Effect of mate selection on fuzzy selective mating criteria in closed dairy multiple ovulation and embryo transfer nucleus programs

In order to control rates of response and inbreeding, mate selection using fuzzy selective mating criteria (FMC) was investigated in adult multiple ovulation and embryo transfer nucleus schemes for dairy cattle. Stochastic simulation was used to model the closed nucleus scheme. This mate selection was examined in four alternative mating and male selection schemes: (i) a hierarchical scheme; (ii) a hierarchical sibship scheme (two males per sibship); (iii) a factorial scheme (two sires per dam); and (iv) a factorial sibship scheme (two males per sibship and two sires per dam). Genetic response and inbreeding rate tended to be reduced by increasing the trade-off parameter of FMC between the expected breeding value and inbreeding of progeny. Inbreeding rates in all schemes were reduced by reducing the variance of family size through selection and the average coancestry of mating pairs through mate allocation.     

The Biology of the Larger Grain Borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

After about 25 years of intensive research a substantial moment of information has accumulated on the basic biology of Prostephanus truncatus in stored products. This article reviews the literature on the geographical distribution, biotypes, symbiotic associations, mating and flight behaviour, oviposition, and development on both agricultural and non-agricultural hosts. The current knowledge about the nutritional biology (including the role of symbionts) and host finding behaviour (including the inter-linked roles of plant chemicals and the insect's own pheronones) are highlighted as research areas which deserve future attention. In addition, few studies have been conducted to determine the extent to which the biology of P. truncatus permits it to survive and reproduce in non-agricultural environments. These areas of study should be pursued as possible routes to providing more effective integrated pest managements strategies for the larger grain borer.     

Potential of sexual reproduction among host-adapted populations of Phytophthora infestans sensu lato in Ecuador

To determine the potential of sexual reproduction among host-adapted populations of Phytophthora infestans sensu lato in Ecuador, 13 A1 isolates belonging to clonal lineages US-1, EC-1 and EC-3, and 11 A2 isolates belonging to the clonal lineage EC-2, were paired on agar plates to induce crossing. In the first experiment, six A1 isolates (three US-1, two EC-1 and one EC-3) were each crossed with three A2 isolates (total = 18 crosses). Matings involving isolates of the EC-1 lineage produced more oospores of healthy appearance than did matings with isolates of US-1 or EC-3. In the second experiment, the oospores of 35 crosses (21 EC-1 × EC-2; 10 US-1 × EC-2; four EC-3 × EC-2) were dispersed on water agar to assess oospore germination. Overall, germination percentages were low. Only one cross produced enough progeny for evaluation. Twenty-three single-oospore offspring were isolated and evaluated for mating type; electrophoretic patterns of glucose-6-phosphate isomerase ( Gpi ) and peptidase ( Pep ) alloenzyme loci; mitochondrial DNA haplotype; and genomic DNA fingerprint. Multilocus genotype data indicated that all 23 isolates resulted from meiotic recombination. Four progeny with homothallic phenotype appeared to be unstable heterokaryons. Markers at several loci segregated according to simple Mendelian expectations for a diploid organism, but the ratios of three RFLP loci and the Pep locus were not consistent with Mendelian expectations. All progeny were nonpathogenic on hosts of the parental genotypes. Reduced mating success and reduced pathogenic fitness of progeny appear to be postmating mechanisms of reproductive isolation in populations of P. infestans sensu lato in Ecuador.     

云南省马铃薯晚疫病菌的交配型、抗药性及生理小种分布的研究

 从云南省陆良县、建水县和南涧县采集2000年秋播的马铃薯晚疫病标本,分离获得124个致病疫霉菌株,连同1999~2000年分离自昆明、曲靖等地的春播马铃薯晚疫病的10个菌株共134个,采用常规技术对这些菌株进行了交配型、抗药性及生理小种的研究。交配型测定结果为:陆良县的18个菌株中有3个为A₂交配型,其余15个菌株为A₁交配型,建水县和南涧县的106个菌株及昆明、曲靖1999~2000年的10个菌株都是A₁交配型。测定了83个菌株对瑞毒霉(metalaxyl)和烯酰吗啉(dimethomorph)的抗药性,结果有12.0%的菌株对瑞毒霉表现抗性,16.9%表现中抗,71.1%表现敏感,其中陆良、昆明和曲靖的抗瑞毒霉菌株的比例大于建水和南涧的抗药性菌株的比例;所测定的83个菌株都对烯酰吗啉表现敏感。生理小种鉴定结果表明,云南晚疫病菌为3.4、0、3和4生理小种,分别占鉴定菌株总数的48.0%、32.5%、15.6%和3.9%。但南涧仅发现3.4和0小种,而昆明有0、3、3.4和4小种,陆良有0、3和3.4小种,可见昆明和陆良地区的晚疫病菌生理小种比南涧地区的生理小种的组成更趋多样。     

大麦杂种优势利用研究,Ⅲ.大麦异棱型和同棱型F1杂种的杂种优势特征

研究了大麦4种杂交类型（含二棱×二棱、二棱×六棱、六棱×二棱和六棱×六棱）的F₁杂种的性状表现和优势特征，比较了同棱型相配组（二棱×二棱和六棱×六棱）和异棱型相配组（二棱×六棱和六棱×二棱）的超高亲优势（H_h）组合数及其出现率。研究性状包括株高、穗长、穗下节间长、穗数、粒数、粒重、籽粒产量、籽粒蛋白质含量和赖氨酸含量等13个.结果表明,(1)二棱×二棱杂种的穗长较长、每株穗数较多、千粒重较高；六棱×六棱杂种的每穗粒数、每株粒数较多、籽粒产量较高；而异棱型相配杂种则比同棱型相配组有较高的株高、穗下节间长和千粒重。（2）4种杂交类型杂种的类型内杂种间变异，在大多数性状上均为同质，仅有株高、穗长和主穗粒数在六棱×六棱杂种中变异增大，有较大的选择潜力。（3）在13个数量性状中，有9个性状的H_h优势出现率与杂交类型显著关联；株高、穗下节间长和千粒重的H_h优势出现率在二棱×六棱和/或六棱×二棱杂种中最高，而主穗粒数、每穗粒数、每株粒数、每粒重和每株干重的H_h优势出现率则在六棱×六棱和/或六棱×二棱杂种中最高。（4）异棱型相配组杂种的株高、穗下节间长和千粒重的Hh优势率显著高于同棱型相配组杂种，依次为20/30对8/33、30/30对18/33和22/30对5/33；但同棱型相配组杂种籽粒产量的H_h优势率显著高于异棱型相配组杂种，为10/33对2/30。说明异棱型杂种易产生生物量和千粒重优势，而同棱型杂种易产生籽粒产量优势。     

Effect of Pheromone Blend Components,Sex Ratio,and Population Size on the Mating of Cadra cautella (Lepidoptera: Pyralidae)

The almond moth Cadra cautella (Walker), a key pest of storage facilities, is difficult to manage using synthetic chemicals. Pheromone-based management methods remain a high priority due to advantages over conventional management practices, which typically use insecticides. Cadra cautella females release a blend of pheromone including (Z, E)-9,12-tetradecadienyl acetate (ZETA) and (Z)-9-tetradecadien-1-yl acetate (ZTA). The effect of these components on mating of C. cautella and how response varies with the population density and sex ratio remain unknown. In this study, the mating status of C. cautella was studied inside mating cages under different ratios of ZETA and ZTA diluted in hexane and at different population sizes either with equal or unequal sex ratio. The lowest percentage of mated females (highest mating disruption [MD] effects), corresponding to roughly 12.5%, was produced by a 5:1 and 3.3:1 ratio of ZETA:ZTA. Populations with equal sex ratio showed the lowest percentage of mated females, at 20% and 12.5% under lower and higher density, respectively. The next lowest percentage of mated females was produced when the sex ratio was set to 1: 2 and 2:1 male:female, with just 25% and 22.5% of moths mated, respectively. This study shows that mating status of C. cautella is influenced by ZETA:ZTA ratio, sex ratio, and population size. This current knowledge would have useful implications for mating disruption programs.     

黑龙江省稻瘟病菌育性及其交配型分析

为明确黑龙江省采集自不同年份、不同地区的稻瘟病菌Magnaporthe oryzae的育性能力和交配型分布,采用2株标准菌株GUY11(MAT1-2)和KA3(MAT1-1)对2016—2017年黑龙江省西部、东部、中部3个地区经单孢分离的241株稻瘟病菌进行育性测定,并利用PCR技术对其交配型进行检测。结果表明,黑龙江省西部、东部、中部的241株稻瘟病菌中可育性菌株比例为11.62%,其中雌性菌株、雄性菌株、两性菌株分别占1.66%、4.56%和1.25%,不能判断其性别的未知菌株占4.15%。采集自不同地区、不同年份的稻瘟病菌可育性差异均较大,西部、东部、中部地区可育性菌株出现频率分别为13.25%、7.27%和12.62%;2016年采集的稻瘟病菌可育性较高,可育性菌株出现频率为25.30%。黑龙江省稻瘟病菌群体中同时存在MAT1-1和MAT1-2两种交配型,主要以交配型MAT1-1占优势,出现频率为58.92%,交配型为MAT1-2的菌株出现频率为8.30%。不同地区稻瘟病菌的交配型亦有差异,交配型为MAT1-1的菌株在黑龙江省东部地区出现频率最高,为72.73%,在中部、西部地区的出现频率次之,分别为61.17%和46.99%。表明黑龙江省水稻种植区的稻瘟病菌同时存在2种交配型菌株,其交配型存在丰富的多态性,但其可育性及交配型分布不均衡。     

玉米大斑病菌和小斑病菌交配型多重PCR 检测方法的建立与应用

【目的】由大斑突脐蠕孢（Exserohilum turcicum）和玉蜀黍平脐蠕孢（Bipolaris maydis）引起的玉米大斑病和小斑病是玉米生产上重要的叶部真菌病害,本研究旨在建立玉米大斑病菌和小斑病菌交配型多重PCR检测方法,为玉米大斑病菌和小斑病菌的交配型田间分布和有性生殖研究提供技术方法。【方法】根据GenBank中已登录的玉米大斑病菌（登录号MAT1-1：GU997138和MAT1-2：GU997137）和小斑病菌（登录号MAT1-1：X68399和MAT1-2：X68398）交配型基因序列,利用Primer Premier 5.0软件设计2种病原菌交配型多重PCR检测特异性引物,采用单因素法对引物的退火温度以及扩增程序中延伸时间和循环数等重要参数进行优化,建立玉米大斑病菌和小斑病菌交配型多重PCR检测方法,并对2种病原菌的交配型多重PCR检测灵敏度和特异性进行检验。同时,对田间采集的129株玉米大斑病菌和194株玉米小斑病菌单孢菌株的交配型进行多重PCR检测,以明确建立的交配型多重PCR检测方法的适用性。【结果】建立的多重PCR方法和设计的交配型特异引物StMAT01-2F/R、StMAT02-3F/R、ChMAT01-3F/R和ChMAT02-2F/R可分别扩增出MAT1-1、MAT1-2型菌株大小为816、132 bp（大病斑菌）与490、136 bp（小病斑菌）的特异性目的条带。25 μL多重PCR扩增体系：2×Multiplex PCR Mix 12.5 μL,引物各10 pmol,DNA模板100 ng,退火温度为57.2℃（大病斑菌）和55.0℃（小斑病菌）,35个循环。该多重PCR对玉米大斑病菌MAT1-1、MAT1-2型单孢菌株的检测灵敏度分别为0.1、0.01 ng基因组DNA,而对玉米小斑病菌MAT1-1、MAT1-2交配型的检测灵敏度均为0.1 ng基因组DNA。该交配型多重PCR检测方法对玉米大斑病菌和小斑病菌特异性很强,能够很好地区分玉米大斑病菌和小斑病菌相应的近缘种和14株其他真菌菌株。不同地理来源的玉米大斑病菌和小斑病菌交配型检测结果表明,该多重PCR能够准确地检出129株玉米大斑病菌和194株玉米小斑病菌的交配型,且检测结果与随机抽取的菌株杂交验证结果完全吻合。【结论】构建的玉米大斑病菌和小斑病菌交配型多重PCR检测方法灵敏度高、特异性好、操作简便,能够准确、快速地检测出玉米大斑病菌和小斑病菌的交配型,为玉米大斑病菌和小斑病菌的交配型田间分布和监测及有性生殖研究提供了可靠的技术方法。     

番茄对番茄晚疫病抗性遗传分析

试验利用04957(感),04968(感),L3708(抗)和Wva700(抗)4个抗感不同的番茄品种,按Griffing(Ⅰ)完全双列杂交方法配置组合,接种番茄晚疫病,调查发病情况进行分析。结果发现:①不同品种、不同组合间抗病性存在极显著差异;②供试品种间一般配合力和特殊配合力存在极显著差异,Wva700,L3708具有较高的一般配合力效应,二者在配制抗性组合时是较为优良的杂交亲本。Wva700×04957,Wva700×04968组合特殊配合力最高,有进一步研究利用的价值;③抗性遗传中加性效应是主要的,同时存在部分显性,存在细胞质效应;④广义遗传力为90.64%,狭义遗传力为81.48%,均较高,说明亲代对后代的影响作用较大,抗性基因可以通过基因累加的方式在后代中表现出来,宜早代选择。     

High vegetative compatibility diversity of Cryphonectria parasitica infecting sweet chestnut (Castanea sativa) in Britain indicates multiple pathogen introductions

Chestnut blight, caused by Cryphonectria parasitica, was identified in Devon, UK, in December 2016. Intensive surveys detected the disease at further sites in Devon (seven), Berkshire (one), Dorset (one), Derbyshire (four) and a cluster of eight sites in southeast London. Over 570 survey samples were tested, and 227 were positive for C. parasitica by isolation and real-time PCR. A total of 227 isolates were tested for mating type, and 197 screened for vegetative compatibility group (VCG) and compared with VCGs known from mainland Europe. The same isolates were also screened for the presence of Cryphonectria hypovirus 1 (CHV-1). Eleven VCGs were identified within the UK population. Five corresponded to already known European VCGs but six were unique. The European VCGs mainly came from the Devon, Dorset, Berkshire and Derbyshire disease outbreaks, whilst unique VCGs were almost exclusively from the southeast London cluster. Both mating types were detected, but only one mating type was present at each site, with the exception of a single Devon site. Perithecia of C. parasitica were never observed at any site. CHV-1 was found in seven isolates from three different locations and was always subtype-I, which has limited hypovirulence. Therefore, although CHV-1 is associated with C. parasitica at some outbreaks, it probably has limited impact on virulence. The diversity of VCGs and their distribution at outbreak sites, together with findings of CHV-1, suggests C. parasitica has been introduced to the UK multiple times over at least two decades through international plant trade.