Development of Spectral Features for Monitoring Rice Bacterial Leaf Blight Disease Using Broad-Band Remote Sensing Systems

As an important rice disease, rice bacterial leaf blight (RBLB, caused by the bacterium Xanthomonas oryzae pv.oryzae), has become widespread in east China in recent years. Significant losses in rice yield occurred as a result ofthe disease’s epidemic, making it imperative to monitor RBLB at a large scale. With the development of remotesensing technology, the broad-band sensors equipped with red-edge channels over multiple spatial resolutionsoffer numerous available data for large-scale monitoring of rice diseases. However, RBLB is characterized by rapiddispersal under suitable conditions, making it difficult to track the disease at a regional scale with a single sensorin practice. Therefore, it is necessary to identify or construct features that are effective across different sensors formonitoring RBLB. To achieve this goal, the spectral response of RBLB was first analyzed based on the canopyhyperspectral data. Using the relative spectral response (RSR) functions of four representative satellite or UAVsensors (i.e., Sentinel-2, GF-6, Planet, and Rededge-M) and the hyperspectral data, the corresponding broad-bandspectral data was simulated. According to a thorough band combination and sensitivity analysis, two novel spectralindices for monitoring RBLB that can be effective across multiple sensors (i.e., RBBRI and RBBDI) weredeveloped. An optimal feature set that includes the two novel indices and a classical vegetation index was formed.The capability of such a feature set in monitoring RBLB was assessed via FLDA and SVM algorithms. The resultdemonstrated that both constructed novel indices exhibited high sensitivity to the disease across multiple sensors.Meanwhile, the feature set yielded an overall accuracy above 90% for all sensors, which indicates its cross-sensorgenerality in monitoring RBLB. The outcome of this research permits disease monitoring with different remotesensing data over a large scale.

In vitro and in silico studies of salicylic acid on systemic induced resistance against bacterial leaf blight disease and enhancement of crop yield

Salicylic acid(SA)is an effective elicitor to promote plant defenses and growth.This study aimed to investigate rice(Oryza sativa L.)cv.Khao Dawk Mali 105 treated with salicylic acid(SA)-Ricemate as an enhanced plant protection mechanism against bacterial leaf blight(BLB)disease caused by Xanthomonas oryzae pv.oryzae(Xoo).Results indicated that the use of SA-Ricemate as a foliar spray at concentrations of more than 100 mg L^(-1)can reduce the severity of BLB disease by 71%.SA-Ricemate treatment also increased the hydrogen peroxide(H_(2)O_(2))content of rice leaf tissues over untreated samples by 39–61%.Malondialdehyde(MDA)in rice leaves treated with SA-Ricemate also showed an increase of 50–65%when comparing to non-treated samples.The differential development of these defense compounds was faster and distinct when the SA-Ricemate-treated rice was infected with Xoo,indicating plant-induced resistance.Besides,SA-Ricemate elicitor at a concentration of 50–250 mg L^(-1)was correlated with a substantial increase in the accumulation of total chlorophyll content at 2.53–2.73 mg g^(-1)of fresh weight which suggests that plant growth is activated by SA-Ricemate.The catalase-and aldehyde dehydrogenase-binding sites were searched for using the CASTp server,and the findings were compared to the template.Chemsketch was used to design and optimize SA,which was then docked to the catalase and aldehyde dehydrogenase-binding domains of the enzymes using the GOLD 3.0.1 Software.SA is shown in several docked conformations with the enzymes catalase and aldehyde dehydrogenase.All three catalase amino acids(GLN7,VAL27,and GLU38)were discovered to be involved in the creation of a strong hydrogen bond with SA when SA was present.In this mechanism,the aldehyde dehydrogenase amino acids LYS5,HIS6,and ASP2 were all implicated,and these amino acids created strong hydrogen bonds with SA.In field conditions,SA-Ricemate significantly reduced disease severity by 78%and the total grain yield was significantly increased which was an increase of plant height,tiller per hill,and panicle in three field trials during Aug–Nov 2017 and 2018.Therefore,SA-Ricemate can be used as an alternative elicitor on replacing harmful pesticides to control BLB disease with a high potential of increasing rice defenses,growth,and yield components.

Hybrid Rice Resistant to Bacterial Leaf Blight Developed By Marker Assisted Selection

Through recurrent backcrossing in combination with molecular marker-assisted selection (MAS), restorer lines R8006 and Rl176 carrying Xa-21, a gene having broad-spectrum resistance to rice bacterial leaf blight, were selected. By crossing the two lines to CMS line Zhong 9A, two new hybrid rice combinations, Zhongyou 6 and Zhongyou 1176 were developed. The hybrids showed high resistance to diseases, good grain quality and high yielding potential in national and provincial adaptability and yield trials.

Marker-Assisted Selection of Xa21 Conferring Resistance to Bacterial Leaf Blight in indica Rice Cultivar LT2

Bacterial leaf blight of rice (BLB), caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive diseases in Asian rice fields. A high-quality rice variety, LT2, was used as the recipient parent.IRBB21, which carries the Xa21 gene, was used as the donor parent. The resistance gene Xa21 was introduced into LT2 by marker-assisted backcrossing. Three Xoo races were used to inoculate the improved lines following the clipping method. Eleven BC_3F_3 lines carrying Xa21 were obtained based on molecular markers and agronomic performance. The 11 lines were then inoculated with the three Xoo races. All the 11 improved lines showed better resistance to BLB than the recipient parent LT2. Based on the level of resistance to BLB and their agronomic performance, five lines (BC_3F_3 5.1.5.1, BC_3F_3 5.1.5.12, BC_3F_3 8.5.6.44, BC_3F_3 9.5.4.1 and BC_3F_3 9.5.4.23) were selected as the most promising for commercial release. These improved lines could contribute to rice production in terms of food security.

RPA-Assisted Cas12a System for Detecting Pathogenic Xanthomonas oryzae,a Causative Agent for Bacterial Leaf Blight Disease in Rice

Xanthomonas oryzae pv.oryzae(Xoo)is a widespread pathogen causing bacterial leaf blight(BLB)disease,devastating rice productivity in many cultivated areas of Thailand.A specific and simple method for Xoo detection is required to improve surveillance of disease transmission and outbreak.This study developed a recombinase polymerase amplification(RPA)assay assisted with CRISPR-cas12a assay(RAC)for Xoo detection from bacterial cell suspension of infected rice samples without DNA extraction.The efficiency of the RAC system for Xoo detection using either Xoo80 or Xoo4009 locus was optimized to amplify and determine the sensitivity and specificity using a Xoo DNA template from bacterial cell suspension of infected rice samples without DNA extraction.The RAC system using the Xoo4009 locus gave a higher specificity than Xoo80 locus,because only Xoo species was amplified positive RPA product with fluorescence signal by cas12a digestion,which indicated no cross reactivity.Optimal RAC using the Xoo4009 locus enabled diagnosis of Xoo presence from both plant extracted samples of Xoo artificially inoculated rice leaves within 3 d post-inoculation without symptomatic BLB appearance,and Xoo naturally infected rice.Findings exhibited that RAC using the Xoo4009 locus offered sensitivity,specificity and simplicity for Xoo detection,with low intensities of Xoo-DNA(1×10^(3) copies/μL)and Xoo-cell(2.5×10^(3) cfu/mL).This developed RAC system showed significantly potential for Xoo detection at point-of-care application for early signs of BLB disease outbreak in rice fields.

Interactive Effect of Different Nitrogen and Potash Levels on the Incidence of Bacterial Leaf Blight of Rice (<i>Oryza sativa L.</i>)

An experiment was conducted at Rice Research Institute, Kala Shah Kaku in 2010 during kharif season to study the influence of nitrogen (N) and potash (K) on severity of Bacterial leaf blight (BLB) of rice (Oryza sativa L.) aimed at improving productivity. The experiment was laid out in randomized complete block design with factorial arrangement with three replications. Treatments comprised of: 0 kg N ha-1, 75 kg N ha-1, 100 kg N ha-1, 125 kg N ha-1 and 0 kg K ha-1, 50 kg K ha-1, 75 kg K ha-1, 100 kg K ha-1. Data on disease severity and paddy yield were recorded using standard procedures. Paddy yield was affected significantly by various combinations of N & K. In case of bacterial leaf blight, minimum diseased incidence percentage was observed when nitrogen alone was applied @ 75 kg·ha-1 in contrast to fertilizer applied @ 125 kg N ha-1 + 50 kg K ha-1 which showed maximum diseased incidence percentage. Maximum paddy yield (4.32 t·ha-1 ) was recorded when rice was fertilized @ 75 kg N ha-1 + 100 kg K ha-1 as compared to sole fertilization of 75 kg K ha-1 that produced minimum paddy yield (2.40 t·ha-1). Maximum gross income, net returns and benefit cost ratio were obtained where rice crop was fertilized @ 75 kg N ha-1 and 100 kg K ha-1.

Preliminary evaluation of resistance genes in rice against bacterial leaf blight in Guilan Province—Iran

The reactions of rice bacterial leaf blight races were identified in Guilan province—Iran on 12 near-isogenic lines and 14 pyramiding lines from International Network for Genetic Evaluation of rice (INGER) and 8 local and improved Iranian varieties were evaluated under natural photoperiod condition in the field. Inoculation was done at panicle initiation by clipping the sterilized scissors in the bacterial suspension to booting stage. Scoring of inoculated plants was made 21 days after inoculation. Infection levels of pyramiding lines containing two to five resistance genes, expect, IRBB53 and IRBB61 with respectively resistance gene combination, Xa5 + Xa13 and Xa4 + Xa5 + Xa7, were not so clear. Among near-isogenic lines IRBB1, IRBB2, IRBB4 and IRBB10 carrying resistance gene Xa1, Xa2, Xa4 and Xa10 were susceptible;IRBB8, IRBB11, IRBB3, IRBB5 and IRBB13 were moderately susceptible;(having resistance gene Xa8, Xa11, Xa3, Xa5 and Xa13) IRBB14, IRBB21 and IRBB7 with respectively resistance gene Xa14, Xa21 and Xa7 were moderately resistance to bacterial blight. Furthermore, most of the time gene combinations support the strategy of pyramiding appropriate resistance gene. Local varieties were more susceptible than improved varieties to leaf blight disease. Among local varieties, Tarom was the most susceptible. And also, there were no significant differences among improved varieties and all of them were moderately resistance.

G ×E Analysis of Rice Germplasm and NILs Having Bacterial Leaf Blight (BLB) Resistant Genes against Local Isolates of <i>Xanthomonas oryzae</i>at Diverse Agro-Ecological Zones

Rice is food for more than half of the world population and the most consumable cereal in most of the countries. Pakistan is the fifth largest exporter of rice. However, Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae is the most devastating and serious threat to rice production in many countries of the world including Pakistan. To combat this disease, innate genetic resistance of the plant plays vital role along with being environmentally friendly and economical. In this study, thirty-one (31) Near Isogenic Lines (NILs) having Xa4, xa5, Xa7, xa13 and Xa21 reported BLB tolerant genes and 34 locally developed rice lines were investigated under natural field conditions at three agro-ecologically different locations with highest disease occurrence records (BLB hotspots) viz., Sheikhupura, Hafizabad and Gujranwala, Punjab, Pakistan in order to assess their respective genetic resistance and G × E interactions against the disease. Thirty-one (31) lines were categorized under resistant cluster, twenty-eight (28) were moderately resistant, six (6) were moderately susceptible and one (susceptible check) was in susceptible category. Grouping of different lines/varieties under same cluster shows their significantly similar response against BLB disease in corresponding environment. Among the studied NILs, only one line showed polymorphism for all five resistant genes, two lines had four;seven lines had three genes, seven lines showed di-genic while five lines showed mono-genic polymorphism. These resistant lines with multiple-genes for BLB resistance can be evolved as a new BLB resistant variety and also be utilized as donor parent in breeding programs for developing new cultivars with horizontal resistance against more than one target pathotypes and environments. Xa4 and xa13 were found to deliver significant resistance against the local pathotypes in studied germplasm and NILs.

Inhibitory Activity of <i>Paenibacillus</i>sp. Isolated from Soil in Gotsu City, Shimane Prefecture, Against Xanthomas <i>oryzae</i>pv. <i>oryzae</i>, the Causal Agent of Rice Bacterial Leaf Blight

Microorganism isolates (n = 49) were obtained from the soil samples collected from field in Gotsu city (Kawahira), Shimane. Isolate GT2-E culture inhibited the growth of Xanthomonas oryzae pv. oryzae in disk diffusion method. Rice bacterial leaf blight was suppressed by GT2-E culture in the pre- and post-treated rice leaves. Sequence analysis of 16S rDNA region of the GT2-E isolate indicated that it shared 99% similarity with Paenibacillus polymyxa. The growth of GT2-E on LB medium was observed at 15°C, 28°C, 37°C, and 45°C, but not at 4°C. GT2-E isolate could be grown even in the presence of agrochemicals (Amister, Blasin and Kasumin). Furthermore, the growth of X. oryzae pv. oryzae was inhibited by the culture filtrate of GT2-E isolate in disk diffusion method. However, the inhibitory activity of the culture filtrate was heat-unstable. This result suggested that GT2-E isolate can produce heat-unstable inhibitory compound(s). In conclusion, GT2-E isolate might contribute to the development of a new bactericide and biological agent against rice bacterial leaf blight.

ORYZA SATIVA SPOTTED-LEAF 41(OsSPL41) Negatively Regulates Plant Immunity in Rice

Identification of immunity-associated leucine-rich repeat receptor-like protein kinases(LRR-RLK) is critical to elucidate the LRR-RLK mediated mechanism of plant immunity.Here,we reported the map-based cloning of a novel rice SPOTTED-LEAF 41(Os SPL41) encoding a putative LRR-RLK protein(Os LRR-RLK41/Os SPL41) that regulated disease responses to the bacterial blight pathogen Xanthomonas oryzae pv.oryzae(Xoo).An 8-bp insertion at position 865 bp in a mutant spotted-leaf 41(spl41) allele led to the formation of purple-brown lesions on leaves.Functional complementation by the wild type allele(Os SPL41) can rescue the mutant phenotype,and the complementary lines showed similar performance to wild type in a number of agronomic,physiological and molecular indices.Os SPL41 was constitutively expressed in all tissues tested,and Os SPL41 contains a typical transmembrane domain critical for its localization to the cell membrane.The mutant exhibited an enhanced level of resistance to Xoo in companion of markedly up-regulated expression of pathogenesis-related genes such as Os PR10a,Os PAL1 and Os NPR1,while the level of salicylic acid was significantly increased in spl41.In contrast,the over-expression lines exhibited a reduced level of H_(2)O_(2) and were much susceptible to Xoo with down-regulated expression of pathogenesis-related genes.These results suggested that Os SPL41 might negatively regulate plant immunity through the salicylic acid signaling pathway in rice.

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.

Identification and Genetic Analysis of a Novel Rice Spotted-Leaf Mutant with Broad-Spectrum Resistance to Xanthomonas oryzae pv. oryzae

A spotted-leaf mutant of rice HM143 was isolated from an EMS-induced IR64 mutant bank. Brown lesions randomly distributed on leaf blades were observed about 3 wk after sowing. The symptom lasted for the whole plant growth duration. Histochemical analysis indicated that cell death occurred in and around the site of necrotic lesions accompanied with accumulation of hydrogen hyperoxide. Agronomic traits were largely similar to the wild type IR64 except seed setting rate and 1 000-grain weight which were significantly decreased in the mutant. Disease resistance of the mutant to multiple races of Xanthomonas oryzae pv. oryzae was significantly enhanced. Genetic analysis showed that the mutation was controlled by a single recessive gene, tentatively termed splHM143. In addition, using molecular markers and 1023 mutant type individuals from an F2 segregating population derived from the cross HM143/R9308, the spotted-leaf gene was finally delimited to an interval of 149 kb between markers XX25 and ID40 on the long arm of chromosome 4. splHM143 is likely a novel rice spotted-leaf gene since no other similar genes have been identified near the chromosomal region.

水稻白叶枯病常态化预防控制技术应用

水稻白叶枯病是水稻生产过程中重要的病害,尽管对该病害的防治做了大量工作,但2015年以来,该病害又有上升趋势,特别是2019年后,衢江区水稻白叶枯病发生面积呈多点式、暴发式增长,尤其是单季晚稻与连作晚稻,对该区水稻生产构成严重威胁。借鉴“中医治未病”理论,探索采用“3+X”模式防控水稻白叶枯病。结果表明,与常规防治方法相比,在水稻种植关键环节,用20%噻唑锌提早进行预防处理,不仅能有效降低病害的发生程度,延缓田间病害扩展速度,对水稻植株生长功能也有一定的改善作用,作物安全性好。利用此模式防控效果达到85%以上,产量比常规防治区增加10%以上。

Establishment of a system for screening and identification of novel bactericide targets in the plant pathogenic bacterium Xanthomonas oryzae pv. oryzae using Tn-seq and SPR

Xanthomonas spp. cause severe bacterial diseases. However, effective strategies for prevention and management of these diseases are scarce. Thus, it is necessary to improve the efficiency of control of diseases caused by Xanthomonas. In this study, Xanthomonas oryzae pv. oryzae(Xoo), which causes rice bacterial leaf blight, has been studied as a representative. A transposon insertion library of Xoo, comprising approximately 200,000 individual insertion mutants, was generated. Transposon sequencing data indicated that the mariner C9 transposase mapped at 35.7–36.4% of all potential insertion sites, revealing 491 essential genes required for the growth of Xoo in rich media. The results show that, compared to the functions of essential genes of other bacteria, the functions of some essential genes of Xoo are unknown, 25 genes might be dangerous for the Xanthomonas group, and 3 are specific to Xanthomonas. High-priority candidates for developing broad-spectrum, Xanthomonas-specific, and environment-friendly bactericides were identified in this study. In addition, this study revealed the possible targets of dioctyldiethylenetriamine using surface plasmon resonance(SPR) in combination with high performance liquid chromatography–mass spectrometry(HPLC–MS). The study also provided references for the research of some certain bactericides with unknown anti-bacterial mode of action. In conclusion, this study urged a better understanding of Xanthomonas,provided meaningful data for the management of bacterial leaf blight, and disclosed selected targets of a novel bactericide.

Characteristic analysis of tetra-resistant genetically modified rice

In this study, the characteristic of three transformants named as B1C106-1, B1C106-2, and B1C106-3 were studied that carried three innate resistant genes Bph14, Bph15, and Xa23, and two enthetic resistant genes CrylCa# and Bar. The five resistant genes were all verified by PCR and the two enthetic genes were identified in single copy insertion by Southern blot. At tillering stage, the CrylC and PAT （phosphinothricin acetyl transferase） protein contents in leaf, sheath, and stem of T2 generation were in the similar pattern： leaf〉stem〉sheath, and showed significant difference （P〈0.01） among three organs. The average contents of CrylC protein in plant of B1C106-1, B1C106-2, and BIC106-3 were 12.95, 6.57, and 11.30 μg g-1, respectively, and showed significant difference （P〈0.01） among them. However, the average contents of PAT in plant of B1C106-1, B1C106-2, and B1C106-3 were 28.54, 27.66, and 28.02 pg g-1, respectively, and there were no significant difference among three transformants. The glufosinate tolerable concentration of three transformants of T3 generation reached at least 6 g L-1, and the mortality of rice leaf rollers were above 97.4% in 5 days after being fed with fresh transformants＇ leaves. The CrylC protein toxicity was also assessed by silkworms, and the mortality of silkworms feeding mulberry leaves smeared with Cry1C protein extracts of leaves of B1 C106-1, BIC106-2, and B1 C106-3 were 90, 67.8, and 87.8%, respectively, that were positive correlation （r=0.993） with CrylC protein contents in plant of three transformants. The three transformants also maintained high resistance to brown planthopper and bacterial blight as the original version. The above results indicate the tetra-resistant rice germplasm was well-developed by pyramiding innate and enthetic resistant genes in an elite line to provide with resistances of glufosinate, rice leaf roller, brown planthopper, and bacterial blight.

Role of LOX3 Gene in Alleviating Adverse Effects of Drought and Pathogens in Rice

Lipoxygenase 3 (LOX3) is a major component of the LOX isozymes in mature rice seeds. To investigate the role of LOX3 gene under stresses, a plant expression vector containing antisense cDNA of LOX3 was constructed. Rice varieties Wuyunjing 7 and Kasalath were transformed by the Agrobacterium-mediated method and transgenic rice plants were generated. PCR and Southern blot results showed that the antisense LOX3 gene was integrated into the rice genome. Analyses of embryo LOX3 deletion and semi-quantitative RT-PCR confirmed the antisense suppression of LOX3 gene in transgenic plants. The T2 antisense plants of LOX3 were sensitive to drought stress, rice blast and bacterial blight compared with non-transgenic plants. These results suggest that the LOX3 gene might function in response to stresses.

Rice Leaves Disease Diagnose Empowered with Transfer Learning

In the agricultural industry,rice infections have resulted in significant productivity and economic losses.The infections must be recognized early on to regulate and mitigate the effects of the attacks.Early diagnosis of disease severity effects or incidence can preserve production from quantitative and qualitative losses,reduce pesticide use,and boost ta country’s economy.Assessing the health of a rice plant through its leaves is usually done as a manual ocular exercise.In this manuscript,three rice plant diseases:Bacterial leaf blight,Brown spot,and Leaf smut,were identified using the Alexnet Model.Our research shows that any reduction in rice plants will have a significant beneficial impact on alleviating global food hunger by increasing supply,lowering prices,and reducing production's environmental impact that affects the economy of any country.Farmers would be able to get more exact and faster results with this technology,allowing them to administer the most acceptable treatment available.By Using Alex Net,the proposed approach achieved a 99.0%accuracy rate for diagnosing rice leaves disease.

Thailand Experience in Developing Wellness-driven Rice as the Key to Fight NCDs and Farmer Poverty

Prevalence of chronic noncommunicable diseases(NCDs)is rapidly increasing and has become a global problem in modern day.Over consumption of simple,processed carbohydrate foods is considered one of the main causes of NCD in young and elderly populations.Whole grain rice is an important source of a complex carbohydrate,dietary fiber,enriched with vitamins,minerals,and antioxidants.However,palatability of brown rice is the key success factor among white-rice-addicted communities.In the initial phase,we successfully breed rice strains with aromatic,soft-whole grain,white rice contains high grain-Fe/Zn density and intermediate glycemic index(GI).The most successful variety was uniquely soft-textured black purple rice named Riceberry,depicting rice enriched with blueberry nutritional characteristics.Product development for fiber-rich,high antioxidant has been extremely active from academia,real sectors,and SMEs.In total,39 patent applications(18 granted patents),12 international publications,and 18,700 Youtubes related to Riceberry.From 2017,Riceberry has become the most popular choice for product development surpassing Thai Hommali Rice.More than 200 food and non-food products were commercialized as dairy replacement,side dishes,meals,hot beverages,bakery,and breakfast cereals.In the second phase,we successfully breed low GI rice strains named Pink+4 equipped with farmers’preferred resistance to flash flooding,bacterial leaf blight,leaf blast,and devastating brown planthopper adapted to organic rice production.Innovative products combined of low GI rice flour with purple Riceberry have been the next trend for functional ingredients and foods.These healthy rice products have high potential globally as healthy foods,gluten-free,fiber-rich,complex carbohydrate,and nutrient-dense from sustainable organic farming.

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。

我国水稻白叶枯病和条斑病发生与防控研究进展

培育和种植抗病品种和研发新型绿色杀菌剂是防治水稻白叶枯病和条斑病的有效措施。最近几年有关稻黄单胞菌Xanthomonas oryzae致病效应蛋白调控水稻抗(感)病性研究取得了突破性进展,为水稻抗性品种培育提供了新思路、新策略。本文对稻黄单胞菌水稻互作系统中已知的TALE效应蛋白与水稻抗(感)病基因(R或S)的对应关系进行了归纳,就tal基因与水稻R或S基因的协同进化进行了分析,结合生物农药和高效低毒杀菌剂的应用现状,提出了我国水稻白叶枯病和水稻条斑病绿色防控关键策略。