Rapid Detection of Wheat Blast Pathogen Magnaporthe oryzae Triticum Pathotype Using Genome-Specific Primers and Cas12a-mediated Technology

Wheat blast,caused by the fungus Magnaporthe oryzae Triticum(MoT)pathotype,is a devastating disease persistent in South America and Bangladesh.Since MoT generally fails to cause visual symptoms in wheat until the heading stage when the infection would have advanced,disease control by fungicide application solely based on the detection of visual symptoms is ineffective.To develop an accurate and sensitive method to detect MoT at the seedling and vegetative stages for disease control,we sequenced the genomes of two MoT isolates from Brazil and identified two DNA fragments,MoT-6098 and MoT-6099,that are present in the MoT genome but not in the genome of the rice-infecting Magnaporthe oryzae Oryzae(MoO)pathotype.Using polymerase chain reaction(PCR),we confirmed the specificity of the two markers in 53 MoT and MoO isolates from South America and Bangladesh.To test the efficiency of the two markers,we first established a loop-mediated isothermal amplification(LAMP)method to detect MoT at isothermal conditions,without the use of a PCR machine.Following this,we used the Cas12a protein and guide RNAs(gRNAs)to target the MoT-6098 and MoT-6099 sequences.The activated Cas12a showed indiscriminate single-stranded deoxyribonuclease(ssDNase)activity.We then combined targetdependent Cas12a ssDNase activation with recombinase polymerase amplification(RPA)and nucleic acid lateral flow immunoassay(NALFIA)to develop a method that accurately,sensitively,and cost-effectively detects MoT-specific DNA sequences in infected wheat plants.This novel technique can be easily adapted for the rapid detection of wheat blast and other important plant diseases in the field.

Medicinal Plants, A promising Source of Natural Fungicides against <i>Magnaporthe oryzae Triticum</i>, Causal Agent of Wheat Blast

Wheat blast, caused by a fungal pathogen, Magnaporthe oryzae Tritichum (MoT) pathotype (wheat isolates), was first reported in Bangladesh among Asian countries in 2016. It is a serious disease of wheat causing yield failures and significant economic losses during epidemic years. Extensive use of persistent synthetic pesticides to control notorious wheat blast imposes enormous threat to human health and environment. In addition, the increasing demand for organic food has stimulated people to look for alternative methods. Nowadays, the need for synthetic chemical-free agricultural practices is gaining importance due to effective in managing crop pests, inexpensive, biodegradable, easily available and have low toxicity to non-target organisms. In order to identify active plants, 12 kinds of methanol extracts obtained from 12 medicinal plants were conducted in vitro to test the effect against Magnaporthe oryzae Triticum (MoT) pathotype. The remarkable inhibitory activity {(29.6 ± 01.5) mm, (25.1 ± 01.0) mm and (20.0 ± 02.0) mm zone of inhibition)} exhibited by the extracts (5 mg/disk) obtained from Artemisia indica (Nagdona), Persicaria orientalis (Bishkatali) and Clerodendrum indicum (Bamonhati), respectively. Other medicinal plant extracts did not show any significant or no activity at all. Therefore, the three plant extracts might be a promising source for developing natural fungicides against wheat blast.

Ecofriendly Management of Wheat Panicle Blast Caused by Magnaporthe oryzae triticum

In this study, three wheat varieties were tested to determine seed germination and the incidence of Magnaporthe oryzae triticum (MoT). Among these varieties, BARI Gom 24 (Prodip) wheat seed exhibited the highest seed germination rate (93%) but also had the highest incidence (30%) of MoT. To manage blast disease in an ecofriendly manner, seven treatments were employed: T1 = Control, T2 = Garlic clove extracts, T3 = Aloe vera leaf extracts, T4 = Black cumin seed extracts, T5 = Neem leaf extracts, T6 = Nativo 75 WG, and T7 = Provax 200 WP. The experiment was conducted using a Randomized Complete Block Design (RCBD) layout with three replications using Prodip wheat variety that exhibited highest MoT infection severity based on laboratory analysis among collected varieties. Data were collected on blast disease incidence (%), disease severity, and various growth and yield parameters of wheat. The experiment’s results indicated that among all the treatments, T7 (Seed treatment with Provax 200 WP) and T5 (Foliar spraying with Neem leaf extract) performed better in controlling blast disease in wheat. The lowest blast disease incidence (%) was observed with T7 (Provax 200 WP), with values of 7.86, 9.86, and 10.19 recorded during the milking stage, soft dough stage, and hard dough stage of wheat, respectively. T5 (Neem leaf extract) also demonstrated a statistically equivalent reduction in blast disease incidence (%). In terms of disease severity, T7 (Seed treatment with Provax 200 WP) showed the lowest values of 1.03, 1.23, and 1.63 during the milking stage, soft dough stage, and hard dough stage of wheat, respectively. Foliar spraying with neem leaf extract also exhibited similar result as of Provax 200 WP regarding panicle blast severity. As a result of these findings, it can be concluded that T5 (Neem leaf extract) is recommended as an ecofriendly management approach for blast disease in wheat.

Genetic sources and loci for wheat head blast resistance identified by genome-wide association analysis

The emergence and spread of wheat blast caused by fungal pathogen Magnaporthe oryzae pathotype Triticum is a threat to global wheat production.The resistance level and genetic loci for blast resistance in Chinese germplasm remain unknown.A panel of 266 bread wheat accessions from China,CIMMYTMexico and other countries was screened for head blast resistance under 12 field experiments in Bolivia and Bangladesh.Subsequently,a genome-wide association study was performed to understand the genetic basis of wheat blast resistance.The average blast index of all the accessions was 53.7%±12.7%,and 10 accessions including Chinese accessions Yumai 10 and Yu 02321 showed moderate to high levels of blast resistance,accounting for only 3.8%in the panel.Fifty-eight significant SNPs clustered in a 28.9 Mb interval on the 2 AS/2 NS translocation region,explaining phenotypic variation between10.0%and 35.0%.The frequency of the 2 AS/2 NS translocation in the Chinese accessions was as low as4.5%.These results indicated that the 2 NS fragment was the only major locus conferring resistance to wheat blast in this panel,and the resistant and moderately resistant lines identified could be deployed in breeding.

Phenotypic and Molecular Assessment of Wheat Genotypes Tolerant to Leaf Blight,Rust and Blast Diseases

Globally among biotic stresses,diseases like blight,rust and blast constitute prime constraints for reducing wheat productivity especially in Bangladesh.For sustainable productivity,the development of disease-resistant lines and high yielding varieties is vital and necessary.This study was conducted using 122 advanced breeding lines of wheat including 21 varieties developed by Bangladesh Wheat and Maize Research Institute with aims to identify genotypes having high yield potential and resistant to leaf blight,leaf rust and blast diseases.These genotypes were evaluated for resistance against leaf blight and leaf rust at Dinajpur and wheat blast at Jashore under field condition.Out of 122 genotypes tested,20 lines were selected as resistant to leaf blight based on the area under the diseases progress curve under both irrigated timely sown and irrigated late sown conditions.Forty-two genotypes were found completely free from leaf rust infection,59 genotypes were identified as resistant,and 13 genotypes were identified as moderately resistant to leaf rust.Eighteen genotypes were immune against wheat blast,42 genotypes were categorized as resistant,and 26 genotypes were identified as moderately resistant to wheat blast.Molecular data revealed that the 16 genotypes showed a positive 2NS segment among the 18 immune genotypes selected against wheat blast under field conditions.The genotypes BAW 1322,BAW 1295,and BAW 1203 can be used as earlier maturing genotypes and the genotypes BAW 1372,BAW 1373,BAW 1297 and BAW 1364 can be used for lodging tolerant due to short plant height.The genotypes WMRI Gom 1,BAW 1349 and BAW 1350 can be selected for bold grain and the genotypes WMRI Gom 1,BAW 1297,BAW 1377 can be used as high yielder for optimum seeding condition but genotypes BAW 1377 and BAW 1366 can be used for late sown condition.The selected resistant genotypes against specific diseases can be used in the further breeding program to develop wheat varieties having higher disease resistance and yield potential.

Integrated pest management programme for cereal blast fungus Magnaporthe oryzae

Magnaporthe oryzae,the causal agent of blast diseases,is a destructive filamentous fungus that infects many plants including most economically important food crops,rice,wheat,pearl millet and finger millet.Magnaporthe oryzae has numerous pathotypes because of its high host-specificity in the field.The Oryza pathotype(MoO)of M.oryzae is the most devastating pathogen of rice,causing 10–30%yield loss in the world.On the other hand,the Triticum pathotype(MoT)causes blast disease in wheat,which is now a serious threat to wheat production in some South American countries,Bangladesh and Zambia.Because of low fungicide efficacy against the blast diseases and lack of availability of resistant varieties,control of rice and wheat blast diseases is difficult.Therefore,an integrated management programme should be adopted to control these two diseases in the field.Here,we introduced and summarized the classification,geographical distribution,host range,disease symptoms,biology and ecology,economic impact,and integrated pest management(IPM)programme of both rice and wheat blast diseases.

郭予元院士在宁夏植保防控事业中的学术贡献——纪念郭予元院士诞辰90周年

五六十年代的宁夏,农业发展落后,农业科学发展刚刚起步,引黄灌区的水稻和南部西海固地区的冬小麦分别是当地的主要粮食作物,其产量直接关乎当地群众温饱。但是由于特殊的地理位置和气候特点,这些地区病虫害发生严重,制约了当地的粮食生产。本文回顾了郭予元院士在宁夏进行病虫害科学研究,为水稻稻瘟病、小麦麦种蝇和小麦腥黑穗病的监测预警,防治示范做出的突出贡献。郭予元院士建立的预测预报体系及防治技术示范一直指导当地的农业生产,并给全国的病虫害防治做了示范。

警惕麦瘟病全球扩散

麦瘟病是南美出现的一种新的小麦病害,流行区域包括巴西、阿根廷、玻利维亚和巴拉圭等热带和亚热带地区,可造成5%~100%的产量损失。气候是影响病害发生流行的主要因素,高温潮湿可导致麦瘟病大流行。麦瘟病的病原菌为Magnaporthe grisea,具有寄主专化性,来自不同寄主的M.grisea菌系对小麦的致病性有显著差异,同时在小麦品种和M.grisea菌系间存在明显的生理专化性。已报道的小麦抗麦瘟病基因有5个,分别是Rmg1、Rmg2、Rmg3、Rmg4和Rmg5。由于生产上尚无控制此病害的有效方法,故应加强研究,以阻止麦瘟病在全球的扩散和蔓延。

CO_2爆破挤压改性麦麸理化特性的初步研究

利用单因素实验法探讨CO_2爆破挤压工艺参数(物料含水量、螺杆转速、终桶温度)对麸皮中的水溶性膳食纤维含量、色泽、持水力、持油力、膨胀力以及抗氧化活性的影响规律。结果表明:在物料含水量为25 g/100 g、螺杆转速为190 r/min、挤压螺桶温度为65-105-135-185℃的工艺条件下,经过CO_2爆破挤压改性后的麸皮中水溶性膳食纤维(soluble dietary fiber,SDF)含量可从最初的2.50 g/100 g提升到9.97 g/100 g,并且其膳食纤维的持水力、持油力、膨胀力得到显著改善。与原料麸皮和传统挤压相比,CO_2爆破挤压处理对麸皮的多糖晶态结构以及热稳定性并未产生显著的影响,但使其抗氧化活性得到显著提高。

小麦湿法清理工艺的利与弊

针对目前我国小麦品质及小麦清理工艺的现状,分析了小麦湿法清理工艺的优势与弊端。小麦湿法清理工艺有良好的分离石子和着水功能,能有效清除有害麦粒以及其他杂质的清理效果,提高好粉精度和增加总粉出率,但用水量大,成本高,且对排污的污水无法净化处理。

气候变化情景下基于MaxEnt的麦瘟病在全球及中国的适生性分析

麦瘟病是小麦生产上的一种毁灭性真菌病害,过去仅在南美洲流行。2016年该病害在亚洲的孟加拉国首次出现,给世界尤其我国小麦生产带来重大潜在威胁。本研究基于麦瘟病当前在全球(包括孟加拉国)的分布数据和生物气候数据,采用MaxEnt生态位模型和ArcGIS软件,预测了当前气候条件下麦瘟病在全球特别是在我国的潜在适生区,以及RCP2.6、RCP4.5、RCP6.0和RCP8.5 4种气候变化情景下2030s、2050s和2070s麦瘟病在中国潜在适生区分布范围,进而以刀切法分析了影响其分布的主要气候因子,并采用ROC对预测结果进行检验。结果表明,在当前和未来不同气候情景下,麦瘟病在中国的中风险和高风险区面积将呈增加趋势,未来情景下与当前气候情景下相比,中风险和高风险区的面积比例增加范围为0.08%~1.63%,其中温度和湿度条件对麦瘟病的潜在分布区影响最大。此研究结果对于我国麦瘟病的检疫和防控提供了技术支撑。

麦瘟病研究进展与展望

由Magnaporthe oryzae引起的麦瘟病是一种毁灭性小麦真菌病害,过去仅在南美流行,可造成10%~100%减产。2016年该病害首次在亚洲出现,给世界小麦生产带来重大潜在威胁。本文对麦瘟病病原生物学与病害流行学、小麦抗性材料筛选、麦瘟病的抗病性机制和综合治理等进行评述,并介绍了该领域国际合作研究的成功经验,以期为国内开展类似工作提供借鉴。尽管我国尚无麦瘟病报道,但南方部分地区为潜在适生区,异常气候可能会导致其在大范围流行,因此需高度警惕。建议与国际麦瘟病协作网合作,尽快开展麦瘟病相关研究,建立对此病害的监测预警和防治关键技术储备体系,以保障我国小麦生产安全。

麦瘟病与小麦抗麦瘟基因研究进展

小麦麦瘟病,由梨孢菌小麦专化型(Magnaporthe oryzae,sp.Triticum,MoT)侵染所致,最早于1985年在巴西发现,随后传播到其他南美国家。2016与2017年,麦瘟病登陆亚洲,相继在孟加拉国和印度暴发,对亚洲乃至全世界的小麦生产形成了潜在威胁。近年来,世界各国的科学家对麦瘟病进行了广泛和深入的研究,取得了较大进展。本文对小麦麦瘟病病原菌、侵染过程、流行因素和小麦抗病基因的研究进展进行了综述,并介绍了小麦麦瘟病抗性评价的方法。本研究组研究发现,在人工接种条件下,水稻来源的稻瘟病菌株(MoO)可侵染小麦引起典型麦瘟症状。笔者认为,虽然目前我国还没有麦瘟病发生的报道,但部分地区存在麦瘟病的发病条件,随着全球气候变暖麦瘟病有暴发的可能,需引起高度重视。建议加快麦瘟病发病机理及小麦抗性基因发掘的研究,以提升我国麦瘟病的研究水平,并为预防麦瘟病的发生未雨绸缪。

麦瘟病研究新进展

麦瘟病是1985年在南美洲出现的一种小麦真菌病害,目前已成为南美洲的主要小麦病害之一。在麦瘟病发病严重区域该病害可导致小麦减产高达100%,抗麦瘟病的小麦资源和基因少,且麦瘟病菌对甲氧基丙烯酸酯(QoIs)类杀菌剂具有较强的耐受性,监测、延缓、抑制其传播对有效控制麦瘟病意义重大。2016年和2018年发生了两次重要的麦瘟病扩散事件,受到广泛关注,两次扩散事件导致麦瘟病分别蔓延至亚洲孟加拉国和非洲赞比亚,麦瘟病的持续蔓延对全球小麦生产安全带来严重威胁。我国科学家与世界同行一道,在病害监测、小麦抗病资源和基因发掘、抗病品种的培育、病原菌生物学等方面的研究均取得了进展。本文从麦瘟病的传播历史、防控方法、国际国内开展麦瘟病相关研究工作进展等方面对麦瘟病进行综述;同时,也为我国应对麦瘟病威胁提供了策略、提出了应对建议。

双挤压膨化可提高对麦麸膳食纤维的溶解性

采用双螺杆挤压膨化机处理添加了0%、10%、20%、30%玉米的小麦麸皮及100%玉米的样品,提取各组样品中的水溶性膳食纤维(SDF)、水不溶性膳食纤维(IDF)、总麦麸纤维(TDF),从而选出SDF含量最高的一组,并测定了100%麦麸与添加20%玉米样品的组分,研究了由该两组样品提取出来的SDF的物理性质。结果表明:水溶性麦麸纤维有了很大的变化,其中添加20%玉米的样品组相对于其他样品组提高了4.33%~7.00%,被改性的物质主要是不溶性纤维中的半纤维素。由添加20%玉米的样品组得到的SDF相对于同条件下未添加玉米的样品组的膨胀力由0.100 4增长到2.291 0m L/g,保水能力由2.098 9增长到4.274 6g/g,水溶解度由79.29%增长到84.02%。

干热风对小麦的危害及防御措施探讨

我国北方地区冬小麦的农业气象灾害观测工作中经常遇到干热风,根据《农业气象观测规范》中有关干热风的规定,结合实际观测经验,介绍干热风对小麦的危害及防御措施。

云南省稻瘟病、小麦锈病预测专家系统

基于稻瘟病、小麦锈病预测领域专家知识,以及借助模式识别势函数法实现的自学习、自提取的知识,采用正向和反向精确推理控制策略,首次建立云南省水稻穗瘟病、小麦条锈病预测专家系统,1994～1995年预测结果与实际情况基本一致。系统创造性地采用全屏幕编辑树图的知识输入法和森林表示技术对知识库进行管理,便于知识库的扩充和维护。推理结果、推理路径及知识查询以彩色图形方式显示,对于学习领域专家的实践经验具有独特优点。