Ecological Fitness of Non-vector Planthopper Sogatella furcifera on Rice Plants Infected with Rice Black Streaked Dwarf Virus

We evaluated the effects of rice black streak dwarf virus （RBSDV）-infested rice plants on the ecological parameters and its relevant defensive and detoxification enzymes of white-backed planthopper （WBPH） in laboratory for exploring the relationship between RBSDV and the non-vector planthopper. The results showed that nymph survival rate, female adult weight and fecundity, and egg hatchability of WBPH fed on RBSDV-infested rice plants did not markedly differ from those on healthy plants, whereas the female adult longevity and egg duration significantly shortened on diseased plants. Furthermore, significantly higher activities of defensive enzymes （dismutase, catalase and peroxidase） and detoxification enzymes （acetylcholinesterase, carboxylesterase and glutathione S-transferase） were found in WBPH adults fed on infected plants. Results implied that infestation by RBSDV increased the ecological fitness of non-vector planthopper population.

The Efficiency of Southern rice black-streaked dwarf virus Transmission by the Vector Sogatella furcifera to Different Host Plant Species

Southern rice black-streaked dwarf disease is a new rice disease that severely affects rice production in South China.To understand transmission capacity of the vector Sogatella furcifera to Southern rice black-streaked dwarf virus（SRBSDV） among different host plant species,potential host plants of SRBSDV collected from the diseased rice field and/or adjacent to the field in Hunan Province,China,were determined by RT-PCR,and the transmission rates of SRBSDV by S.furcifera among different host plant species were investigated.The results showed that host plants of SRBSDV in the rice fields were five of family Gramineae（Oryza sativa,Echinochloa crusgalli,Zea mays,Paspalum distichum,Alopecurus aequali） and two of family Cyperaceae（Juncellus serotinus and Cyperus difformis）.S.furcifera could not transmit SRBSDV between gramineous plants and cyperaceous plants,and could not transmit SRBSDV between the gramineous plants,J.serotinus and C.difformis as well.However,SRBSDV could be transmitted by S.furcifera within gramineous plants.S.furcifera could transmit SRBSDV between interspecies among three species plants（O.sativa,E.crusgalli and Z.mays）,and between P.distichum and A.aequali.At 15,20,25,30,and 35°C,both macropterous and brachypterous adult of S.furcifera could transmit SRBSDV from the plants（e.g.,E.crusgalli,Z.mays and O.sativa） infected with SRBSDV to rice seedlings.The transmission rates were first increased and then decreased with the increase of temperature.Macropterous adults transmitted SRBSDV from the viruliferous E.crusgalli,Z.may and rice plants to the healthy rice seedlings,and the infected rates of rice seedlings were 26.2,18.8 and 23.7% at 15°C,56.6,64.6 and 53.6% at 25°C,and was 11.2,10.2 and 7.3% at 35°C,respectively.Transmission capacity of brachypterous adults was significantly higher than that of macropterous adults at 15,20 and 25°C（P0.05）,while transmission capacity of brachypterous adults was relatively lower compared with that of macropterous ones at 35°C.These results offer evidence on the transmission of SRBSDV via the vector S.furcifer among different host plants,which can be helpful to control Southern rice black-streaked dwarf disease by the appropriate cultural measures in South China.

Detection,Occurrence,and Survey of Rice Stripe and BlackStreaked Dwarf Diseases in Zhejiang Province,China

The major viral diseases that occur on rice plants in Zhejiang Province, eastern China, are stripe and rice black-streaked dwarf diseases. Rice stripe disease is only caused by rice stripe tenuivirus （RSV）, while rice black-streaked dwarf disease can be caused by rice black-streaked dwarf fijivirus （RBSDV） and/or southem rice black-streaked dwarf fijivirus （SRBSDV）. Here we review the characterization of these viruses, methods for their detection, and extensive surveys showing their occurrence and spread in the province.

Transmission of Rice Black-Streaked Dwarf Virus from Frozen Infected Leaves to Healthy Rice Plants by Small Brown Planthopper (Laodelphax striatellus)

In order to preserve virus for identifying the resistance of rice varieties against rice black-streaked dwarf disease, a simple and reliable method was developed, through which virus-free small brown planthopper （SBPH） acquired rice black-streaked dwarf virus （RBSDV） from frozen infected leaves and the virus was transmitted to healthy rice plants. The experimental results showed that SBPH could obtain RBSDV from frozen infected rice leaves and the virus could be transmitted to a susceptible rice variety. For the ability to acquire RBSDV and transmit the virus to healthy plants by SBPH, there was no significant difference between frozen infected leaves and in vitro infected leaves. The novel method could be applied to identification of rice variety resistance to rice black-streaked dwarf disease, facilitating the breeding process for rice black-streaked dwarf disease resistance.

Screening of Broad-spectrum Resistance Resources against Rice Bacterial Leaf Streak

[ Objectives] Rice materials with broad-spectrum resistance against several pathogenic strains of Xanthomans oryzae pv. Oryzicola （Xooc） at multiple growth stages were screened, in order to provide reliable resistance sources for variety breeding against rice bacterial leaf streak. [ Methods] A total of 1 100 rice lines with rich genetic background were offered as selective objects, and highly susceptible cultivar Jingang 30 was used as the control. Inoculation was carried out with five strong pathogenic strains of Xooc through acupuncture method at various growth stages for resistance identification. [ Results] Fourteen disease-resistant materials were obtained through preliminary screening, accounting for 1.27% of the total materials. Nine materials moderately resistant to bacterial leaf streak were obtained via secondary screening, accounting for 0.82% of the total materials. Besides, three of them （ RL6, RL9 and RLL4） were resistant to a number of pathogenic strains of Xooc at three growth stages. In particular, RL16 presented broad-spectrum resistance to multi-strains with high resistance levels. Six of them （ RI2, RIA, RIS, RL8, RL11 and RL12） were resistant to single strain at single growth stage. [ Conclusions] The obtained three materials have broad-spectrum resistance to bacterial leaf streak at multiple growth stages, which can be served as an important source to cultivate disease-resistant rice varieties. RL6 maintains high broad-spectrum resistance at all growth stages, which can be used as a prior resistance source for rice variety breeding. Six materials obtained with resistance against bacterial leaf streak at particular growth stages can be used as candidate resistance sources.

Screening of Rice Genes Interacting with p5b of Rice BlackStreaked Dwarf Virus

Rice black-streaked dwarf virus （RBSDV） is a recognized member of the genus Fijivirus, family Reoviridae. Its genome has ten double-stranded RNA （dsRNA） segments （$1-$10）, in which the fifth genome segment （$5） contains two open reading frames （ORFs） with a partially overlapping region. The second ORF of RBSDV S5 encodes a viral nonstructural protein named p5b with unknown function. To reveal the function of p5b, its gene was ligated into the bait plasmid pGBKT7 and an expression library containing rice cDNAs was constructed using plasmid pGADT7 for yeast two-hybrid assay. The bait protein p5b was detected in yeast by western blot, and the result of an auto-activation test showed that p5b could not autonomously activate the expression of reporter genes in yeast. Then the bait protein p5b was used for screening the cDNA expression libraries of rice. Gene fragments of some pivotal enzymes involved in photosynthesis, respiration and other important metabolic processes, were identified to interact with p5b in yeast, suggesting that these interactions may play roles in symptom development in infected plants.

Resistance of Major Rice Cultivars in Hangzhou Area of China against Southern Rice Black-streaked Dwarf Virus

Resistance of 17 major rice cultivars in Hangzhou region of China against southern rice black-streaked dwarf virus was tested in the paper. The results showed that the incidence rate of southern rice black-streWed dwarf virus had certain positive correlation with quantity of white-backed planthopper （Sogatellafurci-fera） and resistance among various cultivars was significant. Two varieties, Yueyou 9113 and Tianyouhuazhan, were most susceptible ; Yongyou 8, Jiayou 2 and Xi-ushui 134 had best resistance and could be used as disease-resistant varieties to prevent the disease.

Construction of Double Right-Border Binary Vector Carrying Non-Host Gene Rxo1 Resistant to Bacterial Leaf Streak of Rice

Rxol cloned from maize is a non-host gene resistant to bacterial leaf streak of rice. pCAMBIA1305-1 with Rxo1 was digested with Sca I and NgoM IV and the double right-border binary vector pMNDRBBin6 was digested with Hpa I and Xma I. pMNDRBBin6 carrying the gene Rxo1 was acquired by ligation of blunt-end and cohesive end. The results of PCR, restriction enzyme analysis and sequencing indicated that the Rxo1 gene had been cloned into pMNDRBBin6. This double right-border binary vector, named as pMNDRBBin6-Rxol, will play a role in breeding marker-free plants resistant to bacterial leaf streak of rice by genetic transformation.

Serological specificity of leaf streak pathogen of rice

The leaf streak of rice is one of the seedborneand quarantine bacterial disease in China.Therice seeds must be strictly inspected to preventthe disease from spreading.The serologicaltest is a rapid and accurate method of identify-ing seedborne bacterial plant pathogens.Butthe specificity and thus reliability of any sero-logical method depend first on the specificity ofthe antiserum.Therefore,a high specificity of

Inheritance of resistance to bacterial streak and bacterial blight in rice

Bacterial streak (BS) caused by Xanthomonascampestris pv. oryzicola has become one of themajor diseases in southern rice areas. Up todate, there are few reports on the inheritanceof resistance to BS and its relationship with theresistance to bacterial blight (BB). Therefore,we analyzed the inheritance of resistant to BSin three resistant rice cultivars and the geneticrelationship of resistance between BS and BB.

气象因子对河池市南方水稻黑条矮缩病发展的影响

利用河池市2005—2023年南方水稻黑条矮缩病(SRBSDV)的发病面积比例数据和期间气象数据,通过卡方分布的概率密度函数拟合流行周期内的发病趋势概率,分离出发病浮动概率,探究关键气象因子与发病浮动概率的相关性,并基于显著相关气象因子构建发病气象评价模型。结果表明:(1)2010年为河池市SRBSDV的暴发期,2010—2023年为SRBSDV的一个流行周期,发病概率符合自由度为3的卡方分布的概率密度函数;(2)发病浮动概率与12月—次年2月的平均气温、6—7月的降水量和相对湿度呈显著正相关,与安全播种期日序数负相关;(3)发病气象评价模型在预测暴发期的发病程度时预测偏轻,其他年份均预测正确,模型在一个流行周期内的定性评价效果较好。通过气象发病评价模型可定性评价流行周期内的发病程度,研究结论可为河池市的水稻病害防治工作提供参考依据。

南方水稻黑条矮缩病毒在广西兴安的迁入与侵染动态

广西兴安地处白背飞虱Sogatella furcifera(Horváth)迁入廊道要冲,南方水稻黑条矮缩病毒(southern rice black-streaked dwarf virus,SRBSDV)依赖白背飞虱携传。本研究采用探照灯诱集高空白背飞虱,同时采集田间白背飞虱和稻叶,采用dot-ELISA法检测白背飞虱及水稻的带毒状况,以明确SRBSDV的迁入与侵染动态。综合来看,2021年-2022年间兴安的带毒白背飞虱迁入始期为5月下旬,迁入白背飞虱的带毒率高峰为6月中下旬;田间白背飞虱7月上旬-7月下旬带毒率较高(10%~15%);水稻7月中旬-8月上旬带毒率较高(10%~14%)。水稻带毒率与田间白背飞虱带毒率之间存在显著相关关系。本文结果有助于桂北和长江中下游地区开展白背飞虱携传SRBSDV的监测预警。

水稻细条病对叶片反射率和日光诱导叶绿素荧光的影响

【目的】研究水稻细条病对叶片反射率和日光诱导的叶绿素荧光(SIF)的影响,为水稻细条病的多源遥感监测研究提供参考。【方法】以大田自然发病水稻为研究对象,分别采集健康和不同感病程度叶片的叶绿素、反射率光谱和SIF光谱,分析不同感病程度下叶片反射率和SIF光谱的变化特征及其相应的植被指数和SIF产量指数变化特征,并且综合植被指数和SIF产量指数构建病害等级监测模型。【结果】随着病害程度加重,叶片叶绿素含量呈现梯度递减趋势;健康和感病叶片之间的反射率光谱和SIF光谱呈现显著差异;基于反射率的植被指数随病害程度的加重呈现梯度变化规律;近红外波段(740 nm)SIF产量指数随病害程度的加重呈现梯度变化规律,而红光波段(685 nm)SIF产量指数仅在健康至中度感病阶段呈现梯度变化规律;基于全波段(650~850 nm)的SIF产量指数在健康、轻度和中度感病时差异较小,在重度感病时差异显著;植被指数与病害等级的相关性整体强于SIF产量指数,其中,简单比值指数(SR)模型预测精度最高,R2达到0.899。【结论】针对已有明显细条病病斑的叶片,植被指数的监测效果整体优于SIF产量指数。

Genetic Analysis of Streaked and Abnormal Floret Mutant st-fon

A double mutant with streaked leaf and abnormal floret was found and temporarily named streaked leaf and floral organ number mutant （st-fon）. For this mutant, besides white streak appeared on culm, leaves and panicles, the number of floral organs increased and florets cracked. The extreme phenotype was that several small florets grew from one floret or branch rachis in small florets extended and developed into panicles. By using transmission electron microscope to observe the ultrastructure of white histocytes of leaves at the seedling stage, the white tissues which showed abnormal plastids, lamellas and thylakoids could not develop into normal chloroplast, and the development of chloroplast was blocked at the early growth stage of plastid. Scanning electron microscope and paraffin section were also used to observe the development of floral organs, and the results indicated that the development of floral meristem was out of order and unlimited, whereas in the twisty leaves, vascular bundle sheath cells grew excessively, or some bubbly cells increased. Genetic analyses carried out by means of cross and backcross with four normal-leaf-color materials revealed that the mutant is of cytoplasm inheritance.

水稻细菌性条斑病抗性新品系的创制及其农艺性状分析

【目的】创制水稻细菌性条斑病抗性新品系,为进一步培育抗细菌性条斑病水稻新品种提供核心种质材料。【方法】通过多代回交、自交,结合分子标辅助选择技术和GSR40K芯片检测,以来自孟加拉国含抗细菌性条斑病Xo2基因的稻种资源BHADOIA 303为供体,以优良籼稻品种五山丝苗为受体,培育抗水稻细菌性条斑病株系,并分别通过田间成株期人工喷雾法和浸入法接种鉴定这些株系的抗病性,评价其农艺性状。【结果】分子标记和GSR40K芯片检测表明最终获得稳定携带Xo2基因片段的10个新品系(BC4F5);无论是喷雾法接种还是渗入法接种,导入抗病基因的株系和五山丝苗对细菌性条斑病的抗性均差异显著,10个测定株系均表现抗水稻细菌性条斑病,其平均病情指数为5.00~10.37,病斑长度为0.70~0.99 cm,其中以株系1~3抗性表现最好。这3个抗性较好的株系的农艺性状及产量性状指标有些与五山丝苗相似,其中株系1的千粒重、谷粒长、宽与五山丝苗相似,结实率优于五山丝苗;株系2每穗总粒数与五山丝苗相似,谷粒比五山丝苗长些、宽些,千粒重优于五山丝苗;株系3千粒重、结实率与五山丝苗相似,单株穗数优于五山丝苗。【结论】获得水稻细菌性条斑病抗性显著增强且农艺性状较优良的3个株系,为细菌性条斑病抗病育种提供了抗性新材料,有利于加快水稻细菌性条斑病抗性分子育种进程。

Disaster Prevention and Mitigation Technologies of Rice Virus Diseases Spread by Small Brown Planthopper (SBPH)

Rice stripe virus disease （RSVD） and rice black-streaked dwarf virus disease （RBSDVD） are two epidemic diseases in Yancheng City, Jiangsu Province in the last decade. The authors investigated the disaster regularity, prevention and control technology of RSVD and RBSDVD systematically. The occurrence and virus transmission of SBPH and disaster regularity of virus diseases were studied; the resistance of some rice varieties was cleared; the effects of physical and agricultural measures such as insect net blocking, appropriate late sowing and plowing on controlling occurrence and virus transmission of SBPH were figured out; a hatch of chemical agents were screened, providing efficient and harmless pesticides for effective control against SBPH and prevention against virus diseases. A set of disaster control and mitigation technologies was proposed in this paper, which was practical, sustainable, and easy to operate for the local planting patterns.

利用实时荧光定量PCR和数字PCR检测鉴定水稻细菌性条斑病菌

白叶枯病和条斑病是水稻重要的细菌性病害。水稻白叶枯病菌(Xanthomonas oryzae pv.oryzae,Xoo)和水稻细菌性条斑病菌(Xanthomonas oryzae pv.oryzicola,Xoc)属于同种下的2个致病变种。鉴别Xoo和Xoc对检疫和防控这2种病害至关重要。Xoo和Xoc中的铁-红酵母酸/铁-粪生素受体基因fhuE在进化过程中因不同程度地缺失而成为假基因。针对Xoc中有而Xoo中缺失的fhuE部分序列设计引物,筛选出Xoc特异引物XocFhuE-F(5’-ATCGAACGATGTCACCAGGG-3’)和XocFhuE-R(5’-AGAAACGTGCGGCCAGATAA-3’)。用XocFhuE-F/XocFhuE-R能只从Xoc菌株中仅扩增出159 bp片段,并结合荧光染料建立了SYBR Green实时荧光定量PCR(quantitative real-time PCR,qPCR)和EvaGreen微滴数字PCR(digital PCR,dPCR)方法来检测鉴定Xoc。在20μL反应体系中加1μL模板,qPCR检测菌悬液中Xoc的下限是1.6×10^(4)CFU/mL,检测带菌种子中Xoc的下限是1.2×10^(3)CFU/粒;d PCR检测菌悬液中Xoc的下限是1.6×10^(3)CFU/mL,检测带菌种子中Xoc的下限是1.2×10^(2)CFU/粒。综上所述,基于Xoc特异引物XocFhuE-F/XocFhuE-R建立的SYBR Green qPCR和EvaGreen dPCR为检疫Xoc和监测预警水稻条斑病提供了高效的检测方法。

一株兼具防病促生功能的沙阿霉素链霉菌Sz-11

【目的】评估沙阿霉素链霉菌Sz-11的促生能力和对水稻BLS的生防潜力,探究其初步的抑菌机制。【方法】用牛津杯法测定Sz-11对7种植物病原细菌和11种植物病原真菌的抗菌谱。通过浸种和浇灌试验评估Sz-11的促生潜力。SDS-PAGE电泳、琼脂糖凝胶电泳、CLSM、SEM、FTIR分析发酵液中的活性产物对Xooc蛋白质表达、基因组DNA合成、细胞膜通透性、细胞形态、细胞膜表面物质结构和组成的影响。4个水稻品种的盆栽防效试验,初步明确Sz-11对BLS的生防潜力。【结果】Sz-11对番茄叶斑病菌、苦瓜枯萎病菌、西瓜炭疽病菌、烟草赤星病菌等多种植物致病真菌都具有较好的拮抗活性,对水稻黄单胞菌(Xoo和Xooc)具有突出的拮抗作用。Sz-11能够促进水稻种子萌发生长,缩短萌发周期,加速营养生长期水稻有机质的积累和根系的分化。Sz-11能影响Xooc蛋白表达,改变细胞膜透性和膜表面物质组成,使细胞溶胀、变形、死亡,但不影响Xooc基因组DNA合成。盆栽试验显示,Sz-11对4个水稻品种BLS相对防效高达65.63%~84.38%,且提前预防效果优于发病后治理。【结论】Sz-11具有较广的抗菌谱,是一株有益的植物根际促生菌,通过作用于Xooc细胞膜和影响蛋白质合成来抑制病菌的生长繁殖,能有效防治水稻BLS的发生,具有较好的生防应用潜力。

南方水稻黑条矮缩病抗病遗传资源与分子机理研究进展

南方水稻黑条矮缩病(Souther rice black-streaked dwarf virus disease,SRBSDVD)是依靠白背飞虱(Sogatella furcifera)为传播介体,由南方水稻黑条矮缩病毒(Southern rice black-streaked dwarf virus,SRBSDV)侵染引起的一种水稻病毒病。该病害于2001年在我国华南地区首次被发现,随后发生面积不断扩大,危害逐年加重,已成为近年来危害中国南方稻区水稻生产的重要病害之一。白背飞虱迁飞性强、种群数量大、传毒持久等特点,导致化学农药防虫治病效果并不理想,至今还未有可持续和绿色控制SRBSDVD的手段。根据病原病毒的爆发性及其传播介体白背飞虱的生物学特性,预计该病害在未来较长的一段时期内将是我国最严重的水稻病害之一,很有可能再次暴发流行。因此,当前生产上急需培育出能够抵御SRBSDVD的抗性水稻品种。本文综述了SRBSDVD的发病规律、抗病种质资源的收集与评估、抗病基因或数量性状位点(QTL)的精确定位,以及这些抗性基因的分子作用机制,进一步探讨了利用现代分子生物学技术,包括分子标记辅助选择、基因沉默(RNAi)和基因编辑等技术加快SRBSDVD抗病品种的选育,可为今后有效控制SRBSDVD提供基础。

基于QTL-Seq的水稻抗细菌性条斑病QTL定位

【目的】发掘水稻抗细菌性条斑病新基因,丰富抗病基因资源,为水稻抗细菌性条斑病基因克隆及分子育种提供依据。【方法】以抗病材料广西普通野生稻WP1和感病品种9311及其衍生的F8:9代RIL群体为研究材料,利用QTL-Seq初定位与细菌性条斑病抗性相关的区间,之后利用QTLIciMapping4.1进行复合区间作图以验证结果并精细定位。【结果】分别在第4、8、10染色体上鉴定了一个与细菌性条斑病抗性相关的位点,复合区间作图验证了第4染色体抗细菌性条斑病QTL位点qBLS4.1,表型贡献率和LOD值分别为10.65%和5.03,并进一步将qBLS4.1精细定位在521kb的范围内。抗感亲本序列比对分析发现,在41个基因的编码区共有252个非同义突变,可能与细菌性条斑病抗性相关。【结论】通过QTL-seq分析结合复合区间作图法可以更快速高效地对水稻QTL进行定位,鉴定了一个抗细菌性条斑病性QTL新位点qBLS4.1,为水稻抗细菌性条斑病新基因鉴定与克隆奠定基础。