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991.
Fujun Wang Melanie M. Wall 《Journal of Agricultural, Biological & Environmental Statistics》2003,8(3):296-309
In spatial predictions, researchers usually treat the estimated theoretical variogram parameters as known without error and ignore the variability of the parameter estimators. Although the prediction is still unbiased, the prediction error is usually underestimated. Therefore, the coverage probability of the prediction interval usually is lower than the nominal probability. A simulation study is performed to show how the coverage probability for prediction relates to the true range and sill of an exponential variogram. This article proposes two parametric bootstrap methods to incorporate the variability of the corresponding parameter estimators. A simulation study is performed to evaluate the coverage probability of these proposed methods. Finally, we apply the parametric bootstrap methods to a real dataset and compare the results with those from naive (i.e., treating estimated parameters as known) and Bayesian methods. 相似文献
992.
Dong Fu Liang Chen Guohui Yu Yi Liu Qiaojun Lou Hanwei Mei Liang Xiong Mingshou Li Xiaoyan Xu Lijun Luo 《Euphytica》2011,180(2):209-218
Sheath blight, caused by the pathogen Rhizoctonia solani Kühn, is one of the most serious diseases of rice and leads to severe yield loss worldwide. A recombinant inbred line (RIL)
population consisting of 121 lines was constructed from a cross between HH1B and RSB03, the latter of which is a deep-water
rice variety. Five traits were used to evaluate sheath blight resistance, namely disease rating (DR), lesion length (LL),
lesion height (LH), relative lesion length [RLL, the ratio of LL to plant height (PH)], and relative LH (RLH, the ratio of
LH to PH). Using the RIL population and 123 molecular markers, we identified 28 quantitative trait loci (QTLs) for the five
traits in two environments. These QTLs are located on nine chromosomes and most of them are environment specific. A major
QTL for DR (qSBR1) on chromosome 1 was identified with contributions of 12.7% at Shanghai and 42.6% at Hainan, and it collocated with a QTL
for PH. The allele at this locus from RSB03 enhances sheath blight resistance and increases PH. Another QTL for DR on chromosome 7
was adjacent to QTLs for heading date (HD) and four other disease traits. RSB03 also carries the resistant allele at this
locus and shortens HD. The susceptible parent, HH1B, provides the resistance allele at the locus qSBR8, where QTLs for four other disease traits were identified. QTL mapping results showed that most QTLs for LL, LH, RLL, and
RLH are collocated with QTLs for DR. Three QTLs for DR are independent from HD, PH, and four other disease traits, while four
QTLs are closely related to HD and PH. Four QTLs for LL, LH, RLL, and RLH are independent from DR, HD, and PH, while there
is only one region harboring QTLs for these four traits and HD. Correlation analysis and QTL mapping results indicated that
LL, LH, RLL, and RLH might be important indices, like DR, for evaluating the level of resistance to rice sheath blight. 相似文献
993.
András Cseri Mátyás Cserháti Maria von Korff Bettina Nagy Gábor V. Horváth András Palágyi János Pauk Dénes Dudits Ottó Törjék 《Euphytica》2011,181(3):341-356
In the present study, allele mining was conducted on a panel of drought related candidate genes in a set of 96 barley genotypes
using EcoTILLING, which is a variant of the targeting induced local lesions in genomes (TILLING) technology. Analyzing approximately
1.5 million basepairs in barley a total number of 94 verified unique haplotypes were identified in 18 amplicons designed for
9 genes. Overall, 185 single nucleotide polymorphisms (SNPs) and 46 insertions/deletions (INDELs) were detected with a mean
of 1SNP/92 bp and 1INDEL/372 bp genomic sequence. Based on overlapping haplotype sequences, markers were developed for four
candidate genes (HvARH1, HvSRG6, HvDRF1, HVA1), which allows distinguishing between the main haplotypes showing either differences in amino acid sequence or which have
larger INDELs in the promoter region. As “proof of concept”, the HvARH1 and HvSRG6 haplotypes were tested for the level of abscisic acid-induced gene expression in subsets of genotypes belonging to different
haplotype categories. An integrated database was developed to contain information about the genes, genotypes, and haplotypes
analyzed in this study. The database supplies profound information about the natural variation in the tested drought related
candidate genes providing a significant asset for further mapping studies dealing with this highly polygenic trait. 相似文献
994.
Molecular genetics of race non-specific rust resistance in wheat 总被引:1,自引:0,他引:1
Evans S. Lagudah 《Euphytica》2011,179(1):81-91
Over 150 resistance genes that confer resistance to either leaf rust, stripe rust or stem rust have been catalogued in wheat
or introgressed into wheat from related species. A few of these genes from the ‘slow-rusting’ adult plant resistance (APR)
class confer partial resistance in a race non-specific manner to one or multiple rust diseases. The recent cloning of two
of these genes, Lr34/Yr18, a dual APR for leaf rust and stripe rust, and Yr36, a stripe rust APR gene, showed that they differ from other classes of plant resistance genes. Currently, seven Lr34/Yr18 haplotypes have been identified from sequencing the encoding ATP Binding Cassette transporter gene from diverse wheat germplasm
of which one haplotype is commonly associated with the resistance phenotype. The paucity of well characterised APR genes,
particularly for stem rust, calls for a focused effort in developing critical genetic stocks to delineate quantitative trait
loci, construct specific BAC libraries for targeted APR genes to facilitate robust marker development for breeding applications,
and the eventual cloning of the encoding genes. 相似文献
995.
Haejeen Bang Dong Youn Cho Kil-Sun Yoo Moo-Kyoung Yoon Bhimanagouda S. Patil Sunggil Kim 《Euphytica》2011,179(3):439-449
In order to implement reliable marker-assisted selection systems for the restorer-of-fertility locus (Ms) in onions (Allium cepa L.), simple PCR-based codominant markers linked to the Ms locus were developed. Based on the EST probe sequences of previously reported RFLP markers, full-length genomic sequences
of the gene encoding putative oligopeptide transporter (OPT) was obtained by RACE. The first intron contained two 108 and
439-bp indel polymorphisms between the two Ms allele-linked OPT alleles. A simple PCR marker for OPT was developed by designing a primer pair on the flanking regions of
the 108-bp indel which is created by two tandem repeats. The second simple PCR marker was developed from the EST probe encoding
photosystem I subunit O (PsaO). Two 14 and 39-bp tandem repeats were identified from the 5′ upstream sequences of the PsaO-coding
gene, which were isolated by genome walking. Three different compositions of these tandem repeats were identified from diverse
onion germplasm. A primer set binding to the flanking sequence of these polymorphic repeats was used to amplify three different
marker haplotypes. The OPT marker was tightly linked to the Ms locus at a distance of 1.5 cM, but the analysis of the linkage relationship showed little linkage disequilibrium between
the marker and the Ms locus. Even so, these simple PCR markers are valuable tools for the marker-assisted selection of segregating individuals
in onion F1 hybrid breeding programs. 相似文献
996.
Abbas Rezaeizad Benjamin Wittkop Rod Snowdon Maen Hasan Valiollah Mohammadi Abbas Zali Wolfgang Friedt 《Euphytica》2011,177(3):335-342
Association mapping identifies quantitative trait loci (QTLs) by examining the marker-trait associations that can be attributed
to the strength of linkage disequilibrium between markers and functional polymorphisms across a set of diverse germplasm.
In this study, association mapping was performed to detect QTL-linked and genome wide SSR markers linked to phenolic compounds
of extraction meal in a population of 49 genetically diverse oilseed rape cultivars of dark-seeded, winter-type oilseed rape
accessions. Correction for population structure was performed using 559 genome wide SSR markers. Results showed that seed
colour is an important contributor to seed meal quality. Totally, 52 SSR markers linked to phenolic compounds were detected,
five of them being QTL linked markers. Some of these markers were already mapped on Brassica napus chromosomes that contain known QTL controlling oilseed rape meal quality traits. Our results demonstrate that association
mapping is a useful approach to complement and enhance previous QTL information for marker-assisted selection. 相似文献
997.
Genetic impacts under selective breeding of agricultural crops have been frequently investigated with molecular tools, but
inadequate attention has been paid to assess genetic changes under long-term genetic improvement of plant traits. Here we
analyzed allelic changes with respect to wheat trait improvement in 78 Canadian hard red spring wheat cultivars released from
1845 to 2004 and screened with 370 mapped SSR markers. The improvements in quality, maturity, yield, disease, stem rust, leaf
rust, sawfly resistance, and agronomy were considered. A total of 154 (out of 370) loci with significant allelic changes across
21 chromosomes were detected in the 78 wheat cultivars separated into improved versus non-improved groups for eight traits.
The number of significant loci for improving a trait ranged from four for quality to 68 for yield and averaged 35. Many more
loci with significant allelic reduction for improving a trait were detected than those with significant allelic increase.
Selection for early maturity introduced more alleles, but improving the other traits purged more alleles. Significantly lower
numbers of unique alleles were found in the cultivars with improved traits. The distributions of unique allele counts also
varied greatly across the 21 chromosomes with respect to trait improvement. Significant SSR variation between two cultivar
groups was observed for improvement in seven traits, but not in stem rust. The proportional SSR variation residing between
two groups ranged from 0.014 to 0.118. The proportional SSR variations within the improved cultivar groups consistently were
much lower than those within the non-improved groups. These findings clearly demonstrate the association between allelic changes
and wheat trait improvements and are useful for understanding the genetic modification of the wheat genome by long-term wheat
breeding. 相似文献
998.
This paper offers projections of potential effects of climate change on rusts of wheat and how we should factor in a changing
climate when planning for the future management of these diseases. Even though the rusts of wheat have been extensively studied
internationally, there is a paucity of information on the likely effects of a changing climate on the rusts and their influence
on wheat production. Due to the lack of published empirical research we relied on the few published studies of other plant
diseases, our own unpublished work and relevant information from the vast literature on rusts of wheat to prepare this overview.
Three broad areas of potential risks from a changing climate were described: increased loss from wheat rusts, new rust pathotypes
evolving faster and the reduced effectiveness of rust resistances. Increased biomass of wheat crops grown in the presence
of elevated CO2 concentrations and higher temperatures will increase the leaf area available for attack by the pathogen leading to increased
inoculum production. If changed weather conditions were to accelerate the life cycle of a pathogen, the increased inoculum
can lead to severe rust epidemics in many environments. Likewise should the effects of climate change result in more conducive
conditions for rust development there will also be a corresponding increase in the rate of evolution of new pathotypes which
could increase the rate of appearance of new virulences. The effectiveness of some rust resistance genes is influenced by
temperature and crop development stage. Climate change may directly or indirectly influence the effectiveness of some resistance
genes but this can not be ascertained due to a complete lack of knowledge. Since disease resistance breeding is a long term
strategy it is important to determine if any of the important genes may become less effective due to climate change. Studies
must be made to acquire new information on the rust disease triangle to increase the adaptive capacity of wheat under climate
change. Leadership within the Borlaug Global Rust Initiative (BGRI) is needed to broker research on rust evolution and the
durability of resistance under climate change. 相似文献
999.
Five inbred lines, 10 single cross maize (Zea mays L.) hybrids and two standard cultivars as check were used to study the combining abilities and heterosis under three environmental
conditions. Random amplified polymorphic DNAs (RAPDs) markers were used to study the genetic diversity (GD) and further to
analyze relationship of RAPDs based GD with combining ability and heterosis in short duration maize. Spearman’s rank correlation
coefficients and linear regressions were analyzed to identify the most important factor determining heterosis and per se performance
of the hybrids. Variances due to general combining ability (GCA), specific combining ability (SCA) and their interactions
with environment were found to be significant. Twenty random primers generated 179 RAPD fragments. Of these, 102 RAPD fragments
were polymorphic. GD was determined using Jaccard’s similarity coefficient, and a dendogram was constructed by UPGMA cluster
analysis. The RAPDs based GD exhibited non-significant negative or positive association, non-significant linear regression
along with very low coefficient of determination (R
2) with SCA, high and mid parent heterosis (HP and MP) and per se performance of the hybrids. Significant positive correlations
and regressions along with high coefficients of determination were recorded for SCA with HP, MP and per se performance of
the hybrids. The HP and MP also established significant positive association and linear regression along with high coefficient
of determination with per se performance of hybrids whereas the parental mean did not establish any significant correlations
with the GD, HPH, MPH and grain yield of F1s. The present investigation, therefore, did not find any role of RAPDs based GD in determining hybrid heterosis and hybrid
performance in short duration sub-tropical maize. The SCA, however, has emerged as the most important factor in determination
of heterosis as well as per se performance of the hybrids in short duration maize. 相似文献
1000.
Tomatoes are the most important vegetable, globally as well as in Germany. Outdoor tomato production is seriously impaired
due to increasing infections with evolving late blight (Phytophthora infestans) populations. Within organic agriculture, research is being conducted to develop regionally adapted and open pollinated cultivars
of outdoor tomatoes with late blight field resistance. In the present experiment, three crosses, including wild, cocktail,
and beefsteak tomatoes, were selected for field resistance against late blight in F2 at one location per cross. The comparison of positive and negative selection in F3 revealed the selection of single F2 plants to be efficient in all three crosses. F2 selection has proved to be a robust and efficient tool for breeding programs. The correlated response to selection in other
traits, including yield, fruit weight, days to maturity, harvest period, and plant height, depended on the cross. It was evident
that selection for desired traits combined with field resistance against late blight is promising, even in wide crosses. The
most undesired attribute of wild tomatoes is the formation of shoots on leaves and in inflorescences. No correlation was observed
between field resistance and shoot formation, allowing the selection of genotypes with improved field resistance and yield,
but without morphological disadvantages. 相似文献