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1.
Direct seeding of rice is increasingly being practiced in both rainfed and irrigated areas because of labor shortage for transplanting and opportunities for crop intensification. However, poor crop establishment remains a major obstacle facing its large-scale adoption in areas prone to flooding. Screening of over 8,000 gene bank accessions and breeding lines identified a few tolerant genotypes. One of these, Khao Hlan On, was selected for mapping QTLs associated with tolerance using a backcross population with IR64 as a recurrent parent. Survival of BC2F2 lines varied from 0 to 68%, and averaged about 28%. A linkage map of 1475.7 cM with an average interval of 11.9 cM was constructed using 135 polymorphic SSRs and 1 indel marker. Five putative QTLs were detected, on chromosomes 1 (qAG-1-2), 3 (qAG-3-1), 7 (qAG-7-2), and 9 (qAG-9-1 and qAG-9-2), explaining 17.9 to 33.5% of the phenotypic variation, and with LOD scores of 5.69–20.34. Khao Hlan On alleles increased tolerance of flooding during germination for all the QTLs. Graphical genotyping of the lines with highest and lowest survival verified the detected QTLs that control tolerance and some QTLs co-localize with previously identified QTLs for traits relevant to tolerance, which warrant further studies.  相似文献   

2.
Stalk rot, also called as charcoal rot in India, caused by Macrophomina phaseolina, is an economically important, soil borne disease in major sorghum growing areas across the world. A population of F9 generation recombinant inbred lines (RILs), derived from IS22380 (susceptible) × E36-1 (resistant), along with parents were phenotyped in sick plots at two locations (Dharwad and Bijapur, Karnataka, India). A total of 85 polymorphic marker loci (62 nuclear and 4 genic SSRs, 19 RAPDs) was available for the construction of genetic map, spanning 650.3 cM in all the ten linkage groups. Analysis with QTL Cartographer (2.5b), adopting composite interval mapping method (LOD > 2.0) at both locations, revealed 5 QTLs at Dharwad and 4 QTLs at Bijapur locations for the component traits of charcoal rot disease resistance. QTLs for number of internodes crossed, length of infection and per cent lodging accounted for 31.83, 10.76 and 18.90 per cent at Dharwad location and 14.87, 10.47 and 26.44 per cent phenotypic variability at Bijapur location, respectively. The QTLs for number of internodes crossed by the rot, length of infection and percent lodging were common across two locations. These QTLs, consistent over environments for the component traits, are likely to assist in marker-assisted selection (MAS) for charcoal rot resistance in sorghum.  相似文献   

3.
Ascochyta blight (AB) caused by Ascochyta rabiei, is globally the most important foliar disease that limits the productivity of chickpea (Cicer arietinum L.). An intraspecific linkage map of cultivated chickpea was constructed using an F2 population derived from a cross between an AB susceptible parent ICC 4991 (Pb 7) and an AB resistant parent ICCV 04516. The resultant map consisted of 82 simple sequence repeat (SSR) markers and 2 expressed sequence tag (EST) markers covering 10 linkage groups, spanning a distance of 724.4 cM with an average marker density of 1 marker per 8.6 cM. Three quantitative trait loci (QTLs) were identified that contributed to resistance to an Indian isolate of AB, based on the seedling and adult plant reaction. QTL1 was mapped to LG3 linked to marker TR58 and explained 18.6% of the phenotypic variance (R 2) for AB resistance at the adult plant stage. QTL2 and QTL3 were both mapped to LG4 close to four SSR markers and accounted for 7.7% and 9.3%, respectively, of the total phenotypic variance for AB resistance at seedling stage. The SSR markers which flanked the AB QTLs were validated in a half-sib population derived from the same resistant parent ICCV 04516. Markers TA146 and TR20, linked to QTL2 were shown to be significantly associated with AB resistance at the seedling stage in this half-sib population. The markers linked to these QTLs can be utilized in marker-assisted breeding for AB resistance in chickpea.  相似文献   

4.
An initial F2 mapping population of 223 plants of the cross between TM‐1 (Gossypium hirsutum L.) × H102 (Gossypium barbadense L.) was used to map QTLs controlling fibre strength in cotton. A genetic linkage map with 408 SSR markers was constructed with a total length of 3872.6 cM. Multiple‐QTL model of the software MapQTL version 5.0 was used to map QTLs related to fibre strength of the F2 : 3 population. QTL QFS‐D11‐1 conferring fibre strength was mapped between NAU2950 and NAU4855 on chromosome 21 (Chr. 21) which explained 23.4% of phenotypic variation. Introgressed lines (ILs), that is, IL‐D11‐1, IL‐D11‐2 and IL‐D11‐3 were obtained through marker‐assisted backcrossing in TM‐1 background. An F2 population of 758 plants derived from cross IL‐D11‐2 × TM‐1 was used for fine‐mapping QTL QFS‐D11‐1. QFS‐D11‐1 was mapped between markers NAU2110 and NAU2950, adjacent to its initial interval NAU2950–NAU4855 with phenotypic variation explaining 35.8%. QFS‐D11‐1 was further mapped to 0.6 cM from the flanking marker NAU2950. The results will give a basis for marker‐assisted selection of QFS‐D11‐1 in cotton breeding and to lay the foundation for cloning QFS‐D11‐1.  相似文献   

5.
选用感丝裂病的玉米自交系R08与抗丝裂病的自交系Es40组配F2群体共348个单株,构建了包含115个SSR标记的分子遗传连锁图谱,覆盖玉米基因组2 178.6 cM,平均图距为18.9 cM。采用复合区间作图法,对F2:4家系丝裂病数据进行抗性QTL分析,共检测到12个QTL,分别位于第1、2、4、5和7染色体,贡献率为4.22%~37.95%。其中在第1、3染色体上检测到主效QTL,贡献率均大于30%,基因作用方式均为显性,其余10个QTL的作用方式多为加性或部分显性。  相似文献   

6.
X. J. Yuan  X. Z. Li  J. S. Pan    G. Wang    S. Jiang    X. H. Li    S. L. Deng    H. L. He    M. X. Si    L. Lai    A. Z. Wu    L. H. Zhu    R. Cai 《Plant Breeding》2008,127(2):180-188
A 173‐point genetic linkage map of cucumber (Cucumis sativus L.), consisting of 116 SRAPs, 33 RAPDs, 11 SSRs, 9 SCARs, 3 ISSRs, and 1 STS, was constructed using 130 F2 progeny derived from a narrow cross between line S94 (Northern China open‐field type) and line S06 (greenhouse European type). The seven linkage groups spanned 1016 cM with a mean marker interval of 5.9 cM. Using the F2 population and its F3 derived families, a total of 38 QTLs were detected on five linkage groups with an LOD threshold of 3.0 for nine fruit‐related traits: fruit weight, length, and diameter, fruit flesh thickness, seed‐cavity diameter, fruit‐stalk length, fruit pedicel length, length/diameter and length/stalk ratio. Of the identified QTLs, fsl4.3 for fruit‐stalk length explained the largest portion of phenotypic variation (r2 = ～30%). Several QTLs were detected in the same linkage region in different generations and different seasons. Additionally, several QTLs for various fruit traits were mapped to the same or neighbouring marker intervals, suggesting they are possible character associations for controlling cucumber fruit development.  相似文献   

7.
Development of durable resistance to soybean rust (SBR) is challenging due to the pathogenic diversity of Phakopsora pachyrhizi populations. The objective of this research was to investigate and confirm the genomic locations of Rpp genes in the Ugandan line UG-5 that confer resistance to different SBR pathotypes. Bulked segregant analysis revealed two genomic regions associated with resistance in a cross with rust-susceptible 'Williams 82'. Composite interval mapping in the F2 and F2:3 populations had a LOD score of 48.7 in a region 0.38 cM away from the estimated location of the Rpp1 locus on chromosome (Chr.) 18. An approximately 23-Kbp interval spanning the Rpp1 locus was flanked by SNP markers ss715632313 and ss715632318. Another interval was identified at the Rpp3 locus on Chr. 6 between markers Satt100 and ss715594488 (2.4 cM) in the F2 population and between Satt100 and ss715594874 (4.3 cM) in the F2:3 population, with a maximum LOD score of 25.6. UG-5 was thus confirmed to have SBR resistance genes at the Rpp1 and Rpp3 loci that can be pyramided into other elite cultivars.  相似文献   

8.
Broad tolerance to phytophthora root rot (PRR) caused by Phytophthora sojae has become an important goal for the improvement of soybean (Glycine max) because of the rapid spread of races that defeat the available resistance genes. The aim of this research was to identify the location of quantitative trait loci (QTL) in ‘Conrad’, a soybean cultivar with broad tolerance to many races of P. sojae. A PRR susceptible breeding line ‘OX760-6-1’was crossed with Conrad. Through single-seed-descent, 112, F2 derived, F7 recombinant inbred lines (RILs) were advanced. A total of 39 random amplified polymorphic DNA bands (RAPDs) and 89 type 1 microsatellite (simple sequence repeat; SSR) markers were used to construct a genetic linkage map. In the greenhouse, RILs were inoculated with four P. sojae isolates (three from China and one from Canada). Disease was measured as the percent of dead plants 20 days after germination in P. sojae inoculated vermiculite in the greenhouse. Three QTLs (QGP1, QGP2, QGP3) for PRR tolerance in the greenhouse were detected using WinQTLCart 2.0 with a log-likelihood (LOD) score 27.14 acquired through permutations (1,000 at P ≤ 0.05). QGP1 (near Satt509) was located at linkage group F and explained 13.2%, 5.9%, and 6.7% of the phenotypic variance for tolerance to the JiXi, JianSanJiang and ShuangYaShan isolates, respectively. QGP2 (near Satt334) was located in a different interval on linkage group F and explained 5.1% and 2.4% of the phenotypic variance for JiXi and ShuangYaShan isolates, respectively. QGP3 was located on linkage group D1b + W (near OPL18800/SCL18659) and explained 10.2% of the phenotypic variance for Woodslee isolate. QGP1 and QGP2 appeared to be associated with PRR tolerance across a range of isolates but QGP3 was active only against the Woodslee isolate. At Woodslee and Weaver (in Ontario) in 2000, the interval associated with QGP3 explained 21.6% and 16.7% of phenotypic variance in resistance to PRR, respectively and was referred as QFP1. The identified QTLs would be beneficial for marker assistant selection of PRR tolerance varieties against both China and North America P. sojae races. Yingpeng Han and Weili Teng have equal contribution to the paper.  相似文献   

9.
The improvement of cotton fiber quality has become more important because of changes in spinning technology. Stable quantitative trait loci (QTLs) for fiber quality will enable molecular marker-assisted selection to improve fiber quality of future cotton cultivars. A simple sequence repeat (SSR) genetic linkage map consisting of 156 loci covering 1,024.4 cM was constructed using a series of recombinant inbred lines (RIL) developed from an F2 population of an Upland cotton (Gossypium hirsutum L.) cross 7235 × TM-1. Phenotypic data were collected at Nanjing and Guanyun County in 2002 and 2003 for 5 fiber quality and 6 yield traits. We found 25 major QTLs (LOD ≥ 3.0) and 28 putative QTLs (2.0 < LOD < 3.0) for fiber quality and yield components in two or four environments independently. Among the 25 QTLs with LOD ≥ 3, we found 4 QTLs with large effects on fiber quality and 7 QTLs with large effects on yield components. The most important chromosome D8 in the present study was densely populated with markers and QTLs, in which 36 SSR loci within a chromosomal region of 72.7 cM and 9 QTLs for 8 traits were detected.  相似文献   

10.
Stripe (yellow) rust, caused by Puccinia striiformis Westend. f. sp. tritici Eriks. (Pst), is an important disease of wheat (Triticum aestivum L.) globally. Use of host resistance is an important strategy to manage the disease. The cultivar Flinor has temperature-sensitive resistance to stripe rust. To map quantitative trait loci (QTLs) for these temperature-sensitive resistances, Flinor was crossed with susceptible cultivar Ming Xian 169. The seedlings of the parents, and F1, F3 progeny were screened against Chinese yellow rust race CYR32 in controlled-temperature growth chambers under different temperature regimes. Genetic analysis confirmed two genes for temperature-sensitive stripe rust resistance. A linkage map of SSR markers was constructed using 130 F3 families derived from the cross. Two temperature-sensitive resistance QTLs were detected on chromosome 5B, designated QYr-tem-5B.1 and QYr-tem-5B.2, respectively, and are separated by a genetic distance of over 50 cM. The loci contributed 33.12 and 37.33% of the total phenotypic variation for infection type, respectively, and up to 70.45% collectively. Favorable alleles of these two QTLs came from Flinor. These two QTLs are temperature-sensitive resistance loci and different from previously reported QTLs for resistance to stripe rust.  相似文献   

11.
One hundred sixty-one EST-SNP markers were newly developed for analysis of QTLs for resistance to black rot caused by Xanthomonas campestris pv. campestris by determining EST sequences of a resistant line obtained from cabbage ‘Early Fuji’ and a susceptible broccoli line. A linkage map consisting of nine linkage groups was constructed with a total of 209 markers, including these new SNP markers and previously reported DNA markers. F2 plants grown in a field for 1 month were inoculated by spraying bacteria of race 1, and disease severity of each plant was recorded. Three QTLs, i.e., QTL-1, QTL-2, and QTL-3, were detected on linkage group C2, C4 and C5, respectively. QTL-1, which showed the highest LOD score and additive effect, was again detected in another F2 population used the next year, suggesting QTL-1 to be a major QTL. QTL-2 and QTL-3 could be minor QTLs influenced by environmental factors. The genomic region harboring QTL-1 showed synteny with a region from 5.3 to 7.4 Mb from the short arm end of chromosome 5 of Arabidopsis thaliana, which is rich in TIR-NBS-LRR family genes. The identified SNP markers in QTL-1 are considered to be useful in marker-assisted selection for black rot resistance in Brassica oleracea lines.  相似文献   

12.
A genetic linkage map of chromosome 6 was constructed by using 270 recombinant inbred lines originated from an upland cotton cross (Yumian 1 × T586) F2 population. The genetic map included one morphological (T1) and 18 SSR loci, covering 96.2 cM with an average distance of 5.34 cM between two markers. Based on composite interval mapping (CIM), QTL(s) affecting lint percentage, fiber length, fiber length uniformity, fiber strength and spiny bollworm resistance (Earias spp.) were identified in the t1 locus region on chromosome 6. The allele(s) originating from T586 of QTLs controlling lint percentage increased the trait phenotypic value while the alleles originating from Yumian 1 of QTLs affecting fiber length, fiber length uniformity, fiber strength and spiny bollworm resistance increased the trait phenotypic value.  相似文献   

13.
Botrytis grey mould (BGM) caused by Botrytis cinerea Pers. ex. Fr. is the second most important foliar disease of chickpea (Cicer arietinum L.) after ascochyta blight. An intraspecific linkage map of chickpea consisting of 144 markers assigned on 11 linkage groups was constructed from recombinant inbred lines (RILs) of a cross that involved a moderately resistant kabuli cultivar ICCV 2 and a highly susceptible desi cultivar JG 62. The length of the map obtained was 442.8 cM with an average interval length of 3.3 cM. Three quantitative trait loci (QTL) which together accounted for 43.6% of the variation for BGM resistance were identified and mapped on two linkage groups. QTL1 explained about 12.8% of the phenotypic variation for BGM resistance and was mapped on LG 6A. It was found tightly linked to markers SA14 and TS71rts36r at a LOD score of 3.7. QTL2 and QTL3 accounted for 9.5 and 48% of the phenotypic variation for BGM resistance, respectively, and were mapped on LG 3. QTL 2 was identified at LOD 2.7 and flanked by markers TA25 and TA144, positioned at 1 cM away from marker TA25. QTL3 was a strong QTL detected at LOD 17.7 and was flanked by TA159 at 12 cM distance on one side and TA118 at 4 cM distance on the other side. This is the first report on mapping of QTL for BGM resistance in chickpea. After proper validation, these QTL will be useful in marker-assisted pyramiding of BGM resistance in chickpea.  相似文献   

14.
Vigna vexillata is a wild cross‐incompatible relative of cowpea. It is highly resistant to several diseases and pests plaguing cowpea. A linkage map was developed for V. vexillata comprising 120 markers, including 70 random amplified polymorphic DNAs, 47 amplified fragment length polymorphisms, one simple sequence repeat and two morphological traits namely, the cowpea mottle carmovirus resistance locus (CPMo V) and leaf shape (La), utilizing an F2 generation of the intra‐specific cross Tvnu 1443’× Tvnu 73′. The genetic map comprised 14 linkage groups spanning 1564.1 cM of the genome. Thirty‐nine quantitative trait loci (QTLs) associated with nine traits were detected on the linkage map, explaining between 15.62 and 66.58% of their phenotypic variation. Seven chromosomal intervals contained QTLs with effects on multiple traits.  相似文献   

15.
Water yam (Dioscorea alata L.) is the most widely cultivated food yams. Despite its importance, its production is limited by anthracnose disease caused by Colletotrichum gloeosporioides (Penz.). The use of resistant yam varieties is the most reliable approach of management of this disease. The speed and precision of breeding can be improved by the development of genetic linkage maps which would provide the basis for locating and hence manipulating quantitative traits such as anthracnose resistance in breeding programmes. An F1 diploid population was developed by crossing ‘Boutou’ a female clone (with field resistance to anthracnose) with ‘Pyramide’ (susceptible). A linkage map was generated with 523 polymorphic markers from 26 AFLP primer combinations. The resulting map covered a total length of 1538 cM and included 20 linkage groups. It is the most saturated of all genetic linkage maps of yam to date. QTL analysis of anthracnose resistance was performed based on response to two isolates of C. gloeosporioides. Resistance to anthracnose appeared to be inherited quantitatively. Using a LOD significance threshold of 2.6 we identified a total of nine QTLs for anthracnose resistance. The phenotypic variance explained by each QTL ranged from 7.0 to 32.9% whereas the total amount of phenotypic variation for anthracnose resistance explained by all significant QTLs varied from 26.4 to 73.7% depending on the isolate and the variable considered. These QTLs displayed isolate-specific resistance as well as broad spectrum resistance. The availability of molecular markers linked to the QTLs of anthracnose resistance will facilitate marker-assisted selection in breeding programmes.  相似文献   

16.
Sclerotinia stem rot, caused by the fungus Sclerotinia sclerotiorum, is one of the most devastating diseases of rapeseed (Brassica napus L.) in China. The two major factors limiting the development of disease resistance are (1) the absence of accessions with complete resistance and (2) the lack of a single method that can be widely applied to assess tolerance—even though accessions with differential tolerance to S. sclerotiorum have been identified in China. In the study reported here, we have used one doubled haploid (DH) population consisting of 72 lines, which was derived from the F1 generation of a cross between a partially resistant line (DH821) and a susceptible line (DHBao604), to identify quantitative trait loci (QTLs) involved in the resistance to S. sclerotiorum. Three inoculation methods, namely, mycelial toothpick inoculation (MTI), mycelial plug inoculation (MPI), and infected petal inoculation (IPI), were used to assess resistance at the adult plant stage. A genetic linkage map with 20 linkage groups covering 1746.5 cM, with an average space of 6.93 cM, was constructed using a total of 252 molecular markers, including 91 simple sequence repeats, 72 randomly amplified polymorphic DNA, 86 sequence-related amplified polymorphisms, two restriction fragment length polymorphisms, and one expressed sequence tag. Composite interval mapping identified ten, one and ten QTLs using MTI, MPI and IPI methods, respectively, at a LOD > 2.5. One QTL was detected in linkage group N12 by MTI in 2004 and 2005 and by IPI in 2005. Another QTL was detected in linkage group N3 and N4 by MPI in 2006 and 2007. There was one common QTL detected by MTI in 2005 and by MPI in 2006. These results provide information on the genetic control of resistance to S. sclerotiorum in oilseed rape.  相似文献   

17.
Ascochyta blight is a devastating disease of chickpea. Breeders have been trying to introduce resistance from wild Cicer into cultivated chickpea, however, the effort is hampered by the frequent genetic drag of undesirable traits. Therefore, this study was aimed to identify potential markers linked to plant growth habit, ascochyta blight resistance and days to flowering for marker-assisted breeding. An interspecific F2 population between chickpea and C. reticulatum was constructed to develop a genetic linkage map. F2 plants were cloned through stem cuttings for replicated assessment of ascochyta blight resistance. A closely linked marker (TA34) on linkage group (LG) 3 was identified for plant growth habit explaining 95.2% of the variation. Three quantitative trait loci (QTLs) explaining approximately 49% of the phenotypic variation were found for ascochyta blight resistance on LG 3 and LG 4. Flowering time was controlled by two QTLs on LG3 explaining 90.2% of the variation. Ascochyta blight resistance was negatively correlated with flowering time (r = −0.22, P < 0.001) but not correlated with plant growth habit.  相似文献   

18.
Sugarcane mosaic virus (SCMV) is one of devastating pathogens in maize (Zea mays L.), and causes serious yield loss in susceptible cultivars. An effective solution to control the virus is utilizing resistant genes to improve the resistance of susceptible materials, whereas the basic work is to analyze the genetic basis of resistance. In this study, maize inbred lines Huangzao4 (resistant) and Mo17 (susceptible) were used to establish an F9 immortal recombinant inbred line (RIL) population containing 239 RILs. Based on this segregation population, a genetic map was constructed with 100 simple sequence repeat (SSR) markers selected from 370 markers, and it covers 1421.5 cM of genetic distance on ten chromosomes, with an average interval length of 14.2 cM. Analysis of the genetic map and resistance by mapping software indicated that a major quantitative trait locus (QTL) was between bin6.00 and bin6.01 on chromosome 6, linked with marker Bnlg1600 (0.1 cM of interval). This QTL could account for 50.0% of phenotypic variation, and could decrease 27.9% of disease index.  相似文献   

19.
Lagerstroemia (crape myrtle) are famous ornamental plants with large pyramidal racemes, long flower duration and diverse colours. Genetic maps provide an important genomic resource of basic and applied significance. A genetic linkage map was developed by genotyping 192 F1 progeny from a cross between L. caudata (female) and L. indica (‘Xiang Xue Yun’) (male) with a combination of amplification fragment length polymorphisms (AFLP) and simple sequence repeats (SSR) markers in a double pseudo‐testcross mapping strategy. A total of 330 polymorphic loci consisting of 284 AFLPs and 46 SSRs showing Mendelian segregation were generated from 383 AFLP primer combinations and 150 SSR primers. The data were analysed using JoinMap 4.0 (evaluation version) to construct the linkage map. The map consisted of 20 linkage groups of 173 loci (160 AFLPs and 13 SSRs) covering 1162.1 cM with a mean distance of 10.69 cM between adjacent markers. The 20 linkage groups contained 2–49 loci and ranged in length from 7.38 to 163.57 cM. This map will serve as a framework for mapping QTLs and provide reference information for future molecular breeding work.  相似文献   

20.
A high-density molecular marker linkage map of cotton based entirely on polymerase chain reaction-based markers is useful for a marker-assisted breeding program. Four kinds of markers—simple sequence repeats (SSRs), sequence-related amplified polymorphism (SRAP), random amplified polymorphic DNA (RAPD), and retrotransposon-microsatellite amplified polymorphism (REMAP)—were used to assay an F2 population from a cross between “Handan208” (Gossypium hirsutum) and “Pima90” (Gossypium barbadense). Sixty-nine F2 plants were used for map construction using 834 SSRs, 437 SRAPs, 107 RAPDs, and 16 REMAPs. Linkage analysis revealed that 1,029 loci could be mapped to 26 linkage groups that extended for 5,472.3 cM, with an average distance between 2 loci of 5.32 cM. The corresponding 69 F2:3 families were grown, arranged in two replicates, and scored for eight phenotypes. Quantitative trait loci (QTL) analysis was performed by means of composite interval mapping using WinQtlCart ver 2.0. A total of 52 distinct QTLs were detected: 4 QTLs for lint index, 8 for seed index, 11 for lint yield, 4 for seed cotton yield, 9 for number of seed per boll, 3 for fiber strength, 5 for fiber length, and 8 for micronaire value. The present map and QTL analysis may provide a useful tool for breeders to transfer desirable traits from G. barbadense to the mainly cultivated species, G. hirsutum.  相似文献   

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