香蕉枯萎病菌pacC基因的克隆与序列分析

采用PCR和RT-PCR方法扩增尖孢镰刀菌古巴专化型(Fusarium oxysporum f sp.cubense,FOC)1号和4号生理小种的pacC基因(FOC1-pacC,FOC4-pacC),对FOC1-pacC和FOC4-pacC相似序列进行搜索和比对,以及对基因编码蛋白进行结构预测,发现FOC1-pacC和FOC4-pacC开放阅读框分别为1 863、1 905 bp,编码634、620个氨基酸,2个小种之间基因序列和氨基酸序列差异明显,FOC1-pacC比FOC4-pacC缺少1个基因片段,FOC-pacC与其相似序列有显著差异,比对缺少2个基因片段;初入侵转录组表达分析说明,2生理小种pacC基因在小种侵染不同品种香蕉过程中表达有差异,FOC1-pacC基因只在粉蕉中检测到表达,而FOC4-pacC则在粉蕉和香蕉中都检测到表达,但在粉蕉中的表达量明显高于香蕉。     

Assessment of latent infection frequency in progeny tubers of advanced potatoclones resistant to bacterial wilt: A new selection criterion

Summary This paper reports results of a 3-year evaluation of CIP advanced potato clones in a bacterial wilt-infested field (race 3) in Peru. Clones resistant or moderately resistant to wilt were selected and all tubers harvested from each clone were tested for latent infection byRalstonia solanacearum using a sensitive serological technique developed at CIP. A sampling strategy to estimate accurately the frequency of infected tubers in the clones has been evaluated. This method will allow consideration of tuber latent infection as a new selection criterion in breeding for resistance to bacterial wilt. Thirteen clones were found resistant to wilt in all three evaluations (i.e.≤6% wilt), from which five had no wilt in all trials. However, all clones harboured latent infection in tubers averaging 30%. Analysing 30 tubers/clone provides an accurate estimation of the proportion of infected tubers with a high precision level.     

Wild tuber-bearing species ofSolanum and incidence ofPhytophthora infestans (Mont.) de Bary on the Western slopes of the volcano Nevado de Toluca. 5. Type of resistance toP. infestans

Summary Plants of wildSolanum species (S. demissum (dms), S. verrucosum (ver), S. iopetalum (iop), S. brachycarpum (bra), and an unidentified species (unsp), from the natural habitat were inoculated in the laboratory withPhytophthora infestans race 0, to see if major genes for resistance were present, and with the most complex and aggressive race available in an attempt to reveal the level of general resistance. No plant with a susceptible reaction to race 0 was found in 120 plants ofdms, and 34 plants ofunsp. Plants with a hypersensitive reaction to race 0 and susceptible plants were found inver. When infected with a complex aggressive isolate of the fungus 73.5% of the WSS plants were susceptible. It was concluded that WSS in the area possess both complex race specific resistance and a high level of general resistance, whose effects cannot yet be separated.     

Bacterial wilt resistance in the progenies of the fusion hybrids between haploid of potato andSolanum commersonii

Bacterial wilt of potatoes, which used to be a widespread disease in tropics and subtropics, has become a threat to potato production in temperate region. The diploid species Solanum commersonii has several desirable characteristics including cold tolerance and resistance to several diseases. Selected somatic hybrids between S. tuberosum dihaploid and bacterial-wilt-resistant S. commersonii clones were cross pollinated with S. tuberosum cultivars for further selection of bacterial wilt resistance. The chromosome numbers of the fusion parents were confirmed as 24, and the three fusion hybrids crossed were all tetraploids. The chromosome number of 11 backcross 1 progenies (BC1) was 48 and that of the other six was close to the tetraploid number. Backcross 2 progenies (BC2) were obtained from only three of the 44 BC1 clones crossed. The S. commersonii parent clone, LZ3.2, was the most resistant to bacterial wilt among wild species clones tested. The first sexual progenies segregated for resistance, with one clone highly susceptible and four clones highly resistant. Three highly resistant BC1 clones, CT02-4, CT08-4, and CT10b-4, were backcrossed to cultivars. Two cross combinations produced mostly susceptible BC2 progenies; however seven clones were resistant or highly resistant for both race 1 and race 3. The highly resistant three clones, CT204-3, CT206-9 and CT206-10, were selected for the further testing as cultivars or breeding materials.     

Interactions betweenPotato leafroll virus and potato plants and their implications for assessment of infection resistance

The effects of Potato leafroll virus (PLRV) isolates and inoculation method on the resistance to PLRV in potato clones and cultivars were investigated. In the season of inoculation, aphid inoculation resulted in higher proportions of infected plants and higher virus concentration in infected plants, as compared to graft inoculation. In these respects, grafting showed superiority over aphid inoculation in the tuber progeny of inoculated plants, though distinct dominance of aphid inoculation was observed for some tested clones. This leads to the conclusion that both methods should be applied as complementary tests for the efficient selection of highly resistant potato clones. For inoculations, two isolates of PLRV were applied, and one of them, isolate L7, was routinely used in screening breeding materials for resistance to the virus. The second isolate originated from plants of the highly resistant clone DW84-1457, which were incidentally infected with PLRV. The virus isolated from these plants was able to infect only specific clones, which were resistant to isolate L7. At the same time, potato clones with resistance derived from a source different from that present in DW84-1457, and standard susceptible and resistant cultivars, showed generally lower infection ratings after inoculation with the new isolate. This result suggests that the isolates may be different strains of PLRV. It is possible that under the strong selection pressure of resistance genes present in clone DW84-1457, a new isolate I-1457 could evolve the ability to overcome resistance to infection controlled by these genes.     

Latent infection of potato tubers byPseudomonas solanacearum

Strains ofPseudomonas solanacearum differed in their ability to infect tubers of different resistant potato clones grown in infested soil. When eight resistant clones (Solanum phureja orS.phureja ×S. tuberosum hybrids) were grown at 24–28°C in soil infested with a race 1 or a race 3 strain of the bacterium, relatively few plants had wilt symptoms at harvest, but 26.7% and 9.2% of the tubers harvested from plants infected with the race 1 and race 3 strains, respectively, carried latent infections. Some infected clones never yielded diseased tubers, however. The development of symptoms above ground was not correlated with the incidence of tuber infection in any particular clone. No tuber infection occurred in tolerant or resistant clones grown in infested soil at cool (12–22°C) temperatures. Tubers were inoculated directly in an attempt to evaluate the ability of bacteria to multiply in these tissues at different temperatures. Highly virulent strains ofP. solanacearum survived in susceptible tubers in higher numbers and for longer periods than in resistant ones. Low temperature (4°C) had a deleterious effect on survival of the bacterium in tubers, but did not completely eliminate the pathogen even after 40 days.     

大豆花叶病毒诱导的野生大豆抑制差减文库构建及初步分析

以野生大豆Bian0526为试验材料,通过抑制性差减杂交技术(SSH)构建了大豆花叶病毒(SMV)诱导的cDNA 差减文库.在文库中共筛选到15343个阳性克隆,PCR鉴定插入片段大部分集中在500～800 bp之间.利用BLAST 在GenBank文库中进行序列相似性比对,获得有功能的EST 200个.对有功能注释的...     

辣椒酵母单杂交系统的建立及调控CaWRKY40表达的转录因子分离

辣椒CaWRKY40的转录表达受到病原菌和高温的诱导并在辣椒抗青枯病以及耐高温中起着重要的作用,但其应答青枯菌侵染和高温胁迫表达的调节机制还不清楚。为了进一步分离调节CaWRKY40表达的转录因子,建立辣椒酵母单杂交cDNA文库,以CaWRKY40启动子的青枯病原菌及高温应答区域CaWRKY40p(W40p)为诱饵,筛选cDNA文库,共获得56个阳性克隆。序列分析结果表明,有27个克隆为非重复序列,对其推定氨基酸序列进行同源比对和功能结构域分析,发现有1个推定转录因子,即ARF（Auxin response factor）,以及其他蛋白如eIF（Eukaryotic initiation factor,真核起始因子）,EF（延伸因子,Elongation factor）等。进一步通过染色质免疫共沉淀验证这些转录因子与W40p的结合。剖析CaWRKY40表达的分子机制有利于深入解析CaWRKY40介导的辣椒抗病及耐高温分子机制。     

Differential response of Cucumis melo to Fusarium oxysporum f. sp. melonis race 1.2 isolates

Fusarium wilt incited by Fusarium oxysporum f. sp. melonis (Fom) causes severe losses in melon crops. Four physiological races of Fom have been identified: 0, 1, 2 and 1.2. In most cases, resistance to race 1.2 has been described as recessive, polygenic and not race specific. However, some evidence of race-specific effects within melon resistance to race 1.2 has been reported. In this work, we study these effects and assess whether they are due to race-specific resistance. Seeds were obtained from 14 melon accessions that exhibit some level of resistance to race 1.2, and from the lines ‘Charentais-Fom1’ (resistant to races 0 and 2), ‘Charentais-Fom-2’ (resistant to races 0 and 1), and ‘Dinero F₁’ (with partial resistance to Fom race 1.2). Melon seedlings were artificially inoculated using two different procedures: ‘continuous shaking’ and ‘tray immersion’. Symptom severity was assessed on leaves using a rating scale from 0 (no symptoms) to 4 (death of the plant). Symptoms were recorded weekly over the four-week period following the first appearance of symptoms and the area under the disease progress curve (AUDPC) was calculated. Six Fom isolates (3 from pathotype Y and 3 from pathotype W) were used in the inoculation. The less aggressive ‘tray immersion’ procedure seems to be more appropriate for detecting the typically small resistance factors of this type of polygenic partial resistance. ‘Kogane Nashi Makuwa’, ‘BG-5384’, ‘Shiro Uri Okayama’, ‘C-211’ and the control, ‘Dinero F₁’, showed a high level of resistance to all Fom isolates. However, some genotype × isolate effects were also detected. ‘Baza’, when inoculated with isolate Fom 9302, and ‘Korça, when inoculated with Fom 37mls.1.2W, showed resistance levels similar to that of ‘Dinero F₁’; this effect was not observed when ‘Baza’ and ‘Korça’ were inoculated with other isolates. These results are characteristic of race-specific resistance and offer evidence for the presence of this type of resistance to Fom race 1.2 in melons.     

海南桑树青枯病病原菌鉴定及其分子鉴定

桑树青枯病是由青枯雷尔氏菌引起的细菌性病害,热带、亚热带地区发病严重,严重影响蚕桑产业的可持续发展。雷尔氏菌不同种间致病力和宿主各不相同,其防治策略也相应不同,准确地分离鉴定病原菌是青枯病有效防控的先决条件。本研究采集、分离了海南省琼中县桑青枯病发病桑园（‘桂桑优62’）桑树根部、茎部病原菌,并通过致病性、生理小种、生化变种测定,结合16S rDNA、特异性引物、复合PCR检测体系、序列变种等分子鉴定方法初步确定了病原菌的种类和分类地位。结果表明,引发海南省琼中县桑青枯病的病原菌属于青枯雷尔氏菌（Ralstonia solanacearum）、生理小种5（race 5）、生化变种Ⅴ（biovar Ⅴ）,病原菌遗传进化分析结果显示病原菌属演化型Ⅰ（phylotype Ⅰ）即亚洲分支菌株,序列变种12（sequevar 12）。这些结果将为海南桑青枯病的有效防控奠定基础。     

Potential for soybean rust tolerance among elite soybean lines in Uganda

Soybean rust, (Phakopsora pachyrhizi), currently the most devastating disease of soybeans worldwide, is known to challenge single resistance genes deployed against it and therefore, disease tolerance is indisputably the most viable measure in controlling the pathogen. Studies were conducted at Namulonge in Central Uganda to assess the level of tolerance to soybean rust among selected elite soybean lines. Seven elite lines together with three local checks were tested in a split-plot design where some plots were protected with fungicide to estimate the level of tolerance to soybean rust. The experiment was conducted for three cropping seasons beginning second rains of 2005. A rust tolerance index (RTI) was computed for each test line as the ratio of yield from unprotected plots to yield from protected plots. The study showed that high levels of tolerance to soybean rust were present in the test lines. The soybean lines that showed high levels of tolerance included MNG 10.3 and MNG 3.26 all showing RTIs higher than 0.93. These lines also out-yielded the local checks by about 400 kg ha⁻¹ and are recommended for multi-location testing.     

Maturity-Adjusted Resistance of Potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.) Cultivars to Verticillium Wilt Caused by <Emphasis Type="Italic">Verticillium dahliae</Emphasis>

Verticillium wilt is a fungal disease of potato caused by two species of Verticillium, V. dahliae and V. albo atrum. The pathogen infects the vascular tissue of potato plants through roots, interfering with the transport of water and nutrition, and reducing both the yield and quality of tubers. We have evaluated the reaction of 283 potato clones (274 cultivars and nine breeding selections) to inoculation with V. dahliae under greenhouse conditions. A significant linear correlation (r = 0.4, p < 0.0001) was detected between plant maturity and partial resistance to the pathogen, with late maturing clones being generally more resistant. Maturity-adjusted resistance, that takes into consideration both plant maturity and resistance, was calculated from residuals of the linear regression between the two traits. Even after adjusting for maturity, the difference in the resistance of clones was still highly significant, indicating that a substantial part of resistance cannot be explained by the effect of maturity. The highest maturity-adjusted resistance was found in the cv. Navajo, while the most susceptible clone was the cv. Pungo. We hope that the present abundance of data about the resistance and maturity of 283 clones will help potato breeders to develop cultivars with improved resistance to V. dahliae.     

二倍体马铃薯群体青枯病抗性鉴定及遗传分析

将含有青枯病抗性基因的马铃薯二倍体solanumphureja和s.vernei的原始材料E与另外两种材料C、D杂交获得F1和BC1两个群体。对其中140个基因型做温室苗期人工接种鉴定,结果表明,马铃薯青枯病的群体抗性分离变异范围较大,抗病性表现复杂,主要表现为阻止病菌入侵,推迟始发病时间,延长潜伏期,减缓发病速度和降低死亡率等5个方面。对抗病性相关参数分析表明,马铃薯青枯病抗性是受隐性多基因控制的。     

小麦干热风抗性鉴定及热胁迫相关基因TaHSPs的表达分析

为鉴定黄淮麦区小麦品种干热风抗性以及不同抗性品种热激蛋白(TaHSPs)基因的表达差异,以98个小麦品种为试验材料,于花后10~20d进行人工模拟干热风处理,通过测定小麦不同生长时期的叶绿素含量、收获后的千粒重与籽粒品质,评价不同品种干热风抗性;对筛选出的干热风抗性不同的品种在出苗15d进行热胁迫处理,通过荧光定量PCR测定热胁迫0~4.5h内TaHSPs基因表达量的变化。结果表明,干热风处理后,供试小麦品种旗叶的叶绿素含量均降低,高抗干热风品种降幅较小,热敏感型品种降幅较大;供试小麦品种的千粒重均降低。山农23号等3个品种达到高、中抗干热风等级,且抗性比较稳定,师栾02-1为热敏感型品种。干热风处理后籽粒蛋白质含量升高,总淀粉含量降低,抗干热风小麦品种总淀粉相对含量降幅较小。不同小麦品种幼苗在热胁迫0~4.5h期间,TaHSPs基因表达量均为抛物线趋势,抗干热风品种在热胁迫1h时TaHSP16.9基因表达上调幅度大于热敏感型品种。对于TaHSP17.8基因,抗干热风品种在热胁迫期间,上调表达反应时间均早于热敏感型品种;在热胁迫0.5h时,山农23号、周麦18与泰山9818三个抗干热风品种基因表达均上调至590倍以上,而师栾02-1与济南17号的上调幅度在300倍以下。对于TaHSP23.6基因,山农23号的上调表达峰值远高于其他品种。对于TaHSP26.6基因,热敏感型品种在热胁迫后期的上调倍数高于抗干热风品种,师栾02-1与济南17号两个热敏感型品种在热胁迫4.5h时上调幅度均在4 000倍以上,而抗干热风品种山农23号、周麦18与泰山9818上调幅度均在3 000倍以下。     

苦瓜枯萎病抗性材料 Thai4-6 的遗传模型分析

苦瓜枯萎病是尖孢镰刀菌苦瓜专化型引起的真菌病害,探明苦瓜枯萎病的抗性遗传机制对制定抗病育种策略具有现实指导意义。本文以抗枯萎病苦瓜材料 Thai4-6 和感病材料 CN19-1 为亲本配制杂交组合,基于该组合 6 世代遗传群体（P1、P2、F1、F2、BCP1 和 BCP2）,采用主基因+多基因混合遗传模型分析枯萎病抗性遗传特性。 数据分析结果表明,该杂交组合的枯萎病抗性呈连续分布,最适模型为 2 对加性-显性-上位性主基因+加性-显性多 基因遗传模型（E-1）,2 对主基因加性效应值均为–13.85,显性效应值分别是 25.58 和 34.26,主基因遗传率在 BCP1、 BCP2 和 F2 中分别是 86.03%、80.34%和 94.25%,表明该组合枯萎病抗性主要受 2 对主基因控制。环境因素引起的 变异在 3 个分离世代群体中分别占 13.97%、14.06%和 5.75%。本研究可为抗枯萎病苦瓜育种提供理论依据。     

Late blight resistance in the British Neo-Tuberosum potato population

Summary Development of the British Neo-Tuberosum population included selection for resistance to late blight. High levels of foliage resistance are most often found in later-maturing clones but some early-maturing clones have good resistance. Resistance of foliage to Race 4 and to a complex race is associated. Some clones give variable results in tests for resistance in tubers. While those consistently displaying resistance are most frequent among those with resistant foliage, some have rather susceptible foliage. Tuber resistance appears most common among early maturing clones but this could be misleading, perhaps being due to tubers of later-maturing clones tending to be immature when tested (resistance often increasing as tubers mature). However some ‘lates’ are resistant, suggesting that genes for resistance in immature tubers occur. Selections are being used experimentally as parents in breeding for blight-resistant cultivars, and controlled breeding within Neo-Tuberosum to produce superior parents has commenced.     

Resistance toPseudomonas solanacearum in potato: Infectivity titrations in relation to multiplication and spread of the pathogen

When several wilt-resistant potato clones were tested against a highly virulent strain from Mexico (No. 276) by standard stem inoculation methods, only one clone ofSolanum phureja was resistant. When different inoculum concentrations were introduced quantitatively for infectivity titrations, however, different levels of resistance were clearly defined among clones previously rated as susceptible. Linear regression was used to estimate the ED₅₀ values (dosage required to wilt 50% of the population) for each of seven clones. These values ranged from 3 and 100 colony-forming units (CFU) for Katahdin and Russet Burbank, respectively, to 2.1 x 10⁶ CFU for S.phureja clone 1386.15. The distribution of bacteria in stems of Russet Burbank plants inoculated with the compatible strains 276 and K-60 and the incompatible strains B1 and S-210 was very different. In all cases, incompatible bacteria were not detected 10 cm above the inoculation point in the stem, even by 12 days after inoculation, whereas compatible strains multiplied rapidly at this site by 6 days. At the inoculation site and at sites immediately adjacent to it, however, incompatible bacteria attained populations that only differed by one order of magnitude from those of compatible bacteria. Similar results were obtained when a resistant clone (MS 118.24) was inoculated with the virulent strain K-60. Thus, resistance was characterized both by reduced acropetal spread and by tolerance to large numbers of the bacterium.     

中国棉花枯萎病的研究与防治

棉花枯萎病是影响棉花生产的毁灭性病害之一,近年来在我国有加重发展的趋势。本文全面系统的回顾了自我国成立棉花枯黄萎病综合防治研究协作组以来在棉花枯萎镰孢菌生理小种鉴定,抗病育种等方面所取得的成果。并重点介绍了年近来我国在枯萎病防治研究中所取得的成就。     

The Race Structure of the Rice Blast Pathogen Across Southern and Northeastern China

Background

Rice blast, caused by the ascomycete Magnaporthe oryzae (Mo), imposes a major constraint on rice productivity. Managing the disease through the deployment of host resistance requires a close understanding of race structure of the pathogen population.

Results

The host/pathogen interaction between isolates sampled from four Mo populations collected across the rice-producing regions of China was tested using two established panels of differential cultivars. The clearest picture was obtained from the Chinese cultivar panel, for which the frequency of the various races, the race diversity index, the specific race isolate frequency, and the frequency of the three predominant races gave a consistent result, from which it was concluded that the pathogen population present in the southern production region was more diverse than that in the northeastern region. The four blast resistance genes Pi1, Pik, Pik-m, and Piz all still remain effective in the southern China rice production area, as does Pi1 in the northeastern region. The effectiveness of Pita, Pik-p, Piz, and Pib is restricted to single provinces. The distinctive resistance profile shown by the Chinese differential cultivar set implied the presence of at least five as yet unidentified blast resistance genes.

Conclusions

The Chinese differential cultivar set proved to be more informative than the Japanese one for characterizing the race structure of the rice blast pathogen in China. A number of well characterized host resistance genes, in addition to some as yet uncharacterized ones, remain effective across the major rice production regions in China.

     

高温胁迫下茄子耐热性表现及耐热指标的筛选

对7份茄子材料分别进行室内高温鉴定和田间自然高温鉴定,并探讨2种鉴定方式的相关性,以筛选适宜、快速、准确的鉴定指标。结果表明：除可溶性糖外,幼苗热害指数、细胞膜相对电导率、脯氨酸含量、丙二醛（MDA）可有效的评价不同茄子幼苗的耐热性。田间高温条件下,经室内鉴定为耐热品种的正常花率和坐果率均高于不耐热品种。经相关分析结果可知,各品种的正常花率和坐果率与苗期热害指数、细胞膜相对电导率、脯氨酸含量、MDA含量呈显著性相关。本研究结果表明细胞膜相对电导率、脯氨酸含量、MDA及热害指数可作为茄子耐热性快速鉴定的指标。