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1.
The major quantitative trait locus qBR9.1 confers broad-spectrum resistance to rice blast, and was mapped to a ~69.1 kb region on chromosome 9 that was inherited from resistant variety Sanhuangzhan No 2 (SHZ-2). Within this region, only one predicted disease resistance gene with nucleotide binding site and leucine-rich repeat (NBS-LRR) domains was found. Specific markers corresponding to this gene cosegregated with blast resistance in F 2 and F 3 populations derived from crosses of susceptible variety Texianzhan 13 (TXZ-13) to SHZ-2 and the resistant backcross line BC-10. We tentatively designate the gene as Pi56(t). Sequence analysis revealed that Pi56(t) encodes an NBS-LRR protein composed of 743 amino acids. Pi56(t) was highly induced by blast infection in resistant lines SHZ-2 and BC-10. The corresponding allele of Pi56(t) in the susceptible line TXZ-13 encodes a protein with an NBS domain but without LRR domain, and it was not induced by Magnaporthe oryzae infection. Three new cosegregating gene-specific markers, CRG4-1, CRG4-2 and CRG4-3, were developed. In addition, we evaluated polymorphism of the gene-based markers among popular varieties from national breeding programs in Asia and Africa. The presence of the CRG4-2 SHZ-2 allele cosegregated with a blast-resistant phenotype in two BC 2F 1 families of SHZ-2 crossed to recurrent parents IR64-Sub1 and Swarna-Sub1. CRG4-1 and CRG4-3 showed clear polymorphism among 19 varieties, suggesting that they can be used in marker-assisted breeding to combine Pi56(t) with other target genes in breeding lines. 相似文献
2.
The japonica rice cultivar Hokkai 188 shows a high level of partial resistance to leaf blast. For mapping genes conferring the resistance, a set of 190 F 2 progeny/F 3 families was developed from the cross between the indica rice cultivar Danghang-Shali, with a low level of partial resistance, and Hokkai 188. Partial resistance to leaf blast in the F 3 families was assessed in upland nurseries. From a primary microsatellite (SSR) linkage map and QTL analysis using a subset of 126 F 2 progeny/F 3 families randomly selected from the above set, one major QTL located on chromosome 1 was detected in the vicinity of SSR marker RM1216. This QTL was responsible for 69.4% of the phenotypic variation, and Hokkai 188 contributed the resistance allele. Segregation analysis in the F 3 families for partial resistance to leaf blast was in agreement with the existence of a major gene, and the gene was designated as Pi35(t). Another QTL detected on chromosome 8 was minor, explained 13.4% of the phenotypic variation, and an allele of Danghang-Shali increased the level of resistance in this QTL. Additional SSR markers of the targeted Pi35(t) region were further surveyed in the 190 F 2 plants, and Pi35(t) was placed in a 3.5-cM interval flanked by markers RM1216 and RM1003. 相似文献
3.
BackgroundThe coupling of biotic and abiotic stresses leads to high yield losses in rainfed rice ( Oryza sativa L.) growing areas. While several studies target these stresses independently, breeding strategies to combat multiple stresses seldom exist. This study reports an integrated strategy that combines QTL mapping and phenotypic selection to develop rice lines with high grain yield (GY) under drought stress and non-stress conditions, and tolerance of rice blast. MethodologyA blast-tolerant BC 2F 3-derived population was developed from the cross of tropical japonica cultivar Moroberekan (blast- and drought-tolerant) and high-yielding indica variety Swarna (blast- and drought-susceptible) through phenotypic selection for blast tolerance at the BC 2F 2 generation. The population was studied for segregation distortion patterns and QTLs for GY under drought were identified along with study of epistatic interactions for the trait. ResultsSegregation distortion, in favour of Moroberekan, was observed at 50 of the 59 loci. Majority of these marker loci co-localized with known QTLs for blast tolerance or NBS-LRR disease resistance genes. Despite the presence of segregation distortion, high variation for DTF, PH and GY was observed and several QTLs were identified under drought stress and non-stress conditions for the three traits. Epistatic interactions were also detected for GY which explained a large proportion of phenotypic variance observed in the population. ConclusionsThis strategy allowed us to identify QTLs for GY along with rapid development of high-yielding purelines tolerant to blast and drought with considerably reduced efforts. Apart from this, it also allowed us to study the effects of the selection cycle for blast tolerance. The developed lines were screened at IRRI and in the target environment, and drought and blast tolerant lines with high yield were identified. With tolerance to two major stresses and high yield potential, these lines may provide yield stability in rainfed rice areas. 相似文献
4.
Low-temperature-sensitive sterility (LTSS) has become one of the major obstacles in indica-japonica hybrid rice breeding.
In this study, we determined, using RFLP markers, the genetic basis of LTSS in two populations derived from crosses between
indica and japonica parents, the BC 1F 1 of 3037/02428//3037 and the F 2 of 3037/02428. The fertility segregation in the two populations under low-temperature conditions was used as a measurement
of the temperature sensitivity of the various genotypes in the populations. A RFLP survey of bulked extremes from the BC 1F 1 population identified three genomic regions, two on chromosome 1 and one on chromosome 12, that were likely to contain genes
for LTSS (or Ste loci). One-way ANOVA and QTL analysis using a total of 19 markers from these three genomic regions resolved three Ste loci in the BC 1F 1 population and two Ste loci in the F 2 population. On the basis of chromosomal location these loci were distinct from those governing wide-compatibility identified
in previous studies. Two- and three-way ANOVA showed that these loci acted essentially independent of each other in conditioning
LTSS. The main mode of gene action was an interaction between the indica and the japonica alleles within each locus. For each
respective locus this resulted in a drastic fertility reduction in the heterozygote state relative to the homozygote state.
The results have significant implications in indica-japonica hybrid rice breeding programs.
Received : 10 April 1996 / Accepted: 2 June 1997 相似文献
5.
In order to identify quantitative trait loci (QTLs) for leaf senescence and related traits in rice ( Oryza sativa L.), we developed two backcross populations, indica/japonica// japonica and indica/japonica//indica, using IR36 as the indica parent and Nekken-2 as the japonica parent. The QTLs were mapped using a set of simple sequence-repeat markers (SSRs) in the BC 1F 1 population. Senescence was characterized in these plants by measuring the leaf chlorophyll content 25 days after flowering (DAF), the reduction in chlorophyll content (the difference between the chlorophyll content at flowering and at 25 DAF), and the number of late-discoloring leaves per panicle at 25 DAF in five plants from each BC 1F 2 line. These plants were moved into a temperature-controlled growth cabinet at the time of flowering and allowed to mature under identical conditions. Eleven QTLs were detected in the two populations. The major of QTLs for senescence were found on the short arm of chromosome 6 and on the long arm of chromosome 9. Of these, one QTL on chromosome 6 and two on chromosome 9 were verified by confirming the effects of the genotypes on the phenotypes of the BC 1F 3 lines. The japonica parent was found to contribute to late senescence at all but one QTL. Based on a comparison of the effects of heterozygotes and homozygotes on the phenotypic values of each QTL genotype, we concluded that the differential senescence observed in the indica-japonica hybrid was not due to over-dominance; rather, it was the result of partial-dominance genes that were donated from either of the parents. 相似文献
6.
Quantitative trait loci (QTLs) for resistance to rice blast offer a potential source of durable disease resistance in rice. However, few QTLs have been validated in progeny testing, on account of their small phenotypic effects. To understand the genetic basis for QTL-mediated resistance to blast, we dissected a resistance QTL, qBR4-2, using advanced backcross progeny derived from a chromosome segment substitution line in which a 30- to 34-Mb region of chromosome 4 from the resistant cultivar Owarihatamochi was substituted into the genetic background of the highly susceptible Aichiasahi. The analysis resolved qBR4-2 into three loci, designated qBR4-2a, qBR4-2b, and qBR4-2c. The sequences of qBR4-2a and qBR4-2b, which lie 181 kb apart from each other and measure, 113 and 32 kb, respectively, appear to encode proteins with a putative nucleotide-binding site (NBS) and leucine-rich repeats (LRRs). Sequence analysis of the donor allele of qBR4-2a, the region with the largest effect among the three, revealed sequence variations in the NBS-LRR region. The effect of qBR4-2c was smallest among the three, but its combination with the donor alleles of qBR4-2a and qBR4-2b significantly enhanced blast resistance. qBR4-2 comprises three tightly linked QTLs that control blast resistance in a complex manner, and thus gene pyramiding or haplotype selection is the recommended strategy for improving QTL-mediated resistance to blast disease through the use of this chromosomal region. 相似文献
7.
Fine mapping was carried out on three putative QTLs (tentatively designated as Hd-1 to Hd-3) of five such QTLs controlling heading date in rice that had been earlier identified using an F 2 population derived from a cross between a japonica variety, ‘Nipponbare’, and an indica variety, ‘Kasalath’, using progeny backcrossed with ‘Nipponbare’ as the recurrent parent. One BC 3F 2 and two BC 3F 1 plants, in which the target QTL regions were heterozygous and most other chromosomal regions were homozygous for the ‘Nipponbare’
allele, were selected as the experimental material. Self-pollinated progeny (BC 3F 2 and BC 3F 3) of the BC 3F 1 or BC 3F 2 showed continuous variation in days to heading. By means of progeny testing based on BC 3F 3 or BC 3F 4 lines, we determined the genotypes of each BC 3F 2 or BC 3F 3 individual at target QTLs. Their segregation patterns fitted Mendelian inheritance ratios. When the results obtained by RFLP
analysis and progeny tests were combined, Hd-1, Hd-2 and Hd-3 were mapped precisely on chromosomes 6, 7 and 6, respectively, of a rice RFLP linkage map. The results demonstrated that
QTLs can be treated as Mendelian factors. Moreover, these precise locations were in good agreement with the regions estimated
by QTL analysis of the initial F 2 population, demonstrating the high reliability of QTL mapping using a high-density linkage map.
Received: 5 November 1997 / Accepted: 10 February 1998 相似文献
8.
Bacterial Blight (BB) caused by Xanthomonas oryzae pv. oryzae is a major disease of rice in tropical Asia. Since all the Basmati varieties are highly susceptible and the disease is prevalent in the entire Basmati growing region of India, BB is a severe constraint in Basmati rice production. The present study was undertaken with the objective of combining the important Basmati quality traits with resistance to BB by a combination of phenotypic and molecular marker-assisted selection (MAS). Screening of 13 near-isogenic lines of rice against four isolates of the pathogen from Basmati growing regions identified the Xa4, xa8, xa13 and Xa21 effective against all the isolates tested. Two or more of these genes in combination imparted enhanced resistance as expressed by reduced average lesion length in comparison to individual genes. The two-gene pyramid line IRBB55 carrying xa13 and Xa21 was found equally effective as three/four gene pyramid lines. The two BB resistance genes present in IRBB55 were combined with the Basmati quality traits of Pusa Basmati-1 (PB-1), the most popular high yielding Basmati rice variety used as recurrent parent. Phenotypic selection for disease resistance, agronomic and Basmati quality characteristics and marker-assisted selection for the two resistance genes were carried out in BC 1F 1, BC 1F 2 and BC 1F 3 generations. Background analysis using 252 polymorphic amplified fragment length polymorphism (AFLP) markers detected 80.4 to 86.7% recurrent parent alleles in BC 1F 3 selections. Recombinants having enhanced resistance to BB, Basmati quality and desirable agronomic traits were identified, which can either be directly developed into commercial varieties or used as immediate donors of BB resistance in Basmati breeding programs. 相似文献
9.
Key message A minor QTL for heading date located on the long arm of rice chromosome 1 was delimitated to a 95.0-kb region using near isogenic lines with sequential segregating regions. Abstract Heading date and grain yield are two key factors determining the commercial potential of a rice variety. In this study, rice populations with sequential segregating regions were developed and used for mapping a minor QTL for heading date, qHd1. A total of 18 populations in six advanced generations through BC 2F 6 to BC 2F 11 were derived from a single BC 2F 3 plant of the indica rice cross Zhenshan 97 (ZS97)///ZS97//ZS97/Milyang 46. The QTL was delimitated to a 95.0-kb region flanked by RM12102 and RM12108 in the terminal region of the long arm of chromosome 1. Results also showed that qHd1 was not involved in the photoperiodic response, having an additive effect ranging from 2.4 d to 2.9 d observed in near isogenic lines grown in the paddy field and under the controlled conditions of either short day or long day. The QTL had pleiotropic effects on yield traits, with the ZS97 allele delaying heading and increasing the number of spikelets per panicle, the number of grains per panicle and grain yield per plant. The candidate region contains ten annotated genes including two genes with functional information related to the control of heading date. These results lay a foundation for the cloning of qHd1. In addition, this kind of minor QTLs could be of great significance in rice breeding for allowing minor adjustment of heading date and yield traits. 相似文献
10.
A backcross breeding strategy was used to identify quantitative trait loci (QTLs) associated with 14 traits in a BC 2F 2 population derived from a cross between MR219, an indica rice cultivar and an accession of Oryza rufipogon (IRGC 105491). A total of 261 lines were genotyped with 96 microsatellite markers and evaluated for plant morphology, yield components and growth period. The genetic linkage map generated for this population with an average interval size of 16.2?cM, spanning 1,553.4?cM (Kosambi) of the rice genome. Thirty-eight QTLs were identified with composite interval mapping (CIM), whereas simple interval mapping (SIM) resulted in 47 QTLs (LOD >3.0). The O. rufipogon allele was favourable for 59% of QTLs detected through CIM. Of 261 BC 2F 2 families, 26 advanced backcross breeding lines (BC 2F 5) were used for QTL validation. These lines were selected on the basis of the yield traits potentiality in BC 2F 3 and BC 2F 4 generations. The field trial was conducted at three different locations in Malaysia using randomized complete block design with three replications. Trait based marker analysis was done for QTL determination. Twenty-five QTLs were detected in BC 2F 5 generation whereas 29 QTLs were detected in BC 2F 2 generation of the same population. Two QTLs (qPL-1 and qSPL-7) were not considered for validation due to their low R 2 values and two QTLs (qPSS-3-2 and qGW-3-2) were not detected in the BC 2F 5 population. Fifteen QTLs showed the beneficial effect to enhance the trait value of the breeding lines. QTL validation aided to select the promising lines for further utilization. 相似文献
11.
To combat the dreaded diseases in rice like bacterial blight (BB) and blast, host plant resistance has been advocated as the most suitable and sustainable method. Through the present study, we have successfully incorporated three major BB resistance genes, namely Xa21, xa13 and xa5 into NLR3449, a high yielding, blast resistant, fine-grain type, popular rice variety through marker-assisted backcross breeding. Foreground selection was carried out using polymerase chain reaction based, gene-specific markers, namely pTA248 (Xa21), xa13prom (xa13) and xa5FM (xa5) at each generation of backcrossing, while 127 polymorphic SSR markers spanning on 12 chromosomes were used for background selection and backcrossing was limited to two rounds. At BC2F1 generation, a single plant (NLR-87-10) with 89.9% recovery, possessing all the three BB resistance genes was forwarded to BC2F2 generation. A solitary BC2F2 plant, namely NLR-87-10-106 possessing all the three resistance genes and 96% genome recovery was identified and advanced through selfing until BC2F4 generation by adopting pedigree-method of selection. Three best BC2F4 lines, possessing high level of resistance against BB and blast, and equivalent or superior to NLR 34449 in terms of yield, grain quality and agro-morphological traits were identified and advanced for multi-location trials. 相似文献
12.
Introgression has been achieved from wild species Oryza grandiglumis (2 n=48, CCDD, Acc. No. 101154) into O. sativa subsp. japonica cv. Hwaseongbyeo as a recurrent parent. An advanced introgression (backcross) line, HG101, produced from a single plant from
BC 5F 3 families resembled Hwaseongbyeo, but it showed differences from Hwaseongbyeo in several traits, including days to heading
and culm length. To detect the introgressions, 450 microsatellite markers of known chromosomal position were used for the
parental survey. Of the 450 markers, 51 (11.3%) detected O. grandiglumis segments in HG101. To characterize the effects of alien genes introgressed into HG101, an F 2:3 population (150 families) from the cross Hwaseongbyeo/HG101 was developed and evaluated for 13 agronomic traits. Several
lines outperformed Hwaseongbyeo in several traits, including days to heading. Genotypes were determined for 150 F 2 plants using simple sequence repeat markers. Qualitative trait locus (QTL) analysis was carried out to determine the relationship
between marker genotype and the traits evaluated. A total of 39 QTL and 1 gene conferring resistance to blast isolate were
identified using single-point analysis. Phenotypic variation associated with each QTL ranged from 4.2 to 30.5%. For 18 (46.2%)
of the QTL identified in this study, the O. grandiglumis-derived alleles contributed a desirable agronomic effect despite the overall undesirable characteristics of the wild phenotype.
Favorable wild alleles were detected for days to heading, spikelets per panicle, and grain shape traits. Grain shape QTL for
grain weight, thickness, and width identified in the F 2:3 lines were further confirmed based on the F 4 progeny test. The confirmed locus, tgw2 for grain weight is of particular interest because of its independence from undesirable height and maturity. Several QTL
controlling amylose content and grain traits have not been detected in the previous QTL studies between Oryza cultivars, indicating potentially novel alleles from O. grandiglumis. The QTL detected in this study could be a rich source of natural genetic variation underlying the evolution and breeding
of rice. 相似文献
13.
Specific Indonesian lowland rice ( Oryza sativa L.) cultivars elongate thick primary roots on the soil surface of paddy fields. To clarify the genetic factors controlling
soil-surface rooting, we performed quantitative trait locus (QTL) analyses using 124 recombinant inbred lines (RILs) derived
from a cross between Gemdjah Beton, an Indonesian lowland rice cultivar with soil-surface roots, and Sasanishiki, a Japanese
lowland rice cultivar without soil-surface roots. These cultivars and the RILs were tested for soil-surface rooting in a paddy
field. We identified four regions of chromosomes 3, 4, 6, and 7 that were associated with soil-surface rooting in the field.
Among them, one major QTL was located on the long arm of chromosome 7. This QTL explained 32.5–53.6% of the total phenotypic
variance across three field evaluations. To perform fine mapping of this QTL, we measured the basal root growth angle of crown
roots at the seedling stage in seven BC 2F 3 recombinant lines grown in small cups in a greenhouse. The QTL was mapped between markers RM21941 and RM21976, which delimit
an 812-kb interval in the reference cultivar Nipponbare. We have designated this QTL qSOR1 ( quantitative trait locus for SOIL SURFACE ROOTING 1). 相似文献
14.
Glycine soja, the wild progenitor of soybean, is a potential source of useful genetic variation in soybean improvement. The objective of our study was to map quantitative trait loci (QTL) from G. soja that could improve the crop. Five populations of BC 2F 4-derived lines were developed using the Glycine max cultivar IA2008 as a recurrent parent and the G. soja plant introduction (PI) 468916 as a donor parent. There were between 57 and 112 BC 2F 4-derived lines in each population and a total of 468 lines for the five populations. The lines were evaluated with simple sequence repeat markers and in field tests for yield, maturity, plant height, and lodging. The field testing was done over 2 years and at two locations each year. Marker data were analyzed for linkage and combined with field data to identify QTL. Using an experimentwise significance threshold of P=0.05, four yield QTL were identified across environments on linkage groups C2, E, K, and M. For these yield QTL, the IA2008 marker allele was associated with significantly greater yield than the marker allele from G. soja. In addition, one lodging QTL, four maturity QTL, and five QTL for plant height were identified across environments. Of the 14 QTL identified, eight mapped to regions where QTL with similar effects were previously mapped. Many regions carrying the yield QTL were also significant for other traits, such as plant height and lodging. When the significance threshold was reduced and the data were analyzed with simple linear regression, four QTL with a positive allele for yield from G. soja were mapped. One epistatic interaction between two genetic regions was identified for yield using an experimentwise significance threshold of P=0.05. Additional research is needed to establish whether multiple trait associations are the result of pleiotropy or genetic linkage and to retest QTL with a positive effect from G. soja.Communicated by H.C. Becker 相似文献
15.
Blackmold, caused by the fungus Alternaria alternata, is a major ripe fruit disease of processing tomatoes. Previously, we found blackmold resistance in a wild tomato ( Lycopersicon cheesmanii) and quantitative trait loci (QTL) for resistance were mapped in an interspecific population. Five QTLs were selected for introgression from L. cheesmanii into cultivated tomato using marker-assisted selection (MAS). Restriction fragment length polymorphism and PCR-based markers flanking, and within, the chromosomal regions containing QTLs were used for MAS during backcross and selfing generations. BC 1 plants heterozygous at the QTLs, and subsequent BC 1S 1 and BC 1S 2 lines possessing different homozygous combinations of alleles at the target QTLs, were identified using DNA markers. Field experiments were conducted in 1998 (with 80 marker-selected BC 1S 2 lines) and 1999 (with 151 marker-selected BC 1S 2 and BC 1S 3 lines) at three California locations. Blackmold resistance was assessed during both years, and horticultural traits were evaluated in 1999. The BC 1S 2 and BC 1S 3 lines containing L. cheesmanii alleles at the QTLs were associated with a large genetic variance for resistance to blackmold and moderate heritability, suggesting that significant genetic gain may be achieved by selection in this genetic material. L. cheesmanii alleles at three of the five introgressed QTLs showed a significant, positive effect on blackmold resistance. A QTL on chromosome 2 had the largest positive effect on blackmold resistance, alone and in combination with other QTLs, and was also associated with earliness, a positive horticultural trait. The other four QTLs were associated primarily with negative horticultural traits. Fine mapping QTLs using near isogenic lines could help determine if such trait associations are due to linkage drag or pleiotropy. 相似文献
16.
Summary
Oryza minuta J. S. Presl ex C. B. Presl is a tetraploid wild rice with resistance to several insects and diseases, including blast (caused by Pyricularia grisea) and bacterial blight (caused by Xanthomonas oryzae pv. oryzae). To transfer resistance from the wild species into the genome of cultivated rice ( Oryza sativa L.), backcross progeny (BC 1, BC 2, and BC 3) were produced from interspecific hybrids of O. sativa cv IR31917-45-3-2 (2n=24, AA genome) and O. minuta Acc. 101141 (2n=48, BBCC genomes) by backcrossing to the O. sativa parent followed by embryo rescue. The chromosome numbers ranged from 44 to 47 in the BC 1 progeny and from 24 to 37 in the BC 2 progeny. All F 1 hybrids were resistant to both blast and bacterial blight. One BC 1 plant was moderately susceptible to blast while the rest were resistant. Thirteen of the 16 BC 2 progeny tested were resistant to blast; 1 blast-resistant BC 2, plant 75-1, had 24 chromosomes. A 3 resistant: 1 susceptible segregation ratio, consistent with the action of a major, dominant gene, was observed in the BC 2F 2 and BC 2F 3 generations. Five of the BC 1 plants tested were resistant to bacterial blight. Ten of the 21 BC 2 progeny tested were resistant to Philippine races 2, 3, and 6 of the bacterial blight pathogen. One resistant BC 2, plant 78-1, had 24 chromosomes. The segregation of reactions of the BC 2F 2, BC 2F 3, and BC 2F 4 progenies of plant 78-1 suggested that the same or closely linked gene(s) conferred resistance to races 2, 3, 5, and 6 of the bacterial blight pathogen from the Philippines. 相似文献
17.
Breeding for resistance to Fusarium head blight (FHB) in durum wheat continues to be hindered by the lack of effective resistance sources. Only limited information is available on resistance QTL for FHB in tetraploid wheat. In this study, resistance to FHB of a Triticum dicoccum line in the background of three Austrian T. durum cultivars was genetically characterized. Three populations of BC 1F 4-derived RILs were developed from crosses between the resistant donor line T. dicoccum-161 and the Austrian T. durum recipient varieties DS-131621, Floradur and Helidur. About 130 BC 1F 4-derived lines per population were evaluated for FHB response using artificial spray inoculation in four field experiments during two seasons. Lines were genetically fingerprinted using SSR and AFLP markers. Genomic regions on chromosomes 3B, 4B, 6A, 6B and 7B were significantly associated with FHB severity. FHB resistance QTL on 6B and 7B were identified in two populations and a resistance QTL on 4B appeared in three populations. The alleles that enhanced FHB resistance were derived from the T. dicoccum parent, except for the QTL on chromosome 3B. All QTL except the QTL on 6A mapped to genomic regions where QTL for FHB have previously been reported in hexaploid wheat. QTL on 3B and 6B coincided with Fhb1 and Fhb2, respectively. This implies that tetraploid and hexaploid wheat share common genomic regions associated with FHB resistance. QTL for FHB resistance on 4B co-located with a major QTL for plant height and mapped at the position of the Rht- B1 gene, while QTL on 7B overlapped with QTL for flowering time. 相似文献
18.
Cercospora leaf spot (CLS) caused by the fungus Cercospora canescens Illis & Martin is a serious disease in mungbean ( Vigna radiata (L.) Wilczek), and disease can reduce seed yield by up to 50%. We report here for the first time quantitative trait loci
(QTL) mapping for CLS resistance in mungbean. The QTL analysis was conducted using F 2 (KPS1 × V4718) and BC 1F 1 [(KPS1 × V4718) × KPS1] populations developed from crosses between the CLS-resistant mungbean V4718 and CLS-susceptible cultivar
Kamphaeng Saen 1 (KPS1). CLS resistance in F 2 populations was evaluated under field conditions during the wet seasons of 2008 and 2009, and resistance in BC 1F 1 was evaluated under field conditions during the wet season in 2008. Seven hundred and fifty-three simple sequence repeat
(SSR) markers from various legumes were used to assess polymorphism between KPS1 and V4718. Subsequently, 69 polymorphic markers
were analyzed in the F 2 and BC 1F 1 populations. The results of segregation analysis indicated that resistance to CLS is controlled by a single dominant gene,
while composite interval mapping consistently identified one major QTL ( qCLS) for CLS resistance on linkage group 3 in both F 2 and BC 1F 1 populations. qCLS was located between markers CEDG117 and VR393, and accounted for 65.5–80.53% of the disease score variation depending on
seasons and populations. An allele from V4718 increased the resistance. The SSR markers flanking qCLS will facilitate transferral of the CLS resistance allele from V4718 into elite mungbean cultivars. 相似文献
19.
Common wild rice ( Oryza rufipogon Griff.) is the ancestor of cultivated rice ( O. sativa L.), which has a greater genetic diversity and important traits that remain to be employed in cultivated rice. In this study, a set of introgression lines (BC 4F 5 and/or BC 4F 6) carrying various introgressed segments from common wild rice, collected from Dongxiang county, Jiangxi Province, China, in the background of an Indica ( O. sativa L. ssp. indica) cultivar, Guichao 2, was used. A total of 12 drought-related quantitative trait loci (QTL) were identified by investigating drought tolerance of introgression lines under 30% PEG treatment at the young seedlings stage. Of these QTLs, the alleles of 4 QTLs on chromosome 2, 6 and 12 from Dongxiang common wild rice were responsible for increased drought tolerance of the introgression lines. In particular, a QTL qSDT12-2, near RM17 on chromosome 12, was consistently detected in different replications, and expressed stably under PEG stress throughout the study. It was also found that the QTLs located on different chromosomes might express at different stages. 相似文献
20.
A quantitative trait locus (QTL) for grain weight (GW) was detected near SSR marker RM210 on chromosome 8 in backcross populations derived from a cross between the Korean japonica cultivar Hwaseongbyeo and Oryza rufipogon (IRGC 105491). The O. rufipogon allele increased GW in the Hwaseongbyeo background despite the fact that O. rufipogon was the small-seeded parent. Using sister BC 3F 3 near-isogenic lines (NILs), gw8.1 was validated and mapped to a 6.1 cM region in the interval between RM42 and RM210 ( P≤0.0001). Substitution mapping with eight BC 3F 4 sub-NILs further narrowed the interval containing gw8.1 to about 306.4 kb between markers RM23201.CNR151 and RM30000.CNR99. A yield trial using homozygous BC 3F 4 sister sub-NILs and the Hwaseongbyeo recurrent parent indicated that the NIL carrying an O. rufipogon chromosome segment across the entire gw8.1 target region out-yielded its sister NIL (containing Hwaseongbyeo chromosome in the RM42–RM210 interval) by 9% ( P=0.029). The higher-yielding NIL produced 19.3% more grain than the Hwaseongbyeo recurrent parent ( P=0.018). Analysis of a BC 3F 4 NIL indicated that the variation for GW is associated with variation in grain shape, specifically grain length. The locus, gw8.1 is of particular interest because of its independence from undesirable height and grain quality traits. SSR markers tightly linked to the GW QTL will facilitate cloning of the gene underlying this QTL as well as marker-assisted selection for variation in GW in an applied breeding program. 相似文献
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