梨种质对梨火疫病的抗性研究

针对未来梨火疫病侵入我国的风险,采用幼果人工接种鉴定技术,对保存的54份梨种质资源进行梨火疫病抗性评价。通过接种后的症状鉴别、再分离细菌的分子检测,证明有16份种质对梨火疫病表现感病,其中9份为中国种质,7份为引进种质。中国的37份（80．4％）梨种质表现抗梨火疫病,而引进种质中表现抗病的仅有1份（12．5％）。结果初步表明,在中国梨种质中可能存在较丰富的抗梨火疫病资源;东方梨的抗性较西方梨更强;而在梨的地方品种中蕴藏着良好的抗病性。     

Identification of Novel QTLs for Isolate-Specific Partial Resistance to Plasmodiophora brassicae in Brassica rapa

Plasmodiophora brassicae, the causal agent of clubroot disease of the Brassica crops, is widespread in the world. Quantitative trait loci (QTLs) for partial resistance to 4 different isolates of P. brassicae (Pb2, Pb4, Pb7, and Pb10) were investigated using a BC₁F₁ population from a cross between two subspecies of Brassica rapa, i.e. Chinese cabbage inbred line C59-1 as a susceptible recurrent parent and turnip inbred line ECD04 as a resistant donor parent. The BC₁F₂ families were assessed for resistance under controlled conditions. A linkage map constructed with simple sequence repeats (SSR), unigene-derived microsatellite (UGMS) markers, and specific markers linked to published clubroot resistance (CR) genes of B. rapa was used to perform QTL mapping. A total of 6 QTLs residing in 5 CR QTL regions of the B. rapa chromosomes A01, A03, and A08 were identified to account for 12.2 to 35.2% of the phenotypic variance. Two QTL regions were found to be novel except for 3 QTLs in the respective regions of previously identified Crr1, Crr2, and Crr3. QTL mapping results indicated that 1 QTL region was common for partial resistance to the 2 isolates of Pb2 and Pb7, whereas the others were specific for each isolate. Additionally, synteny analysis between B. rapa and Arabidopsis thaliana revealed that all CR QTL regions were aligned to a single conserved crucifer blocks (U, F, and R) on 3 Arabidopsis chromosomes where 2 CR QTLs were detected in A. thaliana. These results suggest that some common ancestral genomic regions were involved in the evolution of CR genes in B. rapa.     

Minor Differences in Anther Extrusion Affect Resistance to Fusarium Head Blight in Wheat

Fusarium head blight (FHB) remains a serious problem due to yield loss and mycotoxin accumulation in wheat production worldwide. We previously reported that the closed‐flowering (no anther extrusion) characteristic was effective for increasing resistance to FHB infection. In this study, we investigated the relationships between the degree of anther extrusion (AE) and FHB damage using double haploid lines (DHLs), derived from F₁ plants from crosses between closed‐flowering and opened‐flowering varieties. These DHLs exhibited various degrees of AE, and the degree of AE was significantly different among DHLs, regardless of the year and environment (pot‐ or field‐grown). FHB severity was the lowest in closed‐flowering DHLs, and DHLs with partially extruded anthers showed significantly higher FHB symptoms than those with closed‐flowering phenotypes. In general, DHLs with partially extruded anthers also had relatively severe FHB symptoms compared with those exhibiting full anther extrusion. FHB severity was significantly correlated with Fusarium‐damaged kernels and deoxynivalenol concentration. The results of this study showed that partially extruded anthers were considered to be a source of FHB infection. The closed‐flowering phenotype improved resistance to FHB infection. Meanwhile, phenotypes with rapid anther extrusion and ejection also could contribute to the avoidance of FHB infection.     

水稻抗白叶枯病基因及其应用研究进展

由黄单胞菌水稻变种Xanthomonas oryzae pv.Oryzae（Xoo）引起的白叶枯病是水稻重要病害之一。目前,已有37个水稻白叶枯抗性基因被鉴定并报道,其中28个被定位到染色体上,7个被克隆。本文简要综述了水稻白叶枯抗性基因的鉴定、定位和克隆的进展,并讨论了合理利用抗性基因防治白叶枯病的前景。     

26个水稻新品种（系）对白叶枯病抗性的鉴定和评价

采用菲律宾10个代表菌株和我国V型菌代表菌株在植株的分蘖初期和孕穗期人工接种,鉴定和评价近年选育的26个“绿色超级稻”品种（系）对白叶枯病的抗性。结果表明多数品种在分蘖初期和孕穗期对病菌的抗感水平相同,少数品种接种在孕穗期接种部分菌株后的病斑长度小于苗期。此外,新黄占、华201S-1 和XF10450在分蘖初期和孕穗期接种10个菌株后的病斑长度均小于5cm,具有高度的广谱抗性;其它品种对不同菌株的抗性水平不同,黄华占、旱优113、新两优3411和天优145对4-5个菌株表现抗病,旱优75、旱优715和009067对测试的10-11个菌株高度感病;其它品系对所有菌株表现中度感病或感病。 关键词：水稻品种;白叶枯病;抗性     

黄瓜枯萎病抗性基因的连锁分子标记

黄瓜枯萎病是危害我国黄瓜的主要病害。本实验以黄瓜抗枯萎病亲本WIS2757和感枯萎病亲本津研2号及其F2代分离群体为试材,采用分离群体分组分析法(BSA)进行了与黄瓜抗枯萎病基因连锁的分子标记研究。AFLP分析表明:引物对P15M5扩增出的特异DNA片段P15M5-310与WIS2757黄瓜枯萎病抗性基因连锁,遗传距离为7cM。     

Identification of QTLs Conferring Resistance to Deltamethrin in Culex pipiens pallens

Culex pipiens pallens is the most abundant Culex mosquito species in northern China and is an important vector of bancroftian filariasis and West Nile virus. Deltamethrin is an insecticide that is widely used for mosquito control, however resistance to this and other insecticides has become a major challenge in the control of vector-borne diseases that appear to be inherited quantitatively. Furthermore, the genetic basis of insecticide resistance remains poorly understood. In this study, quantitative trait loci (QTL) mapping of resistance to deltamethrin was conducted in F₂ intercross segregation populations using bulked segregation analysis (BSA) and amplified fragment length polymorphism markers (AFLP) in Culex pipiens pallens. A genetic linkage map covering 381 cM was constructed and a total of seven QTL responsible for resistance to deltamethrin were detected by composite interval mapping (CIM), which explained 95% of the phenotypic variance. The major QTL in linkage group 2 accounted for 62% of the variance and is worthy of further study. 12 AFLP markers in the map were cloned and the genomic locations of these marker sequences were determined by applying the Basic Local Alignment Search Tool (BLAST) tool to the genome sequence of the closely related Culex quinquefasciatus. Our results suggest that resistance to deltamethrin is a quantitative trait under the control of a major QTL in Culex pipiens pallens. Cloning of related AFLP markers confirm the potential utility for anchoring the genetic map to the physical map. The results provide insight into the genetic architecture of the trait.     

番茄抗青枯病基因的AFLP分子标记

用番茄高抗青枯病品种“T51A”与高感青枯病品种“T9230”配制杂交组合,接种鉴定其正反交Ｆ₁代及Ｆ₂代分离群体的青枯病发生情况。结果表明,T51A对青枯病的抗性属于细胞质遗传,受1对杂合基因加性控制。用64个EcoRＩ/ＭseＩ引物组合对“T51A”、“T9230”两个亲本及其Ｆ₂代抗病和感病基因池进行AFLP分析,共扩增出约4200条可分辨的带,其中2条为稳定的差异。用“T51A”和“T9230”杂交产生的Ｆ₂代分离群体对2个特异条带与目的基因的遗传连锁性进行分析,发现特异条带AAG/CAT与暂定名为RRS-342的抗青枯病基因紧密连锁,二者之间的遗传距离为6.7 cM。将AAG/CAT片段回收、克隆和测序,成功地将其转化为SCAR标记,可以更加方便地用于对番茄青枯病基因的标记辅助选择。      

杂交水稻亲本明恢63对纹枯病水平抗性的QTL定位

利用240份源于组合珍汕97／明恢63的重组自交群体（F11、F12）,连续两年进行2重复的随机区组田间试验,运用改进的纹枯病人工接种鉴定的方法,调查其纹枯病病级,结合该组合F9群体构建的分子标记遗传连锁图谱,运用区间作图法对抗纹枯病QTLs进行了定位。两年在第5染色体的相邻区间C624－C246（1999年）和C246－RM26（2000年）上各检测到一个抗纹枯病QTL,两者一个LOD值置信区间存在较大的重叠,而且LOD峰值位点很接近,推测它们可能是同一个QTL。两年在第9染本上均检测到一个QTL,分别位于C472－R26389（1999年）和RM247－RM242（2000年）区间上,两区间相距9．8cM。两年检测到的所有抗纹枯病QTLs均业自明恢63。     

马铃薯青枯病抗性的共性AFLP标记的初步定位

利用集群分类法(bulked segregant analysis,BSA)对与马铃薯青枯病(Ralstonia solanacearum)抗性连锁的分子标记进行了分析。以马铃薯青桔病高抗性的原始栽培种Solanum phureja获得的二倍体群体为作图群体进行AFLP标记的初步筛选,另选一个与作图群体有较大亲缘关系和相近遗传背景的二倍体群体对所获标记进行验证。在标记鉴定过程中使用了共性AFLP标记(common AFLP marker)的方法。通过与已构建的连锁图谱的比较分析,获得了4个与马铃薯青枯病抗性相关的4个AFLP标记ATG／CTC 307．0,ATG／CTC 246．0,ATG／CTC191．0和AAC／CAC 79．0．将其分别定位于染色体1和12上,可望应用于其它相关研究。     

广西玉米种质资源对纹枯病的抗性鉴定

在人工接种条件下,对860份玉米材料进行了纹枯病抗性鉴定和评价,旨在为进一步开展玉米纹枯病抗性育种和分子生物学研究奠定基础。结果显示,在鉴定的860份玉米材料中,没有发现免疫的材料,高抗、抗、中抗、感和高感的比例分别为3.49%、28.60%、26.16%、10.35%和31.40%;在农家种、群体种和杂交种（组合）等杂合体中,抗病材料所占比例较大,而自交系等纯合体中,感病材料所占比例较大,表明玉米杂合体种质资源材料中可能蕴藏着不同的抗纹枯病基因,特别是广西农家种中可能存在对纹枯病具有稳定抗性的材料,值得进一步研究和利用。     

广西玉米种质资源对纹枯病的抗性鉴定

在人工接种条件下,对860份玉米材料进行了纹枯病抗性鉴定和评价,旨在为进一步开展玉米纹枯病抗性育种和分子生物学研究奠定基础。结果显示,在鉴定的860份玉米材料中,没有发现免疫的材料,高抗、抗、中抗、感和高感的比例分别为3．49％、28．60％、26．16％、10．35％和31．40％;在农家种、群体种和杂交种（组合）等杂合体中,抗病材料所占比例较大,而自交系等纯合体中,感病材料所占比例较大,表明玉米杂合体种质资源材料中可能蕴藏着不同的抗纹枯病基因,特别是广西农家种中可能存在对纹枯病具有稳定抗性的材料,值得进一步研究和利用。     

水稻抗白叶枯病基因的鉴定、定位和克隆进展

由水稻黄单胞菌水稻变种Xoo引起的水稻白叶枯病是全球性的重要病害之一。已有31个水稻白叶枯抗性基因被鉴定并报道,其中18个被定位到染色体上,5个被克隆。简要综述了水稻白叶枯抗性基因的鉴定、定位和克隆的进展,并讨论了合理利用抗性基因防治白叶枯病的前景。     

两个抗水稻纹枯病主效数量基因的鉴定

纹枯病是水稻的重要病害之一。水稻对纹枯病的抗性被认为是一种数量性状 ,迄今没有发现较高水平的抗源。由于该病原菌 (ＲｈｉｚｏｃｔｏｎｉａｓｏｌａｎｉＫｕｈｎ)腐生性强 ,寄主范围宽 ,且病害发生发展受田间小气候影响大 ,因而抗性遗传研究的难度较大。我们构建了特青 Ｌｅｍｏｎｔ的 1 1 5个Ｆ2 代无性系 ,用改进的抗性鉴定方法 ,进行了抗纹枯病基因的初步定位 ,在第 9和第 1 1染色体上各发现了 1个抗纹枯病主效ＱＴＬ :...     

Estimating Skin Resistance to Gas Diffusion in Apples and Potatoes

Banks, N. H. 1985. Estimating skin resistance to gas diffusionin apples and potatoes.?J. exp. Bot. 36: 1842-1850.Two typesof analysis of the rate of efflux of pre-ndash;loaded ethanefrom apples and potatoes into a container of known volume werecompared as methods for estimating skin resistance to gas diffusion(R). An 'exponential model' was fitted to transformed data obtainedover a 24 h period whereas a 'linear model' was fitted to rawdata obtained over a 100 s period. R values for individual applesobtained using the two methods were in close agreement. R washigher in Golden Delicious than in Discovery apples but valuesfor individual fruit within each variety were quite variable.The exponential analysis was unsuitable for estimating R inpotatoes but the linear analysis yielded reproducible R estimates.A computer simulation of ethane efflux from an 'ideal' organshowed that varying the size of container used in either analysisin the range of 250-9000 cm³ would have no detrimental effectson estimates of R. Key words: Skin resistance, gas diffusion, apples, potatoes     

Identification and Fine Mapping of rhm1 Locus for Resistance to Southern Corn Leaf Blight in Maize

rhm1 is a major recessive disease resistance locus for Southern corn leaf blight (SCLB).To further narrow down its genetic position,F 2 population and BC 1 F 1 population derived from the cross between resistant (H95 rhm) and susceptible parents (H95) of maize (Zea mays) were constructed.Using newly developed markers,rhm1 was initially delimited within an interval of 2.5 Mb,and then finally mapped to a 8.56 kb interval between InDel marker IDP961-503 and simple sequence repeat (SSR) marker A194149-1.Three polymorphic markers IDP961-504,IDP B2-3 and A194149-2 were shown to be co-segregated with the rhm1 locus.Sequence analysis of the 8.56 kb DNA fragment revealed that it contained only one putative gene with a predicted amino acid sequence identical to lysine histidine transporter 1 (LHT1).Comparative sequence analysis indicated that the LHT1 in H95 rhm harbors a 354 bp insertion in its third exon as compared with that of susceptible alleles in B73,H95 and Mo17.The 354 bp insertion resulted in a truncation of the predicted protein of candidate resistance allele (LHT1-H95 rhm).Our results strongly suggest LHT1 as the candidate gene for rhm1 against SCLB.The tightly linked molecular markers developed in this study can be directly used for molecular breeding of resistance to Southern corn leaf blight in maize.     

西瓜品种资源的蔓枯病抗性鉴定与评价

对收集引进的42份西瓜品种资源进行了大田成株期及室内苗期蔓枯病抗性的人工接种鉴定。各品种苗期和成株期抗病性的鉴定结果表明,这些品种中没有免疫和高抗的品种,苗期和成株期抗病性表现一致,较好的品种有5个,其中中抗的品种有3个,分别是从美国引进的Au-producer、All-sweet scarlet和Au-Jubilant;耐病品种2个,分别是Sugarlee和SSDL。其中,有8个品种表现较强的综合抗病性,兼具优质、高糖、高产、耐贮及早熟等优良农艺性状,可以作为抗病、优质、早熟西瓜新品种选育的亲本材料。     

小麦抗白粉病基因Pm6的RAPD标记

从提莫菲维小麦转移到普通小麦中的小麦白粉病抗性基因Ｐｍ６是小麦白粉病（Ｅｒｙｓｉｐｈｅ ｈｒａｍｉｎｉｓ ｆ ｓｐ．ｔｒｉｔｉｃｉ）的有效抗性基因。用７００个随机引物对Ｐｍ６近等基因系进行ＲＡＰＤ分析,发现引物ＯＰＶ２０可在抗病近等基因系中产生大小为２ｋｂ的稳定的多态片段。用该引物检测１０个其他携Ｐｍ６的渐渗系材料,均可稳定扩增出该２ｋｂ的多态片段。理一步用ＯＰＶ２０对Ｐｍ６Ｆ２（ＩＧＶ１－４６３