Compounds from the subterranean part of Johnsongrass and their allelopathic potential

The allelopathic effects of the exotic invasive weed, Johnsongrass, on Lactuca sativa, a native plant in China, were evaluated and the phytotoxins were investigated under laboratory conditions. The crude extracts (chloroform and ethyl acetate fractions) that were obtained from the ethanol extract of the subterranean parts of Johnsongrass inhibited the germination speed and growth of the roots and shoots of the test plant. The four compounds, ethyl p‐hydroxybenzoate, diosmetin, apigenin, and luteolin, were isolated from the extract of the subterranean parts of Johnsongrass first, along with three other compounds (reported previously), p‐hydroxybenzaldehyde, p‐hydroxybenzoic acid, and dhurrin, and they all were evaluated on L. sativa. At the concentration of <0.5 mmol L^?1, ethyl p‐hydroxybenzoate, dhurrin, and the mixture of the compounds delayed the germination speed of the seeds of L. sativa at 24 h of incubation, while apigenin delayed the germination speed of the seeds of L. sativa at 72 h of incubation. Ethyl p‐hydroxybenzoate demonstrated the strongest delaying effect among the phenols and a similar effect was found with apigenin among the flavonoids, wheras ethyl p‐hydroxybenzoate induced a drastic inhibition of the germination at 2 mmol L^?1. In contrast, p‐hydroxybenzaldehyde and luteolin had no effect on the germination at any concentration at any stage. All the substances inhibited the shoot and root growth of L. sativa at 3 mmol L^?1. Increasing the concentration increased the inhibition of the growth of L. sativa. The inhibitory activity of ethyl p‐hydroxybenzoate and p‐hydroxybenzaldehyde was greater than that of the other compounds. This result suggested that the isolated phytotoxins might contribute to the successful invasion by Johnsongrass.     

刺萼龙葵种子中适宜内参基因的筛选

入侵杂草刺萼龙葵Solanum rostratum Dunal传播扩散的主要载体是种子,研究其种子休眠萌发基因的激素调控对于其防除具有重要意义,而选择合适的内参基因可以提高相关基因表达分析的准确性。本研究以赤霉素、脱落酸和水处理的刺萼龙葵种子为材料,利用geNorm、NormFinder、BestKeeper和RefFinder 4种软件对15个候选内参基因进行表达稳定性评价,并通过检测ABI5(abscisic acid-insensitive 5)的表达验证所筛选的内参基因的适用性。结果表明,对于赤霉素、脱落酸和水处理过的种子,最稳定的内参基因分别为eIF(eukaryotic initiation factor)、SAND(SAND protein family)和ACT(β-actin);对所有种子样本而言,PP2Acs(a catalytic subunit of protein phosphatase 2A)是最稳定的内参基因。研究结果将为刺萼龙葵种子休眠萌发的遗传调控研究提供重要参考。     

Shift of allelochemicals from Sorghum halepense in the soil and their effects on the soil's bacterial community

Johnsongrass (Sorghum halepense [L.]Pers.), an exotic invasive weed in China, secretes the phenolic compounds, p‐hydroxybenzoic acid (p‐HBA) and p‐hydroxybenzaldehyde (p‐HBAL), as the dominant allelochemicals in the root exudates. To better understand how these two allelochemicals affect the soil microbial community in the rhizosphere of S. halepense, the fate of these compounds in the invaded soil and the effect of these phytotoxins on the soil bacterial community were evaluated. The concentrations of the allelochemicals in the soil were determined by a high‐performance liquid chromatography‐ultraviolet/photodiode array after 1, 2, 4, 6, 12 and 24 h of treatment. MiSeq sequencing was undertaken to understand how the bacterial populations in the soil were affected by the allelochemicals. The HPLC results indicated that p‐HBA was degraded by the microorganisms that were present in the soil after 1 h and disappeared after 6 h of incubation. The compound, p‐HBAL, initially was converted to p‐HBA and then the p‐HBA broke down, disappearing after 12 h of incubation in non‐sterile soil. Both p‐HBA and p‐HBAL were stable under sterile soil conditions for up to 24 h. The relative abundance of Proteobacteria was significantly inhibited. However, those of Acidobacteria, Chloroflexi, Verrucomicrobia and Cyanobacteria were increased by the p‐HBAL treatment. These findings suggest that allelochemicals from S. halepense might affect the bacterial community composition in the soil.     

反枝苋对咪唑乙烟酸抗性水平及分子机制

为初步明确大豆田反枝苋对咪唑乙烟酸的抗药性水平,并从分子角度对抗药性机制进行解释,以我国四川成都和黑龙江嫩江采集的反枝苋种子为材料,通过琼脂法检测了反枝苋对咪唑乙烟酸的抗药性水平,并分别对R(嫩江抗性种群)和S(成都敏感种群)的乙酰乳酸合成酶(ALS)部分序列进行扩增和测序。皿内生测结果表明,成都种群的GI50为11.20,嫩江种群的GI50为52.26,其抗药性指数RI为4.67。分子检测结果表明,与S种群相比,R种群反枝苋ALS位于高度保守区Domain B编码574位氨基酸的基因发生突变,TGG突变为TTG,导致色氨酸被亮氨酸取代。ALS保守区域氨基酸的替换可能是嫩江反枝苋种群对咪唑乙烟酸产生抗性的重要原因之一。     

Characterization of glyphosate-resistant goosegrass(Eleusine indica) populations in China

Goosegrass is a worst grass weed in orchards and turf.The increased use of glyphosate for goosegrass control has led to the occurrence of many resistant populations.Although glyphosate has been used to control weeds for the past 30 years in China,few reports are available on glyphosate-resistant(GR) googegrass.In this study,we determined the GR level of 14 goosegrass populations from Chengdu and Guangzhou,China.Glyphosate only controlled 3.1 and 25.0%of the populations SL5 and SL1,respectively,at the dose of 1 680 g acid equivalent(ae) ha~(-1) at 14 days after treatment(DAT).In contrast,the susceptible population(XD1) was completely(100%) controlled.The resistant index(Rl) of SL5 and SL1 were 5.1 and 4.5,and the Rl for SL2,SL3 and ZC1 were 4.2,3.2 and 2.6,respectively.The Rl for other populations was range from 1.8 to 2.5.Under the dose of glyphosate at 1 640 g ae ha~(-1) at 10 DAT,shikimate accumulation in susceptible population XD1 was 17.6 and 16.4 times higher than SL5 and SL1,respectively.And the chlorophyll content in the plant leaf of populations SL1,SL2 and SL5 were decreased slightly ranging from 22.6 to 28.0.These results confirmed that the SL1,SL2,SL3,ZC1 and SL5 populations had evolved moderate resistance to glyphosate.This is the first report for the GR goosegrass populations confirmed in Chengdu,China.     

Genetic diversity and population structure of Commelina communis in China based on simple sequence repeat markers

Commelina communis (Asiatic dayflower) is a troublesome weed in China. Genetic variation of 46 C. communis populations from different collection sites in our country was investigated using 12 simple sequence repeat (SSR) primer pairs. Polymorphism analysis results showed high level of genetic diversity among these populations. The alleles (bands) were amplified by these primer pairs. The polymorphic proportion was 18.25%, and the average polymorphism information content was 0.1330. The highest effective number of alleles was 1.9915 at locus YP33, and the lowest value was 1.0000 at both loci YP25 and YP31. C. communis showed major average observed heterozygosity value (0.8655) than that of average expected heterozygosity (0.1330). C. communis populations were divided into three groups on the basis of unweighted pair-group method with arithmetic mean cluster analysis (Dice genetic similarity coefficient=0.772) and genetic structure analysis (K=3), and a principal coordinate analysis. The results of this study further illustrated that C. communis populations contained abundant genetic information, and the 12 SSR markers could detect the microsatellite loci of C. communis genomic DNA. These results might indicate that C. communis maintains high genetic diversity among different populations.     

我国杀鼠剂应用现状及发展趋势

杀鼠剂研究与应用是害鼠生物学研究的主要内容之一,化学治理则是鼠害综合治理的关键技术之一。本文针对我国主要杀鼠剂种类及特征,简要介绍了目前我国杀鼠剂应用技术现状以及存在的问题,提出在目前生态文明建设要求下,及以生态学理念为指导的鼠害综合治理的发展趋势中,在有效避免鼠类为害的前提下,如何有效降低杀鼠剂应用可能带来的负面效应,同时最大化发挥鼠类的生态学功能,将是害鼠生物学及杀鼠剂应用研究的基本发展方向。     

Acetolactate synthase proline (197) mutations confer tribenuron-methyl resistance in Capsella bursa-pastoris populations from China

The increasing use of AHAS-inhibiting herbicides has resulted in evolved resistance in key dicot weeds infesting cereal cropping systems worldwide. Shepherd’s purse (Capsellabursa-pastoris) is a common dicot weed species in wheat in China with populations that have evolved resistance to the AHAS herbicide tribenuron-methyl. The seeds of eight resistant populations were collected from wheat fields and one susceptible population from road side in Hebei province of China. All eight populations showed high level resistance to tribenuron-methyl with resistance indices of over 100 fold based on whole plant dose response assays in the greenhouse. Comparison of the AHAS gene sequences of the susceptible and resistant populations with Arabidopsis revealed that proline at position 197 of the AHAS gene was substituted by threonine in population CAPBU-HB-2, serine in populations CAPBU-HB-3, CAPBU-HB-4, CAPBU-HB-5, and CAPBU-HB-6, leucine in population CAPBU-HB-7 and CAPBU-HB-8, histidine in population CAPBU-HB-9. The study confirmed tribenuron-methyl resistance in shepherd’s purse in Hebei province of China due to target site mutations at AHAS codon position 197.     

增效溴敌隆对几种害鼠的毒杀作用

本文涉及一种抗凝血增效灭鼠剂的研制和应用.该灭鼠剂是以溴敌隆为主剂、以双氯芬酸钠、丙三醇等为辅剂,可制成液剂和粉剂.经生物测定表明,对大白鼠、小白鼠、褐家鼠、大仓鼠和布氏田鼠均有很好的毒效,毒杀率基本达到100％,且适口性良好.现场试验对褐家鼠防效达96％以上.该药中溴敌隆含量为0.002％时,防效与0.005％溴敌隆相当起到了增效的作用,降低了成本,减少了环境污染,保证了人畜安全.     

假高粱根状茎和须根的化感潜力

为进一步明确假高粱Sorghum halepense(L.)Pers.成功入侵的化感潜力,利用生物测定方法研究了其地下部分对小麦种子萌发和生长的化感潜力。结果显示,播后第1天,假高粱根状茎、须根和根状茎+须根水浸提液浓度为0.04 g/mL时,对小麦种子萌发抑制率分别为76.00%、96.00%和70.00%;播后第5天,分别为6.77%、22.03%和10.17%。土壤介质中,小麦播种5天后,假高粱根状茎、须根及根状茎+须根粉碎物为0.040 g/g时对小麦种子萌发的抑制率分别为32.20%、42.37%和35.59%。抑制活性随浓度增大而增强,随时间延长而降低。以3种材料干粉混入土壤,均对小麦幼苗苗高和根长有抑制作用。种子萌发及幼苗生长试验中,须根的抑制活性均强于根状茎。