Detection and fine mapping of quantitative trait loci for bone traits on chicken chromosome one

In broiler chickens, bone problems are an important welfare issue that has been linked to genetic selection for rapid growth. The objectives of this study were to identify and fine map quantitative trait loci (QTL) associated with bone traits. The Northeast Agricultural University resource population (NEAURP) being an F(2) population was used in this study, and a total of 17 bone traits were measured. In primary genome scan, the linkage map was constructed with 23 microsatellite markers across the entire chicken chromosome 1. Seventeen QTLs for bone traits were identified and 12 of these were found between LEI0079 and ROS0025 (50.8 cM apart). To fine map the QTLs located between LEI0079 and ROS0025, more markers and more individuals were used and a new partial linkage map was constructed. The confidence intervals for QTLs were sharply narrowed down from 24.5～52.6 to 2.7～17.0 Mb. This study identified chromosome regions harbouring significant QTLs affecting bone traits and showed that the use of more markers and individuals could decrease the confidence interval of QTL effectively. The results provide a useful reference for further candidate gene research and MAS for bone traits.     

凉山半细毛羊初生重QTL的研究

选取凉山半细毛羊7个父系半同胞家系,利用绵羊1号染色体上11个微卫星标记,通过聚合酶链式反应（polymerase chain reaction,PCR）对凉山半细毛羊初生重QTL进行了研究。QTL分析的结果表明,在其中一个家系B3K5055中,1号染色体微卫星标记ILSTS004与CSSM004之间检测到影响初生重的QTL,其LOD值为3.338,位于置信区间95%（2.73）和99%（3.49）之间。     

Further mapping and characterization of Naq1, a quantitative trait locus responsible for maternal inferior nurturing ability in RR mice

Females of the inbred mouse RR strain have a limited ability to nurture their offspring, and frequently the young die during rearing. We previously identified a significant quantitative trait locus (QTL) responsible for the inferior nurturing ability on chromosome 5 (Naq1), on the basis of litter weight of six pups at days 7, 12, and 21 after parturition. Here, we carried out further mapping of Naq1 to define the confidence interval precisely. At the same time, we analyzed new quantitative trait variables, litter weight gain between days 7 and 12 (WG1), and that between days 12 and 21 (WG2), to characterize further the physiology of inferior nurturing ability. Consequently, a peak LOD score for the Naq1 was identified on D5Mit218 (72 cM), which was located approximately 2 cM distal to our previous expectation, as a significant QTL for WG1 (LOD 5.5), but not for WG2 (LOD 0.9). Because the growth of pups depends purely on milk obtained from the dam up to day 12 after birth, it seems possible to assume that the inferior nurturing ability in RR mice is related to defects in maternal nutritional support (that is, lactation) rather than to defects in pup growth. Naq1 is a novel QTL as far as the QTL results of relevant female reproductive traits in cattle and pigs are concerned.     

Fine mapping of quantitative trait loci affecting organ weights by mouse intersubspecific subcongenic strain analysis

The genetic architecture of organ weights is not well understood. In this study, we fine‐mapped quantitative trait loci (QTLs) affecting organ weights by characterizing six intersubspecific subcongenic mouse strains with overlapping and non‐overlapping genomic regions on chromosome 2 derived from wild Mus musculus castaneus. QTLs for heart, lung, spleen and kidney weights were revealed on a 6.38‐Mb genomic region between two microsatellite markers, D2Mit323 and D2Mit472. Effects of the castaneus alleles at the organ weight QTLs were all opposite in direction to a body weight QTL previously mapped to the same genomic region. In addition, new QTLs for lung and kidney weights were revealed on a different 3.57‐Mb region between D2Mit205 and D2Mit182. Their effects were dependent on that of another body weight QTL previously mapped to that genomic region. The organ weight QTLs revealed were all duplicated in independent analyses with F₂ intercross populations between subcongenic strains carrying these QTLs and their background strain. The findings suggested that organ weights are not exclusively regulated by genetic loci that commonly influence overall body weight and rather that there are loci contributing to the growth of specific organs only.     

Quantitative trait locus analysis of plasma cholesterol levels and body weight by controlling the effects of the Apoa2 allele in mice

Colleagues and I previously performed quantitative trait locus (QTL) analysis on plasma total-cholesterol (T-CHO) levels in C57BL/6J (B6) x RR F2 mice. We identified only one significant QTL (Cq6) on chromosome 1 in a region containing the Apoa2 gene locus, a convincing candidate gene for Cq6. Because Cq6 was a highly significant QTL, we considered that the detection of other potential QTLs might be hindered. In the present study, QTL analysis was performed in B6.KK-Apoa2b N(8) x RR F2 mice [B6.KK-Apoa2b N(8) is a partial congenic strain carrying the Apoa2b allele from the KK strain, and RR also has the Apoa2b allele] by controlling of the effects of the Apoa2 allele, for identifying additional QTLs. Although no significant QTLs were identified, 2 suggestive QTLs were found on chromosomes 2 and 3 in place of the effects of the Apoa2 allele. A significant body weight QTL was identified on chromosome 3 (Bwq7, peak LOD score 5.2); its effect on body weight was not significant in previously analyzed B6 x RR F2 mice. Suggestive body weight QTL that had been identified in B6 x RR F2 mice on chromosome 4 (LOD score 3.8) was not identified in B6.KK-Apoa2b N(8) x RR F2 mice. Thus, contrary to expectation, the genetic control of body weight was also altered significantly by controlling of the effects of the Apoa2 allele. The QTL mapping strategy by controlling of the effects of a major QTL facilitated the identification of additional QTLs.     

Quantitative trait loci analysis for growth and carcass traits in a Meishan x Duroc F2 resource population

We constructed a pig F2 resource population by crossing a Meishan sow and a Duroc boar to locate economically important trait loci. The F2 generation was composed of 865 animals (450 males and 415 females) from four F1 males and 24 F1 females and was genotyped for 180 informative microsatellite markers spanning 2,263.6 cM of the whole pig genome. Results of the genome scan showed evidence for significant quantitative trait loci (<1% genomewise error rate) affecting weight at 30 d and average daily gain on Sus scrofa chromosome (SSC) 6, carcass yield on SSC 7, backfat thickness on SSC 7 and SSC X, vertebra number on SSC 1 and SSC 7, loin muscle area on SSC 1 and SSC 7, moisture on SSC 13, intramuscular fat content on SSC 7, and testicular weight on SSC 3 and SSC X. Moreover, 5% genomewise significant QTL were found for birth weight on SSC 7, average daily gain on SSC 4, carcass length on SSC 6, SSC 7, and SSC X and lightness (L value) on SSC 3. We identified 38 QTL for 28 traits at the 5% genomewise level. Of the 38 QTL, 24 QTL for 17 traits were significant at the 1% genomewise level. Analysis of marker genotypes supported the breed of origin results and provided further evidence that a suggestive QTL for circumference of cannon bone also was segregating within the Meishan parent. We identified genomic regions related with growth and meat quality traits. Fine mapping will be required for their application in introgression programs and gene cloning.     

Quantitative trait locus detection in commercial broiler lines using candidate regions

A QTL that explained a large proportion of the phenotypic difference between broiler and layer chickens in an experimental cross was evaluated in a commercial broiler line. A three-generation design, consisting of 15 grandsires, 608 half-sib hens, and more than 50,000 third-generation offspring, was implemented within the existing breeding scheme of a broiler breeding company. Four markers from a candidate region on chicken chromosome 4 were selected for their informativeness in the grandsires and used to genotype the first two generations. Using half-sib analyses, linkage was studied between these markers and 13 growth and carcass traits. The QTL analyses confirmed the presence of significant QTL for body weight (P < 0.01) and residual feed intake (P < 0.05) on chicken chromosome 4. Furthermore, evidence was found for QTL affecting the relative weight of bone and muscle in the thigh. Four more markers were added to increase resolution of the QTL positions. This increased the significance of the QTL for body weight (P < 0.001) and residual feed intake (P < 0.01) and showed evidence (P < 0.05) for additional QTL affecting carcass weight and conformation score. This study showed for the first time that a QTL that explains differences between broilers and layers was segregating in lines that have been selected for body weight over 50 generations. A possible explanation could be a pleiotropic or closely linked effect on fitness-related traits that are not part of the present study. The results demonstrate the feasibility of QTL detection and the potential for marker-assisted selection within a commercial broiler line without altering the existing breeding scheme.     

A proximal genomic region of mouse chromosome 10 contains quantitative trait loci affecting fatness

Body weight and fatness are quantitative traits of agricultural and medical importance. In previous genome‐wide quantitative trait locus (QTL) analyses, two QTLs for body weight and weight gain at an early postnatal growth period were discovered on mouse chromosome 10 from a gene pool of wild subspecies mice, Mus musculus castaneus. In this study, we developed a congenic strain with an approximately 63‐Mb wild‐derived genomic region on which the two growth QTLs could be located, by recurrent backcrossing to the common inbred strain C57BL/6J. We compared body weights at 1–10 weeks of age, body weight gains at 1–3, 3–6 and 6–10 weeks, internal organ weights and body lengths between the congenic strain developed and C57BL/6J. Unfortunately, no effects of the two growth QTLs on body weights and weight gains were confirmed. However, at least two new QTLs affecting fatness traits were discovered within the introgressed congenic region. The wild‐derived allele at one QTL increased body mass index, whereas at another one it decreased white fat pad weight and adiposity index. Thus, the congenic mouse strain developed here is a useful model animal for understanding the genetic and molecular basis of fat deposition in livestock as well as humans.     

Genome-wide linkage and QTL mapping in porcine F2 families generated from Pietrain, Meishan and Wild Boar crosses

Three informative pig F₂ families based on European Wild Boar (W), Meishan (M) and Pietrain (P) crosses have been used for genome‐wide linkage and quantitative trait loci (QTL) analysis. Altogether 129 microsatellites, 56 type I loci and 46 trait definitions (specific to growth, fattening, fat deposition, muscling, meat quality, stress resistance and body conformation) were included in the study. In the linkage maps of M × P, W × P and W × M families, average spacing of markers were 18.4, 19.7 and 18.8 cM, the numbers of informative meioses were 582, 534 and 625, and the total lengths of autosomes measured were 27.3, 26.0 and 26.2 Morgan units, respectively. Maternal maps were on average 1.3 times longer than paternal maps. QTLs contributing more than 3% of F₂ phenotypic variance could be identified at p < 0.05 chromosome‐wide level. Differences in the numbers and positions of QTLs were observed between families. Genome‐wide significant QTL effects were mapped for growth and fattening traits on eight chromosomes (1, 2, 4, 13, 14, 17, 18 and X), for fat deposition traits on seven chromosomes (1, 2, 3, 4, 6, 7 and X), for muscling traits on 11 chromosomes (1, 2, 3, 4, 6, 7, 8, 12, 14, 15 and X), for meat quality and stress resistance traits on seven chromosomes (2, 3, 6, 13, 16, 18 and X), and QTLs for body‐conformation traits were detected on 14 chromosomes. Closely correlated traits showed similar QTL profiles within families. Major QTL effects for meat quality and stress resistance traits were found on SSC6 in the interval RYR1‐A1BG in the W × P and M × P families, and could be attributed to segregation of the RYR1 allele T derived from Pietrain, whereas no effect in the corresponding SSC6 interval was found in family W × M, where Wild Boar and Meishan both contributed the RYR1 allele C. QTL positions were mostly similar in two of the three families for body conformation traits and for growth, fattening, fat deposition and muscling traits, especially on SSC4 (interval SW1073‐NGFB). QTLs with large effects were also mapped on SSC7 in the major histocompatibility complex (MHC) (interval CYP21A2‐S0102) and affected body length, weight of head and many other traits. The identification of DNA variants in genes causative for the QTLs requires further fine mapping of QTL intervals and a positional cloning. However, for these subsequent steps, the genome‐wide QTL mapping in F₂ families represents an essential starting point and is therefore significant for animal breeding.     

家蚕茧丝相关性状的性连锁QTLs定位与分析

家蚕的茧丝性状存在明显的性别差异。以茧丝性状成绩差异较大的家蚕品种兰10和菁松为亲本组配回交1代分离群体(BC1M),在前期研究的基础上,利用Mapmaker软件构建含有17个SSR或SNP分子标记的家蚕性染色体的遗传连锁图,并对茧丝量、全茧量、茧层量、蛹体质量、茧丝长等性状进行数量性状位点(QTL)扫描,获得与上述5项茧丝相关的QTL位点,其LOD值分别为11.175、6.196、11.036、5.156和8.717。研究结果为家蚕茧丝相关QTL位点的精细定位与克隆奠定了基础。     

Many quantitative trait loci for feather growth in an F(2) broiler × layer cross collocate with body weight loci

1. A genome-wide scan of 467 F₂ progeny of a broiler x layer cross was conducted to identify quantitative trait loci (QTL) affecting the rate of growth of the tail, wing and back feathers, and the width of the breast feather tract, at three weeks of age.

2. Correlations between the traits ranged from 0·36 to 0·61. Males had longer tail and wing feathers and shorter back feathers than females. Breast feather tract width was greater in females than males.

3. QTL effects were generally additive and accounted for 11 to 45% of sex average feather lengths of the breeds, and 100% of the breast feather tract width. Positive and negative alleles were inherited from both lines, whereas the layer allele was larger than the broiler allele after adjusting for body weight.

4. A total of 4 genome-significant and 4 suggestive QTL were detected. At three or 6 weeks of age, 5 of the QTL were located in similar regions as QTL for body weight.

5. Analysis of a model with body weight at three weeks as a covariate identified 5 genome significant and 6 suggestive QTL, of which only two were coincident with body weight QTL. One QTL for feather length at 148?cM on GGA1 was identified at a similar location in the unadjusted analysis.

6. The results suggest that the rate of feather growth is largely controlled by body weight QTL, and that QTL specific for feather growth also exist.     

Mapping genes for fatness and growth on pig chromosome 13: a search in the region close to the pig PIT1 gene

Previous research has shown that PIT1 polymorphisms in several resource populations and the chromosomal region near PIT1 in some populations have been significantly associated with fatness and growth QTLs on pig chromosome 13. To confirm these previous results and to clarify the role of the PIT1 gene in the putative QTL region, this research project was enlarged to include two microsatellite markers flanking each side of the PIT1 gene ( Swr1008 , S0068 , Sw398 and Sw1056 ). The ISU Chinese × US resource families were used and the traits analysed were birth weight, 21 day weight, 42 day weight, longissimus muscle area, back-fat thickness at several locations, meat colour, marbling and firmness on the carcass, and growth rate for selected time periods. The total number of F₂ pigs used ranged from 241 to 330. The data were analysed using interval mapping for each breed-cross separately as well as with the pooled data, and single marker least squares analyses for the pooled data. Significant evidence of a QTL for first rib back-fat thickness was detected approximately 20 cM from the PIT1 gene by using both single marker (p < 0.01) and interval mapping analyses in the pooled data (p < 0.0001) as well as in one family (p < 0.01). Evidence of a QTL for birth weight was detected at the estimated PIT1 position in the interval mapping analysis by using the pooled data (p < 0.014) and verified by the single marker analyses. These results confirmed the previously published QTL work on pig chromosome 13 for the birth weight QTL but suggest that other genes in the region may be partly responsible for the earlier results on the back-fat thickness QTL in our resource families.     

A primary screen of the bovine genome for quantitative trait loci affecting carcass and growth traits.

A primary genomic screen for quantitative trait loci (QTL) affecting carcass and growth traits was performed by genotyping 238 microsatellite markers on 185 out of 300 total progeny from a Bos indicus x Bos taurus sire mated to Bos taurus cows. The following traits were analyzed for QTL effects: birth weight (BWT), weaning weight (WW), yearling weight (YW), hot carcass weight (HCW), dressing percentage (DP), fat thickness (FT), marbling score (MAR), longissimus muscle area (LMA), rib bone (RibB), rib fat (RibF), and rib muscle (RibM), and the predicted whole carcass traits, retail product yield (RPYD), fat trim yield (FATYD), bone yield (BOYD), retail product weight (RPWT), fat weight (FATWT), and bone weight (BOWT). Data were analyzed by generating an F-statistic profile computed at 1-cM intervals for each chromosome by the regression of phenotype on the conditional probability of receiving the Brahman allele from the sire. There was compelling evidence for a QTL allele of Brahman origin affecting an increase in RibB and a decrease in DP on chromosome 5 (BTA5). Putative QTL at or just below the threshold for genome-wide significance were as follows: an increase in RPYD and component traits on BTA2 and BTA13, an increase in LMA on BTA14, and an increase in BWT on BTA1. Results provided represent a portion of our efforts to identify and characterize QTL affecting carcass and growth traits.     

Interval mapping of growth quantitative trait loci in Japanese Black beef cattle using microsatellite DNA markers and half-sib regression analysis

A confirmatory scan for the regions of bovine chromosome 1 segregating the quantitative trait loci (QTL) influencing birthweight, weaning weight, yearling weight, and preweaning and postweaning average daily gains was performed by genotyping half‐sib progeny of four Japanese Black sires using microsatellite DNA markers. Data were analyzed by generating an F‐statistic every 1 cM on a linkage map by the regression of phenotype on the probabilities of inheriting an allele from the sire after adjusting for the fixed effects of sire, sex, parity and season of birth as well as age as a covariate. Permutation tests at chromosome‐wide significance thresholds were carried out over 10 000 iterations. A significant QTL for birthweight at 114 cM was detected in the sire 2 family. This identification of a birthweight QTL in Japanese Black cattle may be useful for the implementation of marker‐assisted selection.     

Bone mineral density QTL at sexual maturity and end of lay

1. An F₂ cross of a broiler male line and a White Leghorn layer line was used to identify quantitative trait loci (QTL) for bone density at the onset of lay and at the end of the laying period. A total of 686 measures of humeral bone density were available for analysis.

2. There was no evidence for epistasis.

3. Genome-wide significant QTL for bone density at the onset of lay were identified on chromosomes 1 (311?cM) and 8 (2?cM) and on chromosomes 1 (311?cM), 3 (57?cM) and 8 (2?cM) with a covariate for the number of yellow follicles (a proxy for the concentration of circulating oestrogen).

4. Evidence for only 4 chromosome-wide suggestive QTL were detected at the end of lay (72 weeks).

5. Analysis of the combined data confirmed two genome-wide suggestive QTL on chromosome 1 (137 and 266?cM) and on chromosomes 8 (2?cM) and 9 (10?cM) in analyses with or without the covariate.

6. Positive QTL alleles came from the broiler line with the exception of 2 suggestive QTL at the onset of lay on chromosomes 3 and 5 in an analysis with the covariate.

7. In general, QTL acted additively, except that dominant effects were identified for three suggestive QTL at the onset of lay on chromosomes 3 (57 and 187?cM) and 5 (9?cM).

8. The significant QTL in this study were at similar locations to QTL identified in a range of crosses in other publications, suggesting that they are prime candidates for the search for genes and mutations that could be used as selection criteria to improve bone strength and decrease fractures in commercial laying hens.     

A quantitative trait locus for faecal worm egg and blood eosinophil counts on chromosome 23 in Australian goats

Three microsatellite markers on goat chromosome 23 adjacent to the MHC were used to test for quantitative trait loci (QTL) affecting faecal worm egg count (WEC) and leukocyte traits in ten Australian Angora and twelve Australian Cashmere half‐sib families (n = 16–57 per family). Data were collected from 280 Angora and 347 Cashmere kids over a 3‐ and 4‐year period. A putative QTL affecting trichostrongyle WEC was found in two small families at the 5% chromosome‐wise threshold level. The biggest QTL effect for WEC of 1.65 standard deviations (σ_p) was found within the region of OarCP73‐BM1258. A significant QTL affecting blood eosinophil counts at the 1% chromosome–wise threshold level was detected at marker BM1258 (at 26 cM) in two Angora and Cashmere families. The magnitude of the putative QTL was 0.69 and 0.85 σ_p in Angora and Cashmere families, respectively. Due to the comparatively low power of the study these findings should be viewed as indicative rather than definitive.     

不同羽色儋州鸡生长曲线拟合与分析研究

为研究儋州鸡生长发育规律和各阶段的生长速度,本试验采用Gompertz、Logistic和Bertalanffy 3种非线性模型对黑色羽系和麻花色羽系儋州鸡0~18周龄体重生长数据进行拟合和分析,选取黑色羽系、麻花色羽系儋州鸡各200只（公、母各半）,分别于0、2、4、6、8、10、12、14、16和18周龄晨饲前空腹称重并记录,并利用3种非线性模型对儋州鸡生长曲线进行拟合比较分析。结果显示,2种羽色儋州鸡实测生长曲线基本一致,接近于"S"型,符合正常生长发育规律,2种不同羽色儋州鸡母鸡0~18周龄的体重实测值差异不显著（P>0.05）,公鸡0~16周龄的体重实测值差异不显著（P>0.05）,而16~18周龄麻花色羽系公鸡体重显著高于黑色羽系公鸡（P<0.05）。3种非曲线模型拟合度（R²）均在0.992以上,均能较好地拟合2个羽系儋州鸡的生长曲线,且模型的预测曲线与实际观测曲线基本吻合,但Gompertz模型曲线吻合度高于Logistic和Bertalanffy模型曲线,且母鸡比公鸡拟合效果好。本研究结果初步揭示了儋州鸡的生长发育规律和各阶段的生长特征,可为儋州鸡选育、生产和产业化发展提供科学依据。     

Quantitative trait loci for leg weakness traits in a Landrace purebred population

Leg weakness in pigs is a serious problem in the pig industry. We performed a whole genome quantitative trait locus (QTL) analysis to find QTLs affecting leg weakness traits in the Landrace population. Half-sib progeny ( n  = 522) with five sires were measured for leg weakness traits. Whole genome QTL mapping was performed using a half-sib regression-based method using 190 microsatellite markers. No experiment-wide significant QTLs affecting leg weakness traits were detected. However, at the 5% chromosome-wide level, QTLs affecting leg weakness traits were detected on chromosomes 1, 3, 10 and 11 with QTL effects ranging from 0.07 to 0.11 of the phenotypic variance. At the 1% chromosome-wide level, QTLs affecting rear feet score and total leg score were detected on chromosomes 2 and 3 with QTL effects of 0.11 and 0.13 of the phenotypic variance, respectively. On chromosome 3 and 10, some QTLs found in this study were located at nearby positions. The present study is one of the first reports of QTLs affecting fitness related traits such as leg weakness traits, that segregate within the Landrace population. The study also provides useful information for studying QTLs in purebred populations.     

Mapping of quantitative trait loci for growth and carcass traits in commercial sheep populations

Quantitative trait loci analyses were applied to data from Suffolk and Texel commercial sheep flocks in the United Kingdom. The populations comprised 489 Suffolk animals in three half-sib families and 903 Texel animals in nine half-sib families. Phenotypic data comprised measurements of live weight at 8 and 20 wk of age and ultrasonically measured fat and muscle depth at 20 wk. Lambs and their sires were genotyped across candidate regions on chromosomes 1, 2, 3, 4, 5, 6, 11, 18, and 20. Data were analyzed at the breed level, at the family level, and across extended families when families were genetically related. The breed-level analyses revealed a suggestive QTL on chromosome 1 in the Suffolk breed, between markers BM8246 and McM130, affecting muscle depth, although the effect was only significant in one of the three Suffolk families. A two-QTL analysis suggested that this effect may be due to two adjacent QTL acting in coupling. In total, 24 suggestive QTL were identified from individual family analyses. The most significant QTL affected fat depth and was segregating in a Texel family on chromosome 2, with an effect of 0.62 mm. The QTL was located around marker ILSTS030, 26 cM distal to myostatin. Two of the Suffolk and two of the Texel sires were related, and a three-generation analysis was applied across these two extended families. Seven suggestive QTL were identified in this analysis, including one that had not been detected in the individual family analysis. The most significant QTL, which affected muscle depth, was located on chromosome 18 near the callipyge and Carwell loci. Based on the phenotypic effect and location of the QTL, the data suggest that a locus similar to the Carwell locus may be segregating in the United Kingdom Texel population.     

家鸡豆冠基因定位的研究

构建家鸡1号染色体短臂部分连锁图谱及豆冠冠型基因的定位。通过测交选择豆冠冠型基因型纯合的2只吐鲁番斗鸡(♂)和6只玫瑰冠鸡(♀)为亲本,采用F2代试验设计建立F2代494只,依据己公布的家鸡遗传连锁图谱,分别在1号染色体上筛选了13对微卫星标记,运用MapMaker/EXP 3.0和MapDraw 2.1软件绘制遗传连锁图谱,并结合记录的表型性状值对冠型性状进行定位分析。经卡方检验F2代冠型符合9∶3∶3∶1的遗传定律。在连锁分析中除MCW0007位外,其余12个微卫星座位在试验群体中均表现较高的基因杂合度和多态信息含量。对冠型性状进行初步的分析,结果显示,MCW0428、ADL0319、LEI0174和MCW0058标记位点LOD值＞3,表明这4个微卫星位点与豆冠冠型基因存在连锁关系,其中LEI0174与豆冠基因遗传距离最近为0.12 cM。