小偃6号成株期高温抗条锈性遗传分析

为揭示小偃6号抗病机制和培育持久抗病品种,采用常规杂交分析方法,在小麦抽穗期利用小麦条锈菌小种CYR30、CYR32和Su11-4对小偃6号、铭贤169及其杂交F1、F2、F2∶3接种,平均气温达到21℃时对小偃6号进行了抗条锈性调查和遗传分析。结果显示,接种CYR30、CYR32时,F1代表现高感,F2代群体中抗感分离比例符合1 R∶15 S的理论比例。接种Su11-4时,F1代表现高抗,F2代群体中抗感分离比例符合3R∶1S的理论比例。研究表明小偃6号对CYR30、CYR32的抗病性均由2对隐性基因累加作用控制,对Su11-4的抗病性由1对显性基因控制。     

玉米自交系心叶期对亚洲玉米螟抗性遗传规律的研究初报

不同抗螟性亲本所组配的F_1代在玉米心叶期,对亚洲玉米螟 Ostrinis furnacalis(Guenée)抗性研究表明,玉米抗螟牲为数量遗传,亲本抗性在杂种后代中具有累加效应,杂种的抗性与双亲平均抗性呈高度正相关。中等以上抗性亲本组配的 F_1代为抗螟型。而以中抗系组配杂种时,不论父本或母本,只要一个亲本为感螟系,则 F_1代均为感螟型。不同水平抗性亲本组配的正反交组合 F_1代差异极显著。     

Differences in the responses of melon accessions to fusarium root and stem rot and their colonization by Fusarium oxysporum f. sp. radicis‐cucumerinum

Fusarium root and stem rot caused by the fungus Fusarium oxysporum f. sp. radicis‐cucumerinum is a major disease in greenhouse cucumbers. Over the past decade, the disease has been documented in melon greenhouses in Greece, and recently it has been sporadically recorded in greenhouse melons in Israel. Variations in disease response were found among 41 melon accessions artificially inoculated with the pathogen: 10 accessions were highly susceptible (90–100% mortality), 23 exhibited an intermediate response (20–86%) and eight were resistant (0–4%). Two melon accessions – HEM (highly resistant) and TAD (partially resistant) – were crossed with the susceptible accession DUL. The responses of the three accessions and F₁ crosses between the resistant and susceptible parents were evaluated. HEM contributed higher resistance to the F₁ hybrid than TAD. Roots of susceptible and resistant accessions were 100 and 79% colonized, respectively, following artificial inoculation. However, only susceptible plants showed colonization of the upper plant tissues. Microscopic evaluation of cross sections taken from the crown region of the susceptible DUL revealed profuse fungal growth in the intercellular spaces of the parenchyma and in xylem vessels. In the resistant cultivar HEM, very little fungal growth was detected in the intercellular spaces of the parenchyma, and none in the xylem or any other vascular tissue. Finding resistant accessions may create an opportunity to study the genetics of resistance inheritance and to develop molecular markers that will facilitate breeding resistant melon cultivars.     

Detection of single-base substitution in an esterase gene and its linkage to malathion resistance in the parasitoid Anisopteromalus calandrae (Hymenoptera: Pteromalidae)

Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) is an important parasitoid of stored-grain insect pests. Partial cDNA sequences of an esterase-like enzyme have been obtained from a malathion-resistant (R) strain and a susceptible (S) strain of this wasp. A single-base substitution in the R strain has been confirmed by using PCR amplification of specific allele (PASA) to amplify genomic DNA extracted from individual resistant and susceptible parents, F₁ hybrids from double reciprocal crosses, and progeny from backcrosses. The R allele appeared to be inherited in a strict Mendelian fashion in both diploid female and haploid male progeny. The esterase fragment co-segregated with resistance in these crosses and backcrosses. Female wasps in a mixed population of A calandrae that survived a malathion screen carried the R allele for the esterase-like enzyme, while those wasps that died did not have the R allele. The single base-pair mutation, guanine in the R strain and thymine in the S strain, presumably results in a tryptophan-to-glycine amino acid substitution in the encoded protein. We do not know how these amino acid substitutions may relate to functional differences in the enzyme. However, this esterase gene or another linked esterase gene may encode the resistance-associated malathion detoxifying activity in the R strain. © 1999 Society of Chemical Industry     

中国小麦条锈病菌鉴别寄主中4抗病基因遗传组成分析

中4是中国小麦条锈菌生理小种的重要鉴别寄主之一。采用常规杂交遗传分析法和花粉母细胞染色体镜检,明确中4抗条锈病基因遗传组成,并探讨利用中国春ph1b突变体分析小麦近缘属(种)抗条锈病基因。将中4分别与中国春ph1b突变体和感病品种铭贤169杂交,对亲本及其杂交后代进行苗期抗条锈性鉴定和遗传分析,发现中4对条锈菌小种CY31和CY32的抗病性由1对显性基因控制;通过等位性分析和抗谱比较,发现中4对小种CY32的抗病基因与T. spelta album、Moro及K733中的抗条锈病基因不同,对中国春ph1b突变体×中4组合的F2代植株染色体数目及其核型变化的研究表明,F2代单株的抗条锈性与来自中间偃麦草X组染色体增加有关,并导致F2单株染色体数目发生变化,且X组染色体在F2代群体对小种CY31表现为抗病和感病植株中随机分布。     

Inheritance of resistance to a Bacillus thuringiensis toxin in a field population of diamondback moth (Plutella xylostella)

Inheritance of resistance to the Bacillus thuringiensis Berl. CryIA(b) crystal protein was studied in Plutella xylostella L. (diamondback moth). A field population 50-fold more resistant to CryIA(b) than a control susceptible strain was used. Dose-mortality curves of the resistant population, the susceptible strain and the F₁ from the two reciprocal crosses were compared. Resistance transmission to the F₁ was dependent on the sex of the resistant progenitor. Sex ratio of the survivors to high doses of CryIA(b) in the F₁ of the two reciprocal crosses did not corroborate the preliminary hypothesis of resistance being due to a recessive sex-linked allele. Since, in a previous work, the loss of CryIA(b) binding capacity of resistant insects had been demonstrated, binding to midgut tissue sections from F₁ individuals was also analysed. The presence of binding in all of the F₁ preparations showed that, at least, a recessive autosomal allele was responsible for the loss of binding capacity in the resistant population.     

Identification of allele specific AFLP markers linked with bacterial wilt [Ralstonia solanacearum (Smith) Yabuuchi et al.] resistance in hot peppers (Capsicum annuum L.)

Even though the bacterial wilt is identified as the most destructive disease in hot peppers world-wide, robust molecular markers that facilitate marker assisted selection are absent till date. Kerala Agricultural University (India) has released two hot peppers named Ujwala and Anugraha which show high level field resistance to this pathogen. The variety Anugraha was developed through backcross breeding between a high yielding but highly susceptible variety Pusa Jwala with the highly resistant Ujwala, using Pusa Jwala as a recurrent parent. Thus, Pusa Jwala and Anugraha are near isogenic lines (NILs) differing for the resistance to bacterial wilt only and the resistance is governed by a homozygous recessive (rr) gene action. The F₁s of Anugraha × Pusa Jwala were selfed to generate the segregating F₂ population. The F₂ population has been field screened, 10 highly susceptible and 10 most resistant plants were identified and DNA from these plants were bulked separately. Bulked segregant analysis with AFLP primer combination EcoACT + MseCAC was done using the DNA from donor parent Ujwala, susceptible parent Pusa Jwala, resistant parent Anugraha, bulked susceptible F₂ and bulked resistant F₂ plants. On resolution using capillary electrophoresis system in genetic analyzer, the AFLP products have yielded three polymorphic bands (103, 117, and 161 bp) which were linked with the resistant recessive allele and three polymorphic bands (183, 296, 319 bp) linked with the dominant susceptible allele of the bacterial wilt resistance gene. The results were confirmed through co-segregation analysis in most resistant and susceptible plants of F₂ segregating population.     

Inheritance of mefenoxam resistance in Phytophthora nicotianae populations from a plant nursery

Three sexual crosses involving isolates of P. nicotianae with differing sensitivity to mefenoxam were established to study the inheritance of mefenoxam resistance. Mefenoxam sensitivity was determined by measuring the mycelial growth on both mefenoxam-amended clarified V8 agar and non-amended agar and then calculating the relative growth. When both parents had the same phenotype (both were resistant or both were sensitive), all F ₁ progeny had the parental phenotype and no segregation for a major effect gene was observed in sensitivity to mefenoxam. However, variations in the mycelial growth of progeny indicated the segregation of minor-effect genes. When the cross involving the mefenoxam-resistant isolate 3A4 and a sensitive parent, the F ₁ progeny segregated for mefenoxam resistance in a ratio of 1:1 (resistant: sensitive), indicating that the mefenoxam resistance is controled by a single dominant gene. Mating type was not linked to the mefenoxam-resistance gene locus. One RAPD marker linked in trans to the MEX locus was obtained by bulked segregant analysis using RAPD markers and was converted to a sequence characterized amplified region marker (SCAR). The SCAR maker identified in this study is a limited but useful tool for differentiating homozygous resistant isolates from sensitive isolates of P. nicotianae.     

弱光胁迫下黄瓜霜霉病抗性评价与分析

为明确弱光胁迫下黄瓜霜霉病田间发病规律及遗传特性,筛选抗霜霉病黄瓜品种,以15份黄瓜自交系为试材,在弱光条件下通过子叶接菌诱导寄主植株发病,同时结合田间发病率及病情指数调查进行复合抗性鉴定,进而筛选抗病组合,并对其分离世代进行抗性鉴定与遗传特征分析。结果表明,供试15份材料中共筛选出4个典型品系HB1、HB2、HB3和HB4,其病情指数分别是14.17、28.71、63.33和78.33,分别属于高抗、抗病、感病和高感病类型。这4个亲本的F1代及分离世代群体中霜霉病抗性与亲本抗性均存在正相关关系,抗性亲本的后代表现出较强的抗性;F2代群体病株分离现象比较明显,呈偏态分布,有明显的主基因+多基因存在特征,表明弱光胁迫下黄瓜霜霉病受主基因+多基因控制,主基因效应值较大。经田间抗病性鉴定分析,初步筛选出组合HB12、HB13和HB21为抗霜霉病组合,可用于后续抗病品种的选育。     

小麦纹枯病抗性及抗性遗传的初步研究

 从一个多亲本的复式杂交后代中,选育了4个高抗纹枯病的小麦新品系,编号为MN-3、7、18和19。抗病性鉴定证明,在对照品种绵阳19病株率100%,发病等级4~5级的情况下,这4个新品系的病株率和发病等级分别在3.65%~6.98%和0~1之间。这4个品系与高感纹枯病的小麦品种绵阳19杂交,在F2代群体中植株符合抗:感=3:1的分离比率,在隐性亲本的测交后代中符合1:1的分离比率;在这4个品系之间的杂交后代群体中未观察到抗性的分离。试验结果指出,4个品系均含有同一个抗小麦纹枯病的单显性抗病基因,该基因被命名为Ses 1。本研究指出了小麦抗纹枯病育种的可能性,并为进一步研究小麦宿主和纹枯病菌原的相互关系及其遗传学提供了材料。     

Inheritance of resistance to a new non‐steroidal ecdysone agonist,fufenozide, in the diamondback moth,Plutella xylostella (Lepidoptera: Plutellidae)

BACKGROUND: The diamondback moth (DBM), Plutella xylostella (L.), is a cosmopolitan pest of cruciferous crops. Fufenozide, a novel non‐steroidal ecdysone agonist, exhibits good efficacy and plays an increasingly important role in the control of Lepidopterous pests in China. A laboratory strain of DBM was selected for resistance to fufenozide, and the genetic basis of resistance was studied. RESULTS: The resistant strain, selected under laboratory conditions, exhibited a higher level of resistance to fufenozide (302.8‐fold based on LC₅₀s) than the laboratory susceptible strain. Mortality data from the testing of F₁ progeny of reciprocal crosses of resistant and susceptible DBM indicated that resistance was autosomal and incompletely recessive with a degree of dominance of ?0.664. Chi‐square analysis from responses of a backcross of crossed F₁ progeny and the resistant strain and F₂ progeny were highly significant, suggesting that the resistance was probably controlled by more than one gene. The estimated realised heritability (h²) of fufenozide resistance was 0.08, indicating that diamondback moth may have a lower chance of developing resistance to fufenozide than other kinds of insecticide. CONCLUSION: The resistance of DBM to fufenozide might be autosomal and incompletely recessive, and the resistance is probably controlled by more than one gene. These results provide the basic information for pest management programmes. Copyright © 2009 Society of Chemical Industry     

Molecular basis of resistance to acetolactate synthase-inhibiting herbicides in Sisymbrium orientale and Brassica tournefortii

Three Australian Sisymbrium orientale and one Brassica tournefortii biotypes are resistant to acetolactate synthase (ALS)-inhibiting herbicides due to their possession of an ALS enzyme with decreased sensitivity to these herbicides. Enzyme kinetic studies revealed no interbiotypic differences within species in K_m (pyruvate) (the substrate concentration at which the reaction rate is half maximal) but a greater V_max (the rate when the enzyme is fully saturated with substrate) for two of the resistant S orientale biotypes over susceptible levels. F₁ hybrids from reciprocal crosses between resistant and susceptible biotypes of S orientale showed an intermediate response to chlorsulfuron compared to the parental plants. ALS herbicide resistance in S orientale segregated in a 3:1 (resistant:susceptible) ratio in F₂ plants with a single rate of chlorsulfuron, indicating that resistance is inherited as a single, incompletely dominant nuclear gene. Two regions of the ALS structural gene known to vary in ALS-resistant biotypes were amplified and sequenced. Resistant S orientale biotypes NS01 and SS03 contained a single nucleotide substitution in Domain B, predicting a Trp (in susceptible) to Leu (in resistant) amino acid change. Two adjacent nucleotide substitutions (CC T to AT T) predicting a Pro (in susceptible) to Ile (in resistant) change in the primary amino acid sequence were identified in Domain A of resistant S orientale biotype SS01. Likewise, a single nucleotide substitution at the same site in the resistant B tournefortii biotype predicts a Pro (in susceptible) to Ala (in resistant) substitution. No other interbiotypic nucleotide differences predicted amino acid changes in the sequenced regions, suggesting that the amino acid substitutions reported above are responsible for resistance to ALS-inhibiting herbicides in the respective biotypes. © 1999 Society of Chemical Industry     

大麦抗条纹病基因的定位分析

为发掘大麦中抗条纹病的新基因,采用三明治法通过人工接种大麦条纹病菌Pyrenophora graminea强致病力菌株QWC对甘啤2号(免疫)与Alexis(高感)杂交F_1代及F_2代分离群体进行抗性遗传分析,利用群体分离分析法鉴定与抗病基因连锁的SSR标记,并通过QTL IciMapping软件构建遗传连锁图谱完成对抗病基因的定位。结果显示,甘啤2号与Alexis杂交F_1代对大麦条纹病菌强致病力菌株QWC表现为免疫,F_2代表现3∶1抗感分离,表明甘啤2号对菌株QWC的抗性由1个显性抗性基因控制,将该抗病基因暂命名为Rdg3;该基因位于大麦7H染色体上的SSR标记Bmag206和Bmag7之间,与二者的遗传距离分别为1.78 cM和2.86 cM。经与已定位于7H染色体上的抗病基因比较,发现Rdg3是一个新的抗条纹病基因,可作为大麦抗病育种的新种质资源。     

Beet armyworm (Spodoptera exigua) resistance to spinosad

Susceptibility to spinosad (Success®/Tracer®) of beet armyworm (Spodoptera exigua) from the southern USA and Southeast Asia was determined through exposure of second‐ and third‐instar larvae to dipped cotton leaves. LC₅₀ estimates of susceptibility of second‐ and third‐instar larvae of field populations ranged from 0.279 to 6.14 and 0.589 to 14.0 mg spinosad litre⁻¹, respectively. A Thailand population was 22‐ and 24‐fold less susceptible than the six other US field populations evaluated, and 85‐ and 58‐fold less susceptible than a reference laboratory population, respectively. From these results, we initiated experiments to test the hypothesis that the Thailand population was resistant to spinosad. F₁ crosses between the resistant Thailand population and a susceptible reference strain yielded individuals that were 22‐fold less sensitive to spinosad than the susceptible parent. This same resistant strain exhibited significantly greater survivorship on plants treated with spinosad in the field. Lastly, selection of an Arizona population resulted in a significant reduction in susceptibility to spinosad, further substantiating the hypothesis of a genetic basis for resistance to spinosad. These findings indicate a vulnerability of this new insecticide to resistance development in beet armyworm and should serve as a warning against excessive use of it. © 2000 Society of Chemical Industry     

Inheritance of Resistance to Leptosphaeria maculans in Brassica juncea

ABSTRACT The inheritance of resistance to Leptosphaeria maculans, the causal agent of black leg of crucifers, was studied in Brassica juncea. Three resistant accessions (UM3021, UM3043, and UM3323) and one susceptible accession (UM3132) of B. juncea were crossed in a complete diallel. Parents, F(1), and F(2) progenies were evaluated for all crosses using both cotyledon and stem inoculation. Cotyledon reaction was evaluated with two isolates of L. maculans, but stem reaction was evaluated with one isolate. Disease reactions observed for individual plants were the same for both inoculation methods and for both isolates of the pathogen for cotyledon reaction. No segregation was observed for the crosses between resistant accessions (UM3043 x UM3323 and UM3021 x UM3323), but a few susceptible plants were observed in the F(2) progeny of crosses between resistant parents (UM3021 x UM3043). This was probably due to heterozygosity in some parental plants of UM3021. For crosses be tween the susceptible parent and resistant parents, F(1) plants for two crosses were all resistant. For cross UM3132 x UM3021, some susceptible plants occurred, which was also suggestive of heterozygosity in UM3021. Although resistance in F(1) was dominant, for F(2) populations, segregation fit either 13:3, 3:1, or 1:3 ratios, indicating that resistance can be either adominant or recessive trait. F(3) families derived from some susceptible F(2) plants from crosses UM3021 x UM3132 and UM3043 x UM3132 were evaluated using the cotyledon inoculation method only. Segregation of F(2) plants and F(3) families in crosses involving resistant and susceptible parents indicated that the resistance to L. maculans in B. juncea is controlled by two nuclear genes with dominant recessive epistatic gene action.     

利用分子标记辅助选择技术提高玉米对丝黑穗病的抗性

为了探索分子标记辅助选择(MAS)技术在抗玉米丝黑穗病育种中的应用效果,以吉1037为抗源,吉单209的感病母本8902为轮回亲本,回交5代后,自交2代,从BC4F1开始利用MAS技术把感玉米丝黑穗病的亲本8902改良成抗病自交系,并与吉853配制杂交种,对其进行抗病性、产量和农艺性状评价。改良后的8902及其组合,对玉米丝黑穗病的抗性和产量显著提高,且其它农艺性状没有发生改变。抗性以上自交系超过获得材料的80%以上,抗性以上杂交组合超过配制组合的77%以上;改良后亲本组配的杂交种产量较对照明显增加,11个杂交组合增产10%以上,最大增幅可达26.7%。研究表明MAS技术显著提高了自交系及其杂交种对玉米丝黑穗病的抗病效果。     

SSR-based genetic linkage analysis of resistance to crown rust (Puccinia coronata f. sp. lolii) in perennial ryegrass (Lolium perenne)

Crown rust (caused by Puccinia coronata f. sp. lolii) is a serious foliar disease of the pasture and turfgrass perennial ryegrass (Lolium perenne). Previous genetic studies have detected both qualitative and quantitative resistance mechanisms, and interpretation of the genetic system is complicated by variation within the sexually reproducing pathogen. Resistant and susceptible parental genotypes of ryegrass were identified using a composite urediniospore population collected from three geographically distinct locations. A two-way pseudo-testcross mapping population was obtained as the F₁ progeny of the pair-cross between ryegrass parental genotypes Vedette₆ and Victorian₉. Both parents showed intermediate resistance against a pathogen population collected in a single geographical zone (Hamilton, Victoria), but in the F₁ population, significant variation for a range of resistance-associated characters was detected. Statistical analysis of phenotypic data suggested a major gene effect, hence bulked segregant analysis with map-assigned simple sequence repeat (SSR) markers was used to scan the genome. A marker showing strong association with resistance was assigned to linkage group (LG) 2 of perennial ryegrass. Analysis of 11 LG2 SSR markers defined an interval between loci xlpssrh03f03 and xlpssrk02e02 as containing the gene or genes (LpPc1) conferring crown rust resistance. Resistance gene determinants were inherited from both parents, with up to 80% of the total phenotypic variation explained by markers segregating from Vedette₆ and up to 26% of the variation explained by markers segregating from Victorian₉. The two contributions together resulted in an additive increase in effect, with fully resistant individuals requiring determinants from both parents. A conserved syntenic relationship was observed with linkage group B of Avena strigosa, which is the location of a cluster of resistance genes to the oat form of crown rust. The implications of this study for marker-assisted selection of disease resistance in perennial ryegrass are discussed.     

Resistance to quinclorac and ALS-inhibitor herbicides in Galium spurium is conferred by two distinct genes

Classical Mendelian experiments were conducted to determine the genetics and inheritance of quinclorac and acetolactate synthase (ALS)‐inhibitor resistance in a biotype of Galium spurium. Plants were screened with the formulated product of either quinclorac or the ALS‐inhibitor, thifensulfuron, at the field dose of 125 or 6 g active ingredient (a.i.) ha^?1 respectively. Segregation in the F₂ generation indicated that quinclorac resistance was a single, recessive nuclear trait, based on a 1 : 3 segregation ratio [resistant : susceptible (R : S)]. Resistance to ALS inhibitors was due to a single, dominant nuclear trait, segregating in the F₂ generation in a 3 : 1 ratio (R : S). The genetic models were confirmed by herbicide screens of F₁ and backcrosses between the F₁ and the S parent. F₂ plants that survived quinclorac treatment set seed and the resulting F₃ progeny were screened with either herbicide. Quinclorac‐treated F₃ plants segregated in a 1 : 0 ratio (R : S), hence F₂ progenitors were homozygous for quinclorac resistance. In contrast, F₃ progeny segregated into three ratios: 1 : 0, 3 : 1 and 0 : 1 (R : S) in response to ALS‐inhibitor treatment. This segregation pattern indicates that their F₂ parents were either homozygous or heterozygous for ALS‐inhibitor resistance. Therefore, there were clearly two distinct resistance mechanisms encoded by two genes that were not tightly linked as demonstrated by segregation patterns of the F₃.     

小麦抗白粉病基因Pm2的SSR标记筛选

为筛选与小麦抗白粉病基因Pm2紧密连锁的分子标记,将感病品种Chancellor与Pm2的近等基因系杂交,获得F1、F2分离群体,采用分离群体分组法对Pm2进行了微卫星(microsatellite,又称simple sequence repeats,SSR)标记分析.结果表明,定位于小麦5D染色体上的71对SSR引物中有12对引物能在Pm2的近等基因系、Chancellor间稳定地揭示出多态性差异,7对引物Xcfd189、Xcfd29、Xcfd8、Xcfd102、Xcfd7、Xcfd57和Xgwm190分别能在抗病、感病池间和F2分离群体的抗病、感病单株间稳定地扩增出特异性产物.7对引物所扩增的特异谱带分别为:Xcfd189360、Xcfd29190、Xcfd8160、Xcfd102250、Xcfd7200、Xcfd57245和Xgwm190210,它们与Pm2基因间的遗传距离分别为0、1.5、2.3、5.4、10.2、31.5和54.3 cM,其中标记Xcfd189360与Pm2共分离,标记Xcfd29190、Xcfd8160和Xcfd102250与Pm2紧密连锁,可用于Pm2的标记辅助选择.     

小麦抗源武汉2号和品冬34的抗条锈性遗传分析

为明确小麦品种武汉2号和品冬34对小麦条锈菌流行小种的抗病性及抗病遗传规律,用小麦条锈菌生理小种CYR29、CYR31、CYR32、CYR33以及致病类型Su11-4、Su11-5、Su11-11、PST-Ch42在苗期接种小麦品种武汉2号和品冬34进行抗病性鉴定,并用武汉2号和品冬34分别与感病亲本铭贤169进行杂交,对F₂群体和F_2：3家系在温室进行苗期遗传分析。结果表明：武汉2号对CYR29和CYR32表现感病,对其它小种和致病型均表现抗病,且对CYR31的抗性由1对隐性基因控制;品冬34对所测试的小种和致病类型均表现高抗,且对CYR32的抗性由1对显性基因控制。