0.25 mg l(-1) NAA. Regenerated shoots were best rooted on MS medium containing 1 mg l(-1) IBA and transferred to the greenhouse for flowering and seed set. As such, the present work is the first record of in vitro propagation of critically endangered C. tchihatcheffii, using immature zygotic embryos, and is a step forward towards conservation of this indigenous species.

背景与目标： : 栖息地的破坏导致许多植物物种从地球上灭绝，更多的植物面临灭绝。可能，在土耳其安卡拉Golbasi区生长的一年一度的地中海特有种 (Centaurea tchihatcheffii) 正面临灭绝，需要紧急保护。植物组织培养是一种可能用于异位繁殖的有用技术，用于通过种子发芽，茎节微繁殖以及未成熟合子胚的不定芽再生来恢复这种命运不佳的植物。种子高度休眠，很难发芽。没有从茎节的微繁殖获得结果。然而，未成熟的合子胚在Murashige和Skoog (MS) 培养基上显示出最高的不定芽再生，其中含有1 mg l(-1) 激动素和0.25 mg l(-1) NAA。再生的芽最好在含有1 mg l(-1) IBA的MS培养基上生根，然后转移到温室中进行开花和结实。因此，目前的工作是使用未成熟合子胚对极度濒危的tchihatcheffii进行体外繁殖的第一个记录，并且是朝着保护该土著物种迈出的一步。

BACKGROUND & AIMS: :Amendments of olive orchard soil with two different preparations of olive mill solid waste (OMWMs) at the rate of 9tonha(-1) per year for five years in two different plots were compared with an industry standard soil amendment using urea. Both the OMWMs amendments showed significant increases in total organic carbon and humic substances in soil of approximately 40% and 58%, respectively, without negative effects on tree growth and yield. This work has shown that olive oil mill waste (OMW) can be recycled safely using the bioremediation system used in this study. We suggest that this system is particularly beneficial to organic farming and is an alternative solution to direct spreading of raw OMW on farm lands.

背景与目标： : 在两个不同的地块中，用两种不同的橄榄厂固体废物 (OMWMs) 以每年9吨 (-1) 的速度对橄榄果园土壤进行了改良，并将其与使用尿素的行业标准土壤改良进行了比较。两种OMWMs修正案均显示土壤中总有机碳和腐殖质分别显着增加约40% 和58%，而对树木的生长和产量没有负面影响。这项工作表明，使用本研究中使用的生物修复系统可以安全地回收橄榄油厂废料 (OMW)。我们建议该系统对有机农业特别有利，并且是在农田上直接传播原始OMW的替代解决方案。

BACKGROUND & AIMS: :Sexual eukaryotes reproduce via the meiotic cell division, where ploidy is halved and homologous chromosomes undergo reciprocal genetic exchange, termed crossover (CO). CO frequency has a profound effect on patterns of genetic variation and species evolution. Relative CO rates vary extensively both within and between plant genomes. Plant genome size varies by over 1000-fold, largely due to differential expansion of repetitive sequences, and increased genome size is associated with reduced CO frequency. Gene versus repeat sequences associate with distinct chromatin modifications, and evidence from plant genomes indicates that this epigenetic information influences CO patterns. This is consistent with data from diverse eukaryotes that demonstrate the importance of chromatin structure for control of meiotic recombination. In this review I will discuss CO frequency patterns in plant genomes and recent advances in understanding recombination distributions.

背景与目标： : 有性真核生物通过减数分裂细胞分裂繁殖，倍性减半，同源染色体经历相互的遗传交换，称为交叉 (CO)。CO频率对遗传变异和物种进化的模式有深远的影响。植物基因组内部和之间的相对CO速率差异很大。植物基因组大小变化超过1000倍，这主要是由于重复序列的差异扩展，并且增加的基因组大小与减少的CO频率相关。基因与重复序列与明显的染色质修饰相关，来自植物基因组的证据表明，这种表观遗传信息会影响CO模式。这与来自各种真核生物的数据一致，这些数据证明了染色质结构对控制减数分裂重组的重要性。在这篇综述中，我将讨论植物基因组中的CO频率模式以及理解重组分布的最新进展。

BACKGROUND & AIMS: BACKGROUND:Heterosis in internode elongation and plant height are commonly observed in hybrid plants, and higher GAs contents were found to be correlated with the heterosis in plant height. However, the molecular basis for the increased internode elongation in hybrids is unknown. RESULTS:In this study, heterosis in plant height was determined in two wheat hybrids, and it was found that the increased elongation of the uppermost internode contributed mostly to the heterosis in plant height. Higher GA4 level was also observed in a wheat hybrid. By using the uppermost internode tissues of wheat, we examined expression patterns of genes participating in both GA biosynthesis and GA response pathways between a hybrid and its parental inbreds. Our results indicated that among the 18 genes analyzed, genes encoding enzymes that promote synthesis of bioactive GAs, and genes that act as positive components in the GA response pathways were up-regulated in hybrid, whereas genes encoding enzymes that deactivate bioactive GAs, and genes that act as negative components of GA response pathways were down-regulated in hybrid. Moreover, the putative wheat GA receptor gene TaGID1, and two GA responsive genes participating in internode elongation, GIP and XET, were also up-regulated in hybrid. A model for GA and heterosis in wheat plant height was proposed. CONCLUSION:Our results provided molecular evidences not only for the higher GA levels and more active GA biosynthesis in hybrid, but also for the heterosis in plant height of wheat and possibly other cereal crops.

背景与目标：

BACKGROUND & AIMS: :We demonstrate that naturally occurring C(14) and C(16)-specific acyl-acyl carrier protein (ACP) desaturases from plants can complement the unsaturated fatty acid (UFA) auxotrophy of an Escherichia coli fabA/fadR mutant. Under the same growth conditions, C(18)-specific delta(9)-stearoyl (18:0)-ACP desaturases are unable to complement the UFA auxotrophy. This difference most likely results from the presence of sufficient substrate pools of C(14) and C(16) acyl-ACPs but a relative lack of C(18) acyl-ACP pools in E. coli to support the activities of the plant fatty acid desaturase. Based on this, a substrate-dependent selection system was devised with the use of the E. coli UFA auxotroph to isolate mutants of the castor delta(9)-18:0-ACP desaturase that display enhanced specificity for C(14) and C(16) acyl-ACPs. Using this selection system, a number of desaturase variants with altered substrate specificities were isolated from pools of randomized mutants. These included several G188L mutant isolates, which displayed a 15-fold increase in specific activity with 16:0-ACP relative to the wild-type castor delta(9)-18:0-ACP desaturase. Expression of this mutant in Arabidopsis thaliana resulted in the accumulation of unusual monounsaturated fatty acids to amounts of >25% of the seed oil. The bacterial selection system described here thus provides a rapid means of isolating variant fatty acid desaturase activities for modification of seed oil composition.

背景与目标： : 我们证明了植物天然存在的C(14) 和C(16) 特异性酰基-酰基载体蛋白 (ACP) 去饱和酶可以补充大肠杆菌fabA/fadR突变体的不饱和脂肪酸 (UFA) 营养缺陷。在相同的生长条件下，C(18) 特异性 δ (9)-硬脂酰基 (18:0)-ACP去饱和酶不能补充UFA营养缺陷。这种差异很可能是由于存在足够的C(14) 和C(16) 酰基-ACPs底物库，但大肠杆菌中相对缺乏C(18) 酰基-ACP库来支持植物的活性脂肪酸去饱和酶。基于此，设计了一种底物依赖性选择系统，使用大肠杆菌UFA营养缺陷型分离蓖麻delta(9)-18:0-ACP去饱和酶的突变体，该突变体对C(14) 和C(16) 酰基-ACPs。使用此选择系统，从随机突变体池中分离出许多具有改变的底物特异性的去饱和酶变体。其中包括几个G188L突变分离株，相对于野生型蓖麻delta(9)-18:0-ACP去饱和酶，其16:0-ACP的比活性增加了15倍。该突变体在拟南芥中的表达导致异常的单不饱和脂肪酸积累到种子油的> 25%。因此，此处描述的细菌选择系统提供了一种快速分离变体脂肪酸去饱和酶活性的方法，以修饰种子油成分。

BACKGROUND & AIMS: :Catch crop candidates (corn, guinea grass) for recovering nutrients from farm soil and aquatic plants (water caltrop, water hyacinth) were utilized to produce L-lactic acid. The efficiencies ofpre-treatment methods for enzymatic saccharification and L-lactate production of two fermentation processes, thermophilic simultaneous saccharification and fermentation (SSF), as well as separate saccharification and fermentation, were compared. Conditions were set at 55 degrees C and pH 5.5 for non-sterile fermentation. Alkaline/peroxide pre-treatment proved the most effective for saccharification in pre-treated corn, guinea grass, water caltrop and water hyacinth with glucose yields of 0.23, 0.20, 0.11 and 0.14 g/g-dry native biomass (24-hour incubation period), respectively. Examination of the two types of thermophilic L-lactate fermentation employed following alkaline/peroxide pre-treatment and saccharification demonstrated that the L-lactate yield obtained using SSF (0.15 g/g in the case of corn) was lower than that obtained using separate saccharification and fermentation (0.28 g/g in the case of corn). The lower yield obtained from SSF is likely to have resulted from the saccharification conditions used in the present study, as the possibility of cellulase deactivation during SSF by thermophilic L-lactate producing bacteria existed. A cellulase that retains high activity levels under non-sterile conditions and a L-lactate producer without cellulose hydrolysis activity would be required in order for SSF to serve as an effective method of L-lactate production.

背景与目标： : 用于从农场土壤和水生植物 (水caltrop，水葫芦) 中回收养分的农作物候选物 (玉米，几内亚草) 用于生产L-乳酸。比较了嗜热同时糖化和发酵 (SSF) 以及单独糖化和发酵两种发酵过程的酶促糖化和L-乳酸生产预处理方法的效率。将非无菌发酵的条件设定在55 ℃ 和pH 5.5。碱性/过氧化物预处理被证明对经预处理的玉米，豚草，水caltrop和水葫芦的糖化最有效，葡萄糖产量分别为0.23，0.20，0.11和0.14g/g干天然生物质 (24小时孵育期)。对碱性/过氧化物预处理和糖化后使用的两种嗜热L-乳酸发酵的检查表明，使用SSF获得的L-乳酸产量 (玉米为0.15g/g) 低于使用单独糖化和发酵获得的L-乳酸产量 (在该情况下为0.28g/g) 玉米)。从SSF获得的较低产量可能是由于本研究中使用的糖化条件所致，因为存在嗜热L-乳酸产生细菌在SSF期间纤维素酶失活的可能性。为了使SSF用作生产L-乳酸的有效方法，将需要在非无菌条件下保持高活性水平的纤维素酶和无纤维素水解活性的L-乳酸生产者。