Effects of azoxystrobin, difenoconazole, polyoxin B (polar) and trifloxystrobin on germination and growth of Alternaria alternata and decay in red delicious apple fruit

Alternaria alternata is the predominant fungal pathogen responsible for moldy-core in red delicious strains of apple. In this study, we report on the effects of the polyoxin B compound Polar, the strobilurin fungicides, azoxystrobin and trifloxystrobin, and the sterol inhibitor difenoconazole on spore germination, mycelial growth and fruit decay on detached fruits caused by A. alternata. Germination was most sensitive to polyoxin B and trifloxystrobin among the tested compounds. The 50% and 95% effective concentration (EC₅₀, and EC₉₅), values for in vitro inhibition of conidial germination of the fungus were lowest for polyoxin B and trifloxystrobin, ranging from <0.01 to 0.15 μg/ml and 180 μg/ml, respectively. Germination was least sensitive to difenoconazole and azoxystrobin (EC₅₀ and EC₉₅ values ranging from 25 to 72 μg/ml and 720 μg/ml, respectively). Mycelial growth in vitro of A. alternata was most sensitive to difenoconazole (EC₅₀ and EC₉₅ values of 0.8 and 12 μg/ml, respectively) and least sensitive to both strobilurin fungicides (EC₉₅>1000 μg/ml). Decay formation by A. alternata on mature detached fruits was most affected by trifloxystrobin and azoxystrobin (EC₅₀ and EC₉₅ values of 0.015–0.087 μg/ml and 8 μg/ml, respectively), intermidiate in sensitivity to Polyoxin B (EC₅₀ and EC₉₅ from 1 to 33 μg/ml, respectively), and difenoconazole was the least effective (EC₅₀ and EC₉₅ from 20 to 490 μg/ml, respectively). Polyoxin B applied at 24 or 48 h post-inoculation inhibited fruit decay development. Difenoconazole and trifloxystrobin were less effective and azoxystrobin was ineffective when applied at 48 h post inoculation. The activity of azoxystrobin, difenoconazole, Polyoxin B and trifloxystrobin on one or more stages of the life cycle of A. alternata and on decay development in fruits suggests that these compounds potentially could provide control of moldy-core disease in apple.     

Antifungal modes of action of metalaxyl, cyprofuram, benalaxyl and oxadixyl in phenylamide-sensitive and phenylamide-resistant strains of Phytophthora megasperma f. sp. medicaginis and Phytophthora infestans

The activity of the phenylamide fungicides metalaxyl, cyprofuram, benalaxyl and oxadixyl against phenylamide-sensitive and phenylamide-resistant strains of Phytophthora megasperma f. sp. medicaginis and Phytophthora infestans has been compared in several tests. Metalaxyl showed the highest activity amongst the four fungicides against mycelial growth of sensitive strains on agar media. Benalaxyl and cyprofuram showed the highest activity against resistant strains. RNA synthesis of sensitive strains, measured as [³H]uridine incorporation, was inhibited by about 80% (P. megasperma) and by about 40% (P. infestans) by all phenylamides at concentrations of 1 μg/ml. At higher concentrations inhibition remained at this level, indicating that only part of the RNA synthesis was inhibited. RNA synthesis of resistant strains was completely insensitive to metalaxyl and oxadixyl at concentrations as high as 200 μg/ml. Cyprofuram, however, at concentrations above 1 μg/ml (P. megasperma) and 10 μg/ml (P. infestans) was inhibitory and at 200 μg/ml this compound almost completely inhibited the phenylamide-sensitive part of the RNA synthesis of both strains. In contrast to the other phenylamides, benalaxyl affected [³H]uridine uptake into mycelium at concentrations higher than 10 μg/ml, and at 100 μg/ml inhibition of uptake was almost total with both sensitive and resistant strains of both Phytophthora species. Inhibition of [³H]uridine uptake obviously is a feature of a second mechanism of action of benalaxyl. Endogenous RNA polymerase activity of isolated nuclei from sensitive strains of P. megasperma was inhibited at phenylamide concentrations as low as 0·1 μg/ml whereas that from resistant strains was not affected at concentrations as high as 100 μg/ml. Similarly, endogenous nuclear RNA polymerase activity of sensitive P. infestans strains appeared to be more sensitive to the phenylamides than that of resistant P. infestans strains. This suggests that resistance that developed in field strains of P. infestans has a basis similar to that of mutagen-induced resistance in laboratory strains of P. megasperma. Tests of the fungicidal activity of the phenylamides determined in a lucerne seedling assay (P. megasperma) and a detached potato leaf assay (P. infestans) clearly differentiated between sensitive and resistant strains. Resistance levels to cyprofuram and benalaxyl were as high as those to metalaxyl and oxadixyl, indicating that the additional effect of a second mechanism of action of benalaxyl and the property of cyprofuram to inhibit RNA synthesis of resistant strains at higher concentrations are of limited practical importance for counteracting phenylamide resistance.     

139份大麦种质材料苗期和成株期抗白粉病鉴定评价

为给培育大麦持续性抗白粉病品种提供有价值的抗源,利用7个大麦白粉病菌优势小种,在实验室条件下分别接种139份大麦品种(系),进行苗期抗性鉴定,同时于2009-2011年度在云南保山对参试品种(系)进行田间成株期抗性鉴定,并考查成株期抗病材料的农艺性状.结果表明,参试品种(系)在苗期对7个优势小种表现出48个不同的抗性反应谱,13个大麦品种(系)能抗所有参试的优势小种,22个大麦品种(系)能抗4～6个优势小种.25个大麦品种(系)具有成株期抗病性.大麦苗期抗性与成株期抗性并不完全一致,但苗期抗优势小种数较多的材料中,成株期表现抗性的也较多,5个苗期抗所有优势小种的大麦品种(系)均表现出成株期抗性.25个成株期抗病品种(系)中18个为二棱皮大麦,7个为多棱裸大麦,它们株高、穗长、穗粒数扣千粒重的变异系数较大,二棱皮大麦株高、穗长、穗粒数和千粒重的变异系数分别为10.3％、15.0％、12.0％和20.6％,多棱裸大麦分别为18.3％、26.4％、19.5％和22.8％.     

大麦白粉病抗性的遗传分析

为给大麦抗白粉病育种提供参考依据,以1个感白粉病、4个抗白粉病大麦品种为亲本,按Griffing的双列杂交法Ⅰ配制20个杂交组合,在田间自然条件下研究了大麦白粉病抗性的遗传特性。结果表明,大麦白粉病抗性在杂交组合间存在显著差异。5个亲本中,木石港3号和CM72的一般配合力较好,均表现为较大的负向效应,能极显著提高杂种后代抗白粉病能力;S096的一般配合力中等,也表现为负向效应,能显著地提高杂种后代抗白粉病能力,因而这三个品种在大麦抗白粉病育种中利用价值较高。大麦白粉病抗性遗传符合加性显性模型,同时受加性和显性效应的作用,且加性效应更重要。大麦白粉病抗性的狭义遗传力较低,早代选择不宜太严。     

Algicidal effect of 3-(3-indolyl)butanoic acid, a control agent of the bacterial wilt pathogen, Ralstonia solanacearum

The chemical control agent 3-(3-indolyl)butanoic acid, previously reported as a control agent for the bacterial wilt pathogen Ralstonia solanacearum, was shown to suppress the growth of green algae during hydroponic culture of tomato. The algicidal activity of the compound was effective at 10 μg/ml, completely preventing generation of green algae under non-shaded greenhouse conditions. The algicidal effect was mainly due to suppression of the growth of motile unicellular algal cells tentatively identified as Chlamydomonas spp., which are commonly occurring in the hydroponic solution and vigorously multiply to form an algal mat on the sponge supports. The compound has potential as a non-phytotoxic algicide for hydroponically cultured crop plants.     

Effects of relative humidity and high temperature on spore germination and development of tomato powdery mildew (Leveillula taurica)

The effects of relative humidity (RH) and temperature on tomato powdery mildew (Leveillula taurica) were studied in controlled environments to define conditions that affect disease development in fresh market tomatoes in California. Gradients of RH (20–90%) at constant temperatures (20–30°C) were generated in single growth chambers to determine their effect on mildew development on mature tomato plants. Temperatures of 30°C and above were deleterious for spore germination, germ tube elongation, and disease development. Lesion growth and rate of disease progress were significantly higher at 20°C than at 25°C. Low RH levels (20–40%) reduced spore germination and lesion growth, accelerated host tissue death and reduced disease progress. Intermediate RH levels (50–70%) increased spore germination and optimized disease development, provided temperatures were maintained within favorable limits. High RH levels (80–90%) were favorable for spore germination but continued exposure to these conditions led to a limited lesion growth and disease progress. Short daily periods (two or three daily exposures of at least 2 h) of high temperatures (35°C) suppressed disease development by 70–92%.     

我国栽培大麦白粉病抗性特点分析

对来自全国 2 4个省 (自治区、直辖市 )共 90个代表性栽培大麦品种 ,进行了抗白粉病田间鉴定。统计结果表明 ,(1)品种之间抗病性有明显差异。其中表现高抗的品种 2 1个 ,占总数 2 3.3% ;抗病品种 2 6个 ,占 2 8.9% ;感病 33个 ,占 36 .7% ;高感 10个 ,占 11.1%。可见在我国栽培大麦中 ,抗源较丰富。 (2 )不同类型和棱形的抗性 ,比较发现 ,皮麦抗病品种比裸麦多 ,六棱抗病性强于四棱和二棱。 (3)供种省份之间抗病性不同 ,抗病品种主要集中在江苏、安徽、陕西、河北、四川、贵州、湖北、上海和新疆等省 (自治区、直辖市 )。 (4)从三大麦区看 ,抗病品种主要分布在冬大麦区     

橡胶树种质资源对白粉病和炭疽病的田间抗病性评价

白粉病和炭疽病是我国橡胶树的主要病害,严重影响胶乳产量,给天然橡胶产业带来了很大的经济损失。挖掘培育抗病性种质资源是最经济、有效的防治措施。本研究通过分析2018、2019、2021年白粉病和炭疽病田间自然发病数据,评价192份橡胶树种质的抗病性,旨在为橡胶树抗病育种提供数据支撑。结果表明,白粉病2019年发病严重,种质群体的病情指数平均值达34.37,最大值为94.07;2018年和2021年则发病较轻,病情指数平均值分别为10.68和9.70。炭疽病2021年发病严重,种质群体的病情指数平均值达29.12,最大值为65.31;2018年和2019年则发病较轻,病情指数平均值分别为18.64和18.15。利用重病年数据鉴定出白粉病高抗品种24个、中抗品种9个,炭疽病抗性品种35个。这33份和35份抗性种质在3 a内对白粉病和炭疽病均达到抗性水平,分别占供试种质的22%和19%。利用隶属函数和聚类分析对这些候选抗病种质进行抗性水平排序,对白粉病抗性排名前10的种质隶属函数平均值为0.86~1.00,标准偏差值为0.003~0.073。在白粉病抗性聚类树遗传距离2.5处,排序第1的‘湛试5025’单独聚为一类,排序前2~6位的种质聚为一类,与其他类区分明显;对炭疽病抗性排名前10的种质隶属函数平均值为0.83~0.90,标准偏差值为0.020~0.102。在炭疽病抗性聚类树遗传距离2.5处,排序前5的种质单独聚集为一类,与其他类区分明显。初步筛选出抗白粉病优异的种质‘湛试5025’‘湛试12-3’‘湛试5005’‘天任31-45’‘湛试5026’,筛选出抗炭疽病优异的种质‘湛试477-6’‘湛试366-2’‘湛试485-114’‘湛试41-3’‘RO42’。本研究建立的抗性鉴定、隶属函数和聚类分析相结合的分析方法为橡胶树种质抗病性综合评价提供了重要的技术参考。     

喷施参数对四旋翼植保无人机雾滴在橡胶林中分布的影响

雾滴分布特征影响作物上喷雾的施药效果,而喷施参数是影响植保无人机雾滴分布特性的重要因素之一。为了揭示施药量和雾滴粒径等喷施参数对电动四旋翼植保无人机雾滴在高大乔木橡胶树林段中分布的影响,以成龄‘热研7-20-59’胶林为试验地,分别设置18.75、37.50、75.00、90.00、105.00 L/hm²施药量,70、100、150、250 μm雾滴粒径,采用5点采样法在6个高度上测量水平方向及垂直方向的雾滴谱宽度、雾滴覆盖密度、雾滴分布均匀度等主要作业质量技术指标数据,结合橡胶树白粉病的防治效果,筛选四旋翼无人机的最佳喷施参数。结果表明,随施药量的增加,雾滴谱宽度呈下降趋势,雾滴覆盖密度显著增加;施药量在75 L/hm²及以上时满足最低施药雾滴覆盖密度的要求。随着雾滴粒径的增加,雾滴谱宽度呈上升趋势,雾滴覆盖密度无显著差异,雾滴粒径100 μm的水平分布均匀度最优。不同施药量和雾滴粒径的雾滴在橡胶林垂直方向的分布均匀度一致,穿透性良好。本研究筛选出施药量75 L/hm²和喷雾粒径100 μm的最佳喷施参数,在橡胶树白粉病最佳防治时期使用咪鲜胺（EW）和戊唑醇（SC）复配药剂进行田间飞防试验,效果优异,2块试验地的防效分别为65.7%和82.9%。本研究提供了一组橡胶树白粉病防治的四旋翼无人机施药参数,为植保无人机在橡胶林病虫害防治作业中提供参考。     

Effects of sulfosulfuron soil residues on barley (Hordeum vulgare), sunflower (Helianthus annuus) and common vetch (vicia sativa)

The phytotoxicity and sensitivity of succeeding crops to the new sulfonylurea, sulfosulfuron, have been reported although there is insufficient data on the phytotoxic effect of field soil residues. Growth chamber bioassays were conducted to detect the presence of residues in soil samples previously treated with sulfosulfuron at the recommended rate and double rate (20 and 40 g a.i./ha) that could affect the succeeding crop. Soil samples were collected between 7 and 9 months after sulfosulfuron application in field selectivity assays at nine different locations in Northern and Central Spain. The bioassay test species were barley (Hordeum vulgare L.) ‘Graphic’, sunflower (Helianthus annuus L.) ‘Albasol’ and common vetch (Vicia sativa L.) ‘Neska’, typical crops grown in rotation with wheat (Triticum aestivum L.) in this area. Sulfosulfuron residues did not affect barley and common vetch, but inhibited shoot length, root length and root dry weight of sunflower seeded into some soils treated with the 2× rate (40 g a.i/ha) 9 months earlier.     

Evaluation of Lecanicillium longisporum, Vertalec against the cotton aphid, Aphis gossypii, and cucumber powdery mildew, Sphaerotheca fuliginea in a greenhouse environment

The commercial mycopesticide, Vertalec^® based on Lecanicillium longisporum, was evaluated for simultaneous control of aphids and powdery mildew on cucumbers in a greenhouse setting where temperature and RH were allowed to fluctuate within normal operating ranges. Five to six week old cucumber plants were inoculated with either Sphaerotheca fuliginea (Sf) spores, cotton aphids (Aphis gossypii) or both. Vertalec, Vertalec containing irradiation-inactivated blastospores (II Vertalec) or sterilized water (control) were applied to the plants 1, 4, and 7 days later. Vertalec treatment provided complete control of aphids 16 days after aphid inoculation, whereas effects of the II Vetalec were not significantly different from the water-treated control. The number of powdery mildew spots on cucumber leaves and the number of S. fuliginea spores in each spot were significantly lower in Vertalec-treated plants than II Vertalec-treated plants or the controls, whereas numbers in the II Vertalec treatment were lower that the untreated control. These results demonstrate that Vertalec has potential for simultaneous management of both cotton aphid and powdery mildew in greenhouse cucumber production.     

COS-OGA: A novel oligosaccharidic elicitor that protects grapes and cucumbers against powdery mildew

Many plant protection products have been banned due to their toxicity or because pathogens have become resistant to their active substances. Plant resistance inducers are a promising class of compounds that will hopefully reduce dependence on harmful chemicals for plant protection. The efficacy of COS-OGA, a novel elicitor composed of a complex of oligochitosans and oligopectates as active substances, has been assessed in production conditions against powdery mildew on grapevines and on cucumbers. COS-OGA induced a large reduction in the severity of powdery mildew for both crops. At the end of vineyard trials, COS-OGA, at a spraying rate of 37.5 g ha⁻¹, achieved a considerable reduction in Uncinula necator severity on bunches of grapes with 78% protection in France and 76% protection in Spain. Similarly, in the last evaluation performed in greenhouses to assess the protection of cucumber crops against Sphaerotheca fuliginea, COS-OGA at 25 g ha⁻¹ LWA (leaf wall area) yielded a 72% reduction in leaf disease severity in Belgium and 69% in Spain. In some trials, the efficacy of the COS-OGA active substance was even higher than the conventional chemical reference.     

香蕉果肉类胡萝卜素提取与测定方法

大规模开展香蕉类胡萝卜素种质资源评价,发掘高类胡萝卜素的品种资源,提高主栽品种中类胡萝卜素的含量,对于提升香蕉产业竞争力具有重要的作用。开展此项研究需要建立高效的香蕉果肉类胡萝卜素提取和测定体系。本文拟建立基于超高效液相色谱仪（Agilent 1290）,适用于香蕉果肉的类胡萝卜素提取及测定的方法。利用YMC-C30色谱柱,在450 nm检测波长和柱温20℃条件下,比较了不同的料液比（g:mL,1:6、1:9、1:12、1:15）、定容溶液的比例（V:V,MTBE:甲醇=1:0、1:1、1:2）、流动相（V:V,甲醇:乙腈=4:0、3:1、2:2、1:3、0:4）、流速（0.6、0.8、1.2 mL/min）等对类胡萝卜素组分鉴定和含量测定的影响。结果表明,当提取试剂正己烷:丙酮:无水乙醇=2:1:1（V:V:V）,果肉与提取试剂的料液比为1:9,超声波破碎30 min,重复3次,定容溶液MTBE:甲醇=1:1时,香蕉类胡萝卜素组分分离的效果最好。当色谱条件A相以甲醇:乙腈,B相以MTBE（100%）为流动相,进样量为10 μL,流速为1 mL/min进行梯度洗脱时,可以很好的鉴定并分离类胡萝卜素的主要组分。利用优化后的体系进行检测不同类胡萝卜素含量的香蕉品种,发现香蕉果肉中的主要类胡萝卜素组分为叶黄素、α-胡萝卜素、β-胡萝卜素。高类胡萝卜素含量的‘French somber’香蕉品种约含9.79 μg/g,而低含量的‘中蕉8号’香蕉品种只有约0.201 μg/g,这也表明不同香蕉品种中类胡萝卜素的含量差异相对较大。本文中以香蕉果肉为材料所建立的类胡萝卜素提取与检测方法,操作简单,精确度高,为科研工作者在香蕉类胡萝卜素的功能研究方面提供参考。     

Antifungal properties of quinoa (Chenopodium quinoa Willd) alkali treated saponins against Botrytis cinerea

Quinoa (Chenopodium quinoa Willd) is a Latin American food staple readily available in large quantities in Peru, Bolivia and Ecuador. The outer husk of the grain is removed prior to consumption to reduce its bitter taste. At present, quinoa husks are considered as a by-product with no commercial value, despite its high content of triterpenoid saponins (20–30%). Due to this, the present work was undertaken to test if quinoa saponins have antifungal properties against Botrytis cinerea and if this activity is enhanced after alkaline treatment, since recent reports indicate that alkaline treatment of quinoa saponins increase their biological activity. Six products were tested against B. cinerea: (1) non-purified quinoa extract, (2) purified quinoa extract, (3) alkali treated non-purified quinoa extract, (4) alkali treated purified quinoa extract, (5) non-purified quinoa extract treated with alkali but without thermal incubation and (6) purified quinoa extract treated with alkali but without thermal incubation.

Untreated quinoa extracts showed minimum activity against mycelial growth of B. cinerea. Also, no effects were observed against conidial germination, even at 7 mg saponins/ml. However, when the saponin extracts were treated with alkali, mycelial growth and conidial germination were significantly inhibited. At doses of 5 mg saponins/ml, 100% of conidial germination inhibition was observed, even after 96 h of incubation. Fungal membrane integrity experiments based on the uptake of the fluorogenic dye SYTOX green showed that alkali treated saponins generate membrane disruption, while non-treated saponins had no effects.

The higher antifungal activity of alkaline treated saponins is probably due to the formation of more hydrophobic saponin derivatives that may have a higher affinity with the sterols present in cell membranes.     

Effect of grain type on the insecticidal efficacy of SilicoSec against Sitophilus oryzae (L.) (Coleoptera: Curculionidae)

The insecticidal efficacy of the diatomaceous earth formulation SilicoSec^® (Agrinova GmbH, Germany) against the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) was evaluated on peeled rice, paddy rice, maize and barley in laboratory tests. SilicoSec was applied at five dose rates: 0.125, 0.25, 0.5, 1 and 1.5 g/kg of grain. The treated grains were infested with S. oryzae adults, and the weevil mortality was estimated after 24, 48 h, 7 and 14 d of exposure on treated grain. After the 14 d counts, all the exposed adults were removed and progeny production on treated grains was assessed 45 and 90 d later. Insecticidal efficacy of SilicoSec against the rice weevil was highly affected by grain type, exposure interval and dose rate. In all grains tested, longer exposure intervals increased weevil mortality. The efficacy of SilicoSec on maize was not satisfactory, given that after a 14 d exposure at the highest dose rate the mortality did not exceed 65%. Moreover, progeny production on treated maize was high, regardless of the dose rate. On the other hand, 100% of weevils were dead on barley treated with the two highest dose rates of SilicoSec, after a 7 d exposure. However, a complete suppression of progeny production on treated barley was not achieved, even at the highest dose rate. A satisfactory level of protection was recorded on paddy rice treated with 1 and 1.5 g of SilicoSec/kg. At these two rates, all adults were dead after a 7 d exposure, and no progeny were produced during the 90 d incubation period. In contrast, the mortality on peeled rice treated with 1.5 g of SilicoSec/kg did not reach 100%, even after 14 d of exposure, and a high number of progeny were recorded.     

巴西橡胶树HbRPW8基因克隆与表达分析

RPW8（resistance to powdery mildew locus 8）是对植物多种病害,尤其白粉病具有抗性的广谱抗病基因位点,通过对橡胶树RPW8基因进行克隆及表达分析,为橡胶树抗白粉病机制解析和分子育种等方面打下基础。以橡胶树‘热研73397’为材料,采用RT-PCR克隆HbRPW8基因编码区（CDS）序列;对其进行生物信息学分析,并利用qRT-PCR方法,测定7种激素和白粉菌侵染不同时间、不同病害等级处理后RPW8基因表达量。该基因cDNA全长570 bp,编码189个氨基酸,该蛋白的分子量为21.73 kDa,等电点为9.23,脂肪系数为86.30,总平均亲水性指数为-0.404,为亲水性蛋白,共有8个磷酸化位点,无跨膜域和信号肽,定位于细胞核,具有RPW8的保守结构域,α-螺旋和无规则卷曲是HbRPW8蛋白二级结构的主要元件,分别占氨基酸序列的70.90%和22.22%。亲缘关系显示,HbRPW8基因与木薯RPW8基因相似性最高。过氧化氢（H₂O₂）、水杨酸（SA）、乙烯利（ETH）、赤霉素（GA）和脱落酸（ABA）能迅速诱导HbRPW8转录本的表达,并在处理后0.5 h达到最高水平,分别约为对照的14倍、6倍、75倍、2.5倍和4倍;茉莉酸甲酯（MeJA）处理后6 h达到最高水平,是对照的10倍左右;生长素处理后HbRPW8转录本显著下调;随着白粉菌侵染时间和病害等级的增加,HbRPW8的表达量均呈现先上升后下降的趋势。研究结果初步表明,HbRPW8可能参与橡胶树的抗病反应机制,为橡胶树抗病育种的研究提供参考。     

Biological control of foliar pathogens by means of Trichoderma harzianum and potential modes of action

Biocontrol of foliar diseases is an alternative means of management of foliar pathogens. One of the most studied commercial biocontrol agents is isolate T39 of Trichoderma harzianum which can be regarded as a model to demonstrate biocontrol under commercial conditions and the mechanisms involved. This biocontrol agent (BCA) controls the foliar pathogens, Botrytis cinerea, Pseuperonospora cubensis, Sclerotinia sclerotiorum and Sphaerotheca fusca (syn. S. fuliginea) in cucumber under commercial greenhouse conditions. Control efficacy was similar for three different rates (covering a fourfold range). Involvement of locally and systemically induced resistance has been demonstrated. Cells of the BCA applied to the roots, and dead cells applied to the leaves of cucumber plants induced control of powdery mildew. The BCA suppressed enzymes of B. cinerea, such as pectinases, cutinase, glucanase and chitinase, through the action of protease secreted on plant surfaces. A combination of several modes of action is responsible for biocontrol. However, biocontrol is not achieved by means of antibiotics or by mycoparasitism, in spite of the fact that BCA has the potential to degrade cell-wall polymers, such as chitin.     

西藏青稞种质资源材料白粉病抗性鉴定

为了筛选西藏青稞抗白粉病资源,选取具有代表性的330份青稞材料在田间进行白粉病感染调查,结合室内盆栽幼苗接种鉴定。330份青稞材料的鉴定结果表明,田间发病大多是中下部叶片感染,发病材料169份,占供试材料的51.21%;室内幼苗接种发现高抗材料7份,占供试材料的2.12%,抗病材料12份,占供试材料的3.64%,感病和高感品种311份,占供试材料的94.24%。     

基于SLAF-seq技术的苦瓜白粉病SNP分子标记开发

以高抗白粉病苦瓜MC18和高感白粉病MC105杂交构建遗传分离群体,利用SLAF-seq技术进行深度测序,开发与抗白粉病性状紧密关联的SNP分子标记。结果表明:测序共获得各样品的有效reads为10.48 Mb,获得高质量的SLAF标签91 856个,其中多态性SLAF标签5 502个,多态性比例为5.99%。通过对多态性SLAF标签进行关联分析,筛选出与苦瓜白粉病抗病性状紧密关联的SNP位点共29个。根据关联分析结果 ,通过四引物扩增受阻突变体系PCR技术进行SNP位点多态性的验证,其中Marker4542、Marker11188分子标记特异性强、灵敏度高、稳定性好,建立一套简便快捷的苦瓜SNP分型方法。该方法可对苦瓜育种材料进行分子标记辅助选择,以进一步提高苦瓜抗病育种效率。      

Anti-Human Rhinoviral Activity of Polybromocatechol Compounds Isolated from the Rhodophyta, Neorhodomela aculeata

An extract of the red alga, Neorhodomela aculeata, exhibited antiviral activity against human rhinoviruses. Bioassay-guided purification was performed to yield six compounds, which were subsequently identified as lanosol (1) and five polybromocatechols (2–6) by spectroscopic methods, including 1D and 2D NMR and mass spectrometric analyses. Structurally, all of these compounds, except compound 5, contain one or two 2,3-dibromo-4,5-dihydroxyphenyl moieties. In a biological activity assay, compound 1 was found to possess antiviral activity with a 50% inhibitory concentration (IC₅₀) of 2.50 μg/mL against HRV2. Compound 3 showed anti-HRV2 activity, with an IC₅₀ of 7.11 μg/mL, and anti-HRV3 activity, with an IC₅₀ of 4.69 μg/mL, without demonstrable cytotoxicity at a concentration of 20 μg/mL. Collectively, the results suggest that compounds 1 and 3 are candidates for novel therapeutics against two different groups of human rhinovirus.