玉米重要自交系的肿囊腐霉茎腐病抗性鉴定与评价

由肿囊腐霉菌(Pythium inflatum Matthews)引起的玉米茎腐病是影响玉米产量的一种重要病害。为进一步拓展可利用的抗源,于2010-2011年在田间采用人工接种方法对287份重要的玉米自交系种质进行了玉米茎腐病的抗性鉴定评价。结果表明,287份鉴定材料中有171份自交系对茎腐病的抗性达到中抗以上水平,占鉴定材料的59.58%,其中高抗自交系共43份,占鉴定材料总数的14.98%;感病类型自交系共116份,占鉴定材料的40.42%,其中高感自交系共95份,占鉴定材料总数的33.10%。Lancaster、Reid及P群种质中具有丰富的茎腐病抗源,而塘四平头种质群中茎腐病抗源相对缺乏,多为感病类型。该研究结果可为今后我国玉米茎腐病抗性种质的引进和改良提供重要参考。     

玉米大斑病抗性遗传的研究进展

由于大斑病生理小种的变异,致使原来抗大斑病的玉米品种丧失抗性,对玉米生产造成严重危害,至今已经发现大斑病菌生理小种5个。玉米对大斑病的抗性可分为多基因控制的数量性状和显性单基因控制的质量性状,前者涉及玉米的10条染色体;后者包括t1、Ht2、Ht3、HtN等基因。本文对大斑病生理小种变化,玉米大斑病抗性单基因（Ht）的来源、遗传特点、染色体定位以及数量抗性基因的QTL分析等研究进展作了综述。 Abstract:As the rapid variation and mutation of the races of Exserohilum turcicum (Helminthosporium turcicum),maize varieties lost their resistance to northern corn leaf blight (NCLB) disease caused by new races of E.Turcicum.This brought the disaster in maize production.Up to now 5 races have been found.The maize resistance to E.turcicum can be divided into quantitative and qualitative resistance,the former is associated with 10 chromosomes in maize,and the later includes genes of t1、Ht2、Ht3 and HtN.The race variation of E.turcicum,the original gene resources and genetic characteristics of each Ht monogenic resistance,the chromosome location of t1、Ht2、HtN genes,and the QTL analysis of quantitative resistant genes for E.turcicum in maize were reviewed in this paper.     

桑树对花叶病抗性遗传规律的研究

用7个母本、5个父本品种,按NCII杂交设计,进行桑树对花叶病抗性的遗传分析。首次证明：桑树对花叶病的抗性具有数量遗传特点,符合加性－显性模型,主要受加性基因控制,广义遗传力和狭义遗传力中等,一般配合力显示绝对优势,具有超显性现象。母本品种含有比父本品种更多的显性基因。 Abstract　Seven maternal and five paternal varieties of mulberry were used in inheritance experiment by NCII mating design. Genetic study of mulberry resistance to the mosaic disease was carried out. The results showed for the first time that mulberry resistance to the mosaic disease showed charateristics of quantitative inheritance, it tallied with the model of additive-dominance, it was mainly controlled by additive genes. Broad heritability and narrow heritality were moderate. The general combining ability showed absolute superiority. The resistance showed overdominant phenomenon. The maternal variety had more the dominance gene than paternal.     

玉米株型对遗传增益的影响

在相同条件下,以黄淮夏玉米区60-90年代10个玉米单交种为样本,研究了玉米产量遗传增益及株型性状的改良趋势。结果表明:(1)玉米单交种产量的遗传增益为68.98%;(2)6个株型性状的遗传改良效应依次为:叶向值>叶角>穗位高>穗位/株高>株高>单株叶面积;(3)叶向值、穗位高的显著改良提高了玉米的耐密、耐肥和抗倒伏等群体适应性,而影响单株籽粒产量的单株叶面积和株高等性状的遗传改良进展不大。 Abstract:Experiments in 1994 and 1995 were conducted to inrestigate the effects of hybrid maize on grain production in Huang Huaisummer maize area and the improvement trend in plant-type traits.The value of genetic gain of hybrid on grain production was 68.98 percent from 1963 to 1989.The effects of genetic gain on six plant-type traits showed as follows:leaf direction>leaf angle>height of ear-seat>ratio of ear-seat to plant height>plant height>leaf area.The significant improvements of leaf direction and height of ear-seat may enhance the tolerance capacity of hybrid maize to closely planting,high fertilization and plant-lodging.The progress,however,in improving leaf area and plant height for increasing grain production was not significant.In this article,the scheme on maize improvement in China is briefly discussed.     

Disease Resistance in Maize and the Role of Molecular Breeding in Defending Against Global Threat

Diseases are a potential threat to global food security but plants have evolved an extensive array of methodologies to cope with the invading pathogens. Non-host resistance and quantitative re- sistance are broad spectrum forms of resistance, and all kinds of resistances are controlled by extremely diverse genes called "R- genes". R-genes follow different mechanisms to defend plants and PAMP-induced defenses in susceptible host plants are referred to as basal resistance. Genetic and phenotypic diversity are vital in maize (Zea mays L.); as such, genome wide association study (GWAS) along with certain other methodologies can explore the maximum means of genetic diversity. Exploring the complete genetic archi- tecture to manipulate maize genetically reduces the losses from hazardous diseases. Genomic studies can reveal the interaction be- tween different genes and their pathways. By confirming the specific role of these genes and protein-protein interaction (proteomics) via advanced molecular and bioinformatics tools, we can shed a light on the most complicated and abstruse phenomena of resistance.     

玉米籽粒性状的遗传效应分析

采用二倍体胚和三倍体胚乳种子遗传模型及其分析方法,以5个玉米自交系及其配制的F1,F2,BC1,BC2世代为材料,研究5个玉米种子性状的胚直接效应、胚乳直接效应、母体效应和细胞质效应。分析结果表明,除粒宽外,各性状的遗传同时由细胞质效应和胚、胚乳、母体基因效应所控制,百粒重主要受胚乳和母体效应的影响,粒长的遗传以母体效应为主,粒宽和粒厚以胚乳效应为主。各部位籽粒百粒重的胚乳直接加性效应与母体加性效应的协方差达到显著或极显著水平,其余性状的胚、胚乳直接效应与母体效应间的协方差均不显著,通过母体植株的遗传表现可以对这些性状进行有效的选择。S22 是改良百粒重的优良亲本。 Abstract：The embryo,endosperm and cytoplasm effects of seven seed traits were studied by genetic model for diploid embryo and triploid endosperm plant seeds using five inbreds and their F1, F2, BC1 and BC2 generations. The estimates of genetic variance components indicated that the inheritance of all other kernel traits was controlled by the four effects except kernel width. The 100?kernel weight was mainly controlled by endosperm and maternal effects , and kernel length was controlled by the maternal effects,while endosperm conrrolled kernel width and kernel thickness. Except the significant or highly significant covariances between the endosperm direct additive and maternal additive effects for 100－kernel weight,all other traits between the embryo or endosperm direct effect and the maternal were not significant. So,maize inbreds could be developed by direct selection based on maternal plants for these traits. S22 was the best inbred of the improvement for kernel weight in this study.     

Quantitative genetic analysis of chlorophyll a fluorescence parameters in maize in the field environments

Chlorophyll fluorescence transient from initial to maximum fluorescence("P" step) throughout two intermediate steps("J" and "I")(JIP‐test) is considered a reliable early quantitative indicator of stress in plants. The JIP‐test is particularly useful for crop plants when applied in variable field environments. The aim of the present study was to conduct a quantitative trait loci(QTL) analysis for nine JIP‐test parameters in maize during flowering in four field environments differing in weather conditions. QTL analysis and identification of putative candidate genes might help to explain the genetic relationship between photosynthesis and different field scenarios in maize plants. The JIP‐test parameters were analyzed in the intermated B73 Mo17(IBM) maize population of 205 recombinant inbred lines. A set of 2,178 molecular markers across the whole maize genome was used for QTL analysis revealing 10 significant QTLs for seven JIP‐test parameters, of which five were co‐localized when combinedover the four environments indicating polygenic inheritance and pleiotropy. Our results demonstrate that QTL analysis of chlorophyll fluorescence parameters was capable of detecting one pleiotropic locus on chromosome 7, coinciding with the gene gst23 that may be associated with efficient photosynthesis under different field scenarios.     

Proteins Related to the Biocontrol of Pythium Damping-off in Maize with Trichoderma harzianum Rifai

Induced resistance has been evidenced as one of mechanisms of Trichoderma to control plant diseases, however, no study showed the change of host proteomics in Trichoderma-induced resistance of maize against damping-off caused by Pythium ultimum Trow. The mechanism of Trichoderma harzianum Rifai for controlling maize seedling disease caused by Pythium ultimum Trow was investigated firstly by proteome technique and the result suggested that T. harzianum strain T22 was not only able to promote seedling growth but also protein accumulation. One-dimensional electrophoresis assay showed that more bands appeared on the gel with T22 or T22 combined with P. ultimum （T22 ＋ P. ultimum） treatment than with other treatments. Enzyme assay showed that two chitinases of the root sample were more activated in the treatments with T22 than in the other treatments without T22. Proteins in the seedling roots from the various treatments were separated through protein extraction and 2-D electrophoresis technique. In the seedlings produced from the T22-treated seeds, there were 104 up-regulated proteins and 164 down-regulated proteins relative to the control, and 97 and 150, respectively, aftel treatment with T22 ＋ P. ultimum; however, with P. ultimum alone the values were much lower than with the other two treatments. The correlation coefficient values were 0.72, 0.51 and 0.49 for the comparison of protein spot distribution on gel among control with T22, P. ultimum and T22 ＋ P. ultimum, respectively. So it seemed that P. ultimum infection was more effective than T22 in interfering with the host proteome profile. Furthermore, analysis with MALDITOF-MAS showed that some important proteins associated with defensive reactions were identified in T22 or T22 ＋ P. ultimum treatments, including endochitinase, pathogenesis-related protein PRMS （pathogenesis-related maize seed）, GTP-binding protein, isoflavone reductase and other proteins related to respiration. All those proteins are probably part of the network of resistance or development-related proteins. Interestingly, P. ultimum treatment resulted in elimination of pathogenesis-related protein PRMS on gel, and therefore damping-off could be in part attributed to inhibition of the expression of this protein by P. ultimum infection. Some unknown proteins are also related to the defensive reaction of the host.     

Identification of genes contributing to quantitative disease resistance in rice

Despite the importance of quantitative disease resistance during a plant’s life, little is known about the molecular basis of this type of host-pathogen interaction, because most of the genes underlying resistance quantitative trait loci (QTLs) are unknown. To identify genes contributing to resistance QTLs in rice, we analyzed the colocalization of a set of characterized rice defense-responsive genes and resistance QTLs against different pathogens. We also examined the expression patterns of these genes in response to pathogen infection in the parents of the mapping populations, based on the strategy of validation and functional analysis of the QTLs. The results suggest that defense-responsive genes are important resources of resistance QTLs in rice. OsWRKY45-1 is the gene contributing to a major resistance QTL.NRR,OsGH3-1,and OsGLP members on chromosome 8 contribute alone or collectively to different minor resistance QTLs. These genes function in a basal resistance pathway or in major disease resistance gene-mediated race-specific pathways.     

二个粳稻品种抗稻瘟病遗传特性的分析

本文用累积分布曲线法对东农 363及农东415两个粳稻品种进行了抗稻瘟遗传分析,结果表明东农363对Hokul菌株的抗性是由一对显性抗性基因控制的,东农415对Ken53-33菌株的抗性是由两对互补的显性基因控制的;对Ina72菌株的抗性是由两对显性基因控制的,其中一对控制高抗反应,另一对控制中抗反应。两个杂交组合的正反交分析结果表明,水稻对稻瘟病菌的抗性遗传是由细胞核控制的,细胞质在抗瘟遗传中的作用在本试验的测试品种中并没有表现出来。 Abstract:By means of cumulative distribution curve methods,two Japonica varieties Dongnong 363 and Dongnong 415 were analysed for the inheritance of blast resistance.The results showed that the resistance of Dongnong 363 variety to Hokul blast strain was controlled by one dominant gene.The resistance of Dongnong 415 to Ken53-33 strain was controlled by two complementary dominant genes,to Ina72 strain was controlled by two dominant genes,one dominated over the high-resistant and the other over the middle-resistant.Genetic analysis of F3 plants of two reciprocal crosses showed that the resistance to the rice blast disease was controlled by nuclear gene,no cytoplasmic effect was found in the tested varieties.     

Inheritance of resistance to ear damage caused by Sesamia nonagrioides (Lepidoptera: Noctuidae) in maize

Sesamia nonagrioides Lefebvre is a major insect pest of maize (Zea mays L.) in northwestern Spain. The inheritance of ear resistance in field corn to this pest has not been studied. This work aims to determine the importance of genetic (additive, dominance, and epistatic effects) and environmental effects in the inheritance of ear resistance to S. nonagrioides. Three field corn inbreds (CM109, EP31, and EP42) were used as parents and two crosses (CM109 x EP31 and CM109 x EP42) were made. These inbreds show different ear resistance levels to S. nonagrioides, with CM109 more resistant than EP31 and EP42. For each cross, parents (P1, P2), F1, F2, and backcrosses to each parent (BC1 and BC2) were evaluated. Correlations among ear damage traits showed that general appearance of the ear should be useful indicator of ear resistance. Ear resistance was dominant to susceptibility and was transmitted from inbreds to their hybrids. The additive-dominance model fit the generation mean analysis for both crosses and the degree of genetic control varied depending on the cross and trait. For both crosses, additive and dominance effects were significant for most ear damage traits. Epistatic gene effects were significant for husk and shank damage, and gene effects for number and length of tunnels were not significant. Because ear resistance involved additive and dominance effects for this set of inbreds, breeding procedures based on both types of gene action should be effective.     

Genetics of nonsenescence and charcoal rot resistance in sorghum

Summary Nonsenescence is a delayed leaf and plant death resistance mechanism in sorghum that circumvents the detrimental effects of reduced soil moisture combined with high temperatures during post-anthesis growth. This drought-tolerance mechanism is often equated with charcoal rot resistance, a widespread root and stalk disease of great destructive potential. Therefore, the inheritance of charcoal rot resistance was investigated directly, by exposure of sorghum to Macrophomina phaseolina, the causal organism, and indirectly, by determination of the inheritance of nonsenescence. Sorghum families derived from diallel crosses between two nonsenescent, resistant inbreds (B35, SC599-11E) and two senescent, susceptible inbreds (BTx378, BTx623) were evaluated in 1989 at College Station and at Lubbock, Texas, under controlled and field conditions. We determined that nonsenescence was regulated by dominant and recessive epistatic interactions between two nonsenescence-inducing loci and a third locus with modifying effects. The same conclusion was reached for charcoal rot resistance. The presence of different genetic mechanisms within SC599-11E for nonsenescence and charcoal rot resistance verifies that these two forms of resistance are not different manifestations of a single trait, i.e., they are not to be equated with each other. We conclude that nonsenescence alone cannot account for, and should not be used as the sole breeding criterion for, resistance to charcoal rot in sorghum.     

高粱对丝黑穗病的抗性及遗传研究

1981—1985年在人工接种的条件下,对1239份高粱品种资源,进行了抗丝黑穗病性鉴定。与此同时,用17个抗性不同的品种系,按照不完全双列杂交设计,进行了高粱对丝黑穗病的抗性遗传研究。结果表明,高粱对丝黑穗病的抗性遗传方式因品种而异。有的品种系具数量性状遗传特点,有的则具有质量性状遗传特点。抗病性属数量性状遗传的品种系,其抗性主要是受加性基因控制。     

玉米自交系幼胚培养能力与遗传关系研究(简报)

玉米幼胚培养获得的胚性愈伤组织具有较强的长期继代能力和再生植株能力,常被用于构建转基因受体系统。然而基因型是制约玉米组织培养植株再生的重要因素之一,不同玉米基因型的幼胚培养能力关系到其遗传转化研究的结果[1]。     

Pythium ornacarpum: a new species with ornamented oogonia isolated from soil in France

Pythium ornacarpum sp. nov. was isolated from a soil sample taken from Genlis in the Burgundy region of France. This species is unique because of its ornamented oogonia which are completely surrounded by antheridial filaments. The fungus is closely related to Pythium echinulatum Matthews. Morphological and reproductive aspects of this species as well as a study by PCR of the sequence of the internal transcribed spacer (ITS1) of the nuclear ribosomal gene and its comparison with related species are described here. The nucleotide sequence of the ITS1 region flaking the 5.8S rRNA of this species and other related species are also given here.     

桑树对花叶病抗性遗传规律的研究

用７个母本、５个父本品种,按ＮＣＩＩ杂交设计,进行桑树对花叶病抗性的遗传分析。首次证明：桑树对花叶病的抗性具有数量遗传特点,符合加性－显性模型,主要受加性基因控制,广义遗传力和狭义遗传力中等,一般配合力显示绝对优势,具有超显性现象。母本品种含有比父本品种更多的显性基因     

Characterization and mapping of <Emphasis Type="Italic">Rpi1</Emphasis>, a gene that confers dominant resistance to stalk rot in maize

The maize inbred lines 1145 (resistant) and Y331 (susceptible), and the F₁, F₂ and BC₁F₁ populations derived from them were inoculated with the pathogen Pythium inflatum Matthews, which causes stalk rot in Zea mays. Field data revealed that the ratio of resistant to susceptible plants was 3:1 in the F₂ population, and 1:1 in the BC₁F₁population, indicating that the resistance to P. inflatum Matthews was controlled by a single dominant gene in the 1145×Y331 cross. The gene that confers resistance to P. inflatum Matthews was designated Rpi1 for resistance to P. inflatum) according to the standard nomenclature for plant disease resistance genes. Fifty SSR markers from 10 chromosomes were first screened in the F₂ population to find markers linked to the Rpi1 gene. The results indicated that umc1702 and mmc0371 were both linked to Rpi1, placing the resistance gene on chromosome 4. RAPD (randomly amplified polymorphic DNA) markers were then tested in the F₂population using bulked segregant analysis (BSA). Four RAPD products were found to show linkage to the Rpi1 gene. Then 27 SSR markers and 8 RFLP markers in the region encompassing Rpi1 were used for fine-scale mapping of the resistance gene. Two SSR markers and four RFLP markers were linked to the Rpi1 gene. Finally, the Rpi1 gene was mapped between the SSR markers bnlg1937 and agrr286 on chromosome 4, 1.6 cM away from the former and 4.1 cM distant from the latter. This is the first time that a dominant gene for resistance to maize stalk rot caused by P. inflatum Matthews has been mapped with molecular marker techniques.     

Resistance to Striga hermonthica in a maize inbred line derived from Zea diploperennis

Breeding for resistance to Striga in maize (Zea mays), with paucity of donor source and known mechanisms of resistance, has been challenging. Here, post-attachment development of S. hermonthica was monitored on two maize inbreds selected for field resistance and susceptibility reactions to Striga at the International Institute of Tropical Agriculture. Haustorial invasion of the parasite into roots of these inbreds was examined histologically. Morphological differences were observed between roots of the susceptible and the resistant inbreds. The resistant maize had fewer Striga attachments, delayed parasitic development and higher mortality of attached parasites compared with the susceptible inbred. Striga on the susceptible inbred usually penetrated the xylem and showed substantial internal haustorial development. Haustorial ingress on the resistant inbred was often stopped at the endodermis. Parasites able to reach resistant host xylem vessels showed diminished haustorial development relative to those invading susceptible roots. These results suggest that the resistant inbred expresses a developmental barrier and incompatible response against Striga parasitism.     

Relationship between maize stem structural characteristics and resistance to pink stem borer (Lepidoptera: Noctuidae) attack

The pink stem borer, Sesamia nonagrioides (Lefebvre), is one of the most important insect pests of maize (Zea mays L.) in northwestern Spain. The objectives of this work were to evaluate, at different times during the growth of maize, structural traits related to the entry point and tissues on which larvae feed and to determine the relationship between these structural traits and the stem borer resistance. Six inbred lines with different levels of stem resistance to S. nonagrioides were evaluated in several trials. Potential structural resistance factors included rind and pith puncture resistance (RPR and PPR), rind thickness, length of the meristematic area (LMA), and pith parenchyma interlumen thickness (PPIT). Surprisingly, the inbred lines that showed the strongest stalks, EP42 and EP47, were not stem resistant to pink stem borer attack, while the stem resistant inbreds A509, CM151, and PB130 were among the least resistant to rind puncture. There were no significant differences among resistant and susceptible inbreds for the rind thickness. However, the susceptible inbred EP42 had the softest internode pith, and the resistant inbred PB130 showed the hardest, as was expected. Susceptible inbred lines in general showed higher values for the LMA, while the PPIT was important for individual inbreds. The results suggest that the usefulness of these characters as estimators of pink stem borer resistance is limited to some genotypes. Besides, even among those genotypes, other mechanisms of resistance that do not involve stalk strength could be present. Among the traits considered, the LMA was the most promising as an indicator of resistance to pink stem borer, although further experimentation is necessary.