Genome-wide identification and comparative analysis of drought related genes in roots of two maize inbred lines with contrasting drought tolerance by RNA sequencing

Drought is one of the most important abiotic stresses affecting maize growth and development and therefore resulting in yield loss.Thus it is essential to understand molecular mechanisms of drought stress responses in maize for drought tolerance improvement.The root plays a critical role in plants sensing water deficit.In the present study,two maize inbred lines,H082183,a drought-tolerant line,and Lv28,a drought-sensitive line,were grown in the field and treated with different water conditions(moderate drought,severe drought,and well-watered conditions)during vegetative stage.The transcriptomes of their roots were investigated by RNA sequencing.There were 1428 and 512 drought-responsive genes(DRGs)in Lv28,688 and 3363 DRGs in H082183 under moderate drought and severe drought,respectively.A total of 31 Gene Ontology(GO)terms were significantly over-represented in the two lines,13 of which were enriched only in the DRGs of H082183.Based on results of Kyoto encyclopedia of genes and genomes(KEGG)enrichment analysis,"plant hormone signal transduction"and"starch and sucrose metabolism"were enriched in both of the two lines,while"phenylpropanoid biosynthesis"was only enriched in H082183.Further analysis revealed the different expression patterns of genes related to abscisic acid(ABA)signal pathway,trehalose biosynthesis,reactive oxygen scavenging,and transcription factors might contribute to drought tolerance in maize.Our results contribute to illustrating drought-responsive molecular mechanisms and providing gene resources for maize drought improvement.

Generation and characterization of expressed sequence tags(ESTs) from coralloid root cDNA library of Cycas debaoensis

A normalized full-length cDNA library was constructed from the coralloid roots of Cycas debaoensis by the DSN （duplex-specific nuclease） normalization method combined with the SMART （Switching Mechanism At 5＇ end of the RNA Transcript） technique. The titer of the original cDNA library was about 1.5 × 10^6 cfu·mL^-1 and the average insertion size was about 1 kb with a high recombination rate （97%）. The 5011 high-quality expressed sequence tags （ESTs） were obtained from 5393 randomly picked cDNA clones. Clustering and assembly of ESTs resulted in 2984 unique sequences, consisting of 618 contigs and 2366 singlets. EST sequence annotation revealed that 2333 and 1901 unigenes were functionally anno- tated in the NCBI non-redundant database and Swiss-Prot protein database, respectively. Functional analysis demonstrated that 1495 （50.1%） unigenes were associated with 4082 Gene Ontology （GO） terms. A total of 847 unigenes were grouped into 22 Cluster of Orthologous Groups （COG） functional categories. Based on the EST dataset, 22 ESTs that encoded putative receptor-like protein kinase （RLK） genes were screened. Furthermore, a total of 94 simple sequence repeats （SSRs） were discovered, of which 20 loci were successfully amplified in C debaoensis. This study is the first EST analysis for the coralloid roots of C debaoensis and provides a valuable genomic resource for novel gene discovery, gene expression and comparative genomics, conservation and management studies as well as applications in C debaoensis and related cycad species.

Isolation and Analysis of Drought-Induced Genes in Maize Roots

Maize roots are important component for plant adaptation to soil water deficits because they are supposed to take up water and necessary solutes from the soil. In the present study, the drought-induced genes were isolated in maize roots. A suppression subtractive hybridization protocol was applied to construct a forward subtractive cDNA library from CN165 for drought-stressed maize roots and a number of drought-induced genes were isolated. Totally, 126 uniESTs （containing 82 singlets and 44 contigs） were obtained from 503 available ESTs sequences after macroarray hybridization. UniESTs were analyzed using BLASTN and BLASTX and the results showed that 92% of the uniESTs had homolgous sequences in maize nr database by BLASTN. About 89% of uniESTs appeared the homlogous amino acid sequences in rice protein database but not in maize protein database by BLASTX, implying that those genes are likely new functional genes in maize. Function analysis showed that those genes were involved in a broad spectrum of biological pathways, mainly in signaling and regulatory pathways related to stress tolerance.

Identification of <i>Angelica acutiloba</i>and Related Species by Analysis of Inter- and Intra-Specific Sequence Variations in Chloroplast and Nuclear DNA Sequences

Japanese Angelica Root prepared from Angelica acutiloba var. acutiloba and A. acutiloba var. sugiyamae, known in Japan as “Toki” and “Hokkai Toki”, is an important crude drug used in Kampo medicine (traditional Japanese medicine). However, since these Angelica varieties have recently outcrossed with each other, it is unclear whether Japanese Angelica Root sold for use in Kampo medicine is a pure variety. Here, we describe DNA sequence polymorphisms that can be used to distinguish between A. acutiloba var. acutiloba and A. acutiloba var. sugiyamae. In our analyses, differences in the trnK region of chloroplast DNA distinguished among some A. acutiloba varieties and related species, but not between A. acutiloba var. acutiloba and A. acutiloba var. iwatensis. One geographical strain of A. acutiloba var. acutiloba and A. acutiloba var. sugiyamae showed identical sequences in three regions of chloroplast DNA, but differences in the internal transcribed spacer region of nuclear ribosomal DNA. One strain of A. acutiloba var. iwatensis and A. acutiloba var. sugiyamae had identical sequences in all of the chloroplast and nuclear ribosomal DNA regions examined. These findings show that A. acutiloba var. acutiloba has hybridized with A. acutiloba var. sugiyamae and that the “Hokkai Toki” variety resulted from outcrossing with A. acutiloba var. iwatensis. Molecular authentication based on analyses of chloroplast and nuclear ribosomal DNA sequences of A. acutiloba and related species is an efficient method to authenticate Japanese Angelica Root at the variety level. Therefore, these analyses can determine whether a product is derived from A. acutiloba var. acutiloba or A. acutiloba var. sugiyamae.

Single-cell RNA sequencing reveals the landscape of maize root tips and assists in identification of cell type-specific nitrate-response genes

The root system is fundamental for maize growth and yield.Characterizing its heterogeneity and cell type-specific response to nitrate at the single-cell level will shed light on root development and nutrient uptake.We profiled the transcriptomes of>7000 cells derived from root tips of maize seedlings grown on media with or without nitrate,and identified 11 major cell types or tissues and 85 cell type-specific nitrate-response genes,including several known nitrate metabolic genes.A pseudotime analysis showed a continuous pseudotime series with the beginning at meristematic zone cells and showed that the root hair cell was derived by differentiation of a subset of epidermal cells.Interspecies comparison of root cells between maize and rice revealed the conservation and divergence of the root cell types and identified 57,216,and 80 conserved orthologous genes in root hair,endodermis,and phloem cells respectively.This study provides a global view of maize root tip developmental processes and responses to nitrate at the single-cell level.The genes described in the present work could serve as targets for further genetic analyses and accurate regulation of gene expression and phenotypic variation in specific cell types or tissues.

Biological characteristics of dynamic expression of nerve regeneration related growth factors in dorsal root ganglia after peripheral nerve injury

The regenerative capacity of peripheral nerves is limited after nerve injury.A number of growth factors modulate many cellular behaviors,such as proliferation and migration,and may contribute to nerve repair and regeneration.Our previous study observed the dynamic changes of genes in L4–6 dorsal root ganglion after rat sciatic nerve crush using transcriptome sequencing.Our current study focused on upstream growth factors and found that a total of 19 upstream growth factors were dysregulated in dorsal root ganglions at 3,9 hours,1,4,or 7 days after nerve crush,compared with the 0 hour control.Thirty-six rat models of sciatic nerve crush injury were prepared as described previously.Then,they were divided into six groups to measure the expression changes of representative genes at 0,3,9 hours,1,4 or 7 days post crush.Our current study measured the expression levels of representative upstream growth factors,including nerve growth factor,brain-derived neurotrophic factor,fibroblast growth factor 2 and amphiregulin genes,and explored critical signaling pathways and biological process through bioinformatic analysis.Our data revealed that many of these dysregulated upstream growth factors,including nerve growth factor,brain-derived neurotrophic factor,fibroblast growth factor 2 and amphiregulin,participated in tissue remodeling and axon growth-related biological processes Therefore,the experiment described the expression pattern of upstream growth factors in the dorsal root ganglia after peripheral nerve injury.Bioinformatic analysis revealed growth factors that may promote repair and regeneration of damaged peripheral nerves.All animal surgery procedures were performed in accordance with Institutional Animal Care Guidelines of Nantong University and ethically approved by the Administration Committee of Experimental Animals,China(approval No.20170302-017)on March 2,2017.

Molecular Characterization of <i>Pseudomonas</i>spp. Isolated from Root Nodules of Various Leguminous Plants of Shekhawati Region, Rajasthan, India

Plant growth promontory Pseudomonas strains were isolated from root nodules of five plant species, viz., Trifolium pretense, Cicer arietinum, Amaranthus polygamus, Vigna mungo, and Trigonella foenum;that plants were denizen of Shekhawati region of Rajasthan. A total of 8 bacterial isolates were evaluated for growth promotion using PGP properties. Partial 16S rDNA sequencing data showed that these 8 bacterial isolates belonged to genus Pseudomonas. MEGA 4.0.2, software was used to construct a neighbor joining tree by employing boot strap method. Result exhibited significant diversity among recovered Pseudomonas strains.

油梨根际土壤微生物群落及其共生网络对根腐病的响应

【目的】为研发根腐病绿色综合防控技术提供理论依据,有效推进油梨树种产业发展。【方法】本研究以百色市林业科学研究所的健康和根腐病发病油梨植株根际土壤为研究对象,并利用基于16S核糖体RNA(rRNA)和内部转录间隔区(ITS)扩增子高通量测序技术,分析健康和染病植株根际细菌和真菌群落结构、组成及多样性差异,比较细菌和真菌群落结构及其相互作用,确定土壤病原菌和有益菌的变化。【结果】染病植株相对于健康植株,根际细菌和真菌群落结构和多样性均没有显著性变化。变形菌门Proteobacteria、酸杆菌门acidobacteria、放线菌门actinobacteria、拟杆菌门bacteroidetes和绿弯菌门chloroflexi是油梨根际土壤优势细菌类群,子囊菌门ascomycota和担子菌门basidiomycota是油梨根际土壤优势真菌类群。在门分类水平、纲分类水平以及属分类水平上,细菌和真菌群落组成有明显的变化,但随着分类水平降低,群落组成变化越明显。此外,健康和染病油梨根际细菌群落α多样性显著高于真菌群落,而健康与染病之间细菌群落结构差异小于真菌。细菌物种之间的相互作用比真菌网络物种间的相互作用更紧密,并且负连接百分比和关节类群数量更多,细菌网络的稳定性更高。同样,油梨根际土壤细菌群落相对于真菌群落表现出更高的生态位宽度和生态位重叠。对根腐病有反应的细菌和真菌,如芽孢杆菌Bacillus、假单胞杆菌pseudomonas和溶杆菌lysobacter和球囊菌纲glomeromycetes,由于其在染病油梨根际土壤中的相对丰度均高于健康土壤,可以被视为相关的生物防治菌。【结论】根腐病并不会使油梨根际细菌和真菌群落结构和多样性发生显著性变化,但会使得一些有益菌的相对丰度增加,并且细菌比真菌对根腐病具有更高的抵抗力。

花椒根腐病拮抗菌株W-1基因组测序及抑菌机理研究

【目的】分析贝莱斯芽孢杆菌(Bacillus velezensis)W-1的全基因组序列信息,探究其对花椒根腐病的生防机理,为该菌的高效开发和应用提供生物信息学基础,并为该菌开发为生物农药提供理论支持。【方法】采用三代PacBio平台测序技术对菌株W-1进行全基因组测序,并对测序结果进行基因功能注释和比较基因组学分析;采用菌丝生长速率法测定菌株W-1发酵液乙酸乙酯提取物对花椒根腐病病原菌菌丝形态、病原菌孢子悬浮液电导率和核酸含量的影响。【结果】菌株W-1基因组全长4166284 bp,GC含量为46.32%,其中编码蛋白基因4037个;GO、eggNOG和KEGG数据库中注释到的基因数分别为2935、3087和2185个;预测到菌株W-1能产生14种次级代谢产物合成基因簇,包括sur‐factin、butirosin A/butirosin B、planttazolicin、macrolactin H、bacilaene、fengycin、diffcidin、bacillibactin和bacilysin等9种已知基因簇及5种未知基因簇;菌株W-1特有的基因家族53个,特有基因414个,与模式菌株B.velezensis FZB42的亲缘关系较近。菌株W-1提取物对花椒根腐病病原菌菌丝生长具有明显的抑制作用,最小抑菌浓度(MIC)为4.50 mg/mL、最小杀菌浓度(MFC)为9.00 mg/mL。菌株W-1提取物可造成病原菌菌丝内含物外渗,在提取物浓度9.00 mg/mL处理10 h后,病原菌孢子悬浮液相对电导率比空白对照高57.63%、核酸含量比空白对照高64.91%。【结论】贝莱斯芽孢杆菌W-1能产生多种抗菌物质,其发酵液乙酸乙酯提取物可破坏花椒根腐病病原菌菌丝细胞膜的完整性,具有开发成生物农药的潜力,在花椒根腐病的绿色防控中具有良好的应用前景。

猕猴桃根腐病根际土壤酶活性及真菌群落组成研究

分析猕猴桃根腐病感病植株和未感病植株根际土壤真菌群落差异,可为研究猕猴桃根腐病发生机制及其调控技术提供依据。在浙江省天台县街头镇的“红阳”猕猴桃种植基地,以树龄9年的猕猴桃根腐病感病植株和未感病植株根际土壤真菌为研究对象,对菌群ITS序列进行高通量测序注释后,对比分析了真菌群落结构与多样性指数的差异,并测定分析了根际土壤脲酶、蔗糖酶和酸性磷酸酶的活性。结果表明,猕猴桃根腐病的发生极显著地降低了根际土壤脲酶、蔗糖酶和磷酸酶的活性(p<0.01)。感病植株根际土壤真菌群落丰富度指数(Chao1)显著低于未感病植株根际土壤(p<0.05)。在门分类水平上,感病植株根际土壤真菌中相对丰度降低的有担子菌门、未分类真菌和接合菌门,其差异均为极显著(p<0.01);相对丰度升高的为子囊菌门,其差异达极显著水平(p<0.01)。在属分类水平上,感病植株根际土壤真菌相对丰度增加的有赤霉菌属、丛赤壳属、镰刀菌属、假裸囊菌属和肉座菌属,其差异均达极显著水平(p<0.01);相对丰度降低的有未分类伞菌纲、枝鼻菌属、粗糙孔菌属、线虫草属、支顶孢属、粪盘菌属、木霉属和被孢霉属,其差异均达极显著水平(p<0.01)。猕猴桃感染根腐病后,根际土壤真菌在门和属水平上的菌群变化打破了原有的微生物拮抗平衡关系。

柴达木地区患根腐病枸杞根际土壤微生物多样性分析

为了解枸杞受根腐病菌侵染后植株根组织与根际土壤中真菌与细菌群落结构以及多样性,采用高通量测序技术对柴达木地区患根腐病枸杞的根组织和根际土壤样本进行分析。结果表明,根际土壤中的细菌群落丰度略高于根组织,而真菌多样性和丰度在根际土壤和根组织样本中无显著差异。在门水平,细菌群落中变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes)的相对丰度较高,真菌群落中子囊菌门(Ascomycota)和担子菌门(Basidiomycota)的相对丰度较高;在属水平,细菌中以假单胞菌(Pseudomonas)为主,真菌中以枝孢属(Cladosporium)和被孢霉属(Mortierella)为主。相关性分析显示,细菌群落在根组织和根际土壤样本中差异较大,而真菌群落在根组织和根际土壤样本间相关性较高;枝孢属(Cladosporium)和被孢霉属(Mortierella)的相对丰度在根组织和根际土壤中均显著上调,初步推测这2属真菌可能与枸杞根腐病发病相关。

基于高通量测序的锈腐病西洋参转录组分析

为探究锈腐病对西洋参基因表达模式的影响,本研究采用RNA-seq方法分析比较健康与患锈腐病西洋参根与叶中的基因表达差异,并对差异表达基因(DEGs)进行功能聚类分析。结果显示:BL-vs-AL(感病叶片vs健康叶片)组中共鉴定出8 642个DEGs,包含上调表达4 463个,下调表达4 179个;BR-vs-AR(感病根vs健康根)组中共鉴定出5 308个DEGs,包含上调表达2 609个,下调表达2 699个。GO分析发现,大多数DEGs在细胞过程、代谢过程、细胞、催化活性等方面显著富集。KEGG分析表明,DEGs主要富集到苯丙素生物合成、不饱和脂肪酸的生物合成、MAPK信号通路等与植物抗病相关的代谢通路中。同时,在两组共有DEGs中预测到转录因子116个,分别归属到25类转录因子家族中。qRT-PCR验证7个DEGs结果与转录组测序结果的表达变化趋势相符。本研究明确了异质生境中感染锈腐病的西洋参相关基因的表达特征及相关代谢通路,可为深入研究西洋参抗锈腐病的分子机制提供一定的信息参考。

拟境栽培下两种附生方式金钗石斛化学组成和根内生菌比较及相关性研究

研究拟境栽培下附石(stone epiphytic cultivation,SE)和附木(tree epiphytic cultivation,TE)两种附生方式金钗石斛化学成分组成和根内生菌的差异性及二者的相关性。采用高通量测序技术对根内生菌进行了测序与分析,并初步探究了化学成分含量与根内生菌的差异性和相关性。研究结果表明,SE金钗石斛中石斛碱、总生物碱、总黄酮含量高于TE,TE总多糖含量高于SE。两种附生方式金钗石斛根内生菌物种相对丰度差异较大,SE金钗石斛根内生菌物种丰富性、多样性高于TE,SE中的壳三毛孢属(Robillarda)促生菌、根瘤杆菌属(Rhizobacter)和芽孢杆菌属(Bacillus)固氮菌、镰刀菌属(Fusarium)致病菌属较TE增加,而TE中的柱孢属(Cylindrocarpon)和Ralstonia致病菌属较SE增加。相关性研究发现,SE金钗石斛富集的假诺卡氏菌属(Pseudonocardia)、根瘤杆菌属(Rhizobacter)细菌相对丰度与石斛碱含量显著正相关;TE富集的Cladophialophora真菌、热酸菌属(Acidothermus)、异枝藻属(Allobranchiibius)、链嗜酸菌属(Streptacidiphilus)细菌相对丰度与石斛碱含量呈显著负相关;而SE中富集菌属与总黄酮、总生物碱、总多糖含量呈显著正相关,与TE中相反。综上,SE金钗石斛化学成分较TE升高,这与SE栽培有利于金钗石斛富集促进植物生长、固氮的根内生菌有关,促进了植物化学成分的产生,有利于提升药材品质。为金钗石斛“附生方式-根内生菌-次生代谢产物”相关性研究奠定基础,为石斛“生石上者胜”提供科学依据。

转录组测序技术在甘薯研究中的应用

甘薯是世界上重要的粮食、饲料、工业原料作物。随着高通量测序技术的快速发展,转录组测序技术已广泛应用于甘薯研究之中。为了今后利用转录组学技术更好地开展甘薯功能基因挖掘、重要性状调控机制解析等研究,本综述分析了各国研究机构共享的甘薯转录组数据,并总结了近年来转录组测序技术在甘薯逆境胁迫响应、块根发育和淀粉合成等方面的应用及取得的成果。认为目前甘薯转录组研究在试验设计、数据挖掘以及研究结果实用性方面仍存在不足。提出在未来研究中,可将转录组学技术与其他组学技术及遗传学分析方法相结合,以推动甘薯研究的不断深入。

丹参根腐病病原菌及其生防菌的筛选

本研究旨在筛选用于丹参根腐病防治的生物防治菌株。实验以山东省日照市、临沂市、泰安市发病的丹参及健康丹参的根际土为试材。采用组织分离法从发病丹参中分离病原菌,采用稀释涂布法和平板对峙法从根际土中筛选生防菌,利用形态学和16S rRNA进行鉴定,并在离体丹参上进行防效验证。结果表明,从发病丹参上分离出的病原菌RBT-2-1为木贼镰刀菌(Fusarium equiseti),从根际土中筛选出的生防菌i为绿针假单胞菌橙色亚种(Pseudomonas chlororaphis subsp.aurantiaca)。i对TBG-2-1的抑菌率为66.67%,i在离体丹参上对TBG-2-1的防治效果预防组均高于治疗组,且预防组中追加i菌液的防效最好,为44.45%,比预防组中未追加i菌液的处理提高了1.6倍,比治疗组提高了7.0倍。由此可知,i的接种顺序及使用次数会影响对TBG-2-1的防效。本研究为后期大田试验提供参考依据。

Ng-Perron单位根检验在径流序列非平稳性分析中的应用

在全球气候变化和高强度人类活动的共同影响下,许多流域天然水循环过程受到破坏。径流序列呈现明显的非平稳特性,给水资源规划、管理、预测和调控带来一定的挑战。揭示径流序列的非平稳特性可以有效应对全球气候变化下的复杂水问题,对降低水文分析难度和提高径流预测精度具有十分重要的意义。研究以汾河上游兰村站为研究对象,分析该站1958-2016年年径流和月径流序列是否平稳。首先从随机水文学角度,采用Mann-Kendall检验法和小波分析法识别径流序列的趋势、突变和周期特征。在此基础上,从统计水文学角度引入Ng-Perron单位根检验方法。通过Mann-Kendall趋势检验和散点图法选择合适的检验方程,对径流序列进行广义最小二乘法(Generalized Least Squares,GLS)退势,并利用修正的信息准则(Modified information criterion,MIC)计算最优时间滞后阶数,判别径流序列是否具有非平稳性。结果显示,径流序列存在趋势、突变和周期成分,为非平稳径流序列。同时Ng-Perron单位根检验表明,该站年、月径流序列在1%显著性水平上具有非平稳特性。相较传统单位根检验方法,Ng-Perron单位根检验采用更为稳健的修正检验统计量,显著调整小样本情况下水平扭曲的现象,具有更好检验水平和功效,因而可以得到更合理的检验结果。研究成果为径流序列非平稳性检验理论的进一步改进及径流预测模型发展与应用提供参考。

甘孜州燕子沟4种高山杜鹃根系真菌群落组成与多样性分析

为促进四川甘孜州燕子沟高山杜鹃的引种驯化与移栽,并探索不同生境条件下根系微生物多样性,采集了羊踯躅、棕背杜鹃、光亮杜鹃、腺房杜鹃4种高山杜鹃的根系,通过高通量测序和生物信息学分析,评估该地区高山杜鹃类型根系真菌的组成和多样性。结果显示:4种高山杜鹃根系样品中共获得有效序列746,973条,进而聚合得到1,101个操作分类单元(OTUs);这些真菌分属于6门、27纲、30目、30科、30属,其中子囊菌门和担子菌门为主要类群,它们在群落丰度上表现出较大的差异;在属级水平上,主要优势菌属差异显著,特别是光亮杜鹃根系真菌群落不仅拥有最多的特异性OTUs,且群落丰度最高;棕背杜鹃的根系真菌群落拥有最少的特异性OTUs,而羊踯躅的根系真菌群落丰度最低。整体而言,该试验区域内4种高山杜鹃的根系真菌多样性,与同一地区低海拔地带相比,显著偏低,这符合高海拔地区真菌多样性减少的普遍趋势。

砀山酥梨根系土壤微生物种类鉴定

近年来,砀山县个别梨园砀山酥梨出现树势衰弱,甚至死亡的现象。为了探明砀山酥梨树势衰弱的成因,以砀山酥梨根系土壤为材料,利用宏基因组测序鉴定土壤中微生物种类。结果表明,濒临死亡的砀山酥梨根系土壤中硝化螺旋菌丰度均低于正常生长砀山酥梨根系土壤。在正常生长的砀山酥梨根系土壤中含有9种微生物,其中1种为其所特有;濒临死亡的砀山酥梨根系土壤中含有10种微生物,其中亚硝化螺菌和固氮螺菌为其所特有。

健康与患根腐病三七根际和根内微生物群落结构与多样性研究

[目的]研究三七健康植株和根腐病植株根内及根际土的微生物群落结构,探究其与三七根腐病发生的相关性。[方法]利用Illumina高通量测序技术对云南文山连作3年的健康植株根内及其根际土壤、根腐病植株根内及其根际土壤中的微生物群落结构及多样性进行分析。[结果]健康植株及其根际土壤与根腐病植株及其根际土壤中微生物群落的丰富度存在显著差异。黄腐植株根际土中的优势微生物为节杆菌属(Arthrobacter)、毛壳菌属(Chaetomium)和周刺座霉属(Volutella),绿腐植株根际土中的优势微生物为节杆菌属(Arthrobacter)和短梗蠕孢属(Trichocladium)。黄腐植株根内优势微生物为被孢霉属(Mortierella)和木霉属(Trichoderma),绿腐植株根内优势微生物为假单胞菌属(Pseudomonas)、土赤壳菌属(Ilyonectria)和小不整球壳属(Plectosphaerella)。[结论]三七根腐病的发生与植株根际及根内微生物多样性和群落结构密切相关。

例说黄金分割定律在平面设计中的应用

目的旨在分析现代视觉平面设计中黄金分割定律的应用研究。方法以黄金分割概念和种类为基础,对于13种黄金分割图例结合几种常见的黄金分割应用(如黄金线段分割、黄金矩形、黄金螺旋线、根号矩形、斐波那契数列),理解分析其应用原理在视觉平面设计中的应用。结果使平面设计作品在视觉上得到最佳呈现,客观设计思维与逻辑达到和谐与平衡。结论通过学习黄金分割理论与知识,结合现代设计灵活运用黄金分割原理,认识设计的造型规律、比例关系,在各类设计中发现其设计关系的黄金比例之美,认识黄金分割所蕴含的设计美学意义,并理解这种美学意义在自然界中的客观与合理性,并将这种客观规律充分利用在现代设计当中,从而认识现代设计的客观理性思维。