向日葵枯萎病拮抗芽胞杆菌的筛选与生防评价

目的筛选向日葵枯萎病拮抗芽胞杆菌菌株并研究其抗菌谱,探讨环境条件对菌株抑菌活性的影响并通过植物栽培完成生防评价。方法从向日葵根际土壤中选择性分离芽胞杆菌,通过5点对峙法确定1株高效拮抗菌株,进行鉴定后,测定其抑菌谱;单因素实验探讨环境条件对抑菌活性的影响;向日葵发芽实验完成生防评价。结果确定1株高效的枯萎病拮抗菌株WBFL-1,经鉴定为枯草芽胞杆菌,该菌对镰刀菌属具有广谱抗性,其抑菌活性的最佳条件是温度40℃,pH值7.0,接种量150μL,发酵时间48 h。生防评价表明该菌对枯萎病的拮抗效果显著。结论该菌可为农作物枯萎病的生物防治提供有效菌种储备。     

西安市城市化对景观格局及生态系统服务价值的影响

我国处于城市化高度发展阶段,截止2018年全国城市化率达到59.58%。城市的快速扩张,显著改变了区域景观格局,深刻影响城市生态系统的供给、调节、文化、支持等服务功能。近30年来,西安市城市用地扩张554.23 km²,基于西安市景观格局变化分析,利用同心缓冲区探讨城乡梯度内景观指数与生态系统服务价值的特征及其相互关系,揭示城市发展对城市生态系统的影响。结果表明,1980-2015年西安市各景观类型面积发生明显变化,耕地、草地面积逐渐减少,建设用地面积波动增加,主要来源于优势景观耕地的转化。景观破碎度最高的区域主要分布在距市中心10 km左右的城乡结合部,斑块密度、边缘密度、景观分割度最高,且随城市扩张,拐点距离逐渐增加。林地和耕地是提供生态系统服务的主要土地类型,西安地区总生态服务价值减少了9.56亿元,耕地减少最多（6.83亿元）,沿城乡梯度,总生态系统服务价值均值呈现从市中心到农村递增的趋势,土壤保持的生态服务价值增长最快;沿时间梯度上,生态服务价值均值呈现逐年减少现象;从景观格局对生态服务价值影响分析得知,多样性指数与各类型生态系统服务价值之间存在显著的相关关系,最大斑块指数与不同类型的服务价值呈高度负相关。城市建设使得区域的生态系统服务价值降低,在城市发展中需要科学规划用地、合理布设景观格局,提高生态环境质量,达到城市生态宜居的目的。     

叶施NO对NaCl胁迫下红砂幼苗叶片和根系中氮代谢酶及营养物质的影响

以当年生红砂(Reaumuria soongorica)幼苗为材料,采用盆栽实验,考察叶面喷施不同浓度(0、0.01、0.10、0.25、0.50、1.00 mmol·L^-1)NO供体硝普钠 (SNP) 对NaCl(300 mmol·L^-1)胁迫下红砂根、叶中可溶性蛋白、游离氨基酸和硝态氮含量,以及谷氨酰胺合成酶(GS)、谷氨酸合酶(GOGAT)、硝酸还原酶(NR)活性的影响,并采用主成分分析和隶属函数法筛选NO对NaCl胁迫缓解效应的氮代谢指标和最佳NO浓度,以探讨外源NO对NaCl 胁迫下红砂缓解效应的氮代谢响应机制。结果表明：(1)在300 mmol·L^-1 NaCl胁迫处理下,红砂幼苗根、叶中可溶性蛋白、硝态氮含量以及GS、GOGAT、NR活性均比对照显著下降。(2)外源NO能显著提高盐胁迫下红砂叶、根中GS、GOGAT、NR活性和硝态氮含量,增加根中可溶性蛋白和游离氨基酸含量。(3)NR和GOGAT活性可用于评价NO对NaCl胁迫下红砂幼苗的缓解作用,外源NO(SNP)对红砂幼苗在NaCl胁迫下的缓解效果强弱表现为0.25 mmol·L^-1> 0.50 mmol·L^-1> 0.10 mmol·L^-1> 1.00 mmol·L^-1> 0.01 mmol·L^-1。研究发现,300 mmol·L^-1 NaCl胁迫显著抑制了红砂幼苗氮代谢,外源NO(SNP)有助于提高盐胁迫下红砂NR活性,加快硝态氮转化为铵态氮,促进红砂叶片和根中GS/GOGAT对转化物的同化,从而增强红砂幼苗的耐盐性,并以0.25 mmol·L^-1SNP处理时缓解作用最佳;NR和GOGAT活性可作为NO缓解盐胁迫的评价指标。     

An Efficient Plant Regeneration System of <i>Hydrangea bretschneideri</i> Dipp via Stem Segments as Explants

Hydrangea bretschneideri Dipp is a highly popular ornamental plant for garden decoration. Genetic engineering technology has been successfully used in many plant species, but it is limited in Hydrangea. Here we established an efficient regeneration system by using stem segments as explants for the first time. In our study, the plant growth regulators (PGRs) were evaluated at the different regeneration processes, including axillary shoots regeneration and root induction. We found that the optimal concentration for axillary buds’ induction was 2.0 mgL⁻¹ 6-BA and 0.5 mgL⁻¹ 1 IAA, its highest induction rate was 70%. Moreover, the highest axillary shoots proliferation coefficient was 10.7 on the Murashige and Skoog (MS) medium with 2.0 mgL⁻¹ 6-benzyladenine (BA), 0.2 mgL⁻¹ indole-3-butyric acid (IBA), and 1.0 mgL⁻¹ gibberellin A3 (GA3). The highest frequency of root induction was 80.0 ± 0.06% by culturing the elongated shoots in 1/2 MS medium containing 0.1 mgL⁻¹ IBA. In summary, our study will provide an effective technology for large-scale propagation and important pathway for promoting the popularization and application of Hydrangea bretschneideri Dipp.     

DNA barcoding of Oryza: conventional,specific, and super barcodes

Key message

We applied the phylogenomics to clarify the concept of rice species, aid in the identification and use of rice germplasms, and support rice biodiversity.

Abstract

Rice (genus Oryza) is one of the most important crops in the world, supporting half of the world’s population. Breeding of high-yielding and quality cultivars relies on genetic resources from both cultivated and wild species, which are collected and maintained in seed banks. Unfortunately, numerous seeds are mislabeled due to taxonomic issues or misidentifications. Here, we applied the phylogenomics of 58 complete chloroplast genomes and two hypervariable nuclear genes to determine species identity in rice seeds. Twenty-one Oryza species were identified. Conspecific relationships were determined between O. glaberrima and O. barthii, O. glumipatula and O. longistaminata, O. grandiglumis and O. alta, O. meyeriana and O. granulata, O. minuta and O. malampuzhaensis, O. nivara and O. sativa subsp. indica, and O. sativa subsp. japonica and O. rufipogon. D and L genome types were not found and the H genome type was extinct. Importantly, we evaluated the performance of four conventional plant DNA barcodes (matK, rbcL, psbA-trnH, and ITS), six rice-specific chloroplast DNA barcodes (psaJ-rpl33, trnC-rpoB, rps16-trnQ, rpl22-rps19, trnK-matK, and ndhC-trnV), two rice-specific nuclear DNA barcodes (NP78 and R22), and a chloroplast genome super DNA barcode. The latter was the most reliable marker. The six rice-specific chloroplast barcodes revealed that 17% of the 53 seed accessions from rice seed banks or field collections were mislabeled. These results are expected to clarify the concept of rice species, aid in the identification and use of rice germplasms, and support rice biodiversity.

     

以CasX为例简述新型CRISPR-Cas系统的基本属性和研究方法

在细菌与古菌中广泛存在的CRISPR-Cas系统,作为目前发现的原核生物唯一的适应性免疫系统,抵御着病毒和质粒的入侵。自20世纪80年代首次被发现至今,CRISPR-Cas系统的基本情况逐渐清晰,包括名称缩写、分类、进化关系等方面。近年来,由于第二类CRISPR-Cas系统作为一种有潜力的基因编辑工具而逐渐成为应用研究被关注,对CRISPR-Cas系统的基础研究热度也持久不衰。为了使此类基因编辑工具在实际应用领域更加安全便捷,针对已发现的CRISPR-Cas系统在根据基础研究领域的成果进行优化的同时,对新型CRISPR-Cas系统的发掘工作也同等重要。本文以2017年发现的CasX为例,简要概述针对一种新发现的CRISPR-Cas系统需要研究确定的基本属性及相关研究方法。     

miR-194-5p negatively regulates the proliferation and differentiation of rabbit skeletal muscle satellite cells

Molecular and Cellular Biochemistry - Skeletal muscle satellite cells (SMSCs), also known as a multipotential stem cell population, play a crucial role during muscle growth and regeneration. In...     

MicroRNA-197-3p mediates damage to human coronary artery endothelial cells via targeting TIMP3 in Kawasaki disease

Kawasaki disease (KD) causes cardiovascular system injury in children. However, the pathogenic mechanisms of KD have not been well defined. Recently, strong correlation between aberrant microRNAs and KD nosogenesis has been revealed. A role of microRNA-197-3p (miR-197-3p) in the pathogenesis of KD is identified in the present study. Cell proliferation assay showed human coronary artery endothelial cells (HCAECs) were suppressed by serum from KD patients, which was correlated with high levels of miR-197-3p in both KD serum and HCAECs cultured with KD serum. The inhibition of HCAECs by miR-197-3p was confirmed by cells expressing miR-197-3p mimic and miR-197-3p inhibitor. Comparative proteomics analysis and Ingenuity Pathway Analysis (IPA) revealed TIMP3 as a potential target of miR-197-3p, which was demonstrated by western blot and dual-luciferase reporter assays. Subsequently, by detecting the endothelium damage markers THBS1, VWF, and HSPG2, the role of miR-197-3p/TIMP3 in KD-induced damage to HCAECs was confirmed, which was further validated by a KD mouse model in vivo. The expressions of miR-197-3p and its target, TIMP3, are dramatically variational in KD serum and HCAECs cultured with KD serum. Increased miR-197-3p induces HCAECs abnormal by restraining TIMP3 expression directly. Hence, dysregulation of miR-197-3p/TIMP3 expression in HCAECs may be an important mechanism in cardiovascular endothelium injury in KD patients, which offers a feasible therapeutic target for KD treatment.