烟草及向日葵上列当Orobanche cumana的发生及其生物防治

 近年,在河北省部分烟草和向日葵种植地发现大量寄生性杂草列当发生并造成严重为害。经鉴定为向日葵列当Orobanche cumana Wallr.。向日葵、烟草、番茄和黄瓜等作物的根分泌物能够刺激向日葵列当O. cumana种子萌发,而油葵根的分泌物则不能刺激向日葵列当种子萌发。利用列当致病镰刀菌L2菌株进行田间生物防治,防治效果达到92.4%。L2菌株对小麦、玉米、棉花、烟草和向日葵等作物生长无影响,L2菌株粗毒素能够抑制列当种子萌发,并造成列当种子萌芽管损伤。     

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。     

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。     

胡杨根际可培养细菌的分离及抑制瓜列当种子萌发研究

从胡杨生存的干旱强光照逆境中获得新的细菌资源,从中筛选新的可抑制瓜列当种子萌发的生防菌。采用3种分离培养基,以稀释涂布法对塔里木河流域3处胡杨根系样品进行可培养细菌分离,通过分析分离菌株16S rRNA基因序列确定其种属分类。采用皿内培养法测定其对瓜列当种子萌发的抑制活性,利用盆栽试验检测分离菌株M2-3对瓜列当寄生的防治效果。结果分离获得98株细菌,分属于28个属,马赛菌属Massilia、Pontibacter、玫瑰单胞菌属Roseomonas为优势菌属。其中,菌株M2-3与Pontibacter salisaro HMC5104T的相似度最高,为97.92%,其菌体发酵液10倍稀释液对瓜列当种子萌发抑制率为87.8%,盆栽试验表明该菌株对瓜列当防效可达36.9%,具备进一步开发可能性。     

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。     

水溶性氟乐灵纳米制剂对向日葵列当的毒力及田间药效

向日葵列当Orobanche cumana是一种检疫性恶性寄生杂草。本研究采用透析法制备了一种水溶性氟乐灵纳米制剂(Tf-OR-CC),评价其对向日葵列当的室内毒力和田间药效。种子发芽毒力测定结果表明:在独脚金内酯类似物GR24的诱导下,用5μg/mL Tf-OR-CC处理向日葵列当种子,7 d后表现出良好的抑制发芽活性,列当种子发芽率为28.5%,与对照相比差异显著。消解动态试验表明,Tf-OR-CC消解半衰期比48%氟乐灵乳油延长6.56 d,说明Tf-OR-CC具有一定的缓释作用。田间药效试验结果表明,滴灌施用有效成分含量为75 g/667 m~2Tf-OR-CC 45 d后,向日葵列当寄生率为32.1%,寄生强度为5.3,Tf-OR-CC制剂对向日葵列当的田间防效为36.3%。该方法可为向日葵滴灌施药技术防治向日葵列当提供科学依据。     

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。     

分枝列当寄生甜瓜时吸器形成过程中内源激素的动态变化

本研究采用石蜡切片和显微观察分析分枝列当寄生甜瓜时的吸器形成过程, 利用液相色谱-质谱联用 (LC-MS) 检测吸器形成过程中24种植物内源激素变化。结果表明:分枝列当种子在接种甜瓜根部第3 天开始萌发, 接种第7 天分枝列当吸器顶端稳固地附着在寄主根部, 吸器侵入甜瓜根皮层, 并在甜瓜根皮层细胞内扩展, 扩展过程中形成大量的爪状结构, 接种第11 天时分枝列当吸器细胞与寄主根维管束连接。共有17种植物激素参与了吸器形成过程, 其中生长素类吲哚-3-甲醛含量在列当吸器形成过程中降低了83.36%，细胞分裂素类反式玉米素核苷的含量在增长了5.02倍;油菜素内酯含量增长了481.95倍, 推测这3类植物激素在分枝列当吸器形成过程中可能起到重要的调控作用。     

深绿木霉TraT2A对5种作物的促生作用研究

为明确来源于深绿木霉(Trichoderma atroviride)T2菌株发酵液的蛋白提取物TraT2A对小麦、玉米、豇豆、辣椒和黄瓜5种作物的促生作用,本试验采用种子萌发和室内盆栽试验测定了4种不同浓度的TraT2A对5种作物种子发芽情况、幼苗形态变化和生理特性的影响。结果表明：4种不同浓度的TraT2A对5种作物均具有促生作用,可显著促进作物生长,促生率可达104.69%,同时提高叶绿素含量和根系活力,促生率达24.95%,且降低丙二醛含量,促生率达36.69%。10 mg·mL^-1 TraT2A对5种作物的促生效果最好,且不同作物不同指标之间促生效果存在差异,表现为对黄瓜干质量的促生率最大,为104.69%,其次是对黄瓜活力指数的促生率为91.86%,第三是对辣椒胚轴的促生率为70.17%;对其他作物的发芽率、发芽指数、胚根、鲜质量、干质量、叶绿素含量和根系活力的最大促生率在17.65%～46.46%范围内;10 mg·mL^-1 TraT2A处理5种作物后小麦丙二醛含量降幅最大(36.69%)。4种不同浓度的TraT2A处理5种作物后...     

4种微生物菌剂对辣椒主要病害的生物防治作用

本文选择4种不同微生物活性成分的生防菌剂，采用盆栽生物量测定、温室和田间小区试验对辣椒主要病害进行抗病效果及促生增产作用评价。结果表明，木霉-芽胞杆菌复合菌剂对辣椒的枯萎病、疫病、炭疽病和灰霉病防效分别达到72.2%、78.3%、71.9%和59.7%，枯草芽胞杆菌-粉红粘帚霉复合菌剂对辣椒4种病害的防效分别达到60.5%、62.1%、60.5%和50.9%；而淡紫紫孢菌菌剂只对辣椒炭疽病具有很好防效（77.5%）。同时，4种微生物菌剂对辣椒植株生物量均有显著促生作用，其中木霉-芽胞杆菌复合菌剂及枯草芽胞杆菌-粉红粘帚霉复合菌剂在盆栽试验中鲜重和干重增幅分别为132.79%、190.35%和211.80%、293.84%；两者在温室及田间小区试验中比对照增产182.3%、152.7%和65.0%、23.9%。本研究表明，生防菌剂可以替代化学药剂用于植物病害的防治，同时还能够促进作物植株生长，有增产作用。     

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。     

In vitro culture of Orobanche ramosa

Orobanche spp. (broomrapes) are holoparasites that subsist on the roots of many important crops and can considerably reduce yield. The control of Orobanche spp. includes physical, chemical and biological methods. Interactions between parasitic angiosperms and their hosts first occur at the level of parasite seed germination. The seeds of all Orobanchaceae germinate in soil under natural conditions only in response to specific chemical exudates from the host plant. This study describes the influence of different plant growth regulators and host plant root exudates on germination and development of calli from Orobanche seeds in vitro . The effect of indole-3-acetic acid, gibberellic acid and kinetin on the germination of Orobanche seeds varied with concentration. These plant growth regulators also affected the period of germination and the structure of calli and protrusions. An in vitro system for the collection of tobacco root exudates was established. Compounds released from the host roots of three different tobacco cultivars were found to provoke high levels of germination of the Orobanche seeds without any period of pre-conditioning. This study developed methods for the investigation of host–parasite interactions and the effect of germination stimulants in Orobanche spp.     

Intraspecific seasonal variation of dormancy and mortality of Phelipanche ramosa seeds

Phelipanche ramosa (Branched broomrape) is an obligate root parasitic plant that is a major pest of oilseed rape in France. Knowledge on seed viability and dormancy under field conditions is crucial to understand how to control P. ramosa, but is as yet unknown. Our study aimed to quantify these processes with a 2‐year seed burial experiment. Two genetically distinct populations of P. ramosa were studied, collected on winter oilseed rape (population O) and hemp (population H). Seed mortality was very low in both populations (4–7% per year). Although obligate parasitic seeds are assumed to germinate only after exposure to germination stimulants from host root exudates, a high proportion of population H seeds germinated spontaneously (up to 90%). Seeds of both populations displayed seasonal dormancy, with timing and magnitude depending on the population. Dormancy was low at the time each native host crop is usually sown. Populations differed in germination dynamics, with seeds of population H germinating faster. The difference in behaviour that we observed between populations is consistent with reported adaptations of pathovars to their preferred hosts. The results indicate that the parasitic plant management requires targeting at the populations concerned. For example, delayed sowing is more promising against population O than against population H.     

Fenugreek root exudates show species-specific stimulation of Orobanche seed germination

Various Orobanche species are weedy and cause severe reduction in the yields of many important crops. The seeds of these parasitic weeds may remain dormant in the soil for many years until germination is stimulated by the release of a chemical signal from a host plant. In order to determine the effects of fenugreek root exudate on the induction of Orobanche crenata, Orobanche ramosa and Orobanche foetida seed germination, root exudate was collected from hydroponically grown fenugreek seedlings. Fractionation patterns obtained from column and thin layer chromatography of the fenugreek root exudate showed a set of metabolites differing in their polarity with stimulatory activity on Orobanche seed germination. The crude root exudate stimulated both O. ramosa and O. crenata seed germination to the same level caused by the synthetic germination stimulant GR24 at 10 mg L^?1. It also stimulated O. foetida seed germination which did not respond to GR24. Active fractions of root exudate stimulated the germination of Orobanche species differentially.     

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计7个向日葵地块中采集的列当种子的生理小种进行了鉴定,结果表明除了呼和浩特市武川县头号村采集的向日葵列当样本为E小种外,其他6个不同地点采集到的向日葵列当样本均鉴定为G小种。为了更好地对向日葵品种抗列当水平进行准确的评价,本研究选择了已经鉴定为E、F和G三个小种类型的向日葵列当的样本进行了单株纯化以及扩繁。扩繁得到的列当的种子将用于准确评价向日葵不同的育种材料和品种对列当不同生理小种的抗性水平。     

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.