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1.
Pre-harvest sprouting (PHS) in wheat (Triticum aestivum L.) is a significant problem. Introgression of genes controlling grain dormancy into white-grained bread wheat is one means of improving resistance to PHS. In this study seven dormant (containing the SW95-50213 and AUS1408 sources) × non-dormant crosses were produced to investigate the effectiveness of selection for grain dormancy in early segregating generations. Each generation (F1–F4) was grown in a temperature controlled glasshouse with an extended photoperiod (i.e. continuous light). F2 and F3 generations were subject to selection. Five hundred harvest-ripe grains were tested for germination over a 14 day period, and the 100 most dormant grains were retained and grown-on to produce the next generation within each cross. The response to selection was assessed through analysis of the time to 50% germination (G50) in the F2, F3 and F4 generations. In addition, changes in marker class frequencies for two SSR markers (barc170 and gpw2279) flanking a known quantitative trait locus (QTL) for grain dormancy on chromosome 4A were assessed in DNA from F2 plants selected from early germinating (non-dormant) and late germinating (dormant) phenotypic extremes within each cross. Selection for grain dormancy in the F2 and F3 generations effectively recovered the dormant phenotype in all seven crosses, i.e. the F4 generation was not significantly different from the dormant parent. Further, selection based on individual F2 grains changed marker class frequencies for the 4A dormancy QTL; in most cases eliminating the marker class homozygous for the non-dormant alleles. Application of this screening method will enable breeders to better select for grain dormancy and may lead to development of new cultivars offering effective resistance to PHS in the near future.  相似文献   

2.
Pre-harvest sprouting (PHS) in developing wheat (Triticum aestivum L.) spikes is stimulated by cool and wet weather and leads to a decline in grain quality. A low level of harvest-time seed dormancy is a major factor for PHS, which generally is a larger problem in white-grained as compared to red-grained wheat. We have in this study analyzed seed dormancy levels at the 92nd Zadok growth stage of spike development in a doubled-haploid (DH) white wheat population and associated variation for the trait with regions on the wheat genome. The phenotypic data was generated by growing the parent lines Argent (non-dormant) and W98616 (dormant) and 151 lines of the DH population in the field during 2002 and 2003, at two locations each year, followed by assessment of harvest-time seed dormancy by germination tests. A genetic map of 2681 cM was constructed for the population upon genotyping 90 DH lines using 361 SSR, 292 AFLP, 252 DArT and 10 EST markers. Single marker analysis of the 90 genotyped lines associated regions on chromosomes 1A, 2B, 3A, 4A, 5B, 6B, and 7A with seed dormancy in at least two out of the four trials. All seven putative quantitative trait loci (QTLs) were contributed by alleles of the dormant parent, W98616. The strongest QTLs positioned on chromosomes 1A, 3A, 4A and 7A were confirmed by interval mapping and markers at these loci have potential use in marker-assisted selection of PHS resistant white-grained wheat.  相似文献   

3.
White-grained wheat cultivars have long been recognized to be less resistant to preharvest sprouting (PHS) than the red-grained ones. Previously two QTLs for grain dormancy, QPhs.ocs-3A.1 (QPhs-3AS) and QPhs.ocs-4A.1 (QPhs-4AL) were identified in a highly dormant Japanese red wheat, Zenkoujikomugi (Zen). Aiming at improvement of PHS tolerance in white-grained wheat, the introgression effect of these two QTLs in a white-grained population consisting of 40 recombinant inbred lines (RILs) developed from a cross between Zen and white-grained Spica was examined here. Random 20 RILs with red grains were also developed from the same cross and used as a control population. The RILs were grown in the field and in the glasshouse to evaluate the grain dormancy by germination test. Several SSR markers closely linked to the QPhs-3AS and QPhs-4AL were used to estimate the alleles at the QTLs. Dormancy variation in the RILs was significantly associated with the differences for grain color and the alleles at QPhs-3AS over several years. Although allelic variation was detected in a SSR marker closely linked to QPhs-4AL there was no difference in germination data between the Zen-allele and the Spica-allele groups. As expected, the red-grained RILs with the Zen allele at QPhs-3AS were the most dormant. Some white-grained RILs with the Zen allele at QPhs-3AS showed higher dormancy compared to the red-grained RILs with the alternative allele. These results demonstrated that introgression of the QPhs-3AS gene could contribute to the increased grain dormancy in white-grained wheat.  相似文献   

4.
Pre-harvest sprouting (PHS) in wheat (Triticum aestivum L.) can be a significant problem, causing deleterious effects on grain quality. However, the adverse impacts of PHS can be reduced by introgressing genes controlling grain dormancy into white-grained bread wheat. Screening for grain dormancy typically involves germination testing of harvest-ripe grain grown in a glasshouse or field. However, the more uniform environmental conditions provided by temperature controlled glasshouses (i.e. controlled environmental conditions—CEC) may provide significant benefits for the assessment of grain dormancy. In this study, the dormancy phenotype of grain grown under CEC incorporating an extended photoperiod, was compared with 2 years of data from field grown material. Four dormant double haploid lines (derived from SW95-50213 and AUS1408) and two locally adapted non-dormant cultivars EGA Gregory and EGA Wills were compared in three replicated experiments grown under CEC (22 ± 3°C and 24 h photoperiod). The germination response of harvest-ripe grain was examined to assess the expression of grain dormancy. Two measures of germination, the predicted time to 50% germination (G 50) and a weighted germination index, both clearly differentiated dormant and non-dormant lines grown under CEC. In addition, levels of grain dormancy were similar to field-grown plants. These results demonstrated that CEC with an extended photoperiod can be used for rapid and reliable characterisation of grain dormancy in fixed lines of bread wheat.  相似文献   

5.
Preharvest sprouting (PHS) in spring wheat (Triticum aestivum L.) and durum wheat (T. turgidum L. var durum) causes significant economic losses due to a reduction in grain yield, grain functionality and viability of seed for planting. Average annual estimated losses in Canada are about $100 million. Genetic resistance to PHS reduces these losses. Development of PHS resistant cultivars is complicated by the effects of factors under genetic control, such as spike morphology, seed dormancy, environment, and kernel diseases. Resistance to PHS has been a breeding priority since the late 1960s. Development of RL4137, which is the primary source of PHS resistance in the Canada Western Red Spring market class, has led to cultivar improvements. A white-seeded derivative of RL4137 is the primary source of PHS in the Canada Prairie Spring White and Canada Western Hard White Spring wheat market classes. Procedures to select for PHS resistance vary among breeding programs, market classes and by degree of inbreeding. Methods include artificial sprouting of intact spikes, germination tests, natural weathering in field trials, artificial weathering trials, and indirect assessment of sprouting by measuring Hagberg falling number. Although many genetic loci have been attributed to preharvest sprouting resistance, application of molecular markers is currently limited due to the complex inheritance of the trait. In Canada, cultivars are characterized for their relative level of PHS resistance and the information is made available to producers.  相似文献   

6.
Pre-harvest sprouting (PHS) is one of the serious problems for wheat production, especially in rainy regions. Although seed dormancy is the most critical trait for PHS resistance, the control of heading time should also be considered to prevent seed maturation during unfavorable conditions. In addition, awning is known to enhance water absorption by the spike, causing PHS. In this study, we conducted QTL analysis for three PHS resistant related traits, seed dormancy, heading time and awn length, by using recombinant inbred lines from ‘Zenkouji-komugi’ (high PHS resistance) × ‘Chinese Spring’ (weak PHS resistance). QTLs for seed dormancy were detected on chromosomes 1B (QDor-1B) and 4A (QDor-4A), in addition to a QTL on chromosome 3A, which was recently cloned as TaMFT-3A. In addition, the accumulation of the QTLs and their epistatic interactions contributed significantly to a higher level of dormancy. QDor-4A is co-located with the Hooded locus for awn development. Furthermore, an effective QTL, which confers early heading by the Zenkouji-komugi allele, was detected on the short arm of chromosome 7B, where the Vrn-B3 locus is located. Understanding the genetic architecture of traits associated with PHS resistance will facilitate the marker assisted selection to breed new varieties with higher PHS resistance.  相似文献   

7.
为探索我国小麦微核心种质及地方品种籽粒休眠的遗传基础,利用已报道的4个3AS上的SSR标记(Xbarc57、Xbarc294、Xbarc310和Xbarc321)和1个3BL上的Viviparous-1基因标记Vp1-b2对107份我国小麦微核心种质及31份地方品种进行籽粒休眠的分子标记鉴定。结果表明,5个分子标记在试验材料中表现出丰富的等位变异,具有5～6种等位类型,与籽粒萌芽指数(GI)密切相关。根据一般线性模型分析结果,各位点的等位变异显著影响籽粒休眠,其中Vp1-b2和Xbarc294对籽粒休眠作用较其他标记大,可分别解释65.8%和61.2%的表型变异;其次是Xbarc310(56.3%)和Xbarc57(55.8%),最小的是Xbarc321(53.3%)。而5个标记联合可解释95.9%的性状变异,其次是Vp1-b2和Xbarc294的组合(89.1%),解释变异最小的标记组合是Vp1-b2和Xbarc321(79.4%)。5个分子标记即可解释籽粒休眠的绝大部分表型变异,说明我国小麦微核心种质及地方品种籽粒休眠特性受3AS和3BL上的2个主效基因控制。  相似文献   

8.
The possibility of breeding white-grained wheats tolerant to pre-harvest sprouting under Japanese humid weather conditions is discussed. New genetic dormancy sources, such as, AUS1408, 8019R1 and RyuuMai7, were evaluated for seed dormancy in different weather conditions. Some white-grained dormant wheats showed a strong dormancy similar to that of red-grained dormant wheats in a greenhouse trial, in the field their dormancy expression was much less than the red wheats. Three populations involving crosses with these new sources for winter wheat breeding were examined under repeated selection for seed dormancy. Some dormant white-grained lines, as judged under glasshouse conditions, were developed. Again the level of dormancy in these lines was not sufficient compared to red dormant varieties in field trial. In order to develop truly superior dormant white-grained materials, one population involving crosses with two dormant varieties, AUS1408 and 8019R1, was examined under repeated selection. From these materials we succeeded in breeding lines that had not only a good dormancy but also showed adaptation to Japanese weather conditions, including earliness, scab resistance and good seed appearance. However again the dormancy of these lines in field trial was not sufficient compared to that of red wheats and there was not a clear difference for seed dormancy between breeding lines and their parents. We conclude therefore that more work involving the use of new genetic sources or new breeding techniques, will be necessary for breeding advanced lines that maintain a sufficient tolerance to PHS in humid Japanese weather condition. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

9.
H. H. Bi  Y. W. Sun  Y. G. Xiao  L. Q. Xia 《Euphytica》2014,195(2):197-207
Pre-harvest sprouting (PHS) of wheat greatly reduces the quality and economic value of grain, and PHS resistance is one of the most important traits in wheat breeding. Red-grained wheat varieties are generally more resistant to PHS than white-grained ones; however, some are still susceptible. The red pigment of red-grained wheat is synthesized through the flavonoid biosynthetic pathway, in which the dihydroflavonol-4-reductase gene (DFR) is one of the genes involved in anthocyanin synthesis. In this study, a set of 120 red-grained Chinese wheat cultivars and lines with distinct PHS resistance were used to characterize TaDFR genotype variations and their association with PHS resistance. Whereas no variation or functional variation of TaDFR genes was detected on chromosomes 3A and 3D, a novel TaDFR allele, designated TaDFR-Bb, was explored on chromosome 3B. Compared with TaDFR-Ba, an 8 bp insertion (CTCTAGGA) was identified in the promoter region of TaDFR-B in most of the PHS resistant red-grained wheat varieties and advanced lines. Based on this, a CAPS marker was designed and validated with a set of Chinese red-grained wheat cultivars and lines with distinct PHS resistance. In most cases, TaDFR-Bb was associated with higher PHS resistance. An association study indicated that wheat varieties with the 8 bp insertion (average seed germination index 23.6 %) were significantly more resistant (P < 0.01) to PHS than those without the insertion (average seed germination index 69.5 %). Further study on gene expression demonstrated that the insertion led to increased TaDFR-B expression in cultivars with PHS resistance. Transient expression of TaDFR-B in coleoptiles of wheat cv. Chinese Spring revealed that increasing TaDFR gene expression did not induce the synthesis of anthocyanins.  相似文献   

10.
H. Miura    N. Sato    K. Kato  Y. Amano  R. A. McIntosh 《Plant Breeding》2002,121(5):394-399
Preharvest sprouting (PHS) in wheat represents a major constraint to the production of high‐quality grain. Genetic variation for tolerance to PHS is associated with seed dormancy. The present study was initiated to detect homologous chromosome variation associated with seed dormancy genes in a PHS tolerant cultivar ‘Zenkojikomugi’ (Zen) and ‘Chinese Spring’ (CS) using the backcross reciprocal monosomic method. The most striking effect on variation in seed dormancy was associated with chromosome 3A, and followed by group 4 chromosomes. These chromosomes of Zen increased dormancy compared with the respective CS homologues. Chromosomes 2D and 7D of Zen, and 6A of CS seemed to contribute smaller positive effects on dormancy. Chromosomes 2A of CS and Zen, as well as 3B, were equally effective in enhancing dormancy. The chromosome 3 A factors were independent of the grain‐colour gene R‐A1 because Zen was found to carry the white‐grained R‐A1a allele, which was identical to that of CS, and there was no difference in dormancy between the reciprocal F1 seeds.  相似文献   

11.
Pre-harvest sprouting (PHS) causes significant yield loss and degrade the end-use quality of wheat, especially in regions with prolonged wet weather during the harvesting season. Unfortunately, the gene pool of Triticum durum (tetraploid durum wheat) has narrow genetic base for PHS resistance. Therefore, finding out new genetic resources from other wheat species to develop PHS resistance in durum wheat is of importance. A major PHS resistance QTL, Qphs.sicau-3B.1, was mapped on chromosome 3BL in a recombinant inbred line population derived from ‘CSCR6’ (Triticum spelta), a PHS resistant hexaploid wheat and ‘Lang’, a PHS susceptible Australian hexaploid wheat cultivar. This QTL, Qphs.sicau-3B.1, is positioned between DArT marker wPt-3107 and wPt-6785. Two SCAR markers (Ph3B.1 and Ph3B.2) were developed to track this major QTL and were used to assay a BC2F8 tetraploid population derived from a cross between the durum wheat ‘Bellaroi’ (PHS susceptible) and ‘CSCR6’ (PHS resistant). Phenotypic assay and marker-assisted selection revealed five stable tetraploid lines were highly PHS resistant. This study has successfully established that PHS-resistance QTL from hexaploid wheat could be efficiently introgressed into tetraploid durum wheat. This tetraploid wheat germplasm could be useful in developing PHS resistant durum cultivars with higher yield and good end-use quality.  相似文献   

12.
Septoria tritici blotch (STB) is one of the most destructive foliar diseases in many of the wheat (Triticum aestivum) growing regions of the world. Gene Stb2, derived from cultivar ‘Veranopolis’, provides effective resistance against STB. In our attempts to refine the map location of this resistance gene we could not confirm a previous report that Stb2 is on wheat chromosome 3BS. Instead, based on characterization of the same doubled-haploid population used for the original mapping derived from a cross between Veranopolis and susceptible line RAC875-2, and linkage analysis of the resistance phenotype to previously mapped SSR loci, we report that Stb2 is located on the short arm of wheat chromosome 1B, flanked by microsatellite loci Xwmc406 and Xbarc008 (with Xwmc230 closely located) at map distances of 6 and 5 cM, respectively. Presence of the markers on chromosome arm 1BS was confirmed by analysis of nullisomic-tetrasomic lines. These three co-dominant markers can be used in wheat breeding programs to facilitate combining Stb2 with genes of interest. Other STB resistance genes, including Stb11, have been reported on wheat chromosome arm 1BS, with locus Xbarc008 as a diagnostic marker. Whether Stb2, Stb11 and the previously identified Stb11-like genes are the same, allelic, or different but closely linked has not been determined. In addition to STB, numerous genes for resistance to many other fungal pathogens have been reported on wheat chromosome arm 1BS, including those for yellow (or stripe) rust, leaf rust and common bunt. The approximate locations for all of these genes were added onto the Stb2 map based on published distances from common markers to provide a rough guide for future wheat improvement.  相似文献   

13.
Grain dormancy provides protection against pre-harvest sprouting (PHS) in cereals. Composite interval mapping and association analyses were performed to identify quantitative trait loci (QTL) contributing grain dormancy in a doubled haploid (DH) barley population (ND24260?×?Flagship) consisting of 321 lines genotyped with DArT markers. Harvest-ripe grain collected from three field experiments was germinated over a 7-day period to determine a weighted germination index for each line. DH lines displaying moderate to high levels of grain dormancy were identified; however, both parental lines were non-dormant and displayed rapid germination within the first two?days of testing. Genetic analysis identified two QTL on chromosome 5H that were expressed consistently in each of the three environments. One QTL (donated by Flagship) was located close to the centromeric region of chromosome 5H (qSDFlag), accounting for up to 15% of the phenotypic variation. A second QTL with a larger effect (from ND24260) was detected on chromosome 5HL (qSDND), accounting for up to 35% of the phenotypic variation. qSDFlag and qSDND displayed an epistatic interaction and DH lines that had the highest levels of grain dormancy carried both genes. We demonstrate that qSDND in the ND24260?×?Flagship DH population is positioned proximal and independent to the well-characterised SD2 region that is associated with both high levels of dormancy and inferior malt quality. This indicates that it should be possible to develop cultivars that combine acceptable malting quality and adequate levels of grain dormancy for protection against PHS by utilizing these alternate QTL.  相似文献   

14.
Bidirectional selective genotyping (BSG) carried out on recombinant inbred lines (RILs) derived from the 541 × Ot1-3 intercross revealed three classes of selection responsive loci underlying preharvest sprouting (PHS) in rye. Ten PHS directional loci (PHSD) located on chromosomes 1RL (3), 3RS (2), 3RL (2), 5RL (2), and 7RS (1) responded significantly to both directions of the disruptive selection and were epistatic to the remaining two classes. Nine PHS resistance loci (PHSR) mapped on chromosomes 1RS, 1RL, 2RS, 3RS, 4RS, 5RS, 5RL, and 6RL (2) responded only to selection for sprouting resistance, being neutral for selection carried out in opposite direction. Eight PHS enhancing loci mapped on chromosomes 2RL, 3RL, 4RL, 5RL, 6RS, and 7RS (3) were affected by selection for sprouting susceptibility and did not respond to selection for sprouting resistance. Map positions of the selection responsive loci coincided with QTLs for PHS and alpha-amylase activity (AA) detected earlier, but BSG coupled with molecular mapping increased precision of PHS dissection in rye. Efficient strategy of marker assisted selection for preharvest sprouting resistance in rye should be based on PHSD and PHSR loci.  相似文献   

15.
F. Y. Gao  G. J. Ren  X. J. Lu    S. X. Sun    H. J. Li    Y. M. Gao    H. Luo    W. G. Yan    Y. Z. Zhang 《Plant Breeding》2008,127(3):268-273
Preharvest sprouting (PHS) is caused by early breaking of seed dormancy. In Sichuan, a major hybrid rice seed production area of China, PHS in hybrid seeds originated from ‘G46A’ parent may lead to severe yield loss, causing serious damage to agricultural production. To detect quantitative trait loci (QTLs) governing PHS, we developed an F2 population of 164 plants derived from ‘G46B’ and ‘K81’, a near‐isogenic introgression line of G46B, with high level of resistance to PHS. PHS was evaluated under controlled field and laboratory conditions. Using simple sequence repeat markers, we constructed a linkage map from this population and identified three QTLs for PHS, namely qPSR2, qPSR5 and qPSR8, which were located on chromosomes 2, 5 and 8, respectively. Among these QTLs, qPSR8, residing in the interval between RM447 and RM3754 on chromosome 8, was the major QTL controlling PHS, for it had a relative high logarithm of the odds (LOD) score and explained 43.04% of the phenotypic variation. These results were correspondent to those identified in extreme low germination rate plants (ELGP) using linkage and linkage disequilibrium. At all loci, ‘K81’ was responsible for enhancing the resistance to PHS.  相似文献   

16.
Stripe rust resistance gene YrC591, present in wheat cultivar C591, is effective against currently important Puccinia striiformis Westend. f. sp. tritici isolates in China. An F2:3 population (127 lines) was developed by crossing C591 with susceptible cultivar Taichung 29. Thirty four simple sequence repeat (SSR) and 155 sequence tagged site (STS) markers located on chromosome 7BL were used to perform bulk segregant analysis. Eight SSR markers, cfa2040, wmc273, wmc166, gwm984, barc32 wmc276, barc182 and gwm146, and 6 STS markers, mag1714, mag1757, mag1811, BE425120, BE471173 and BG607810, were polymorphic between the parents and contrasting resistant and susceptible DNA pools. F2:3 lines were genotyped with these polymorphic markers. Linkage analysis indicated that YrC591 was flanked by Xmag1714 and Xbarc182 with genetic distances of 1.2 and 0.4 cM, respectively. In addition, validation of the SSR markers cfa2040, wmc273 and barc32, and STS markers mag1714 and BE425120 was carried out using wheat lines with C591 as a parent, indicating that these markers should be effective in tracing this gene in marker-assisted selection.  相似文献   

17.
Leaf rust, caused by Puccinia triticina, is an important disease for wheat production, both in China and worldwide. In laboratory studies spelt wheat (Triticum aestivum ssp. spelta) landrace Altgold was resistant to P. triticina races THT and PHT and genetic analysis indicated that it possessed a dominant leaf rust resistance gene, temporarily designated LrAlt. F6 recombinant inbred lines (RILs) derived from a cross with the susceptible common wheat cultivar Nongda 3338 were used to map LrAlt with SSR markers. The resistance gene was distal to SSR loci Xbarc212, Xwmc382, Xgwm636, and Xwmc407 on the short arm of chromosome 2A. The closest markers Xbarc212 and Xwmc382 which co-segregated were 1.8 cM away from LrAlt. The relationships of LrAlt and other wheat leaf rust resistance genes located on the short arm of chromosome 2A were discussed, suggesting that LrAlt might be a new leaf rust resistance gene.  相似文献   

18.
The most important breeding objectives in crop improvement are improving grain yield, grain quality, and resistances to various biotic and abiotic stresses. The objectives of our study were to compare two crossing and four selection schemes for grain yield, yield traits, and slow rusting resistance to leaf rust (Puccinia recondita) based on additive genes in wheat (Triticum aestivum), and to identify the most efficient crossing and selection methodologies in terms of genetic gains and cost efficiency. Segregating populations were derived from 18 simple crosses and the same number of top (three-way) crosses. Half of the crosses were derived from Yecora 70 and the other half from Veery #10 as the common leaf rust susceptible parents. The four selection schemes were: pedigree, modified bulk (F2 and F1-top as pedigree, selected lines in F3, F4, F2-top, F3-top as bulk; and pedigree in F5 and F4-top populations), selected bulk (selected plants in F2, F3, F4, F1-top, F2-top and F3-top as bulk; and pedigree in F5 and F4-top populations), and nonselected bulk (bulk in F2, F3, F4, F1-top, F2-top and F3-top; and pedigree in F5 and F4-top populations). A total of 320 progeny lines, parents and checks were tested for grain yield, other agronomic traits and leaf rust resistance during the 1992/93 and 1993/94 seasons in Ciudad Obregon (Sonora State, Mexico) which represents a typical high yielding irrigated site. The influence of the type of cross and the selection scheme on the mean grain yield and other traits of the progenies was minimal. The selection of parents was the most important feature in imparting yield potential and other favourable agronomic traits. Moreover, the highest yielding lines were distributed equally. Progeny lines derived from Veery #10 crosses had significantly higher mean grain yield compared to those derived from the Yecora 70 crosses. Furthermore, a large proportion of the highest yielding lines also originated from Veery #10 crosses. Mean leaf rust severity of the top cross progenies was lower than that of the simple cross progenies possibly because two parents contributed resistance to top cross progenies. Mean leaf rust severity of the nonselected bulk derivatives was twice that of lines derived from the other three schemes. Selected bulk appears to be the most attractive selection scheme in terms of genetic gains and cost efficiency. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

19.
L. Kong    H. W. Ohm    S. E. Cambron    C. E. Williams 《Plant Breeding》2005,124(6):525-531
Hessian fly [Mayetiola destructor (Say)] is one of the major insect pests of wheat (Triticum aestivum L.) worldwide. Hessian fly resistance gene H9 was previously reported to condition resistance to Hessian fly biotype L that is prevalent in many wheat‐growing areas of eastern USA and an RAPD marker, OPO051000, linked to H9 in wheat was developed using wheat near‐isogenic lines (NILs). However, marker‐assisted selection (MAS) with RAPD markers is not always feasible. One of the objectives in this study was to convert an RAPD marker linked to the gene H9 into a sequence characterized amplified region (SCAR) marker to facilitate MAS and to map H9 in the wheat genome. The RAPD fragment from OPO051000 was cloned, sequenced, and converted into a SCAR marker SOPO05909, whose linkage relationship with H9 was subsequently confirmed in two F2 populations segregating for H9. Linkage analysis identified one sequence tagged site (STS) marker, STS‐Pm3, and the eight microsatellite markers Xbarc263, Xcfa2153, Xpsp2999, Xgwm136, Xgdm33, Xcnl76, Xcnl117 and Xwmc24 near the H9 locus on the distal region of the short arm of chromosome 1A, contrary to the previously reported location of H9 on chromosome 5A. Locus Xbarc263 was 1.2 cM distal to H9, which itself was 1.7 cM proximal to loci Xcfa2153, Xpsp2999 and Xgwm136. The loci Xgwm136, Xcfa2153 and SOPO05909 were shown to be specific to H9 and not diagnostic to several other Hessian fly resistance genes, and therefore should be useful for pyramiding H9 with other Hessian fly resistance genes in a single genotype.  相似文献   

20.
Grain dormancy in wheat is an important component of resistance to preharvest sprouting and hence an important trait for wheat breeders. The significant influence of environment on the dormancy phenotype makes this trait an obvious target for marker-assisted-selection. Closely related breeding lines, SUN325B and QT7475, containing a major dormancy QTL derived from AUS1408 located on chromosome 4A, but substantially different in dormancy phenotype, were compared with a non-dormant cultivar, Hartog, in a range of controlled environments. As temperature increased, dormancy at harvest-ripeness decreased particularly for QT7475. The dormancy phenotypes of reciprocal F1 grains involving all possible combinations of Hartog, QT7475 and SUN325B were also compared in two environments with different temperatures. The results were consistent with the presence of QTL in addition to 4A in SUN325B, compared with QT7475, at least one of which was associated with the seed coat. Genetic analysis of a doubled haploid population derived from SUN325B × QT7475 identified a highly significant QTL located on chromosome 3BL, close to the expected position of the mutant allele of the red seed coat colour gene in white-grained wheat, R-B1a. When the lines in the population were grouped according to the parental alleles at marker loci flanking the 3B QTL, the dormancy phenotype frequency distribution for the SUN325B group was shifted towards greater dormancy compared with the QT7475 group. However, significant variation for dormancy phenotype remained within each group. Lines representing the extremes of the range of phenotypes within each group maintained their relative ranking across seven environments consistent with the presence of another unidentified QTL contributing to dormancy in SUN325B.  相似文献   

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