水稻稻曲病室内人工接种技术

为提高稻曲病人工接种的发病效果和稳定性,在温棚条件下采用水稻孕穗期注射接种法分别研究了稻曲病菌不同接种体、培养时间、接种浓度和接种时期的接种效果。采用病菌马铃薯蔗糖液体培养基（potato sucrose broth,PSB）作为接种体,其穗发病率为100%,明显好于病菌米糠培养液（23.33%）。病菌在PSB中培养5～7天接种效果较好,随病菌培养天数的延长,接种效果明显下降。接种的分生孢子浓度越低水稻病穗率和病粒数也越低。在水稻品种两优培九孕穗中后期,采用含分生孢子浓度为4×106个/mL的病菌PSB培养液注射接种,穗发病率达100%,平均病粒数35.1粒,最高达87粒。研究表明,温棚条件下建立的稻曲病人工接种技术能获得稳定的发病效果,并可区别水稻品种间的抗性差异。     

稻曲病病菌孢子飞散动态与环境因素相关性研究

2010年对沈阳地区稻曲病病菌孢子捕捉发现,稻曲病病菌分生孢子始见于7月下旬,飞散期为7～9月.其中8月为飞散盛期,9月初进入消退期.自捕捉到孢子20d后田间开始陆续发病.稻曲病分生孢子飞散动态与积温呈极显著正相关(r=0.822,Sig=0.007＜0.01),与积累降雨量呈显著性正相关(r--0.774,Sig=0.014＜0.05),与田间病情扩散动态呈显著正相关.     

来源于同一穗不同稻曲球的稻曲病菌的致病性及遗传多样性

 本研究从源于6穗稻曲病穗的48个稻曲球中分离获得稻曲病菌（Ustilaginoidea virens）48株,从3个稻曲球的不同部位分离获得稻曲病菌23株。用注射接种法将菌株分别接种到水稻品种两优培九（感病品种）、淮稻5号（中抗品种）和武育粳3号（抗病品种）上,结果显示分离的菌株致病力分化较大,而菌株在水稻品种上的致病力强弱与已知水稻品种对稻曲病菌的感、抗性趋势基本一致。相同孢子量接种水稻,不同分离菌株之间仍有致病力分化,生长速率测定也发现菌株之间可能存在差异。利用REP PCR (repetitive extragenic palindromic sequence PCR)技术进行菌株遗传多样性分析表明,同穗不同稻曲球分离的菌株中,1号穗分离的4个菌株聚在同一簇群,其余5穗的菌株分别聚在3～5个簇群;同一稻曲球不同部位分离的菌株中,一个稻曲球分离的8个病菌聚在同一簇群,而其余2个稻曲球分离的病菌则分别聚在2～3个簇群。由此推测同一稻穗上不同稻曲球可能是由来源不同的稻曲病菌侵染所形成;而一个稻曲球可以由同一稻曲病菌引起,也存在多个侵染源共同侵染的可能。     

稻曲病病菌薄壁分生孢子培养技术研究

对稻曲病病菌薄壁分生孢子培养制备技术进行了系列比较试验。结果发现,利用振荡方法培养孢子,培养7 d后孢子数量基本达到饱和状态;移植时用处于幼始状态菌丝体比老化状态更容易获得高产孢量;初始移植的菌丝体数量越多及菌丝体碎化程度高其产孢量越高;常规的继代培养操作可逐步导致菌株丧失产孢能力;黑光灯或日光灯光照不同处理和不同营养成分培养基诱导处理,不能使原来不产孢菌株产生孢子。     

湖口县稻曲病发生情况调查

1980年我县二晚不少品种特别是杂优稻稻曲病发生严重,发病面积达5-6万亩,给二晚带来一定的损失.此病是我县推广杂优以来,在杂优品种上发病最重的一年.据10月中下旬在五个公社抽样检查,杂优品种南优二号、汕优二号、银优等穗发病率一般1.4-2.3%,严重达4.07%;一病穗最多有稻曲7个,平均每病穗有稻曲1.08个.常规品     

稻曲病菌无性孢子萌发及在不同培养基上生长特性

采用不同的培养基研究稻曲病菌孢子萌发及病菌生长特性.结果表明,稻曲病菌厚垣孢子和分生孢子在蒸馏水和2%蔗糖溶液中3h不能萌发;6h时分生孢子、厚垣孢子分别萌发产生次生分生孢子和分生孢子;新采集的黄色和黑色稻曲球上的厚垣孢子在2%蔗糖溶液中的萌发率均高于其在蒸馏水中的萌发率.供试的9种固体培养基中,以马铃薯蔗糖琼脂培养基(PSA)最适于病原菌生长.生长速率为2.54 mm/天;病菌在7种培养液中振荡培养7天后,在马铃薯葡萄糖培养液(PDB)中菌丝干重最大,达24.5mg/mL,在大米汁和马铃薯蔗糖培养液(PSB)中产生的分生孢子量最多,孢子浓度分别为2.63×107和2.28×107个/mL;而固、液态的Czapek、稻秆汁和胁本哲氏培养基均不适宜于稻曲病菌的培养.     

2014年江汉平原水稻稻曲病促病气象条件指数分析

以华中江汉平原地区荆州市中稻为研究对象,2014年选择广两优香66、丰两优香1号籼型两系杂交水稻品种和宁9108常规粳稻品种为供试品种,采取传统水育秧人工移栽、机插秧、直播3种栽培方式。每种栽培方式分3期播种。在水稻黄熟期调查总穗数、稻曲病自然发病病穗数和每穗病粒数,计算病穗率和病情指数。在稻曲病感病关键生育期孕穗至齐穗期气象要素与稻曲病病穗率相关分析基础上,从稻曲病发生机理出发,筛选满足稻曲病病菌侵入寄主繁殖流行的气象因子条件,即水稻稻曲病的促病气象指标:日平均气温20~28℃,日平均空气相对湿度≥80%,日降水量≥0.1 mm(或日照时数≤1 h),建立了稻曲病促病气象条件指数。促病气象条件指数与稻曲病病穗率、病情指数的相关性分析结果均通过了1%水平显著性检验。在相关分析的基础上确立了稻曲病发生发展气象条件预报等级指标。     

稻曲病菌分生孢子的生物学研究

 本文对稻曲病菌分生孢子的一些生物学特性进行了研究,结果表明,基质养分对分生孢子萌发影响较大,纯水不利于孢子萌发,PSA最适于孢子萌发,葡萄糖则强烈抑制孢子萌发,马铃薯煮汁既可抵消葡萄糖的抑制作用,又可刺激孢子萌发。分生孢子在琼脂面上比在液滴中萌发率高。分生孢子萌发的适宜温度为22~31℃,以28℃最好。分生孢子萌发对pH值敏感,以pH 6~7最适宜。用振荡培养法获取分生孢子,培养10 d后,孢子的萌发力开始下降。分生孢子的存活对水的依赖性强,在水中保存8 d萌发力不变,在100% RH中8 d萌发力略有降低,而在25% RH中5 h萌发力即迅速下降。根据这些特性,作者对分生孢子在田间的动态作了一些推测。     

稻区杂草上的梨孢菌与稻瘟病发生的关系

 新发现的稻曲病菌白化菌株其分生孢子座白色,厚垣孢子表面光滑,大小为3.5-6.0×3.5-6.8μm。在麦芽糖-稻芽浸渍液中可产生较多的分生孢子。pH值为6时生长最好。普通培养基中加入几种供试碳源和氮源均有利于菌落生长,以蔗糖为碳源,浓度为2%或以L-天门冬酰胺为氮源浓度为0.2%~0.3%时时其菌落生长有促进作用。培养过程中可产生对稻种萌发有抑制作用的毒素,而固体培养时产毒能力高于液体培养。白化菌株回接到水稻上可重新产生白色稻曲球。该菌和稻曲病菌的酯酶同功酶和RAPD扩增谱带明显不同。可见白化菌株具有独立于稻曲病菌的新的分类地位。     

青花菜根肿病苗期抗性鉴定技术的建立

为建立快速、有效的青花菜根肿病苗期抗性鉴定技术,将芸薹根肿菌Plamodiophora brassicae Woron.人工接种于高感根肿病青花菜自交系90196,研究了接种菌液浓度、接种寄主苗龄、接种基质p H和接种方法等对人工接种鉴定效果的影响。结果表明,在一定范围内,根肿病发病率及病情指数随着接种菌液浓度的升高而增大,接种菌液浓度为3×108CFU/m L时,发病率及病情指数分别为97.22%和86.11,可以反映寄主真实的抗性水平;接种寄主苗龄为2~6叶期均能使植株发病,但2~3叶期发病效果最佳;接种基质偏酸性(p H 5~6)有利于根肿病的发生;使用伤根灌菌法进行鉴定,青花菜根肿病发病率和病情指数均最高,分别为100.00%和88.10,优于蘸根法和浸芽法。用已知抗性水平的12个自交系和8个杂交种进行验证,鉴定结果表明该苗期抗性鉴定技术可客观反映供试材料的实际抗性水平。     

水稻穗部农艺性状与稻曲病抗性的相关性分析

 人工接种试验和田间多年自然发病调查发现,目前生产上应用的水稻品种均感稻曲病;但在自然条件下,不同水稻品种稻曲病的发生程度存在较大差异,可以人为的分为多病粒高感品种和寡病粒相对抗病的品种。为了探究水稻穗部性状与其病害抗性间的关系,本文对孕穗期不同阶段的不同水稻品种的穗部性状进行了比较分析。结果发现表型为多病粒的高感多病粒品种与表型为寡病粒的相对抗病的品种之间在穗子大小、小花密度、穗鞘闭合程度和密封性、旗叶面积等方面均存在明显差异,寡病粒相对抗病的水稻品种穗鞘闭合程度优于高感多病粒品种。     

Infection processes of Ustilaginoidea virens during artificial inoculation of rice panicles

Ustilaginoidea virens is a ubiquitous plant pathogen that causes rice false smut disease, one of the most destructive diseases of rice (Oryza sativa L.) production. However, data concerning the effect of inoculation on disease development and the infection process of this pathogen are not comprehensive. In this study, the developmental processes of U. virens in rice panicles were characterized using an enhanced green fluorescent protein (EGFP) labelled strain. A mixture of hyphae and conidia of U. virens was used to inoculate rice panicles by leaf sheath injection during the booting stage of rice plants grown in a greenhouse. The panicles were assessed to determine the relationship between artificial inoculation and disease occurrence. Increasing volumes of inocula (0.2, 0.5, 1, and 2 ml of a mixture of hyphae-fragment and 2?×?10⁶ conidia/ml suspension) caused more severe infections, and small differences were also observed for the different inoculation sites at the base, apex and mid-point of rice panicles. The optimum inoculation condition was 1–2 ml inoculum injected into the mid-point of rice panicles. Spikelet samples were collected as the disease progressed and observed by confocal laser scanning microscopy and scanning electron microscopy. The images collected showed that the primary site of U. virens colonization was at the base of the filaments with the inner spikelets becoming infected by hyphae at 24 h post inoculation (hpi). The accumulation of hyphae reached its highest level at 168 hpi, before the rice heading stage, as the infection extended upward from basal filaments to the anther apex, and then enclosed all the floral organs to produce a velvety smut ball.     

稻曲病产量损失测定及调查测报因子研究

稻曲病是水稻穗部的重要真菌性病害。本研究分析了13个供试水稻品种每穗稻曲病病粒数与水稻产量损失的线性关系,根据每个品种线性方程及南方稻区实际情况,得出了田间稻曲病经济允许水平、成灾因子,即平均每穗病粒数分别为0.57、5.44粒。     

Geographic distribution of false smut disease of rice in India and efficacy of selected fungicides for its management

False smut disease of rice caused by the fungus Ustilaginoidea virens, has become a serious production constraint in various rice-growing regions of India. Analysis of rice false smut disease survey data of last 24 years revealed significant changes in the intensity of the disease in various rice-growing regions of India over the years. We evaluated three fungicide formulations viz., trifloxystrobin-tebuconazole (TT) combination (0.04%), kresoxim methyl (KM) (0.1%) and propiconazole (PC) (0.1%) for their effectiveness against false smut disease of rice. Under in vitro condition, TT and PC completely inhibited the fungal growth while KM inhibited the growth by 80%. We evaluated the efficacy of these chemicals in a multi-location trial in 3 hot spot locations, consecutively for three years. A single fungicide spray was given in 3 different crop stages (booting, 50% panicle emergence and 100% panicle emergence). The results indicated that all the treatments significantly reduced the percentage of both infected panicles and spikelets in all the three locations. Both TT and PC were most effective in reducing the disease intensity and increasing the yield when applied either in booting or in 50% panicle emergence stage.     

安徽省稻曲病气象等级预报方法研究—以池州为例

为进一步明确安徽省稻曲病发生关键期, 探索稻曲病气象等级预报方法, 以满足对该病害气象等级预报的服务需求?本文以安徽省池州市为例, 利用1995年-2018年一季稻稻曲病观测数据和同期气象资料, 通过相关分析确定稻曲病发生关键期?根据稻曲病大发生对适温高湿环境的需求及不同降水等级和温度对稻曲病发生程度的影响不同, 以稻曲病发生关键期降水日数为基础, 引入雨量系数和温度系数, 形成稻曲病发生综合气象条件指数, 通过最优曲线回归分析, 建立稻曲病预报模型?结果表明, 7月下旬至8月中旬是池州市一季稻稻曲病发生关键期; 综合气象条件指数与稻曲病病穗率相关性明显高于降水日数与病穗率相关性; 预报模型回代检验准确率为81.0%, 2016年-2018年模型预测结果均与实际情况相吻合, 由于样本中轻发生和大发生年份较少, 对轻发生和大发生预报的准确性需在样本丰富条件下进一步验证?模型在业务应用中, 可结合CFSv2模式逐日降水和气温预报产品, 提前10~30 d开展稻曲病气象等级预报, 对做好稻曲病的防治工作具有重要参考价值?     

Epiphytic colonization of Ustilaginoidea virens on biotic and abiotic surfaces implies the widespread presence of primary inoculum for rice false smut disease

Ustilaginoidea virens (Uv), the causative agent of rice false smut disease, infects developing rice spikelets at the booting stage, and transforms individual grains of the panicle into smut balls. Epidemics of the disease occur when the rice booting and heading stages coincide with rainy days. Using a green fluorescent protein (GFP)‐labelled Uv isolate that can form false smut balls on rice panicles, it was found that under high humidity and free water conditions the Uv isolate could colonize leaves of plants belonging to various families including the Poaceae (Oryza sativa, Echinochloa crusgalli, Digitaria sanguinalis and Leptochloa chinensis), the Brassicaceae (Arabidopsis thaliana) and the Solanaceae (Nicotiana benthamiana) without symptoms. Over several days, some conidia could germinate on the leaves of these plants and in water on the surface of Parafilm and cellophane, form hyphae and differentiate conidiophores to generate a large number of secondary conidia, while other conidia were able to directly produce secondary conidia. Conversely, in the absence of water some conidia could either bud to form new conidia or were converted into chlamydospores. These data indicate that Uv is one of a few fungal pathogens reported to have epiphytic characteristics. The rapid generation of a large number of spores on biotic and abiotic surfaces greatly increases the inoculum that can infect rice spikelets, resulting in the occurrence of rice false smut disease epidemics. These findings are important in the development of disease control strategies.     

四川水稻抗稻曲病种质资源筛选和多态性分析

 稻曲病近年来逐步上升为世界多个水稻产区的主要病害之一。利用丰富的抗性种质资源进行抗性品种选育是控制稻曲病害的重要手段。通过在四川省进行三年病圃筛选试验,我们从843份水稻材料中鉴定出179份完全不感稻曲病的抗性材料和两份高感材料(病穗率高达50%以上),其余材料的病穗率介于0.1%~48.8%之间,55.1%的病穗只有一个稻曲球,而高感稻曲病的蒲江6号单穗稻曲球高达38粒。然后我们选取36份材料进行多点多期播种,进一步验证其稻曲病抗感性。结果表明,有3份材料在所有试验中都不感稻曲病,18份材料偶发稻曲病呈现高抗,蒲江6号仍然表现为高感。我们用450对SSR引物对其中35份材料与蒲江6号进行多态性分析,发现其中12份材料与蒲江6号的多态性达10%以上,其中最高为ITAT144(16.1%),其次是泸香90-2(14.8%)和Domsia-2(14.4%)。因此,我们选择这些材料与蒲江6号杂交构建基因定位与克隆群体。     

3种防御酶在水稻抗稻曲病中的活性变化

不同水稻品种对稻曲病抗性存在明显差异。本研究选用12个不同抗、感病水稻品种,在抽穗前7~10 d,用注射法接种稻曲病菌分生孢子悬浮液。结果表明,在抗病品种中苯丙氨酸解氨酶（PAL）、过氧化物酶（POD）和多酚氧化酶（PPO）3种酶活性接种后迅速提高,变化幅度较大;而感病品种的酶活性在接种后缓慢增加,变化幅度小。由此说明,这3种防御酶与水稻抗稻曲病有一定的关系。     

Detection of quantitative resistance loci associated with resistance to rice false smut (Ustilaginoidea virens) using introgression lines

False smut, caused by Ustilaginoidea virens, is a rice disease of increasing importance worldwide, with no source of high‐level resistance in the existing rice germplasm. To facilitate breeding varieties with good levels of field resistance to false smut, quantitative resistance loci (QRL) were identified using 213 introgression lines (ILs) from a cross between Teqing (recipient) and Lemont (donor) evaluated using natural infection at two hotspots of false smut in northeast China. Ten QRL affecting percentages of diseased hills, diseased panicles and diseased spikelets were detected and mapped to rice chromosomes 2, 3, 4, 6, 8, 10, 11 and 12. The Lemont alleles at all QRL increased false smut resistance. Four QRL (qFSR‐6‐7, qFSR‐10‐5, qFSR‐10‐2 and qFSR‐11‐2) had relatively larger and consistent effects across the two testing sites. Promising resistant ILs were identified, most of which had multiple QRL, suggesting that pyramiding multiple QRL by marker‐assisted selection would be an effective strategy for improving rice resistance to false smut. The identified QRL and their linked DNA markers will facilitate this breeding effort in the future.