Genetic resistance to bacterial blight disease in Persian walnut

Bacterial blight disease of Persian walnut (Juglans regia, L.), caused by Xanthomonas arboricola pv. juglandis (Xaj), leads to significant nut losses in northern, central and western areas of Iran. To identify the natural sources of resistance to disease in the endemic walnut genotypes of Iran, sixteen walnut genotypes, collected from different areas of Hamedan province, were inoculated with Xaj in a randomized complete block design with five replicates for each genotype. Two-year old genotypes were gently sprayed with a suspension of bacteria adjusted to approximately 2 × 10⁹ cfu ml⁻¹ of distilled water in May. Infected leaves were rated for disease 28 and 42 days after inoculation, using a 0 to 5 severity scale, based on the number, size and distribution of lesions on the leaves. Data analyses showed that there were variations among genotypes in response to pathogen. Upon inoculation by bacterial suspension genotype 94 showed the highest resistance to both disease incidence and its progress after 4–6 weeks of infection. Genotype 65 showed high susceptibility to disease and genotype 69 showed high susceptibilities both to disease incidence and its progress after 4–6 weeks of infection.     

转cryAb基因克螟稻对水稻白叶枯病和纹枯病的抗性评价

转cryAb基因克螟稻对水稻白叶枯病、纹枯病的抗病性在田间进行了人工接种鉴定,根据亲本材料秀水11及2个转基因材料克螟稻1号(KMD1)和克螟稻2号(KMD2)的发病情况,初步明确两个转基因材料的抗病性与亲本存在显著的差异,对白叶枯病的抗性比亲本材料有所上升,但对纹枯病的抗性则不如亲本秀水11。     

Primary disease gradients of bacterial blight of rice

ABSTRACT The dispersal potential of Xanthomonas oryzae pv. oryzae, causal agent of bacterial blight of rice (Oryzae sativa), was investigated through measurement of primary disease gradients. Plants within individual hills of rice were inoculated, and the number of new lesions in the primary generation of dispersal from these inoculated sources was counted. Two dispersal models that can describe the number of infections at the source (the Kiyosawa and Shiyomi and the modified Gregory) were fit to the lesion counts. Estimated gradient slopes were similar in the 2 years of the study for both gradient models. However, the Kiyosawa and Shiyomi model gave a better fit in both years, as indicated by higher coefficients of determination and significances of slopes and by a more random pattern of residuals. Primary disease gradients were very steep, with half-distances (distances over which lesion numbers are calculated to decrease by half) estimated from the Kiyosawa and Shiyomi model of 0.091 and 0.081 m in 1994 and 1995, respectively. Splash dispersal of X. oryzae pv. oryzae is the most likely explanation for both the steep slopes measured and the superior fit of the Kiyosawa and Shiyomi model over the modified Gregory model.     

OsHsp18.0-CI调控水稻对白叶枯病的抗性

 热激蛋白广泛存在于各种生物中,响应多种生物胁迫和非生物胁迫。前期研究结果显示,在水稻中超量表达小热激蛋白OsHsp18.0-CI基因,能通过增强水稻的基础防卫反应提高对水稻细菌性条斑病的抗性。本研究发现,OsHsp18.0-CI基因也能够受到白叶枯病菌的诱导表达,超量表达OsHsp18.0-CI的转基因水稻也增强了对多个白叶枯病致病菌株的抗性。转录组测序分析发现,OsHsp18.0-CI基因介导的水稻对白叶枯病的抗病信号途径有部分类似于其介导的对细菌性条斑病的抗性路径,同时也有大量新的未知功能基因的参与。以上结果表明,OsHsp18.0-CI基因受到病原菌的侵染时,也能通过增强水稻的基础防卫反应来提高对白叶枯病的抗性。     

杂交稻对稻瘟病和稻白叶枯病的抗性鉴定

对广东省将推广的54份杂交稻组合对稻瘟病和白叶枯病的抗病性进行了鉴定。对稻瘟病的抗病性鉴定表明:抗病组合共49个,占90.7%;其中,高抗(抗性比≥91%)组合30个,占55.6%。对稻白叶枯病的抗病性鉴定表明:没有高抗(HR)和抗(R)的组合,仅有一个杂交稻组合(西胜2175)表现为中抗(mR),仅占1.9%,其余53个组合都表现感病,占98.1%。进一步分析表明:对稻瘟病表现高抗的30个杂交稻组合都不抗白叶枯病,而中抗白叶枯病的杂交稻组合西胜2175对稻瘟病表现为中抗,抗性比为74%。     

Influence of rice development on the function of bacterial blight resistance genes

Disease resistance genes most commonly used in breeding programs are single, dominant genes with relative effectiveness that is sometimes influenced by plant developmental stage. Knowing the developmental stages at which a resistance gene is functional is important for disease management. In rice, resistance at the seedling stage is crucial, because wounding during transplanting increases the potential for bacterial blight disease, and not all bacterial blight resistance genes are effective at the seedling stage. Effectiveness of the bacterial blight resistance genes Xa4, xa5, and Xa7, all in a common genetic background, was evaluated at different developmental stages by measuring lesion length and bacterial numbers after inoculation with the bacterial pathogen, Xanthomonas oryzae pv. oryzae. The Xa4 and xa5 genes controlled disease at all growth stages. In contrast, Xa7 was not fully functional in very young seedlings, but was completely effective by 21 days after sowing (das). The effects of plant developmental stage on interactions of the Xa7 gene with X. oryzae pv. oryzae strains carrying different mutant avrXa7 alleles were also tested. If a partial or fully functional avrXa7 allele was present, Xa7 resistance was effective at all growth stages tested after the transplant stage (>21 das).     

Inheritance of resistance to bacterial blight in 21 cultivars of rice

ABSTRACT Genetic analysis for resistance to bacterial blight (Xanthomonas oryzae pv. oryzae) of 21 rice (Oryza sativa L.) cultivars was carried out. These cultivars were divided into two groups based on their reactions to Philippine races of bacterial blight. Cultivars of group 1 were resistant to race 1 and those of group 2 were susceptible to race 1 but resistant to race 2. All the cultivars were crossed with TN1, which is susceptible to all the Philippine races of X. oryzae pv. oryzae. F(1) and F(2) populations of hybrids of group 1 cultivars were evaluated using race 1 and F(1) and F(2) populations of hybrids of group 2 cultivars were evaluated using race 2. All the cultivars showed monogenic inheritance of resistance. Allelic relationships of the genes were investigated by crossing these cultivars with different testers having single genes for resistance. Three cultivars have Xa4, another three have xa5, one has xa8, two have Xa3, eight have Xa10, and one has Xa4 as well as Xa10. Three cultivars have new, as yet undescribed, genes. Nep Bha Bong To has a new recessive gene for moderate resistance to races 1, 2, and 3 and resistance to race 5. This gene is designated xa26(t). Arai Raj has a dominant gene for resistance to race 2 which segregates independently of Xa10. This gene is designated as Xa27(t). Lota Sail has a recessive gene for resistance to race 2 which segregates independently of Xa10. This gene is designated as xa28(t).     

水稻抗纹枯病的研究进展

多年来通过对水稻抗纹枯病的筛选 ,没有发现免疫品种 ,但筛选鉴定出不同程度的抗性品种。本文就水稻抗纹枯病的机制、抗性遗传及生物工程育种进行了综述 ,对今后水稻抗纹枯病基因工程等研究进行了讨论与展望     

水稻抗白叶枯病基因Xa47(t) a的敲除及抗性鉴定

为鉴定水稻Xa47(t)a基因对白叶枯病的抗性,以水稻种质L214为材料,通过构建针对Xa47(t)a基因的Xa47(t)a-Cas9敲除载体来获得敲除突变体,利用生物信息学技术对突变的Xa47(t)a基因进行突变类型分析,同时采用实时荧光定量PCR(quantitative real-time PCR,qPCR)技术分析突变体中Xa47(t)a及病程相关基因的表达情况,并于水稻孕穗期对突变体及其野生型植株接种11株白叶枯病菌Xanthomonas oryzae pv. oryzae菌株进行抗性鉴定。结果表明,在Xa47(t)a基因的第2外显子区域进行基因编辑后成功获得25株T₀代突变体株系;测序分析发现T₀代突变体株系中有13种不同的突变体类型,其中纯合突变体有3种类型,且突变位点均在靶标位点的11位碱基处缺失1～4个A碱基;氨基酸序列分析发现大部分突变体中Xa47a编码的蛋白翻译会提前终止,由原来的803个氨基酸变为144～166个氨基酸;qPCR分析结果表明突变体中Xa47(t)a及大部分病程相关基因的表达水平显著低于野生型株系;抗性鉴...     

Epidemiological effect of gene deployment strategies on bacterial blight of rice

ABSTRACT Experiments were conducted in farmers' fields at two locations of the irrigated lowlands of Laguna province in southern Luzon island, Philippines, during the wet seasons of 1993 and 1994. Nine rice populations were studied including pure stands, two-component mixtures, two-gene combinations of backcrossed lines containing varying combinations of the bacterial blight resistance genes Xa-4, xa-5, and Xa-10, and a non-isogenic cultivar containing Xa-4 and partial resistance to bacterial blight. The area under the disease progress curve (AUDPC) of both gene combinations studied was significantly less than the single most effective gene of each combination deployed singly. A mixture of a susceptible and a resistant line expressed an AUDPC significantly less than the mean of its component pure stands, but two other mixtures did not. The cultivar IR20, which contains both Xa-4 and partial resistance, reduced the AUDPC by about two-thirds as compared with IR-BB4, which contains Xa-4 and little or no partial resistance.     

南方水稻区域试验品种对水稻白叶枯病抗性调查

1983-2007年,对南方稻区水稻区域试验品种、组合的白叶枯病抗性进行了研究。结果表明,在1 805个参试品种、组合中,78个表现抗白叶枯病,抗病品种频率为4.3%;其中,常规水稻74个,占抗病品种的94.9%。在1 219个籼型杂交水稻中,抗病的组合3个,中抗的76个,抗病和中抗组合频率分别为0.2%和6.2%。不同类型和不同生态型水稻的抗病品种频率差异显著,晚粳>早籼>中籼>晚籼;常规水稻>杂交水稻。籼型杂交水稻中抗病组合频率为:杂交晚稻>杂交早稻>杂交中稻。1990-2004年,17个抗或中抗白叶枯病的优良水稻新品种、组合通过国家审定。     

水稻抗病基因Xa21转入3个粳稻品种的抗性初步分析

 通过农杆菌介导转化,将已克隆的水稻白叶枯病抗性基因Xa21转入我国辽宁省3个粳稻品种:沈农606、辽粳454、辽粳294,共获得独立转基因系205个。通过PCR、GUS染色和Southern blot分析,证明Xa21基因已经整合到3个粳稻栽培品种的基因组中。通过温室接种菲律宾白叶枯病小种6的代表菌系PXO99,T₀代转基因水稻除了3-34表现部分抗性外,其它的转基因材料均表现高度抗病,表明Xa21转基因水稻已经获得抗性;温室接种T₁和T₂代试验表明,单拷贝整合的转化体呈现3:1分离,同时单拷贝3-34材料也表现部分抗性和感病3:1分离,证明已整合的Xa21基因能稳定遗传;同时对3-34部分抗性机制进行了分子生物学检测,证明GUS基因全部丢失、Xa21基因部分丢失并导致部分抗性。获得部分抗性材料,对于深入研究Xa21基因的功能区和研究抗病分子机制具有重要的意义。     

江苏省水稻区试品种(系)对白叶枯病的抗性分析

通过 1996～2000年213份江苏省水稻区试品种(系)对水稻白叶枯病抗性鉴定 ,抗性较好的品种有94-44、96218、镇稻272、汕优抗63、汕优084、金优63、109、701、7057、9510、9619、5-172、92-133、扬粳7057、泗稻98-3789、新108、镇稻 99、44/157、9522等品种 ,其中 9510、9522等在生产上推广面积较大。试验表明 ,江苏省区试品种 (系 )中常规中籼、杂交籼稻和杂交中粳稻对水稻白叶枯病抗性较差 ,全抗率分别为36.4 %、27.3%和43.3% ,而中粳稻、单季晚粳和杂交晚粳稻对水稻白叶枯病的全抗率为67.2%、71.4%和72.2% ,抗性相对较好。根据白叶枯病菌不同致病型菌株对参试品种致病率的分布情况分析 ,浙173菌株 (致病型Ⅳ)对杂交中籼、常规中粳稻和杂交中粳稻的致病率较高。这种情况和Ⅳ型菌为江苏省白叶枯病主要致病型相一致。     

苯并噻二唑诱发水稻对纹枯病的抗性

研究了苯并噻二唑(B1H)诱发水稻产生对纹枯病的抗性。离体条件下，1．0mmol／L BTH对纹枯病菌菌丝生长无明显抑制作用。BTH叶面或灌根处理四叶一心期水稻幼苗，并将植株第2、3和4叶离体接种纹枯病菌，水稻叶片纹枯病病斑长度明显下降，BTH诱发苗期水稻产生抗性的最佳诱导期在处理后的3—5天，最佳浓度为0．1mmol／L，BTH灌根处理诱发抗性的效果较好。用BTH溶液叶面喷雾处理成株期水稻倒二叶后离体接种纹枯病菌，倒二叶、倒一叶和剑叶上病斑长度显著低于对照，最佳诱导期在处理后3—5天。用BTH处理苗期水稻第2叶或成株期倒二叶，可使未经处理的苗期水稻第3和4叶以及成株期水稻倒一叶和剑叶上纹枯病病斑长度显著下降。     

茉莉酸甲酯诱导大田水稻抗白叶枯病的效应研究

本研究以感白叶枯病水稻品种‘温229’为试验材料,通过茉莉酸甲酯(MeJA)浸种和喷雾处理幼苗期和孕穗期水稻,探索MeJA诱导大田水稻抗白叶枯病的效应。水稻幼苗期,0.004mmol/L MeJA浸种、0.1mmol/L MeJA喷雾、0.004mmol/L MeJA浸种后再用0.1mmol/L MeJA喷雾处理,均表现诱导幼苗抗白叶枯病的作用,其诱导效果最高达27.65%;其中,MeJA浸种再喷雾双重处理的效果与单一喷雾处理差异不显著,但与单一浸种处理达到显著性差异水平;水稻孕穗期,0.05~2.00mmol/L的MeJA喷雾后均可降低白叶枯病的病情指数,其中2011年MeJA诱导效果最佳的浓度为0.50mmol/L,而2012年和2013年则为1.00mmol/L,诱导效果最高为17.17%。以上结果表明,MeJA处理可有效缓解大田水稻幼苗和孕穗期白叶枯病的发生,其诱导效果可能与MeJA处理浓度、方法及水稻生育期有关。     

miR1320表达水平与水稻白叶枯病抗性的关联性分析

水稻白叶枯病是由稻黄单胞菌水稻致病变种Xanthomonas oryzae pv. oryzae(Xoo)引起的一种细菌性病害,严重影响水稻的产量和品质。miR1320是水稻与Xoo互作中重要的调控因子。本研究在接种Xoo后的0、12、24 h分别检测了10个粳稻和8个籼稻品种中miR1320的积累和4个防卫基因的转录水平,测量了各品种叶片上的病斑长度,分析了miR1320的积累和防卫基因的表达与水稻白叶枯病抗性之间的相关性。结果表明:接种Xoo后,miR1320的表达模式在不同品种中有所不同;籼稻和粳稻对白叶枯病的抗性分别与接种后24 h和12 h时miR1320的表达量呈紧密负相关;且相对于防卫基因,miR1320更能反映品种间的抗病性。因此,miR1320可应用于评估水稻品种对白叶枯病的抗性,辅助水稻抗病种质的鉴定。     

New gene for bacterial blight resistance in rice located on chromosome 12 identified from minghui 63, an elite restorer line

ABSTRACT Bacterial blight, caused by Xanthomonas oryzae pv. oryzae, is a serious disease of rice worldwide. A new dominant gene for bacterial blight resistance in rice, Xa25(t), was identified from Minghui 63, a restorer line for a number of rice hybrids that are widely cultivated in China. This gene conferred resistance to Philippine race 9 (PXO339) of X. oryzae pv. oryzae in both seedling and adult stages. It was mapped to the centromeric region of chromosome 12, 2.5 cM from a disease resistance gene-homologous sequence, NBS109, and 7.3 cM from a restriction fragment length polymorphism marker, G1314. The genomic location of this gene is similar to the previously identified blast resistance genes, Pi-ta and Pi-ta2.     

东北地区水稻种质资源抗纹枯病研究初报

为明确东北地区水稻种质资源对纹枯病的抗性, 收集了本地区水稻种质资源152份, 在苗期和分蘖期进行离体叶片接种; 在分蘖末期对79份种质进行了牙签嵌入法接种鉴定?结果表明, 供试的152份稻种资源中, 苗期离体叶片接种表现抗病的种质有2份, 中抗种质有42份?分蘖期离体叶片接种表现抗病的种质2份, 中抗种质8份; 进行牙签嵌入法接种鉴定的79份种质中, 表现中抗的种质16份?在苗期?分蘖期离体叶片接种?牙签嵌入法接种鉴定中均表现为中抗以上的种质仅有‘沈农9819’?分蘖期离体叶片接种和牙签嵌入接种法所获结果符合率最高, 为77.22%?     

不同水稻品种对条纹叶枯病抗(耐)病性比较

田间对比试验表明,供试7个水稻品种对条纹叶枯病的抗性可初步分为高抗、中抗、中感、高感4个类型。其中常优1号、常农粳3号抗病性较强,丰产性能也好。