摘要:

AbstractExperiments with primary triticale genotypes produced from defined wheat and rye parents provide a strong indication of a preponderance of specificgenomecombining ability in the phenotypic expression of triticale. Studying line families developed from specific cross combinations by means of the single seed descent method revealed that, in contrast to wheat, the distribution of genotypes in an F2population of triticale is strongly skewed, with the majority of them being inferior to the mid‐parent value. This is the case even if recombination is restricted to one fourth of one of the parental components of triticale, i.e. wheat or rye. Correlations of yield components were found to deviate substantially from known types of correlations in wheat, an established natural allopolyploid species. These findings give a strong indication for a genomic inbalance in triticale being a major cause for slow advance in varietal improvement. New breeding strategies designed for the specific genetic structure of triticale are necessary to accelerate breeding progress and to help triticale ultimately to live up to its promis

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00144.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractTetraploidrolCtransformants have been analyzed considering the level ofrolCexpression and yield parameters. InrolCtransformants a maximum of five integrated copies of the gene were detected by Southern analysis. A relation between copy number of therolCgene, phenotypicrolCexpression and intensity of morphological alterations was established. Three experiments were performed to assess the differential effect of therolCgene on yield and its interaction with growth factors. In the first experiment, the influence of day length on plant morphological and physiological characters was studied. The phenotype of the transgenic plants with a lowrolCexpression was like the control under the two day‐regimes tested, while the intermediate expressing genotype showed a different reaction. In the second and third experiment, tuber yield, tuber number and weight per tuber were recorded under short and long day conditions. When grown in smaller pots of 1.15 1 volume, the control plants had the highest yield of tubers under both day lengths tested. Yield decreased with increasingrolCexpression. Tuber number revealed to be genotype dependent: it was higher for lowrolCexpressing plants and lower for intermediaterolCtransformants (Experiment 2). In the third experiment the influence of variable pot size and shape was analyzed for one clone with intermediate and two with low level ofrolCexpression. Remarkable differences between pots and flat boxes of the same volume were noted for tuber yield and number: Under the two conditions the control clone and the lowrolCexpressing genotypes gave similar tuber yield and number in both growth containers, whereas therolCintermediate genotype yielded significantly more in flat boxes. The effect of variable hormonal levels induced in transgenic plants through prokaryotic genes are discussed with the existence of non‐predictable genotype in relation to environmental interactions. It is concluded that at least the agronomic performance of potatoes transformed with these genes cannot be predicted on the basis of simple linear relationships among the expression of the gene and of the tra

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00145.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractIn many fields of application in plant breeding and crop science, ratios of two component traits X and Y are of interest (harvest index in cereals, leaf‐to‐stem ratio in forage legumes, height‐to‐diameter ratio in forest trees etc.). When selection is practised on the ratio X/Y of two traits X and Y, the experimenter may be interested in the resulting changes of both trait means.Based on improved approximations for the covariances between X and X/Y and between Y and X/Y and for the variance of X/Y the changes in the means of X and Y can be predicted by applying the regression approach from conventional selection theory. Explicit expressions for these correlated responses in X and Y when selection is practised on their ratio X/Y are derived and discussed.The different outcomes (decrease, zero change or increase) for the selection pressures on X and Y are characterized by phenotypic coefficients of variation of X and Y, phenotypic and genotypic correlations between X and Y and heritabilities of

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00146.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractSeveral methods have been proposed over the years to detect linkage between a marker gene and quantitative trait locus (QTL). Use of isozymes and restriction fragment length polymorphisms as genetic markers, has encouraged the development of new methods to detect linkage. We present three methods to detect linkage and two methods to measure recombination frequency (r). The three methods that detect linkage can be used when a single QTL or a tightly linked cluster of QTLs control the quantitative trait. The two methods that measure recombination frequency could not be used in the latter case because r would not be properly estimated. Procedures to calculate the additive and dominance gene effects of the QTL and the respective variances of these estimates were also presented.

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00147.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractTwenty‐four near‐isogenic barley lines, with a cv.‘Pallas’ background, carrying different mildew resistance genes were subjected in 1987, 1989 and 1990 to natural infection by the pathogen at several different and contrasting Spanish sites in order to study its virulence. The virulence genes proved to be geographically grouped into three regions: western (Valladolid), southern (Sevilla) and northern and northeastern (Navarra, Lleida and Girona). The mildew population of Lleida was more variable when compared with Navarra and Valladolid. Overall, the most effective resistance genes were:Ml‐a13 + Ml‐(Ru3), mloa

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00148.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe agronomic performance and chromosome behavior of autotetraploid sorghum [Sorghum bicolor(L.) Moench] inbreds and F1hybrids were investigated. Autotetraploids have possible commercial use and can serve as bridging species in crosses to natural tetraploids. Autotetraploid sorghum inbreds (2n = 40) had higher kernel weight, seed yield, and protein and amino acid content than their diploid counterparts. Stalk height and panicle length of the autotet‐raploids, however, were not different from those of the diploids, and seed set of autotetraploids was lower in early generations. Seed set of autotetraploid Ft hybrids was related to and higher than that of the autotetraploid parental inbred lines. Frequency of quadrivalents, anaphase I and II laggards, and quartet micronuclei varied among autotetraploids. Frequency of quadrivalents did not appear to be an important factor in seed set nor was it significantly associated with frequency of laggards. Aneuploids (2n = 39, 41) had higher percentages of laggards and micronuclei than did euploids (2n = 40). Methods of pollination significantly affected seed set in autotetraploid S4 lines. Differences in seed set among autotetraploid lines indicated the feasibility of selecting for lines with high seed set and utilizing those lines for hybrid productio

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00149.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract‘BJ 104’ was the most widely grown pearl millet hybrid in India until it became susceptible to downy mildew (DM) in 1984—85. Residual variability for resistance was found in both parental lines, 5141 B (maintainer of 5141 A) and J 104, and through four generations of pedigree selection under intense disease pressure in the DM nursery, two lines, IC‐MA841 (from 5141 B) and ICMP 84814 (from J 104), were selected resulting in a reconstituted DM resistant hybrid (‘ICMH 84814’) which was equal in yield to the original ‘BJ 104’. The reconstituted hybrid, though phenotypically similar, can be distinguished from “BJ 104” being slightly taller, flowers later, has heavier heads, and 1000‐seed weight, but tillers less.A similar exercise was attempted on Tifton 23 B, the female parent of the first widely grown hybrid (‘HB 3’— the male parent was also J 104), but no variability for

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00150.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA mungbean (V. radiata) line (BC3F3generation) which is resistant to two species of bruchid beetles (Callosobruchus chinensisandC. maculatus) was successfully developed in Thailand using a wild mungbean variety (V. radiatavar.sublobata). One accession (TC1966) of wild mungbean was found to be completely resistant toC. chinensisandC. maculatusoccurring at Chainat Field Crops Research Center in Thailand. The resistance was controlled by a single dominant gene (R). A breeding program to develop a bruchid‐resistant mungbean cultivar with good agronomic characters under the environmental conditions of Thailand was initiated in 1987.‘Chainat 60’ (‘CN60’), a recommended mungbean cultivar in Thailand, was crossed with TC1966 to incorporate the resistance gene. Agronomic characters of the hybrids were improved by recurrent backcrossing using ‘CN60’ as a pollen parent. Seed yield per plant, days to flowering, and seed size of the bruchid‐resistant BC3F2population reached the level of ‘CN60’ after three consecutive backcrossings. Bruchid‐resistant line (BC3F3,R/R) was selected from i

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00151.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractAlloplasmic forms of the cultivated carrot,Daucus carota sativusHoffm., were created by substitution backcrosses. The wild Daucus formsD. muricatusL.,D. gingidiumL., D.c. gummiferHook, andD. c. libanotifoliaWiinst. were used as cytoplasm donors. In the first two backcross generations disturbances in fertility and plant physiology did not occur. The plants of the generations BC2F2and BC2F3look like cultivated carrots.The alloplasmic forms were compared with cultivars for economic traits such as yield and yield components. The high content of total sugar in the alloplasmic forms was considerable. A new type of male sterility was found and described in a BC3F2generation of the cross D.c. gummifer× D.c. sativus.Results of RFLP‐analyses of mt‐DNA and cp‐DNA were dis

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00152.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractAn effective method for the isolation and restriction fragment analysis of mitochondrial (mt) DNA from a few grams of plant material ofDaucus carota sativusis presented. Employing radioactive end‐labelling of mtDNA restriction fragments, 12 single plants from a carrot cultivar, ‘Vitaminaja’, were investigated for mitochondrial genome diversity. Analyses revealed four different types of characteristic mtDNA restriction fragment patterns within the same cultivar. The mitochondrial genome diversity in the cultivar ‘Vitaminaja’ may result from non‐homogenous ancestor cytoplasms as well as from nuclear‐induced mtDNA rearrangements. Evaluation of intraspecific mitochondrial genome diversity may become an important issue in breedi

ISSN:0179-9541    

DOI:10.1111/j.1439-0523.1992.tb00153.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY