我国新疆焉耆垦区作物轮作种植模式防除列当的有效性研究

本研究以新疆地区危害最严重的向日葵列当和瓜列当为研究对象,通过室内水培试验和室外盆栽模拟轮作试验来探究焉耆垦区轮作模式对两种列当的防除效果。结果表明,室内水培试验中各轮作作物的根系分泌物及萃取相刺激瓜列当种子的萌发率均在20.0%以下,但刺激向日葵列当种子产生的萌发率达到了50.0%以上;室外盆栽模拟轮作试验中,甜菜、小麦、辣椒与加工番茄轮作后,瓜列当的寄生数量未显著降低;但与向日葵轮作后,向日葵列当的寄生数量显著减少了60.0%以上。不同品种甜菜、辣椒和小麦地上部甲醇提取液刺激瓜列当种子的萌发率均低于10.0%,但是刺激向日葵列当种子的萌发率均达70.0%以上。本研究表明新疆焉耆垦区轮作种植模式不能有效防除瓜列当,但模式中的轮作作物均能够有效防除向日葵列当。本研究结果为防除新疆焉耆垦区向日葵列当和瓜列当提供理论依据。     

多功能列当生防镰刀菌的筛选及种类鉴定

从河北省张家口地区种植的烟草上采集的感病弯管列当植株,从中分离得到20株镰刀菌,采用孢子悬浮液浸根和灌根法对小麦、玉米、棉花、向日葵、番茄、烟草、辣椒、茄子、西瓜、甜瓜等作物和蔬菜进行了安全性检测,筛选出对主栽作物和蔬菜安全且具有促生作用的4个菌株。其中菌株Br-2对烟草、辣椒、西瓜有显著促生作用,且对弯管列当的防治效果最好：施用菌株Br-2后烟草、辣椒、西瓜增高分别为123.53%、62.16%、28.95%;其发酵上清液对弯管列当种子萌芽抑制率为71.79%;小区试验中对弯管列当的寄生率防效为50%,寄生度防效为79.38%;田间试验中对弯管列当的寄生率防效为58.27%,寄生度防效为75.70%。形态学和分子生物学鉴定结果表明菌株Br-2为尖孢镰刀菌。     

贝莱斯芽胞杆菌JTB8-2的筛选、鉴定及其对瓜列当拮抗作用研究

为了筛选适宜新疆本地田间土壤环境且对瓜列当具有生防潜力的微生物,本研究采集加工番茄田罹病瓜列当根际土壤,分别采用稀释涂布平板法分离和滤纸平板法筛选到一株瓜列当生防菌JTB8-2,经形态学和分子生物学鉴定为贝莱斯芽胞杆菌Bacillus velezensis。菌株JTB8-2发酵液25、50、100、250和500倍液对瓜列当种子萌发校正抑制率分别为100%、100%、93.60%、43%和32.59%,其250和500倍液对瓜列当种子萌发校正抑制率显著高于其他菌株;浓度为1和0.5 μg/mL菌株发酵液粗提物对瓜列当种子萌发抑制率分别为100%和53.25%;浇灌浓度约5×10⁵cfu/mL菌株发酵液对瓜列当防治效果为66.51%。该菌株具有防治瓜列当的潜力,可以作为新疆本地瓜列当防治生防菌资源。     

瓜列当致病真菌的鉴定及其发酵产物活性研究

为筛选对瓜列当具有良好防治效果的生防真菌,本研究从新疆加工番茄田自然发病的瓜列当茎基部分离病原真菌,采用盆栽瓜列当接种无菌发酵滤液原液,筛选对瓜列当具有强致病性的菌株;采用共培养法测定菌株不同浓度无菌发酵滤液及其发酵产物萃取物对瓜列当种子萌发的影响;利用形态学特征和分子生物学方法对其进行种类鉴定。结果表明：盆栽瓜列当接种无菌发酵滤液原液可使瓜列当植株伤口变褐,严重的可造成整株萎蔫死亡;菌株JTF001发酵原液对瓜列当种子萌发抑制率可达100%,25倍、50倍稀释液抑制率分别为92.88%和87.62%;浓度为5μg/mL和1μg/mL JTF001发酵产物对瓜列当种子萌发抑制率均达100%;浓度为0.5、0.25μg/mL和0.1μg/mL的JTF001发酵产物对瓜列当种子萌发的抑制率分别为91.03%、81.87%和60.04%;结合形态学和基于rpb2、tef 1和gapdh基因序列分析,将菌株JTF001鉴定为交链格孢Alternaria alternata。上述结果表明菌株JTF001有作为开发防治瓜列当生物农药的潜力。     

根寄生杂草种子萌发剂概述

独脚金属（Striga spp.）及列当属（Orobanche spp.和Phelipanchce spp.）杂草是世界范围内对农业生产危害严重的根寄生杂草,主要依靠寄生茄科、豆科、谷类等作物获得水分和营养。根寄生杂草种子只有在合适的萌发诱导物（如独脚金内酯）刺激下才能萌发。文章从根寄生杂草的分类、分布及危害,种子萌发剂类型及适用范围,种子萌发剂独脚金内酯的生物合成及分离鉴定,根寄生杂草种子萌发诱导剂的作用机制以及种子萌发过程中激素间协同调控作用等方面进行了综述,并展望了种子萌发剂设计筛选及其在根寄生杂草化学防控中的潜在应用前景。     

室内条件下向日葵列当和弯管列当在三种不同寄主上寄生能力的比较

以向日葵列当Orobanche cumana Wallr.和弯管列当O.cernua Loefl.为研究对象,利用已有的室内寄生体系来研究两种列当在向日葵、烟草、番茄3种寄主上的寄生能力。结果表明,向日葵列当在室内条件下不仅能够寄生在向日葵上,同时也可以在烟草与番茄上寄生;但其寄生效率在上述不同的寄主之间存在显著差异,而在相同寄主的不同品系间没有差异。交互侵染的结果表明,在寄主番茄上,弯管列当平均每株寄生的瘤结数量为16.3个,向日葵列当只有2.5个;在寄主向日葵上,向日葵列当的平均寄生瘤结数量为25.2个,弯管列当为27.6个,预示着弯管列当在番茄上寄生效率均显著高于向日葵列当,而在寄主向日葵上,二者寄生效率差异不显著,均能高效寄生在向日葵根系上。上述研究结果将为向日葵列当和弯管列当发生严重地区作物轮作对象的选择提供理论依据。     

向日葵列当综合防控措施

向日葵Heliantus annuus L.属菊科一年生草本植物,以花序托(花盘)及种子入药,具养肝补肾、降压、止痛之功效。向日葵列当直接影响向日葵的正常生长,造成向日葵产量下降,品质降低,影响农民的收入。笔者介绍向日葵列当在田间发生的症状,并提出综合防治措施。     

列当生防菌Br-2的DsRed红色荧光标记及定殖

为探明生防菌Br-2在分枝列当体内及番茄根围的定殖能力,采用PEG-CaCl_2介导的原生质体转化体系将红色荧光蛋白基因DsRed转入到菌株Br-2中,并构建其生长曲线,测定其对分枝列当种子萌发的抑制率,通过共聚焦显微镜观察其在分枝列当茎内及番茄根围的定殖情况。结果表明:通过原生质体转化体系得到了标记菌株Br-2-DsRed,继代培养5代后,其在共聚焦显微镜下仍可观察到亮红色荧光,经PCR检测带有DsRed基因,证明其稳定性好。标记菌株Br-2-DsRed与野生菌株Br-2的生长曲线基本一致,对分枝列当种子萌发的抑制率分别为75.86%和74.14%,无显著差异。显微观察发现,标记菌株Br-2-DsRed接种1 d后即能够侵染分枝列当的茎部表皮,3 d后主要分布在茎表皮和厚壁细胞间隙,5 d后侵染到厚壁细胞及维管束细胞内部并导致茎部腐烂;而标记菌株Br-2-DsRed不能侵染番茄根尖的内部,主要定殖在番茄根尖表面。     

寄生性杂草列当的种类调查及鉴定

列当是一类难以防治的恶性根寄生杂草,目前在番茄、向日葵、烟草和瓜类上危害日益严重。列当的种类多且难以区分,明确列当的种类对制定有效防治措施具有重要意义。从新疆维吾尔自治区、河北省、内蒙古自治区和吉林省4个地区采集了19份列当样品,通过形态观察和DNA条形码技术进行种类鉴定并对其亲缘关系进行讨论。结果发现,寄生于新疆番茄上的列当样品为分枝列当,寄生于河北烟草、河北向日葵和吉林向日葵上的列当样品为弯管列当;在系统发育树中分枝列当与弯管列当有明显的系统进化差异性,弯管列当被分为2个大类群,地理区划明显而与寄主植物无关,采集自河北省的7个样品为1个类群,采自吉林省、新疆维吾尔自治区、内蒙古自治区的8个样品为第2个类群,其中第2类群中采自吉林省的4个样品亲缘关系最近。     

烟草尖孢镰刀菌拮抗真菌的筛选鉴定及促生作用研究

为获得烟草镰刀菌根腐病拮抗真菌菌株,试验以河南省豫中烟区烟草根际土壤为试材,以主要致病菌尖孢镰刀菌Fusarium oxysporum为主要靶标,采用稀释涂布平板法分离获得土壤真菌371株,平板对峙培养法测定获得1株具有明显抑制效果的拮抗菌株,利用形态学和分子生物学的方法将其鉴定为棘孢木霉Trichoderma asperellum Tr-0111。抑制效果测定表明,该菌株对尖孢镰刀菌的抑制率最高可达93.13%,对根串珠霉菌、拟茎点霉、链格孢菌等其他8种烟草病原菌均具有较强的抑制效果。促生作用测定结果表明,菌株发酵液使烟草种子萌发率提高5.34%,烟苗根长增长率为62.39%,对盆栽烟草的最大叶面积和地上部鲜重也具有显著的促生效果。为进一步相关机理的研究和生防菌剂的研制奠定了基础。     

我国向日葵列当发生危害现状调查

向日葵列当是危害我国向日葵最严重的杂草。为明确我国向日葵田列当的发生危害情况及防治现状,采用对角线5点取样法对新疆、内蒙古、吉林和河北等主要向日葵种植区进行调查,对向日葵列当的寄生率和寄生强度等数据进行分析。结果表明,向日葵列当在向日葵产区广泛分布,严重危害向日葵的生产,其对食葵的寄生率高于油葵,对抗性品种的寄生率较低。在所有调查地区中内蒙古地区向日葵列当发生最严重,寄生率高达100%,寄生强度达到38.5,单株寄生数量最高,达118株;新疆地区的向日葵列当寄生率居中,吉林、河北向日葵列当发生相对较轻。通过实地调研结合文献报道,对目前国内外向日葵列当的研究进展进行了综述,研究结果为指导向日葵列当防治提供参考。     

Orobanche cumana race F: performance of resistant sunflower hybrids and aggressiveness of populations of the parasitic weed

The production of sunflower is threatened by Orobanche cumana (broomrape) infections in many countries of southern and eastern Europe. The most virulent race of this parasitic weed, race F, is widespread in Spain. Most of the current commercial hybrids of resistant sunflower do not completely prevent broomrape emergence in the field. The performance (broomrape incidence and severity, final yields and oil contents) of four resistant and two susceptible sunflower hybrids was studied in different years in several O. cumana – infested locations. O. cumana – sunflower interactions were characterised by low severity and intermediate incidence in the resistant hybrids; both depended on the environment. An increase in sunflower yield because of the use of resistant hybrids was most noticeable under heavy field infestations and under drought. Characterisation of 20 populations of O. cumana classified as race F in terms of the standardised area under the degree of attack progress curve (SAUDC) and O. cumana incidence (BI) suggested differential intrinsic pathogenicities. These results highlight the variability within race F of O. cumana , mirroring the environmentally dependent horizontal resistance in sunflower.     

列当(Orobanche spp. and Phelipanche spp.)种子的采集与预处理方法

列当(Orobanche spp.and Phelipanche spp.)是一种在世界范围内危害严重的根寄生杂草,防除列当的研究也越来越多。正确地采集和预培养列当种子是获得正确防除列当研究结果的前提。列出了大田正确采集列当种子的方法,以及对采集到的种子进行过筛提纯、加洗洁精和吐温20清洗后,再表面消毒和预培养,并通过发芽试验检验此方法的可行性。结果表明,经过处理的向日葵列当、瓜列当种子的发芽率最高分别为54.4%、59.1%。此方法可以应用于列当的采集和预处理过程中,可为列当研究和防除提供参考。     

Prohexadione-calcium induces sunflower (Helianthus annuus) resistance against the root parasitic weed Orobanche cumana

Prohexadione-calcium (PHDC) is a plant growth retardant that inhibits gibberellin biosynthesis and transiently alters the spectrum of flavonoids and their phenolic precursors. In this study, root chamber and pot experiments were conducted to evaluate the effects of PHDC on Orobanche cumana seed germination and induction of sunflower resistance to this root parasitic weed. Root chamber experiments indicated that PHDC did not interfere with the progress of Orobanche seed germination, but retarded O. cumana tubercle formation and development. In pot experiments, control of O. cumana by PHDC depended on its dose, method of application and sunflower cultivar. In sunflower cv. HA89, PHDC at 10 mg LS⁻¹ (litre soil) as two drenches or at 1 m m as two foliar sprays significantly reduced the total number and dry matter of O. cumana without influencing flower, leaf and root development. In sunflower cv. Albena, PHDC at 20 and 30 mg LS⁻¹, but not at 10 mg LS⁻¹, as two drenches significantly reduced O. cumana infection. Sunflower cv. HA89 was less susceptible to O. cumana and more inducible by PHDC than sunflower cv. Albena. The biochemical analysis of root extracts revealed a significantly higher accumulation of free phenolics in sunflower cv. HA89 after PHDC soil drench, but not in Albena. No significant lignification was observed after PHDC treatments. The results suggest that PHDC reduces O. cumana infection in sunflower by inducing host resistance, not by directly interfering with the parasite. Free phenolics play an important role in sunflower response to the parasite.     

向日葵抗列当品种(系)筛选及其应用评价

为了全面评价不同向日葵品种(系)对列当的抗寄生性和其在生产中的应用价值,对‘TP3313’等50个食葵品种(系)、‘内蒙杂4号’等6个油葵品种(系)进行了田间自然寄生试验,结果表明:食葵‘TP3313’为对列当免疫的品种,且病虫害发生较轻,产量相对较高(261.11kg/667m~2),因而具有极高的推广应用价值;‘TP3314’为高抗列当品种,但是受向日葵菌核病危害较重,产量为219.64kg/667m~2;‘SH361-L’、‘SH338-M’等8个品种表现为中感,属耐列当品种(系),并且产量相对较高,在生产中具有一定的应用价值。     

阴山北麓地区向日葵列当生理小种的鉴定及种子的单株纯化

向日葵列当是一种全寄生的种子植物,对向日葵生产造成严重的影响,而选育抗列当品种是目前防控向日葵列当最为有效的防控措施.由于向日葵列当种群存在生理小种分化现象,因此明确不同地区的向日葵列当生理小种的类型以及分布对于抗列当品种的布局非常重要.本研究利用国际通用的向日葵列当生理小种鉴别寄主,对阴山北麓地区的武川县和四子王旗共...     

Molecular analysis of resistance mechanisms to Orobanche cumana in sunflower

Resistance to the dicotyledenous parasite Orobanche cumana in sunflower is characterized by a low number of parasitic attachments and a confinement of the parasite in host tissues leading to its necrosis. To help understand what determines such resistance mechanisms, molecular, biochemical and histological approaches were employed before (early response) and after (late response) attachment of the broomrape parasite to susceptible (2603) and resistant (LR1) sunflower genotypes. The expression patterns of 11 defence-related genes known to be involved in different metabolic pathways (phenylpropanoids, jasmonate, ethylene) and/or in resistance mechanisms against microorganisms were investigated. RT-PCR and cDNA blot experiments revealed that the resistant genotype exhibited a stronger overall defence response against O. cumana than the susceptible one, involving marker genes of the jasmonate (JA) and salicylic acid (SA) pathways. Among them, the SA-responsive gene, def. (defensin), appeared to be characteristic of LR1 sunflower resistance. However, no JA accumulation and similar SA contents (250–300 ng g⁻¹ FW) were measured by GC/MS in both genotypes, parasitized or not. In addition, three cDNAs, isolated by a suppression-subtractive hybridization, were shown to be strongly induced only in the resistant genotype 8 days post-inoculation, when the first O. cumana attachments occurred. These genes, putatively encoding a methionine synthase, a glutathione S-transferase and a quinone oxidoreductase, might be involved in detoxification of reactive oxygen species, suggesting the occurrence of an oxidative burst during the incompatible interaction. Finally, host cell-wall modifications leading to parasite-confinement were correlated with more intense callose depositions in the resistant genotype, concomitant with over-expression of the callose synthase cDNA HaGSL1 .