Genetic basis and origin of resistance to acetolactate synthase inhibitors in Amaranthus palmeri from Spain and Italy

BACKGROUND

Amaranthus palmeri is an aggressive annual weed native to the United States, which has become invasive in some European countries. Populations resistant to acetolactate synthase (ALS) inhibitors have been recorded in Spain and Italy, but the evolutionary origin of the resistance traits remains unknown. Bioassays were conducted to identify cross-resistance to ALS inhibitors and a haplotype-based genetic approach was used to elucidate the origin and distribution of resistance in both countries.

RESULTS

Amaranthus palmeri populations were resistant to thifensulfuron-methyl and imazamox, and the 574-Leu mutant ALS allele was found to be the main cause of resistance among them. In two Spanish populations, 376-Glu and 197-Thr mutant ALS alleles were also found. The haplotype analyses revealed the presence of two and four distinct 574-Leu mutant haplotypes in the Italian and Spanish populations, respectively. None was common to both countries, but some mutant haplotypes were shared between geographically close populations or between populations more than 100 km apart. Wide genetic diversity was found in two very close Spanish populations.

CONCLUSION

ALS-resistant A. palmeri populations were introduced to Italy and Spain from outside Europe. Populations from both countries have different evolutionary histories and originate from independent introduction events. ALS resistance then spread over short and long distances by seed dispersal. The higher number and genetic diversity among mutant haplotypes from the Spanish populations indicated recurrent invasions. The implementation of control tactics to limit seed dispersal and the establishment of A. palmeri is recommended in both countries. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Ace and ace-like genes of invasive redlegged earth mite: copy number variation,target-site mutations,and their associations with organophosphate insensitivity

Background

Invasive Australian populations of redlegged earth mite, Halotydeus destructor (Tucker), are evolving increasing organophosphate resistance. In addition to the canonical ace gene, the target gene of organophosphates, the H. destructor genome contains many radiated ace-like genes that vary in copy number and amino acid sequence. In this work, we characterise copy number and target-site mutation variation at the canonical ace and ace-like genes and test for potential associations with organophosphate insensitivity. This was achieved through comparisons of whole-genome pool-seq data from alive and dead mites following organophosphate exposure.

Results

A combination of increased copy number and target-site mutations at the canonical ace was associated with organophosphate insensitivity in H. destructor. Resistant populations were segregating for G119S, A201S, F331Y at the canonical ace. A subset of populations also had copy numbers of canonical ace > 2, which potentially helps overexpress proteins carrying these target-site mutations. Haplotypes possessing different copy numbers and target-site mutations of the canonical ace gene may be under selection across H. destructor populations. We also detected some evidence that increases in copy number of radiated ace-like genes are associated with organophosphate insensitivity, which might suggest potential roles in sequestration or breakdown of organophosphates.

Conclusion

Different combinations of target-site mutations and (or) copy number variation in the canonical ace and ace-like genes may provide non-convergent ways for H. destructor to respond to organophosphate selection. However, these changes may only play a partial role in organophosphate insensitivity, which appears to have a polygenic architecture. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

“花间隐榭，水际安亭”——基于华南植物园水榭和桂林芦笛岩水榭的营境分析

华南植物园水榭和桂林芦笛岩水榭是20世纪七八十年代岭南园林建筑的两处经典作品。它们与明代造园专著《园冶》里"花间隐榭,水际安亭"的字句遥相呼应,以现代主义建筑的创作风格构造出中国传统山水居游的惬意情境。以这两个经典现代风景建筑为例,尝试从情境、场景和身体体验3个不同角度,具体探讨风景建筑的营境操作。情境旨在针对建筑总体布局进行分析;场景则着眼于空间组合的探讨;最后从身体体验出发,讨论建筑的细部设计。     

新疆部分地区生乳中金黄色葡萄球菌的分离鉴定及耐药性分析

【目的】探明新疆部分地区生乳中金黄色葡萄球菌流行情况及耐药性,为该地区生乳中金黄色葡萄球菌的监测及保障生乳质量安全提供理论依据。【方法】试验随机从南北疆规模化奶牛场采集110份生乳样品。采用增菌培养、分离纯化、革兰氏染色、生化鉴定及PCR法对奶样中金黄色葡萄球菌进行分离鉴定,并利用微量肉汤稀释法及PCR方法对金黄色葡萄球菌进行16种抗菌药物的耐药表型及耐药基因分析。【结果】从110份奶样中分离出18株金黄色葡萄球菌,分离株呈浅黄色、光滑凸起的圆形菌落,革兰氏染色镜检呈紫色、短链状排列的革兰氏阳性菌,生化试验结果符合金黄色葡萄球菌生化特点,经16S rDNA及nuc基因PCR扩增鉴定为金黄色葡萄球菌,分离率为16.36%(18/110)。药敏试验结果显示,金黄色葡萄球菌分离株对氨苄西林、青霉素及磺胺异噁唑具有较高的耐药性,耐药率分别为100%、83.33%和77.78%,而对万古霉素、复方新诺明、苯唑西林、头孢噻吩、头孢噻呋、利福昔明及环丙沙星7种抗菌药物高度敏感,敏感率分别为100%、100%、94.44%、94.44%、94.44%、94.44%和94.44%。其中有14株金黄色葡萄球菌为多重耐药菌,多重耐药率为77.78%。耐药基因检测结果显示,大环内酯类耐药基因ermB检出率最高,为50.00%,其次为β-内酰胺类耐药基因mecA,检出率为27.28%,磺胺类耐药基因Sul1的检出率为22.22%。【结论】新疆奶牛场生乳中分离的金黄色葡萄球菌的流行及耐药情况仍较严重,且存在多重耐药现象,因此,对生乳中金黄色葡萄球菌耐药性的监测有重要意义。     

退化高寒草甸斑块根—土复合体特征研究

高寒草甸斑块的根-土复合体对局部水土流失过程具有调控作用,为研究其特征及抗侵蚀效应,本研究选取三江源区达日县境内典型中度退化草甸的植被斑块为研究对象,调查草甸斑块中心与边缘植物群落特征,测定斑块边缘0～10 cm土层和斑块中心0～20 cm土层的容重、含水率、毛管孔隙度等土壤物理性质,并开展单根拉伸和根-土复合体直剪试验。结果表明：受优势种矮嵩草的分布影响,地上生物量主要分布在斑块中心,根系主要分布在0～10 cm土层;斑块中心区域土壤抗剪强度、内摩擦角和粘聚力均随土层深度的增加而减小;斑块边缘区域土壤粘聚力,抗剪强度明显高于斑块中心区域,草甸斑块植物根系是土壤抗剪强度的主要影响因素。草甸斑块根-土复合体能明显增加退化草甸土壤的抗侵蚀能力,研究结果可为深入研究高寒草甸根系固土功能及水土流失调控提供科学依据。     

低磷胁迫对红豆草光合、叶绿素荧光及内源激素的影响

为探究低磷胁迫对红豆草(Onobrychis viciaefolia)光合作用、叶绿素荧光以及内源激素的影响,本试验采用营养液沙培法,以耐低磷5号和磷敏感1号红豆草为试验材料,设置常磷(1.00 mmol·L^-1 KH₂PO₄)和低磷(0.01 mmol·L^-1 KH₂PO₄)胁迫处理,于不同胁迫天数后测定形态、光合以及内源激素含量变化。结果表明：低磷胁迫抑制红豆草生长和光合作用,在低磷胁迫下,除非光化学淬灭系数外,供试红豆草叶绿素荧光参数均下降。随着胁迫时间的延长,2份红豆草材料地上和地下部玉米素(ZT)、脱落酸(ABA)、生长素(IAA)和赤霉素(GA₃)及其之间的比值变化趋势不一致,耐低磷红豆草地上和地下部ZT,GA₃,IAA,ABA耐低磷系数大于磷敏感材料。相关性分析表明,IAA与光合作用和叶绿素荧光显著相关,ABA与IAA,ZT,GA₃呈负相关。研究结果可为红豆草耐低磷特性研究提供...     

基于ISSR分子标记的紫云英种质资源遗传多样性及结构分析

紫云英(Astragalus sinicus L.)是我国重要的稻田绿肥作物,为揭示不同地区种质资源遗传特征,本研究利用ISSR分子标记对77份紫云英种质资源进行了遗传多样性及结构分析。研究发现,77份供试紫云英种质资源遗传相似性系数为0.567 7～0.868 6,可划分为6个聚类。不同地区群体间分化系数为0.136 3,达到极显著水平(P<0.001),其中种群间变异占比13.9%,种群内变异占比86.1%。不同ISSR引物扩增信息鉴别紫云英资源的能力存在差异,构建了以P809第3,8,9,10,12,15扩增位点以及P886第1,3,5,9,10,11扩增位点为特征的指纹图谱,能有效区分77份供试紫云英资源。以资源所在省份为单元进行群体分析,供试紫云英资源遗传结构呈现分化特征,河南-安徽-江苏-上海资源遗传结构相似,构成北方亚群;四川-广西-湖南-江西资源相似,构成西南方亚群;福建种质资源则呈现混合型特征。本研究结果可为我国紫云英种质资源的科学利用及新品种选育提供依据。     

Prevalence of incidental humeral intracondylar fissures in brachycephalic breed dogs in CT studies

Humeral intracondylar fissures (HIF) have been predominantly reported in spaniel breeds and proposed to be possible risk factors for humeral condyle fractures (HCF). We hypothesized that the prevalence of incidental HIF in French Bulldogs may be greater than that of other brachycephalic breeds. A retrospective, observational, prevalence study was performed using CT examinations of French bulldogs and other brachycephalic breed dogs presenting for an unrelated condition. Two European College of Veterinary Diagnostic and Imaging-certified radiologists reviewed the images of the humeral condyles of these dogs. A classification system was devised to grade the findings. We considered a Score 1 to be normal, Score 2 to have centralised sclerosis, Score 3 to have a partial fissure and Score 4 to have a complete fissure. A total of 228 elbows were reviewed from 122 dogs. Of this population, 145 elbows were from French Bulldogs, 54 were from Pugs, and the remainder were from a mix of other brachycephalic breeds. The prevalence of HIF (score 3 or 4) in elbows of the French bulldog, pug and other breed groups was 6.9% (CI 2.8–11%), 5.6% (CI 0–11.7%), and 3.4% (CI 0–10.15%), respectively. At a dog level, the prevalence of HIF (score 3 or 4 present in at least one elbow) was found to be 11.8% (CI 4.6–19%) in French Bulldogs, 11.1% (CI 0–22.9%) in Pugs, and 5.26% (CI 0–15%) in the other breed group. There was no significant difference between the breed groups. The inter-reviewer reliability for CT scoring of HIF based on Cohen's weighted kappa was low at 0.19.     

磷肥对甘肃临夏地区燕麦干草及种子生产的影响

为确定甘肃高寒雨养区燕麦(Avena sativa)种子生产中磷肥最佳用量,提高肥料利用效率,试验在氮肥(尿素)用量75 kg·hm^-2的固定水平下,设计4个磷肥(P₂O₅)水平(0(CK),65(C₁),100(C₂),135(C₃)kg·hm^-2),对各磷肥水平下干草产量、种子产量和相关性状的变化进行了研究。结果表明：施用磷肥使燕麦的株高、茎粗、分蘖和干草产量均有提高,灌浆期C₁,C₂,C₃干草产量较CK依次提高13.85%,25.96%,22.65%,干草产量与磷肥水平显著正相关(相关系数0.91);施用磷肥提高了燕麦的有效分蘖数、主穗长,显著提高主穗粒数、穗粒重、千粒重、种子产量和秸秆产量,C₁,C₂,C₃种子产量较CK依次提高12.37%,16.72%,14.38%,种子产量与磷肥水平显著正相关...