Endophytic Bacteria Promote the Growth of Suaeda glauca in Saline-Alkali Stress:Regulation of Osmotic Pressure and Antioxidative Defense System

Endophytic bacteria are promising bacterial fertilizers to improve plant growth under adverse environment.For ecological remediation of coastal wetlands,it was necessary to investigate the effect and interaction of endophytes on halophytes under saline-alkali stress.In this study,an endophytic bacterium strain HK1 isolated from halophytes was selected to infect Suaeda glauca under pH(7 and 8)and salinity gradient(150,300 and 450mmolL^(-1)).Strain HK1 was identified as Pantoea ananatis and it had ability to fix nitrogen,dissolve inorganic phosphorus and produce indole-3-aceticacid(IAA).The results showed that strain HK1 could promote the growth of S.glauca seedings when the salinity was less than 300mmolL^(-1),in view of longer shoot length and heavier fresh weight.The infected plants could produce more proline to decrease the permeability of cells,which content increased by 26.2%–61.1%compared to the non-infected group.Moreover,the oxidative stress of infected plants was relieved with the malondialdehyde(MDA)content decreased by 16.8%–32.9%,and the peroxidase(POD)activity and catalase(CAT)activity increased by 100%–500%and 6.2%–71.4%,respectively.Statistical analysis revealed that increasing proline content and enhancing CAT and POD activities were the main pathways to alleviate saline-alkali stress by strain HK1 infection,and the latter might be more important.This study illustrated that endophytic bacteria could promote the growth of halophytes by regulation of osmotic substances and strengthening antioxidant activities.This finding would be helpful for the bioremediation of coastal soil.

Plant Growth-Prompting Bacteria Influenced Metabolites of <i>Zea mays var. amylacea </i>and <i>Pennisetum americanum p. </i>in a Species-Specific Manner

Poor soil is one of the agricultural world’s principal challenges, inciting the use of chemical fertilizer’s to improve overall soil quality. However, the use of chemical fertilizer has significant and cascading environmental consequences. Therefore, the use of beneficial microbes’ inoculation in treating poor soil is a considerably ecofriendly sustainable solution. In the current study, we supplemented nutrient-deprived soil with plant growth promoting bacteria (PGPB), Pseudomonas fluorescens. The bacterial inoculations of Pseudomonas fluorescenswere added to the poor soil following two days post-sowing of Zea mays var. amylacea and Pennisetumamericanum p. seedlings. Metabolite analyses were conducted two months after treatment for both shoots and roots using nuclear magnetic resonance method (NMR). The data indicated significant changes in 19 metabolites relative to control in both plants shoot and roots. Among these metabolites, 7 were upregulated in roots of Zea mays var. amylacea, and 9 metabolites were upregulated in roots of Pennisetum americanum p. The PGPB enhanced sugars (fructose, glucose, sucrose) and amino acids (glutamate, alanine and succinate) in roots, while down regulating in shoots of Pennisetum americanum p. The Pseudomonas fluorescens induced, predominantly,Aminoacyl-tRNA related metabolite, and Alanine, aspartate and glutamate metabolite biosynthesis in Zea mays var. amylacea), whereas PGPB induced metabolites in Pennisetum americanum p., dominated by up regulated carbohydrate related (starch and sucrose) metabolites. The difference in some metabolic response between the two plants indicated that PGPB influence has a species-specific manner.

PGPR调控植物响应逆境胁迫的作用机制

盐碱、干旱等非生物胁迫是限制植物生长和产量的重要环境因子。植物根际促生菌(PGPR)是一类定殖于植物根系的有益微生物,利用其生物学功能制成的生物菌剂具有低成本、高效和环保等优点,不仅可促进植物生长与作物产量,还能提高植物对非生物胁迫的耐受性。本研究对PGPR定义和种类、生物学功能及其在植物响应盐碱、干旱、高低温及重金属等非生物胁迫中的作用加以综述,并对其未来研究方向进行展望,以期为今后PGPR介导植物抗逆性的研究与生物菌剂的开发和应用提供理论支撑。

生物法修复盐渍化土壤研究进展

我国盐渍化土壤面积大,已严重制约了农业的发展和土壤的循环利用,修复盐渍化土壤有利于增加我国耕地面积、提高粮食产量。盐渍化土壤通常采用物理、化学和生物3种方法进行修复。相比于化学和物理修复法,生物修复法利用生物的生命代谢活动降低土壤的盐分,更经济、环保和高效,因此已在盐渍化土壤修复中得到广泛应用。文章总结了土地盐渍化危害及我国土地盐渍化现状,论述了植物、微生物和微生物-植物联合修复盐渍化土壤的机制和研究现状,并展望了生物法修复盐渍化土壤的应用前景。

金属抗性促生细菌Burkholderia sp.减缓玉米幼苗镉毒害和阻抗镉转运

为探明金属抗性促生细菌对减缓玉米镉毒害和阻抗镉转运的影响,本研究采用砂培试验向营养液中添加不同浓度重金属镉,研究接种镉抗性促生细菌YM3(Burkholderia sp.)对玉米苗干质量、生理指标、镉含量及金属转运基因表达情况的影响。结果表明,接种菌株YM3能促进玉米生长,且在镉胁迫环境中菌株促生效果更显著,使玉米根、茎、叶干质量分别增加9.09%~40.00%、63.33%~84.41%、48.50%~67.48%;接种处理玉米叶绿素总量增加1.70%~53.17%、根系活力增加7.40%~16.93%;游离脯氨酸降低3.04%~21.82%;当镉浓度为12 mg·L^(-1)时,丙二醛含量降低26.37%;接种菌株显著降低玉米地上部镉含量,使茎、叶镉含量分别降低13.64%~41.84%和17.85%~20.29%;q-PCR对金属转运相关基因HMA2、HMA3和Nramp5进行表达量的检测,结果表明接种菌株对重金属转运相关基因转录水平的表达调控受镉浓度影响。在0 mg·L^(-1)和8 mg·L^(-1)镉处理中,接菌处理HMA2、HMA3和Nramp5表达量在根中均表现为下调,在8 mg·L^(-1)和12 mg·L^(-1)镉处理中,接菌处理HMA2和Nramp5表达量在叶中均表现为下调。接菌处理通过不同程度影响基因HMA2、HMA3和Nramp5表达量来阻控玉米苗对镉的吸收转运。研究表明,在镉胁迫环境下接种镉抗性促生菌株Burkholderia sp.YM3能促进玉米苗生长,减缓玉米苗镉毒害,并阻控镉从根部向地上部转运,这对于玉米安全生产具有重要应用潜力。

耐盐促生菌提高盐胁迫下植物生长的研究进展

土壤盐渍化是全世界面临的环境难题之一,严重影响作物的生长发育。而施用耐盐促生菌能够快速、高效提高植物的生长量,改善盐渍土壤的性质。介绍了耐盐促生菌的种类,从其促生机制、提高植物耐盐机制的角度出发,阐述了盐胁迫下耐盐促生菌在不同植物中的应用。今后还需加强对耐盐促生菌的筛选、载体固定化以及与土著微生物的相互作用机制方面的研究,以期为耐盐促生菌进一步的大规模使用提供参考。

3株玉米根际解磷菌筛选鉴定及促生作用研究

为获得优良的植物根际促生菌,研究其对玉米植株的促生效果。利用有机磷和无机磷固体培养基,从玉米植株根际土壤中筛选得到3株解磷能力较强的解磷菌株,通过细菌形态学鉴定和16S rRNA基因序列分析,确定菌株A23为阿氏肠杆菌(Enterobacter asburiae),菌株A24为桑树肠杆菌(Enterobacter mori),菌株H10为神户肠杆菌(Enterobacter kobei)。结果表明,菌株A23、A24和H10解有机磷能力为146.19~158.52μg·mL^(-1);解无机磷能力为132.29~339.18μg·mL^(-1)。3株菌株还具有产生铁载体、合成玉米素和生长素的能力,并产生不同种类和含量有机酸。接种3株菌株的玉米植株株高、茎围、干重和鲜重等植株性状分别提高36.99%、21.32%、170.14%和102.11%。3株解磷菌株可为植物促生菌剂研制和应用提供理论基础。

氧化亚氮还原细菌YSQ030的筛选、鉴定及其植物促生特性

筛选获得具有氧化亚氮(N_(2)O)还原活性及植物促生特性的细菌,为新型微生物肥料的研发与应用提供微生物资源。通过固氮培养基筛选以及含硝酸钠和琥珀酸钠的营养肉汤培养基纯化,从水塘芦苇根际土中分离得到一株细菌YSQ030;通过形态观察、16S rRNA基因序列和生理生化特征分析,对菌株进行鉴定;采用无氮反硝化培养基测定菌株的N_(2)O还原能力;通过纯培养试验测定菌株的促生特征并通过水培试验研究其对水稻的促生效应。结果显示,菌株YSQ030为反硝化无色杆菌(Achromobacter denitrificans),含nosZ基因;在30℃、转速为200r/min、氧气浓度为0%的前提下,还原N_(2)O的效率为66.3%;分泌吲哚乙酸、具有溶磷和产生1-氨基环丙烷-1-羧酸(ACC)脱氨酶的能力;温室水培试验结果表明,与未接菌的对照组相比,接种YSQ030菌液显著提高了水稻幼苗的地上部鲜重和根鲜重,分别增加了48.3%和37.6%。本研究表明,YSQ030具有明显的N_(2)O还原能力,同时对水稻生长具有显著的促进作用,可为进一步构建具有N_(2)O还原能力的生物肥料提供良好的种质资源。

耐盐植物促生菌W-1鉴定及其对红豆草耐盐性的影响

【目的】为获得耐盐植物促生菌,从甘肃景泰一处盐碱地中的植物根系中分离出多株耐盐菌,其中部分耐盐菌具有明显的植物促生特性。【方法】在前期研究基础上,选取1株耐盐菌W-1和盐敏感植物红豆草(Onobrychis viciaefolia)为试验材料,对菌株W-1的物种分类、耐盐、耐酸碱能力和植物促生特性进行检测,并探究其对不同浓度NaCl处理下红豆草生长和生理特性的影响。【结果】耐盐菌W-1为革兰氏阳性菌、产芽孢、无荚膜、有鞭毛,16S rDNA测序及比对结果显示,菌株W-1为暹罗芽孢杆菌(Bacillus siamensis)。菌株W-1对NaCl最高耐受度为13%,pH耐受范围为4.5-8.5。菌株W-1具有溶磷、解钾、固氮、产铁载体、产吲哚-3-乙酸(indole-3-acetic acid,IAA)和1-氨基环丙烷-1-羧酸(1-aminocyclopropane-1-carboxylic acid,ACC)脱氨酶活性等多种植物促生功能。接种菌株W-1可显著提高红豆草的干重、鲜重,促进其根系生长。在100和150 mmol/L NaCl胁迫下,接种W-1可显著增加红豆草可溶性糖、可溶性蛋白、脯氨酸和叶绿素含量以及过氧化氢酶活力,降低过氧化氢含量以及叶片黄化率和死亡率,减缓盐胁迫对红豆草生长的不利影响。【结论】W-1是一株具有耐盐、耐酸碱的优良植物促生菌,可增强豆科牧草的耐盐性。

荒漠植物根际促生菌的筛选及其对青贮玉米幼苗的促生效应

选取实验室前期分离所得的植物根际促生菌(PGPR),对其进行形成生物膜能力、产铁载体能力、产IAA能力、产ACC脱氨酶能力以及溶磷和解钾能力测定,选取具有促生特性的菌株进行盆栽试验。共筛选出16株具有促生特性的菌株,其中BW2-6、MC35、BW35、HS1-1和SHM2在活体试验中促生效果较优。菌株BW2-6对青贮玉米幼苗的株高、基茎粗、地上部干质量、根鲜质量、根长、根表面积、根体积、相对含水量、比根长和全株鲜质量促生效果最佳,相比对照分别增加了81.00%、54.70%、156.79%、163.27%、107.35%、131.18%、175.12%、44.96%、74.48%和190.69%;菌株SHM2对地上部鲜质量和根干质量促生效果最佳,相比对照分别增加了237.85%和72.96%;菌株BW35对平均叶面积促生效果最佳,约为对照的2.33倍;对照组根冠比均高于处理组,处理组中菌株BW35根冠比最高,相比对照降低了10.18%,菌株BW2-6根冠比最低,相比对照降低了51.93%,不同菌株之间促生效果差异显著。主成分分析结果表明,5株对青贮玉米幼苗生长促进作用较好的菌中以菌株BW2-6促生效果最佳。

广西亚热带植物根际促生菌的筛选、鉴定及促生作用研究

[目的]本文旨在从植物根际土壤中分离具有多种促生性能的菌株,并明确其促生特性和抗病效果。[方法]采用选择培养方法从植物根际土壤中筛选具有固氮、产氨、溶磷、解钾、分泌吲哚乙酸(indole acetic acid,IAA)、产铁载体和产蛋白酶等特性的菌株,通过16S rRNA对菌株分类学鉴定。测定其对小麦根腐病菌(Bipolaris sorokiniana)、小麦冠腐病菌(Fusarium gramiuearum)、黄瓜织球壳菌(Plectosphaerella cucumerina)、香蕉炭疽病菌(Colletotrichum musae)、交链格孢菌(Alternaria alternate)和尖孢镰刀菌(Fusarium oxysporum)的抑制作用,并通过盆栽试验探究植物根际促生菌对植物的促生效果。[结果]从植物根际土壤中分离细菌191株,固氮及产氨菌171株,解有机磷菌66株,解无机磷菌62株,解钾菌28株,产铁载体菌98株,产IAA菌41株,产蛋白酶菌45株。抑菌试验表明贝莱斯芽胞杆菌C32对6种致病菌均表现出较强的抑菌活性,抑菌率均在50%以上。盆栽试验结果表明,1株IAA高产菌株川大肠杆菌0208对番茄和玉米植株促生效果最为显著。与对照组相比,玉米盆栽株高、茎粗、根长、地上部鲜重和地下部鲜重分别增加21.49%、19.35%、42.98%、19.58%和56.67%,番茄盆栽分别增加53.51%、14.90%、12.28%、43.12%和48.62%。[结论]从广西亚热带植物根际土壤中筛选到多株具有高效促生和防病功能的菌株,为微生物肥料的开发提供优质菌种资源。

微生物肥料菌种筛选及优化

植物根际促生菌是生活在植物根际土壤中,能够促进植物生长、防病害和增加作物产量的有益菌。由植物根际促生菌制成的微生物肥料,不仅经济、环保,还能大力推动绿色农业的发展。基于此,本实验通过对不同高效解磷菌株与解淀粉芽孢杆菌拮抗作用以及与玉米大斑病病原菌拮抗作用进行评价,筛选出制备微生物肥料的目标菌种,为微生物肥料的进一步研发和利用提供依据。

植物促生菌提高植物耐盐性的研究进展

土壤盐碱化会导致农作物产量急剧下降,已成为全球农业生态系统的一大威胁。目前生产中已采用多种修复盐碱地和恢复其生产力的方法。其中,植物促生菌(Plant Growth Promoting Bacteria, PGPB)的利用被认为是一种很有前景的盐渍土壤修复生物肥料,适用于盐渍土壤复垦和提高作物生产力。耐盐PGPB利用多种机制影响植物的生理、生化和分子生物学响应以应对盐胁迫。这些机制包括通过离子稳态和渗透液积累的渗透调节,通过形成自由基清除酶保护植物免受自由基的侵害,产生氧化应激反应,通过合成植物激素及其他代谢物维持植物正常生长。本文综述了盐胁迫下PGPB促进植物生长的各种机制,并着重介绍了PGPB在改善植物盐胁迫方面的最新进展,并对其后续研究热点进行展望。

两株耐寒PGPB的分离及其对藏北当地牧草生长的影响

为了从青藏高原北部(简称藏北)退化草原的土壤中分离筛选可以促进当地典型牧草生长的促生菌株,以促进藏北植被修复。该文通过采用稀释涂平板的方法,分离耐低温植物促生菌株,并结合盆栽试验设计,评估分离细菌对当地牧草生长的影响。结果表明:(1)从西藏土壤中成功筛选得到两株耐低温细菌TS22和TS27,经16S rRNA基因鉴定分别属于Brevibacterium sp.和Bacillus mycoides。(2)通过离体评估两株分离菌植物促生属性的结果显示,菌株TS22和TS27均具有产生IAA、SID的能力和ACC-脱氨酶活性,TS22具有较高的ACC-脱氨酶活性(264.69 nmol·α-KB mg^(-1)·h^(-1)),TS27显示出较强的产IAA[(7.52±3.85)mg·L^(-1)]和SID(92%)的能力。(3)盆栽试验显示,在10℃低温环境下,菌株TS22和TS27对早熟禾和老芒麦生长的影响因植物和菌种的不同而有所不同;菌株TS22在株高、根长、地上和地下干重方面显著促进了早熟禾的生长,且促生能力优于TS27。该研究结果为植物-微生物技术在藏北高寒地区植被恢复中的使用提供了很好的菌种资源和实践基础。

Applications of beneficial plant growth promoting rhizobacteria and mycorrhizae in rhizosphere and plant growth:A review

Because of climate change and the highly growing world population,it becomes a huge challenge to feed the whole population.To overcome this challenge and increase the crop yield,a large number of fertilizers are applied but these have many side effects.Instead of these,scientists have discovered beneficial rhizobacteria,which are environmentally friendly and may increase crop yield and plant growth.The microbial population of the rhizosphere shows a pivotal role in plant development by inducing its physiology.Plant depends upon the valuable interactions among the roots and microbes for the growth,nutrients availability,growth promotion,disease suppression and other important roles for plants.Recently numerous secrets of microbes in the rhizosphere have been revealed due to huge development in molecular and microscopic technologies.This review illustrated and discussed the current knowledge on the development,maintenance,interactions of rhizobacterial populations and various proposed mechanisms normally used by PGPR in the rhizosphere that encouraging the plant growth and alleviating the stress conditions.In addition,this research reviewed the role of single and combination of PGPR,mycorrhizal fungi in plant development and modulation of the stress as well as factors affecting the microbiome in the rhizosphere.

Effects of EDTA and plant growth-promoting rhizobacteria on plant growth and heavy metal uptake of hyperaccumulator Sedum alfredii Hance

Phytoremediation is a cost-effective and environment-friendly strategy for decontaminating heavy-metal-contaminated soil.However, the practical use of phytoremediation is constrained by the low biomass of plants and low bioavailability of heavy metals in soil.A pot experiment was conducted to investigate the effects of the metal chelator ethylenediaminetetraacetic acid(EDTA) and EDTA in combination with plant growth-promoting rhizobacteria(Burkholderia sp.D54 or Burkholderia sp.D416) on the growth and metal uptake of the hyperaccumulator Sedum alfredii Hance.According to the results, EDTA application decreased shoot and root biomass by 50% and 43%, respectively.The soil respiration and Cd,Pb, Zn uptake were depressed, while the photosynthetic rate, glutathione and phytochelatin(PC) contents were increased by EDTA application.Interestingly, Burkholderia sp.D54 and Burkholderia sp.D416 inoculation significantly relieved the inhibitory effects of EDTA on plant growth and soil respiration.Compared with the control, EDTA + D416 treatment increased the Cd concentration in shoots and decreased the Pb concentration in shoots and roots, but did not change the Zn concentration in S.alfredii plants.Furthermore,EDTA, EDTA + D54 and EDTA + D416 application increased the cysteine and PC contents in S.alfredii(p < 0.05);among all tested PCs, the most abundant species was PC2, and compared with the control, the PC2 content was increased by 371.0%, 1158.6% and 815.6%,respectively.These results will provide some insights into the practical use of EDTA and PGPR in the phytoremediation of heavy-metal-contaminated soil by S.alfredii.

Genomic analyses of metal resistance genes in three plant growth promoting bacteria of legume plants in Northwest mine tailings, China

To better understand the diversity of metal resistance genetic determinant from microbes that survived at metal tailings in northwest of China, a highly elevated level of heavy metal containing region, genomic analyses was conducted using genome sequence of three native metal-resistant plant growth promoting bacteria（PGPB）. It shows that： Mesorhizobium amorphae CCNWGS0123 contains metal transporters from P-type ATPase, CDF（Cation Diffusion Facilitator）, Hup E/Ure J and CHR（chromate ion transporter） family involved in copper, zinc, nickel as well as chromate resistance and homeostasis. Meanwhile, the putative Cop A/Cue O system is expected to mediate copper resistance in Sinorhizobium meliloti CCNWSX0020 while Znt A transporter, assisted with putative Czc D, determines zinc tolerance in Agrobacterium tumefaciens CCNWGS0286. The greenhouse experiment provides the consistent evidence of the plant growth promoting effects of these microbes on their hosts by nitrogen fixation and/or indoleacetic acid（IAA） secretion,indicating a potential in-site phytoremediation usage in the mining tailing regions of China.

多功能根际生防促生放线菌的分离鉴定及其对辣椒的益生效果

从健康辣椒根际土壤筛选具防病促生功能的菌种并应用于生物障碍土壤,可为辣椒提质增产和根腐病的防治提供优质的菌剂资源。本研究以辣椒根腐病的病原菌——腐皮镰孢菌(Fusarium solani)为靶标菌,采用平板对峙法筛选优良生防菌株,对其固氮、溶磷、解钾、分泌3-吲哚乙酸(3-indole acetic acid,IAA)、产铁载体、产纤维素酶和蛋白酶、利用酚酸类连作障碍物质等能力进行定性和定量测定。采用形态学、生理生化及16S rRNA基因序列对分离菌株进行鉴定,并采用田间原位栽培试验检测其生防和促生效果。结果表明,从设施连作抗病辣椒根际土中获得6株具有抑菌作用的放线菌,通过定性、定量测试发现菌株G-1拮抗效果最强,其对设施蔬菜5种常见病原菌均具有较好的抑制效果,抗菌谱广,且具有分泌IAA、产铁载体、产纤维素酶和蛋白酶、溶解有机磷、利用酚酸类化感物质等特性。结合形态学、生理生化及16S rRNA进化树分析结果,将其鉴定为弗氏链霉菌(Streptomyces fradiae)。田间原位栽培试验显示,G-1菌剂对辣椒根腐病具有较好的防病作用,可显著降低根腐病的病情指数,促进辣椒根系生长,且可使辣椒增产31.04%。研究表明,弗氏链霉菌G-1具有优良的防病促生功能,其固体菌剂的田间应用对辣椒根腐病具有较好的防治效果,且对辣椒具有明显的促生增产作用,可作为辣椒益生菌剂的候选菌株资源。

Effect of Inoculation with Three Phytohormone Producers Phytobacteria with ACC Deaminase Activity on Root Length of Lens esculenta Seedlings

Plant-associated bacteria that inhabit the rhizosphere may influence the plant growth by their contribution to the endogenous pool of phytohormones and by the activity of ACC deaminase to decrease the ethylene concentration. The aim of this study was to analyse the root length growth by the promoting effect of indole acetic acid producers phytobacteria with ACC deaminase activity, on inoculated seeds of Lens esculenta as synergistic effect on root elongation. In this study, although the roots of L. esculenta seedlings do not show a significant promotion, these phytobacteria could be recommended to treat plants analyzing their added inoculum to increase plant biomass and retard the effect of ethylene on cultures supplied with Tryptophan and ACC.

植物促生菌的功能及在可持续农业中的应用

全球气候变化以及人口增长加剧了农业生产中各种生物(如病原菌)和非生物(如干旱、盐渍、高温等)胁迫,并通过影响植物形态、生理生化特征和代谢功能等阻碍植物的生长、发育和生产力提升,最终影响农作物的产量和品质并严重威胁着农业的可持续发展。随着现代农业的大力发展,有益微生物因其能够改良土壤质量、提高土壤肥力、提升农作物抗胁迫性能和增产提质的功效显著而备受关注。简要概述了植物促生菌(PlantGrowth-PromotingBacteria,PGPB)的种类和施用效应,重点剖析了PGPB产生植物生长激素、固氮作用、加强对营养物质的吸收利用(溶磷、解钾和合成铁载体)、缓解生物和非生物胁迫以及调节植物根系构型和根际微生物群落结构等促生和抗胁迫机制,系统梳理了近年来运用于现代农业中的PGPB菌剂制备和施用方式的前沿科学技术,并进一步讨论了PGPB在未来农业生产中的应用前景以及研究方向。