几种化感物质替代物间的互作效应分析

运用正交旋转回归试验设计分析5种常见的化感物质替代物水杨酸、对羟基苯甲酸、肉桂酸、香草酸和阿魏酸间对稗草根长的互作效应,以探明化感物质抑草作用机理.结果表明,水杨酸和对羟基苯甲酸、水杨酸和肉桂酸间增效或拮抗的互作效应与各因子在化合物中浓度水平密切相关.水杨酸在浓度<0.14mmol·L^-1时,对对羟基苯甲酸表现为增效作用;当浓度>0.14mmol·L^-1时,则表现为拮抗作用.而对羟基苯甲酸在浓度为0.425mmol·L^-1时,对水杨酸表现为拮抗作用.在所考察的浓度范围内,水杨酸对肉桂酸都具有拮抗作用,而肉桂酸在浓度为0.14mmol·L^-1时对水杨酸表现出拮抗作用.在所考察的浓度范围中,香草酸与肉桂酸的作用效果都是增效的.     

不同外源酚酸化感物质组合对棉花种子萌发和幼苗生长的化感效应

为阐明不同外源酚酸类化感物质组合对棉花种子萌发及幼苗生长发育的化感效应, 选择在棉花连作30年土壤中检测到的对-羟基苯甲酸(P-HA)、香草醛(VA)、阿魏酸(FA)3种酚酸类化感物质, 以田间自然状态下含量为处理浓度研究对棉花种子萌发和幼苗生长的影响。结果表明: 3种酚酸化感物质对棉花种子萌发和幼苗生长有显著影响。对种子萌发有促进作用, 对幼苗生长有抑制作用,对幼苗生理酶活性有着不利影响。两种或两种以上化感物质混合时比一种酚酸化感物质对棉花的作用效果小, 说明对羟基苯甲酸、香草醛和阿魏酸三者之间存在拮抗效应。P-HA对VA和FA存在着抵消作用, 3种化感物质组合之间的拮抗效应与化感物质的浓度和作用效果密切相关。     

甜瓜根系分泌物中酚酸物质对尖孢镰孢菌的化感效应

采用HPLC法对甜瓜根系分泌物进行分离鉴定,检测到甜瓜根系分泌物中含有没食子酸、邻苯二甲酸、丁香酸、水杨酸、阿魏酸、苯甲酸和肉桂酸7种酚酸物质,通过外源添加法研究该类物质对尖孢镰孢菌的化感效应.室内试验结果表明: 阿魏酸、苯甲酸、肉桂酸在0.1、0.25 mmol·L^-1处理浓度下能够显著促进尖孢镰孢菌的孢子萌发,水杨酸则对孢子萌发具有一定的抑制作用;丁香酸、阿魏酸在菌丝培养后期表现出较强的促进作用.盆栽结果显示,在0.05、0.1和0.5 mmol·L^-1处理浓度下肉桂酸、阿魏酸、苯甲酸可显著促进甜瓜枯萎病病情.
     

发育时期对紫茎泽兰化感作用的影响

为探讨紫茎泽兰化感作用与其入侵性的关系,利用生物检测法研究了不同发育时期紫茎泽兰叶片水提液对4种本地草本植物种子萌发和幼苗生长的影响。结果表明,高浓度时紫茎泽兰叶片水提液能显著抑制4种本地植物种子发芽率、发芽速度,但低浓度时有时抑制作用不显著,甚至有促进作用;除狗肝菜胚轴生长外,不同浓度下紫茎泽兰叶水提液均能抑制4种本地植物胚轴和胚根生长,但有时对胚轴生长的抑制作用不显著,甚至有促进作用。不同植物和同种植物的不同参数对紫茎泽兰化感作用的敏感程度不同,拔毒散和狗肝菜的种子萌发参数较敏感,莎草砖子苗的生长参数较敏感,种子发芽速度和胚根生长较敏感。总的看,随发育时间的增加,紫茎泽兰抑制本地植物种子萌发和幼苗生长的最低叶片提取液浓度减小,相同浓度下叶片水提液对本地植物的抑制作用增强,表明紫茎泽兰化感作用增强。化感作用在紫茎泽兰入侵的不同阶段所起的作用可能不同。     

酚酸类物质对苜蓿种子萌发及抗氧化物酶活性的影响

实验选用紫花苜蓿体内的4种化感物质包括阿魏酸、香豆素、香草酸、香豆酸,以10-3、10-4、10-5mol·L-1和10-6mol·L-1四个浓度,采用培养皿试纸法和沙培法进行苜蓿种子萌发及幼苗生长试验,研究了苜蓿种子萌发和幼苗生长以及抗氧化保护性酶活性的变化,并就生物量、种子萌发和酶活性等三大指标的敏感性进行了讨论。结果表明,4种化感物质对苜蓿种子萌发及幼苗生长有明显的影响作用,这种影响效应与化感物质的种类及浓度显著相关。其中,10-3mol·L-1的4种化感物质均表现出对苜蓿种子萌发有显著的抑制作用,阿魏酸、香豆素和香草酸达到了极显著的抑制效果。当浓度为10-3mol·L-1时,除香豆酸外,其它3种化感物质均表现出对幼苗体内超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸酶(APX)活性有显著的抑制作用,同时使幼苗体内丙二醛(MDA)的含量显著增加;随着浓度的降低,化感物质抑制作用减弱;当浓度降低为10-6mol·L-1时,阿魏酸、香豆素、香草酸则表现出了对上述各种酶活性的轻微促进作用。阿魏酸表现出的化感效应最强,香豆素、香草酸次之,香豆酸最弱。发芽指标受化感物质的影响最敏感、其次是生物量指标,而酶活性指标相对较弱。     

不同化感物质对西瓜幼苗生长的影响

西瓜是受连作障碍影响最为严重的作物之一,由化感物质引起的自毒作用被认为是造成连作障碍的主要原因。为阐明化感物质对西瓜种子萌发及生长发育的影响,本研究选择4种最为普遍的化感物质——苯甲酸、肉桂酸、阿魏酸与丁香酸处理6个品种的西瓜种子,利用平底圆柱玻璃瓶培养法直接观察测量西瓜种子萌发以及幼苗根系与下胚轴生长动态变化。结果表明,浓度超过10 mg/L的化感物质处理显著抑制了西瓜种子的萌发和幼苗的生长,其中幼苗根系受化感物质的影响最大。不同西瓜品种对化感物质的响应差异显著,苯甲酸、肉桂酸处理后,‘郑麻10号’受到的抑制作用最强,‘利丰3号’与‘新优16号’受到的抑制作用较弱;‘晋抗6号’和‘中优杂1号’受阿魏酸、丁香酸的抑制作用最强,但这2种化感物质对‘新优16号’的抑制作用相对较弱。总体上,化感物质对西瓜抑制效果从强到弱依次为苯甲酸肉桂酸阿魏酸丁香酸。在所研究的材料中,‘利丰3号’与‘新优16号’对化感物质相对不敏感,可能在连作障碍防控中有一定的应用价值。     

酚酸类物质对三七幼苗的化感影响

该文研究了不同浓度的阿魏酸、对香豆酸、丁香酸、对羟基苯甲酸、香草酸5种酚酸类物质对三七幼苗生长和生理的影响。结果表明:处理后,三七幼苗的苗高、根长、可溶性蛋白质含量、根系活力、CAT以及POD活性均有所降低。其中,阿魏酸各处理组幼苗的苗高及POD活性均显著降低,50、100 mg·L~(-1)的对香豆酸以及100 mg·L~(-1)的香草酸处理组幼苗苗高也分别比对照显著降低16.19%、16.67%和29.29%;对香豆酸、丁香酸以及对羟基苯甲酸各处理组幼苗根长均显著低于对照;香草酸处理组幼苗的根系活力也显著低于对照,且幼苗的CAT活性在10、50、100 mg·L~(-1)丁香酸、对羟基苯甲酸以及香草酸处理下也达到了显著降低水平。此外,1 mg·L~(-1)阿魏酸以及100 mg·L~(-1)香草酸处理组幼苗的叶绿素含量也均显著降低;中高浓度的阿魏酸、对香豆酸、丁香酸、对羟基苯甲酸增加了三七幼苗的MDA含量,而香草酸在0.1、1、10、100 mg·L~(-1)浓度下显著降低幼苗的MDA含量;丁香酸、香草酸、对羟基苯甲酸以及中高浓度的对香豆酸增加了三七幼苗的SOD活性,且香草酸各处理组均达到了显著性水平。综上结果表明,5种酚酸类物质对三七幼苗均具有一定的化感抑制作用,但各酚酸物质的作用方式及强度并不完全一致,阿魏酸的化感影响较大,这为进一步研究三七的化感自毒作用提供了一定的理论参考。     

黄瓜种子及其萌发期的化感作用研究

以大白菜、萝卜、番茄和黄瓜种子为受体,采用实验室培养皿种子发芽生物测试法研究了黄瓜种子浸提液、种子萌发、胚根和芽苗分泌物、芽苗腐解物和芽苗浸提液的化感效应。结果表明:(1)黄瓜种子浸提液对大白菜、萝卜、番茄和黄瓜种子萌发均有化感抑制作用,即黄瓜种子内含有某些化感抑制物质。(2)在水浸提过的黄瓜种子萌发过程中,它不仅对其近邻套种的大白菜、萝卜和番茄种子萌发产生化感抑制作用,而且其胚根和芽苗分泌物对后茬播种的4种蔬菜种子发芽也表现出不同程度的化感抑制作用;黄瓜芽苗腐解物和芽苗水浸提液也对各受体蔬菜种子发芽与生长产生不同程度的化感抑制作用,且随着腐解芽苗量的增加或浸提液浓度的升高,各受体蔬菜种子的发芽指标值、化感效应指数值和综合效应值随之降低。(3)黄瓜种子浸提液及芽苗各器官的化感物质对黄瓜种子的萌发与生长产生了自毒作用,且黄瓜芽苗腐解物、芽苗浸提液、胚根及芽苗分泌物对受体黄瓜的自毒作用均为最大。研究发现,黄瓜种子浸提液、种子萌发时期以及芽苗各器官的化感物质主要是通过抑制受体胚根的生长而起化感抑制作用,即受体蔬菜种子胚根对化感效应最为敏感;因黄瓜种子及萌发期释放化感物质的途径有所不同,导致受体大白菜、萝卜、黄瓜和番茄的化感响应也不相同;在黄瓜种子萌发和芽苗生长的早期,化感物质即开始在芽苗体内进行合成与积累,一部分可通过胚根和芽苗分泌途径释放到环境中,另一部分可通过芽苗腐解途径释放化感物质,并对受体蔬菜种子萌发与生长表现出较强的化感抑制作用。     

葡萄根系浸提液的化感作用

以晚红(Red Globe)葡萄组培苗为材料,研究了葡萄根系浸提液对葡萄幼苗生长的影响,并采用LC-MS技术对其中的主要化感物质进行鉴定.结果表明:0.02g.ml-1(风干根质量/浸提液体积,下同)、0.1g.ml-1、0.2g.ml-1的葡萄根系浸提液显著抑制了葡萄幼苗的生长,且浓度越高,抑制作用越强.葡萄根系浸提液中含有对羟基苯甲酸、水杨酸、苯丙酸和香豆酸4种酚酸类物质.盆栽模拟试验表明,不同浓度的(0.1、1、10mmol.L-1)水杨酸和苯丙酸显著抑制了葡萄植株的生长,随着作用浓度的升高,葡萄的株高、茎粗、地上和地下鲜质量、叶片净光合速率和根系活力降低,叶片可溶性糖、MDA含量升高,淀粉含量降低,而叶片蛋白质含量无明显变化规律.     

茄子自毒物质对辣椒种子萌发及枯萎菌的化感效应

运用模拟的方式,采用生物测定和室内培养的方法,研究了两种茄子自毒物质香草醛和肉桂酸各浓度对辣椒种子萌发和幼苗生长的化感效应,及其对辣椒枯萎菌菌丝生长的影响.结果表明:这两种自毒物质对辣椒种子萌发和幼苗生长具有低浓度促进,高浓度抑制的化感效应.香草醛和肉桂酸对辣椒和茄子种子的化感效应存在较大差异,辣椒种子受这两种自毒物质的抑制强度明显弱于茄子种子.香草醛和肉桂酸对辣椒枯萎菌菌丝生长表现为各浓度(0.1, 0.5, 1, 4mmol/L)下均具有抑制作用,作用强度随着浓度增加而增强,肉桂酸低浓度时对菌丝生长的抑制作用即达到显著水平.     

Plant-Parasitic Nematodes of South Viet Nam

Between 1974 and 1978, 2,842 identifications of plant-parasitic nematodes were made from more than 1,700 soil and plant samples collected in eight provinces of South Viet Nam. Species in nine genera—Helicotylenchus, Criconemoides, Meloidogyne, Pratylenchus, Tylenchorhynchus, Hoplolaimus, Hirschmanniella, Xiphinema, and Rotylenchulus—comprised 96.1% of the identifications; the remaining 3.9% were species of 11 genera. Fourteen genera were associated with rice which was grown on about 2,500,000 ha in 1970. Of these, Ditylenchus, Hirschmanniella, and Meloidogyne were most important. Ditylenchus angustus caused severe damage to about 50,000 ha of flooded rice in the Mekong Delta in 1976. Hirschmanniella spp. were found in all samples examined from flooded rice fields. Meloidogyne spp. were common in rice seedbeds, upland rice, and rice not kept flooded continuously. Meloidogyne and Pratylenchus spp. were found in roots of 22 of the 32 crop plants sampled. Little or no attempt was made in South Viet Nam to control nematodes.     

Identification key for European strand-forming house-rot fungi

An identification key for 20 common strand-forming indoor wood decay fungi is given. The key is based on observations of material from affected buildings and on wood samples that have been incubated in the laboratory. The key is with macro- and microscopic photographs.     

Parasites, emerging disease and wildlife conservation

In this review some emerging issues of parasite infections in wildlife, particularly in Australia, are considered. We discuss the importance of understanding parasite biodiversity in wildlife in terms of conservation, the role of wildlife as reservoirs of parasite infection, and the role of parasites within the broader context of the ecosystem. Using a number of parasite species, the value of undertaking longitudinal surveillance in natural systems using non-invasive sampling and molecular tools to characterise infectious agents is illustrated in terms of wildlife health, parasite biodiversity and ecology.     

Phylogenetic relationships among Southeast Asian climbing bamboos (Poaceae: Bambusoideae) and the Bambusa complex

A phylogenetic analysis of Bambusa and allies based on the plastid DNA non-coding regions rps16-trnQ, trnC-rpoB, trnH-psbA and trnD-T, and a partial nuclear GBSSI gene, was carried out. This included representatives from all four Bambusa subgenera (including type species), a group of segregate Southeast Asian genera distinctive by their climbing–scrambling culms (Dinochloa, Holttumochloa, Kinabaluchloa, Maclurochloa, Soejatmia, Sphaerobambos), and two other Bambusinae genera (Dendrocalamus, Gigantochloa). The results do not support the present subgeneric classification of Bambusa. The climbing Southeast Asian genera, all of which include species previously placed in Bambusa, are distinct from the “core Bambusa group” (type species and alliance) and the Bambusa complex generally.     

The identification of microRNAs in the whitespotted bamboo shark (Chiloscyllium plagiosum) liver by Illumina sequencing

MicroRNAs are indispensable players in the regulation of a broad range of biological processes. Here, we report the first deep sequencing of the whitespotted bamboo shark (Chiloscyllium plagiosum) liver. We mapped 91 miRNAs in the Callorhinchus milii genome that have previously been described in the Danio rerio, Fugu rubripes, Oryzias latipes, Xenopus laevis, Xenopus tropicalis, Homo sapiens, and Mus musculus. In addition, 156 new putative candidate (PC) C. plagiosum miRNAs were identified. From these 247 miRNAs, 39 miRNA clusters were identified, and the expression of these clustered miRNAs was observed to vary significantly. A total of 7 candidate miRNAs were selected for expression confirmation by stem-loop RT-PCR. This study resulted in the addition of a significant number of novel miRNA sequences to GenBank and laid the foundation for further understanding of the function of miRNAs in the regulation of C. plagiosum liver development.     

Semicircular canal system in early primates

Mammals with more rapid and agile locomotion have larger semicircular canals relative to body mass than species that move more slowly. Measurements of semicircular canals in extant mammals with known locomotor behaviours can provide a basis for testing hypotheses about locomotion in fossil primates that is independent of postcranial remains, and a means of reconstructing locomotor behaviour in species known only from cranial material. Semicircular canal radii were measured using ultra high resolution X-ray CT data for 9 stem primates (“plesiadapiforms”; n = 11), 7 adapoids (n = 12), 4 omomyoids (n = 5), and the possible omomyoid Rooneyia viejaensis (n = 1). These were compared with a modern sample (210 species including 91 primates) with known locomotor behaviours. The predicted locomotor agilities for extinct primates generally follow expectations based on known postcrania for those taxa. “Plesiadapiforms” and adapids have relatively small semicircular canals, suggesting they practiced less agile locomotion than other fossil primates in the sample, which is consistent with reconstructions of them as less specialized for leaping. The derived notharctid adapoids (excluding Cantius) and all omomyoids sampled have relatively larger semicircular canals, suggesting that they were more agile, with Microchoerus in particular being reconstructed as having had very jerky locomotion with relatively high magnitude accelerations of the head. Rooneyia viejaensis is reconstructed as having been similarly agile to omomyids and derived notharctid adapoids, which suggests that when postcranial material is found for this species it will exhibit features for some leaping behaviour, or for a locomotor mode requiring a similar degree of agility.