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1.
Lodging tolerance is an important agronomic trait as it can have a severe negative impact on grain yield and quality. Here, we used a large mapping population of 647 doubled haploid triticale lines derived from four families to dissect the genetic architecture underlying lodging tolerance and to assess different approaches for a genomics‐based improvement of the trait. The plants were evaluated for lodging in two environments and genotyped with 1710 genomewide DArT markers. We observed a large genotypic variation for lodging and transgressive segregation in all families. Employing two complementary QTL mapping approaches, we identified both main effect and epistatic QTL. Using cross‐validation, we showed that the proportion of genotypic variance explained by the detected QTL is low, thus limiting the efficiency of marker‐assisted selection to improve this trait. By contrast, the cross‐validated predictive ability of genomic prediction was approximately twice as high as that of the QTL‐based selection approaches. In conclusion, our results show that lodging tolerance is a complex trait that can be improved by classical breeding but also assisted by marker‐based approaches.  相似文献   

2.
Rubeena  P. W. J. Taylor    P. K. Ades    R. Ford 《Plant Breeding》2006,125(5):506-512
Quantitative trait locus (QTL) analysis of ascochyta blight resistance in lentil was conducted using genomic maps developed from two F2 populations, viz. ILL5588/ILL7537 and ILL7537/ILL6002. Five QTLs for ascochyta blight resistance were identified by composite interval mapping (CIM) across four linkage groups (LG) in population ILL5588/ILL7537. Three QTLs were identified by CIM in population ILL7537/ILL6002 (two in close proximity on LGI and one on LGII). Two of these coincided with regions identified using multiple interval mapping (MIM) and were shown to be conditioned by dominant and partial dominant gene action. Together, they accounted for approximately 50% of the phenotypic variance of disease severity. Comparison between the two populations revealed a potentially common QTL and several common regions that contained markers significantly associated with resistance. This study demonstrated the transferability of QTLs among populations and identified markers closely linked to the major QTL that may be useful for future marker‐assisted selection for disease resistance.  相似文献   

3.
To improve salt tolerance of two elite rice varieties, Ce258 and Zhongguangxiang1 (ZGX1), two sets of introgression lines (ILs) each comprising 200 BC1F10 lines derived from a common donor, IR75862, and two recipient parents, Ce258 and ZGX1, were used for mapping of QTLs for four salt tolerance‐related traits at the seedling stage. Although the three parents were susceptible to salt, the two IL populations showed transgressive segregations for salt tolerance with 12 and 8 salt tolerance ILs in the Ce258‐ILs and ZGX1‐ILs. Eighteen main‐effect QTLs were identified for the four traits in the two IL populations, and the IR75862 alleles at most loci showed increased and decreased salt tolerance in the ZGX1 and Ce258 backgrounds, suggesting overwhelming genetic background effects on QTL detection for salt tolerance. The qDSS11 simultaneously detected in the two backgrounds was validated in a F2 population derived from a salt tolerance line and ZGX1. Our results indicated that salt tolerance‐enhancing allele could be identified in the elite susceptible breeding lines and that introgression of the favourable alleles could facilitate the development of superior lines with greater salt tolerance levels.  相似文献   

4.
Photoacclimation (PA) and freezing tolerance (FT) have been identified as closely related traits, due to common mechanisms of environmental control. In this study, diversity array technology (DArT) was used for identification of the quantitative trait loci (QTL) of FT and PA in winter barley. Simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers were subsequently used to saturate QTL regions. Two F2 mapping populations were created, for two‐rowed (P44) and six‐rowed barley (CaP). Different regions of the genome were responsible for differences in traits between parents in these two populations. Eleven QTLs were identified in the P44 population, including five typical for FT and PA, on chromosomes 2H, 3H and 7H. In the CaP population, only one QTL connected with PA and 10 connected with FT were found on all chromosomes except 2H. Our results demonstrate that different sets of markers should be applied in marker‐assisted selection for FT in two‐ and six‐rowed barley, as several loci determine FT at the level of biparental crosses.  相似文献   

5.
High-oil maize (Zea mays L.) has special value in animal feed and human food. Two hundred and eight-four and 265 F2:3 families developed from two crosses between one high-oil maize inbred and two normal dent maize inbreds were evaluated for grain oil and starch contents under two environments. Using composite interval mapping, 1–6 QTL for each trait were detected under each environment and in combined analysis in both populations. Only one common QTL across two environments in each population and across two populations were found for starch content. Among the detected QTL, nine digenic interactions with small effects were identified. Comparison of single-trait QTL and the results of multiple-trait QTL mapping showed that oil content might be complicatedly correlated with starch content. Although single-trait QTL with the same parental effects for both traits and oil-starch QTL were all detected at the same genetic bin 6.04 as the cloned high-oil QTL (qHO6) with no unfavorable effects on grain weight, our results did reflect the difficulty to realize simultaneous improvement on grain oil and starch contents. Of course, these results should be validated in further experiments under more environments using RILs, NILs and other permanent populations.  相似文献   

6.
In an earlier advanced‐backcross quantitative trait locus (QTL) analysis of an interspecific cross of Gossypium hirsutum cv. ‘Xinluzhong 36’(‘XLZH36’) and G. barbadense cv. ‘Xinhai 21’(‘XH21’), a QTL for fibre strength in the chromosome segment introgression line IL23‐09 was analysed. Single marker analysis revealed that the markers on chro.23 were associated with fibre strength. Using composite interval mapping with the F2 population (1296 plants), a QTL for fibre strength was detected on chro. 23. The QTL explained 8.9% and 15.9% of phenotypic variances in the F2 and F2 : 3 generations, respectively. Substitution mapping suggested that the QTL was located at a physical distance of 23.4 kb between the markers BNL1414 and the single nucleotide polymorphism (SNP) locus D09_43776813 C‐G. We designated this QTL as qFS‐chr.23 (quantitative trait locus for fibre strength on chro.23). This work provides a valuable genetic resource for the breeding of high fibre quality in cotton and will facilitate future efforts for map‐based cloning.  相似文献   

7.
Quantitative trait loci for agronomic traits in soybean   总被引：2，自引：0，他引：2  
There continues to be improvement in seed yields of soybean by conventional breeding, but molecular techniques may provide faster genetic gains. The objective of this study was to identify quantitative trait loci (QTL) associated with the agronomic traits seed yield, lodging, plant height, seed filling period and plant maturity in soybean. To achieve this objective, 101 F6‐derived recombinant inbred lines (RIL) from a population developed from a cross of N87‐984‐16 × TN93‐99 were used. Experiments were conducted in six environments during 2002–2003. Heritability estimates on an entry mean basis from data combined across environments ranged from 0.12 to 0.65 for seed yield and seed filling period, respectively. Composite interval mapping detected one QTL for yield (near Satt076), two for lodging (near Satt225 and Satt593) and four for maturity (near Satt263, Satt292, Satt293 and Satt591) in this population. Additional environmentally sensitive QTL for these traits, and for seed filling period and plant height are also reported. The QTL associated with agronomic traits that we report and the recently released germplasm (PI 636460) from this population may be useful in soybean breeding programmes.  相似文献   

8.
W-C. Zhou    F. L. Kolb    G-H. Bai    L. L. Domier    L. K. Boze  N. J. Smith 《Plant Breeding》2003,122(1):40-46
The objectives of this study were to validate the major quantitative trait locus (QTL) for scab resistance on the short arm of chromosome 3B in bread wheat and to isolate near‐isogenic lines for this QTL using marker‐assisted selection (MAS). Two resistant by susceptible populations, both using ‘Ning7840’ as the source of resistance, were developed to examine the effect of the 3BS QTL in different genetic backgrounds. Data for scab resistance and simple sequence repeat (SSR) markers linked to the resistance QTL were analyzed in the F2:3 lines of one population and in the F3:4 lines of the other. Markers linked to the major QTL on chromosome 3BS in the original mapping population (‘Ning7840’/‘Clark’) were closely associated with scab resistance in both validation populations. Marker‐assisted selection for the QTL with the SSR markers combined with phenotypic selection was more effective than selection based solely on phenotypic evaluation in early generations. Marker‐assisted selection of the major QTL during the seedling stage plus phenotypic selection after flowering effectively identified scab resistant lines in this experiment. Near‐isogenic lines for this 3BS QTL were isolated from the F6 generation of the cross ‘Ning7840’/‘IL89‐7978’ based on two flanking SSR markers, Xgwm389 and Xbarc147. Based on these results, MAS for the major scab resistance QTL can improve selection efficiency and may facilitate stacking of scab resistance genes from different sources.  相似文献   

9.
Maize kernel row number (KRN) is an important agronomic trait. In this study, 13 quantitative trait loci (QTL) for maize KRN were identified in different environments using F2:3 and F2:4 populations developed from two inbred lines. These QTL are distributed on chromosomes 2,3,5,8 and 10, and the genic effects are additive or partially dominant. Using the BC3F2:3 populations developed from the same parental lines, QTL of KRN located on chromosomes 5 and 10 were also identified in two environments. Three BC5F2:3 populations were used to confirm the major QTL for KRN between ssr1430 and umc1077 on chromosome 10(qKRN10). This result will facilitate the fine mapping and map‐based cloning of this major QTL in the future.  相似文献   

10.
Rhizoctonia root and crown rot caused by the fungus Rhizoctonia solani is a serious disease of sugar beet. An F2:3 population from a cross between a resistant and a susceptible parent has been tested for R. solani resistance and a genetic map has been constructed from the corresponding F2 parents. The map encompasses 38 expressed sequence tags (ESTs) with high similarity to genes which are involved in resistance reactions of plants (R‐ESTs) and 25 bacterial artificial chromosomes (BACs) containing nucleotide binding site (NBS)‐motifs typical for disease resistance genes. Three quantitative trait loci (QTL) for R. solani resistance were found on chromosomes 4, 5 and 7 collectively explaining 71% of the total phenotypic variation. A number of R‐ESTs were mapped in close distance to the R. solani resistance QTL. In contrast, the NBS‐BACs mapped to chromosomes 1, 3, 7 and 9 with two major clusters of NBS‐BACs on chromosome 3. No linkage between NBS‐BACs and R. solani resistance QTL was found. The data are discussed with regard to using R‐ESTs and NBS markers for mapping quantitative disease resistances.  相似文献   

11.
In a previous study, we reported the grain weight QTL, tgw2 in the 150 F2:3 lines derived from a cross between Oryza sativa subssp. Japonica cv. Hwaseongbyeo and HG101. This QTL was confirmed in F4 lines (CR1242) segregating for the target region. For fine mapping of tgw2, one F5 plant homozygous for the O. grandiglumis DNA in the target region was selected from CR1242 and crossed with Hwaseongbyeo to produce the F2 and F3 populations. QTL analysis using 490 F2 plants confirmed the existence of tgw2 with an R 2 value of 28.0%. This QTL explained 61.3% of the phenotypic variance for 1,000-grain weight in 64 F3 lines. Substitution mapping with 47 F3 lines and 74 F4 plants with informative recombination breakpoints in the target region was carried out to narrow down the position of the tgw2. The result indicated that tgw2 was located in the 384-kb interval between two SSR markers, RM12813 and RM12836. Annotation data of BACs in this 384-kb region revealed that forty-five putative genes exist in this interval including the GW2 gene responsible for grain weight and width. Considering the position of the QTL tgw2, it appears that tgw2 is functionally related to the gene GW2. However, the possibility that another unknown mechanism might be responsible for regulation of grain weight at tgw2 cannot be ruled out. Four QTLs for grain length, grain width, and grain thickness were also located in the same interval suggesting that a single gene is involved in controlling these four traits. Substitution mapping also indicated that two QTLs for grain weight and culm length, tgw2 and cl2, were tightly linked.  相似文献   

12.
Four agronomic traits were analysed including dry matter concentration (DMC) and dry matter yield (DMY) for stover, plant height (PHT) and days from planting to silking (DPS). We mapped quantitative trait loci (QTL) in three populations with doubled haploid lines (DHL), one RIL population and two testcross (TC) populations derived from crosses between two of the four populations mentioned above to elite tester lines, based on field phenotyping at multiple locations and years for each; 146–168 SSRs were used for genotyping of the four mapping populations. Significant high phenotypic and genotypic correlations were found for all traits at two locations, while DMC was negatively correlated with the other traits. A total of 42, 41, 54, and 45 QTL were identified for DMC, DMY, PHT, and DPS, respectively, with 9, 7, 12, and 7 major QTL for each trait. Most detected QTL displayed significant interactions with environment. Major QTL detected in more than two populations will contribute to marker‐assisted breeding and also to fine mapping candidate genes associated with maize agronomic traits.  相似文献   

13.
Heterosis, or hybrid vigour, has been used to improve seed yield in several important crops for decades and it has potential applications in soybean. The discovery of over‐dominant quantitative trait loci (QTL) underlying yield‐related traits, such as seed weight, will facilitate hybrid soybean breeding via marker‐assisted selection. In this study, F2 and F2 : 3 populations derived from the crosses of ‘Jidou 12’ (Glycine max) × ‘ZYD2738’ (Glycine soja) and ‘Jidou 9’ (G. max) × ‘ZYD2738’ were used to identify over‐dominant QTL associated with seed weight. A total of seven QTL were identified. Among them, qSWT_13_1, mapped on chromosome 13 and linked with Satt114, showed an over‐dominant effect in two populations for two successive generations. This over‐dominant effect was further examined by six subpopulations derived from ‘Jidou12’ × ‘ZYD2738’. The seed weight for heterozygous individuals was 1.1‐ to 1.6‐fold higher than that of homozygous individuals among the six validation populations examined in different locations and years. Therefore, qSWT_13_1 may be a useful locus to improve the yield of hybrid soybean and to understand the molecular mechanism of heterosis in soybean.  相似文献   

14.
In this study, a F2 population derived from the cross between deep-rooted variety “Moroberekan” with shallow-rooted variety “IR20” were used to identify and validate of SSR markers associated with root morphological traits. The F2 lines were divided into two groups. In the first group, 152 seedling having minimum of four tillers were chosen and separated into four plantlets to plant them in polyvinyl chloride pipes for root study under well-watered (WW) condition at maturity stage. The lines were genotyped using SSR markers. QTLs for maximum root length (MRL) and root dry weight showed co-segregation with RM472, RM7 and RM201. The same material was forwarded to next generation (F3) to validate the linked markers under both WW and low-moisture stress (LMS) conditions. These three markers were associated consistently with MRL across generations. In the second group, 1240 F2 plants were forwarded to F5 using SSD breeding method to test the effectiveness of the marker-assisted selection (MAS) method for drought resistant. The high performing genotypic group was significantly superior to low performing genotypic group for MRL, grain yield, root volume, root dry weight and root number, indicating the efficiency of MAS for root-related traits under LMS. Comparing MAS with farmer selection in F6, the results showed that MAS group means were significantly different from farmer group means for MRL, root volume, root dry weight and root number. Thus, MAS was combined with participatory selection to select five high-yielding and deep rooted promising lines. Identification of stable QTL for root morphological traits under WW and LMS conditions can aid in MAS and to introduce them into varieties with good yield potential and accepted by farmer.  相似文献   

15.
H. Funatsuki    M. Ishimoto    H. Tsuji    K. Kawaguchi    M. Hajika    K. Fujino 《Plant Breeding》2006,125(2):195-197
Shattering of soybean pods prior to harvest leads to a reduction in yield. In order to identify simple sequence repeat (SSR) markers linked to quantitative trait loci (QTLs) conditioning pod shattering, QTL analysis was conducted using an recombinant inbred line (RIL) population segregating for this trait. The degrees of pod‐shattering resistance were evaluated by heat treatment applied to pods harvested from plants in the field and in a growth chamber. Composite interval mapping identified one major QTL between SSR markers Sat_093 and Sat_366 on linkage group J for both environments. The position and the effect of this QTL were confirmed in an F2 population derived from a cross between the pod shattering‐susceptible parental cultivar and a pod shattering‐resistant RIL. The SSR markers linked to the major QTL will be useful for marker‐assisted selection in soybean‐breeding programmes.  相似文献   

16.
Seed protein and oil contents are important quantitative traits in soybean. Previously, quantitative trait loci (QTL) associated with seed protein and oil were mostly identified in single genetic background. The objective of this work was to identify QTL and their epistatic effects underlying seed protein and oil contents in three recombinant inbred line populations (two of them used one common female parent) across eight environments by composite interval mapping. Forty QTL underlying protein content and 35 QTL underlying oil content were identified. Among them, nine were universal QTL underlying protein content and four were universal QTL underlying oil content. Epistatic interactions between QTL underlying seed protein/oil and different genetic backgrounds were detected. Different pairs of epistatic interactions were observed in diverse genetic backgrounds across multi‐environments. Common marker intervals were observed to simultaneously underlie seed protein and oil contents with different epistatic interactions. The results in this study suggested that a specific genotype with high oil content and low protein content might significantly affect the selection of soybean lines for high seed protein.  相似文献   

17.
Adventitious root formation (ARF) at the soil surface is one of the most important adaptations to soil flooding or waterlogging. Quantitative trait loci (QTL) controlling ARF under flooding condition were identified in a 94 F2 individual population by crossing maize (Zea mays L., B64) × teosinte (Z. mays ssp. huehuetenangensis). A base-map was constructed using 66 SSR and 42 AFLP markers, covering 1,378 cM throughout all ten maize chromosomes. The ARF capacity for seedlings was determined by evaluating the degree of root formation at the soil surface following flooding for 2 weeks. ARF showed continuous variation in the F2 population. Interval mapping and composite interval mapping analyses revealed that the QTL for ARF was located on chromosome 8 (bin 8.05). Utilising a selective genotyping strategy with an additional 186 F2 population derived from the same cross combination and 32 AFLP primer combinations, regions on chromosomes 4 (bin 4.07) and 8 (bin 8.03) were found to be associated with ARF. Z. mays ssp. huehuetenangensis contributed all of the QTL detected in this study. Results of the study suggest a potential for transferring waterlogging tolerance to maize from Z. mays ssp. huehuetenangensis.  相似文献   

18.
Stay-green maize genotypes have been associated with tolerance to biotic and abiotic stresses, including tolerance to drought, and to stalk and root lodging, but there is limited information on its inheritance. Thus, this research was conducted to study the inheritance of the stay-green trait using both conventional analysis and QTL mapping of the Design III in a tropical maize population developed from two inbred lines genetically divergent for this trait. Two-hundred and fifty F2 plants were genotyped with 177 microsatellite markers, and their backcrossed progenies to both parental inbreds were evaluated at three locations. Ten plants per plot were assessed 120 days after sowing and the plot means scores for stay-green, adjusted for days to silking emergence, were used for analysis. The additive variance was larger than the dominance variance, the genetic by location interaction variance presented a high magnitude, and the heritability coefficient on a plant-basis a low magnitude. Seventeen QTL were mapped, most of them were clustered on four chromosomes and accounted for by 73.08 % of the genetic variance. About half of the QTL interacted with location, and the average level of dominance was partial dominance. The additive effects were larger than the dominance effects; the latter were not unidirectional, so that heterosis could not be exploited in crosses. Procedures for marker-assisted selection to increase the level of stay-green are discussed and an approach is suggested for using both stable and non-stable QTL in a marker-assisted backcross program.  相似文献   

19.
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   

20.
陆地棉衣分差异群体产量及产量构成因素   总被引：14，自引：5，他引：9  
 以衣分差异较大的陆地棉品种为材料,构建了包含188个F2单株的作图群体,应用6111对SSR引物对亲本进行了分子标记筛选,结果仅获得了123个多态性位点,其中88个位点构建了总长为666.7 cM、平均距离为7.57 cM的遗传图谱,覆盖棉花基因组的14.9%。通过复合区间作图法对F2单株和F2∶3家系进行QTL检测,共鉴定出了18个控制产量及产量构成因素变异的QTLs,包括2个衣分QTLs、4个子棉产量QTLs、4个皮棉产量QTLs、2个衣指QTLs、3个单株铃数QTLs、2个铃重QTLs和1个子指QTL。 解释的表型变异分别为\{6.9%\}～16.9%、5.6%～16.2%、4.8%～15.6%、7.7%～13.3%、8.2%～11.6%、6.1%～7%和6.6%。不同QTLs在相同染色体区段上的成簇分布表明与产量性状相关的基因可能紧密连锁或一因多效。产量及产量构成因素QTLs的遗传方式主要以显性和超显性效应为主。检测到的主效QTLs可以用于棉花产量及产量构成因素的分子标记辅助选择。  相似文献   

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