装载机八连杆机构工作装置优化设计     

王少雷  刘长生 《林业机械与木工设备》2006,34(10):28-30

八连杆机构是装载机工作装置的重要部分。本文以铲掘位置时的八连杆机构传力特性为目标函数,建立了八连杆机构工作装置的数学模型。采用惩罚函数法,结合样机对其进行优化设计。结果表明,优化设计后工作装置的性能得到进一步完善和提高。  相似文献   

Detecting and estimating segregation distortion and linkage between glufosinate tolerance and blackleg resistance in Brassica napus L.     

Rong-Cai Yang  Mohan R. Thiagarajah  Vipan K. Bansal  Gary R. Stringam  M. Habibur Rahman 《Euphytica》2006,148(3):217-225

Summary The segregation and linkage between glufosinate (transgenes ‘Rf3’ and ‘T177’) and blackleg resistance genes in canola (Brassica napus L.) were assessed using F₁ microspore-derived doubled haploid (DH) populations from four crosses including reciprocals, two involving the transgene ‘Rf3’ and the other two involving the transgene ‘T177’. To relax the assumption of no segregation distortion required for the conventional analysis of segregation and linkage, we employed Bailey's analysis that allows detecting segregation distortion at linked loci. The significant departures from the 1:1 segregation were detected in the crosses involving the transgene ‘T177’ but not in the crosses involving the transgene ‘Rf3’. The apparent deficit of the herbicide tolerant DH lines in the crosses with the transgene ‘T177’ is likely due to differential selection against the gametes carrying ‘T177’ during microspore culture. The linkage was strong between blackleg resistance and the transgene ‘Rf3’ but weak or absent between blackleg resistance and the transgene ‘T177’, suggesting that the two transgenes are probably inserted into distant regions of the genome. The observed linkage offers an opportunity to develop new canola cultivars with both glufosinate tolerance conferred by transgene ‘Rf3’ and blackleg resistance.  相似文献   

Molecular mapping of an aluminum tolerance locus on chromosome 4D of Chinese Spring wheat   总被引：13，自引：0，他引：13  

Ming-Cheng Luo  Jan Dvořák 《Euphytica》1996,91(1):31-35

Summary The tolerance of aluminum (Al) of disomic substitution lines having the chromosomes of the D genome of Triticum aestivum L. cv. Chinese Spring individually substituted for their homoeologues in T. turgidum L. cv. Langdon was investigated by the hematoxylin method. The disomic substitution lines involving chromosome 4D were more Al tolerant than Langdon. The tolerance was found to be controlled by a single dominant gene, designated Alt2, that is in the proximal region of the long arm of chromosome 4D. The locus was mapped relative to molecular markers utilizing a population of recombinant chromosomes from homoeologous recombination between Chinese Spring chromosome 4D and T. turgidum chromosome 4B. Comparison of the location of Alt2 in this map with a consensus map of chromosomes 4B and 4D based on homologous recombination indicated that Alt2 is in a vicinity of a 4 cM interval delineated by markers Xpsr914 and Xpsr1051. The Alt2 locus is distal to marker Xpsr39 and proximal to XksuC2. The Altw locus is also proximal to the Knal locus on chromosome 4D that controls K⁺/Na⁺ selectivity and salt tolerance. In two lines, Alt 2 and Knal were transferred on a single 4D segment into the long arm of T. turgidum chromosome 4B.  相似文献   

Genetics of Five Seed Esterase Isozymes in Pearl Millet     

M. V. Subba  Rao  Y. Saideswara  Rao V. Manga 《Plant Breeding》1989,102(2):133-139

Inheritance and linkage relationships of pearl millet seed esterase isozymes were studied using; polyacrylamide dise: gel electrophoresis and α-naphthyl acetate as substrate. The Zone of enzyme activity was resolved into five bands. The presence of a band showed complete dominance over its absence. Each one of the bands (1 to 4) was under the control of a single gene. Band five was found to be controlled by three independent loci with duplicate gent action Loci for Est₁, Est₃ and Est₄ Were found to be linked. Est₂ Was independent of this linkage group.  相似文献   

Co-heritability: Its relation to correlated response,linkage, and pleiotropy in cases of polygenic inheritance     

M. J. J. Janssens 《Euphytica》1979,28(3):601-608

Summary The concept of co-heritability is proposed in order to describe the genetic associations within pairs of quantitative traits. The mathematical relations between co-heritability, correlated response, and the coefficient of genetic prediction are shown. From observations in a diallel experiment with 10 year-old slash pine it appeared that the genetic association of a character pair is a phenomenon of low genetic variability and high inheritance. Exploratory indicators are proposed to estimate the nature of the genetic association.  相似文献   

A Possible Association Between Heading Time and the GM-A2 Locus in Bread Wheat     

D. Laflandra    B. Margiotta  E. Porceddu 《Plant Breeding》1987,99(4):333-335

A line without expression (null form) o: the α-gliadins controlled by the 6A chromosome was found when screening electrosboretically single seeds of the bread wheat ‘Raeder’. Differences in heading time were also observed between this null line and the normal one. A linkage between 6A gliadin genes and heading time gene(s) is hypothesized.  相似文献   

The degree of phenotypic resemblance of the near-isogenic lines of the wheat cultivar thatcher with their recurrent parent     

A. C. Zeven  J. Waninge 《Euphytica》1986,35(3):665-676

Summary Thatcher, 16 of its near-isogenic lines (NIL) and 8 donors were investigated for the degree in which the NILs phenotypically resembled their recurrent parent. In general the NILs have a good phenotypic resemblance. In a few NILs characters occur that are not seen in Thatcher. In some cases these are found in the donor indicating the presence of donor genes other than the marker gene in the NIL. In other cases a character possessed by a NIL is not present in Thatcher or in its donor. In such cases either inhibitor genes may play a part, or the donor accession that accompanies the set of NILs may not be the donor used to breed the NIL. Two causes are possible. One is that the donor was a mixture of genotypes, the other is contamination.The presence of donor genes other than the marker Lr gene(s) in a NIL may lead to unexpected results or, what is worse, to wrong conclusions.  相似文献   

Studies on the relationship of Dioscorea cayenensis and Dioscorea rotundata cultivars     

J. C. Onyilagha  J. Lowe 《Euphytica》1986,35(3):733-739

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An introduction to markers, quantitative trait loci (QTL) mapping and marker-assisted selection for crop improvement: The basic concepts   总被引：24，自引：2，他引：24  

B. C. Y. Collard  M. Z. Z. Jahufer  J. B. Brouwer  E. C. K. Pang 《Euphytica》2005,142(1-2):169-196

Recognizing the enormous potential of DNA markers in plant breeding, many agricultural research centers and plant breeding institutes have adopted the capacity for marker development and marker-assisted selection (MAS). However, due to rapid developments in marker technology, statistical methodology for identifying quantitative trait loci (QTLs) and the jargon used by molecular biologists, the utility of DNA markers in plant breeding may not be clearly understood by non-molecular biologists. This review provides an introduction to DNA markers and the concept of polymorphism, linkage analysis and map construction, the principles of QTL analysis and how markers may be applied in breeding programs using MAS. This review has been specifically written for readers who have only a basic knowledge of molecular biology and/or plant genetics. Its format is therefore ideal for conventional plant breeders, physiologists, pathologists, other plant scientists and students.  相似文献   

Integration of AFLP markers into a linkage map of sugar beet (Beta vulgaris L.)   总被引：2，自引：0，他引：2  

J. Schondelmaier    G. Steinrücken  C. Jung 《Plant Breeding》1996,115(4):231-237

The AFLP (amplified fragment length polymorphism) technique has been applied in establishing an extended linkage map of sugar beet. A total of 120 AFLPs were integrated into an existing linkage map based on RFLP markers. Four primer combinations yielded between 19 and 40 polymorphic bands in an F₂ population consisting of 94 plants. The AFLP loci were evenly distributed over the nine linkage groups, with the exception of linkage group V where the number of AFLPs was significantly low. The AFLPs were found to be reproducible even against the background of different combinations of Taq DNA polymerases and buffers. However, the quantity of higher molecular weight fragments (>400 bp) was reduced when using plant DNA of poor quality as a template. The results of these experiments are discussed, together with possible applications of AFLPs in sugar beet breeding.  相似文献