Identification of Novel Polymorphisms in Porcine Ring Finger Protein 4 and Matrix Metalloproteinase 9 Genes and Association Analysis with Litter Size Traits

Reproduction trait plays an important role in pig production.Identification of molecular markers that are linked to litter size may contribute to the genetic development of porcine reproduction traits.In this study,porcine ring finger protein 4(pRNF4) and Matrix metalloproteinase 9(pMMP-9) were selected as candidate genes on the basis of their physiological roles in reproduction.Two single-nucleotide polymorphisms(416C>Tin pRNF4 and-1257G>A inpMMP-9) that could be detected by PCR restriction fragment length polymorphism(PCR-RFLP) were discovered and tested for statistical associations with litter size traits in three populations.For416C>T,TT genotype was associated with a significantly higher(p<0.05) number of live births than those recorded for CC sows and the additive effect was significant(p<0.05) in Qingping and Min Pigs populations in later parities.For-1257G>A,inconsistent results were found in three populations.The results suggested that T allele in pRNF4 gene might confer a high prolificacy in breeding and further studies were needed to confirm the results.

Expression of genes involved in progesterone receptor paracrine signaling and their effect on litter size in pigs

Background: Embryonic mortality during the period of implantation strongly affects litter size in pigs. Progesterone receptor(PGR) paracrine signaling has been recognized to play a significant role in embryonic implantation. IHH,NR2F2, BMP2, FKBP4 and HAND2 were proved to involve in PGR paracrine signaling. The objective of this study was to evaluate the expression of IHH, NR2F2, BMP2, FKBP4 and HAND2 in endometrium of pregnant sows and to further investigate these genes' effect on litter size in pigs. Real-time PCR, western blot and immunostaining were used to study target genes/proteins expression in endometrium in pigs. RFLP-PCR was used to detect single nucleotide polymorphisms(SNPs) of target genes.Results: The results showed that the m RNA and protein expression levels of IHH, NR2F2 and BMP2 were up-regulated during implantation period(P < 0.05 or P < 0.01). All target proteins were mainly observed in luminal epithelium and glandular epithelium. Interestingly, the staining of NR2F2 and HAND2 was also strong in stroma. SNPs detection revealed that there was a-204 C > A mutation in promoter region of NR2F2 gene. Three genotypes were found in Large White, Landrace and Duroc sows. A total of 1847 litter records from 625 sows genotyped at NR2F2 gene were used to analyze the total number born(TNB) and number born alive(NBA). The study of the effect on litter size suggested that sows with genotype CC tend to have higher litter size.Conclusions: These results showed the expression patterns of genes/proteins involved in PGR paracrine signaling over implantation time. And the candidate gene for litter size was identified from genes involved in this signaling. This study could be a resource for further studies to identify the roles of these genes for embryonic implantation in pigs.

Heritabilities and genetic and phenotypic correlations of litter uniformity and litter size in Large White sows

Litter uniformity,which is usually represented by within-iitter weight coefficient of variation at birth(CVB),could influence litter performance of sows and the profitability of pig enterprises.The objective of this study was to characterize CVB and its effect on other reproductive traits in Large White sows.Genetic parameters and genetic correlation of the reproductive traits,including CVB,within-iitter weight coefficient of variation at three weeks(CVT),total number born(TNB),number born alive(NBA),number born dead(NBD),gestation length(GL),piglet mortality at birth(M_0),piglet mortality at three weeks(M_3),total litter weight at birth(TLW_0),and total litter weight at three weeks(TLW_3)were estimated for 2 032 Large White litters.The effects of parity and classified litter size on CVB,CVT,TNB,NBA,NBD,GL,M_0,M_3,TLW_0,and TLW_3 were also estimated.The heritabilities of these reproductive traits ranged from 0.06 to 0.17,with the lowest heritabiiity for CVB and the highest heritabiiity for TLW_0.Phenotypic and genetic correlations between these reproductive traits were low to highly positive and negative(ranging from-0.03 to 0.93,and-0.53 to 0.93,respectively).The genetic correlations between TNB and CVB,and between M_0 and CVB were 0.32 and 0.29,respectively.In addition,CVB was significantly influenced by parity and litter size class(P<0.05).All the results suggest that piglet uniformity should be maintained in pig production practices and pig breeding programs.

Analysis of PRLR and BF Genotypes Associated with Litter Size in Beijing Black Pig Population

This study is aimed at using the DNA mutations in the prolactin receptor (PRLR) and properdin (BF) genes to determine associations between the genotype and litter size in the Beijing Black pig population. A total of 321 Beijing Black pig sows were genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method,with the Alu I and Sma I for PRLR and BF genes,respectively. Two different alleles of PRLR and BF genes were identified:allele A (0.25) and B (0.75) of the PRLR gene,allele A (0.13) and B (0.86) of the BF gene. The association analysis between the genotypes and the litter size were estimated with the method of the general linear model. The analysis results of PRLR showed that in first parity,sows with genotype AA had a larger litter size than sows with genotype AB and BB,but the difference was statistically not significant. In later parities,statistically significant (P < 0.05) differences were seen between sows with genotypes AA and AB,and BB of the PRLR gene. The associated analysis results between genotypes and litter size (total number born,TNB,and number born alive,NBA) showed that there were no significant differences in the first parity sows with different genotypes of the BF gene,but significant differences appeared in NBA between the sows of genotypes AB and BB,in later parity,for which significantly higher values were observed in the offspring of heterozygotes. Considering the consistent genotypic effect on the litter size of both sows in first parity and later parity,it was concluded that the locus of the PRLR gene,digested with Alu I,could be the gene maker for the litter size in Beijing Black pigs.

Study on the Effect of ESR and FSH β Genes on Litter Size in Local Northeast Three Pig Breeds

The method of PCR RFLP was used to analyze the effects of ESR and FSH β genotypes on the litter size,especially the corresponding changes with the difference of genotype distributions in the Min,Sanjiang and Junmu I pigs.The results show that the ESR and FSH β genes are the major genes of litter size;the heterozygous genotype for ESR as well as for FSH β locus has a more litter size than others.However,the combined genotype ABDD means a more litter size than other genotypes,the frequencies of the heterozygous genotypes in Sanjiang and Junmu I are lower than in Min which maybe one of the most important reasons for the little litter sizes of those two breeds.

Characterization of Porcine Matrix Metalloproteinase 23 (pMMP-23) Gene and Its Association with Litter Size Traits

The matrix metalloproteinase 23 (MMP-23), which might play a role in ovulation in mammals, was one of the promising candidate genes for litter size traits in pigs. In the present research, partial sequence of porcine MMP-23 (pMMP-23) gene, including exons 2-8 (GenBank: EU360790), was obtained. Real-time PCR analysis revealed that pMMP-23 gene was highly expressed in ovary. PCR-Sau3A I-RFLP and PCR-Acc II-RFLP assay were established to detect a C/T mutation in exon 3 (EU360790: g. 269C>T) and an A/G mutation in exon 4 (EU360790: g. 505A>G), respectively. Association study for these two SNPs with litter size was assessed in three independent populations (Minzhu, Landrace I and Landrace II). Statistical analysis demonstrated that for second and subsequent litters, TT sows produced more TNB than CC pigs in Landrace breed (P<0.05) at g. 269C>T locus, and the additive effect was significant (P<0.05); GG sows produced more TNB and NBA than AA pigs in Minzhu (P<0.01) and Landrace breeds (P<0.05) at g. 505A>G locus, and the additive effect was significant (P<0.01 or P<0.05). Our study suggested that the pMMP-23 gene might be a novel candidate gene for litter size traits, and g. 505A>G locus might be a useful molecular marker for marker assisted selection (MAS).

Erythropoietin Receptor Gene (EPOR) Polymorphisms are Associated with Sow Litter Sizes

The erythropoietin receptor (EPOR) has shown to play an important role in fetal survival by promoting the maturation of red blood cells in many studies of uterine capacity and litter size in swine. In this study, we screened the porcine EPOR gene for mutations and identified five single nucleotide polymorphisms (SNPs): g.705G>T in intron 1, g.2 373C>T in intron 4, and g.2 882C>T, g.3 035A>G, and g.3 132A>T in intron 6. We then genotyped 247 Beijing Black (BB) sows and compared the polymorphism data with the litter sizes of 1 375 parities among the sows. At first parity, there was no association of g.2 882C>T and g.3 132A>T with litter sizes. However, the CT sows in g.2 882C>T had 2.13 higher total number born (TNB) (P<0.01) and 1.81 higher number born alive (NBA) (P<0.01) than the CC sows and the heterozygous sows in g.3 132A>T had the highest litter size when compared to the two homozygotes for the later parities (P<0.05). In the g.3 035A>G SNP, for the later parities, the TNB of the sows with the GG genotype was 3.81 higher (P<0.01) and the NBA was 2.75 higher (P<0.01) than that with the AA genotype but no difference at first parity. The G allele of the EPOR g.705G>T SNP was associated with a greater litter size at both the first parity (P<0.05) and later parities (P<0.01). Furthermore, we determined the allele frequencies for this SNP among five Chinese indigenous pig breeds (Erhualian, Laiwu Black, Meishan, Min, and Rongchang) and three western commercial pig breeds (Duroc, Landrace, and Large White). The G allele of the EPOR g.705G>T SNP was significantly more common in the more prolific Chinese breeds. These results indicated that the EPOR could be an important candidate gene for litter size and g.705G>T can serve as a useful genetic marker for improving litter size in both first and later parities in swine.

Polymorphism of BMPR-IB Gene and its Relationship with Litter Size in Small Tail Han Sheep

[Objective] To open an exit for breeding high-fecundity Small Tail Han sheep according to genotypes. [Method] By the PCR-RFLP,the polymorphism of ovine BMPR-IB gene was detected in Small Tail Han sheep of basic population and breeding population. And its relationship with litter size was analyzed. [Result] In the basic population,the frequencies of B+ and BB genotypes were 77.78% and 14.81%,respectively,and their litter size per parity was 1.77 and 2.40,respectively. In the breeding population,the frequencies of B+ and BB genotypes were 51.79% and 40.18%,respectively,and their litter size per parity was 2.54 and 3.02,respectively. [Conclusion] The ovine BMPR-IB gene can be used as a molecular genetic marker for fecundity traits to establish high-fecundity Small Tail Han sheep.

Model Optimization of Litter Size and Genetic Analyses of Model Parameters in Sows

According to two properties of the life cycle and to fluctuation with parities,four mathematical models,the Poisson cycle model,the cubic polynomial model,the modified quadratic polynomial model-I and the modified quadratic polynomial model-II,were used to fit the records of litter size in Jiangquhai sows.From the viewpoint of statistics and biological significance,the modified quadratic polynomial model-I was found to be the optimum model.A single trait animal model and DFREML procedures were further used to estimate the heritability values of optimum model parameters.The results show that the heritability values for the coefficients A and B and the heritability value for the acme of the model pure quadric curve are larger than the heritability value for the litter size.This suggests that selection for model parameters may be more effective than direct selection for litter size.

Association Analysis between a Polymorphism in the 5' Regulatory Region of the IL-6 Gene and Litter Size in Pigs

The aim of this study was to determine the effects of an IL-6 gene polymorphism,discovered in the 5' regulatory region,on porcine litter size.An association analysis was performed between the polymorphism and total number born(TNB) and number born alive(NBA) in 421 sows.The polymorphism was at Hpy188I within the 5' regulatory region of IL-6 gene.Three genotypes of AA,AG,and GG were detected in Landrace,and two genotypes,AA and AG,were detected in Yorkshire and Duroc pigs.The A allele was the superior allele in all three breeds,with allele frequencies ranging from 0.901 to 0.993.The IL-6 genotype was highly significantly associated with TNB and NBA in the third and following parities(P<0.01),and with total parities(P<0.05).In general,the TNB and NBA showed a tendency of GG>AG>AA,indicating that the common allele was the least favorable for litter size.Thus,there is an enormous opportunity to increase litter size if this effect is confirmed in other studies.

Relevance between BMPR-IB Genotypes and Litter Size in Small Tail Han Sheep

[Objective] To detect the polymorphism of BMPR-IB gene and analyze the relevance between genotype frequency of FecB gene and litter size. [Method] Mutation sites in the BMPR-IB gene of Small Tail Han sheep were analyzed by PCR-RFLP. [Result] The percentages of individuals with BB, B+ and ++ genotypes were 24.69%, 54.89% and 20.42%, respectively, and their average litter size per parity was 3.01, 2.81 and 2.16, respectively. [Conclusion] The BMPR-IB gene can be used as a molecular genetic marker in fecundity traits. The FecB gene can effectively increase litter size of the Small Tail Han sheep and has additive action on litter size.

Effects of catechins on litter size,reproductive performance and antioxidative status in gestating sows

This study was conducted to investigate the effects of catechins on reproductive performance, antioxidative capacity and immune function of gestating sows. A total of 60 cross-bred（Landrace × Large White） multiparious sows were blocked by body weight, parity and backfact and randomly allocated to 1 of 5 treatments: 0.100,200,300, or 400 mg/kg catechins. Dietary treatments were imposed from mating to d 40 of gestation of sows. At farrowing, litter total born, born alive, dead, and normal-（healthy piglets,>0.85 kg） and low-birth weight piglets（<0.85 kg） were recorded. Within 3.00 ± 0.50 days after farrowing litter size was standardized to 8,00 ± 1.50 piglets within treatment. The piglets were weighed at birth（d 1） and weaning（d 28）. Sows serum samples were obtained from blood samples collected on d 40 of gestation for analyses of glutathione peroxidase（GSH-Px）, superoxide dismutase（SOD）, catalase（CAT）,malondialdehyde（MDA）, hydrogen peroxide（H2 O2）, nitric oxide synthetase（NOS） and nitrogen monoxide（NO）. Our results showed that supplementation of catechins at levels of 200 or 300 mg/kg led to improvements in litter born alive（P < 0.01） and piglet born healthy（P < 0.01） and a decrease in stillborn（P < 0.05） at farrowing when compared with the control. In comparison with the control, catechins at any supplemental levels all enhanced the serum SOD（P < 0.05） and CAT（P < 0.01） activities of sows at farrowing but no obvious differences in the serum GSH-Px and NOS activities were observed in this trial（P > 0.05）. Sows received 200 mg catechin per kg diets showed a reduction（P < 0.05） of the serum MDA level at farrowing compared with all other treatments. Sows received all the levels of catechin showed a reduction（P < 0.05） of serum H2 O2 level compared with sows received the control diet on both d 40 of gestation and farrowing. Our results demonstrated that the catechins may be a potential antioxidant to increase the reproductive performance and antioxidative capacity of sows when it was added into diets during the early gestation.

Cathepsin D knockdown regulates biological behaviors of granulosa cells and affects litter size traits in goats

Cathepsin D(CTSD),the major lysosomal aspartic protease that is widely expressed in different tissues,potentially regulates the biological behaviors of various cells.Follicular granulosa cells are responsive to the increase of ovulation number,hence indirectly influencing litter size.However,the mechanism underlying the effect of CTSD on the behaviors of goat granulosa cells has not been fully elucidated.This study used immunohistochemistry to analyze CTSD localization in goat ovarian tissues.Moreover,western blotting was applied to examine the differential expression of CTSD in the ovarian tissues of monotocous and polytocous goats.Subsequently,the effects of CTSD knockdown on cell proliferation,apoptosis,cell cycle,and the expression of candidate genes of the prolific traits,including bone morphogenetic protein receptor IB(BMPR-IB),follicle-stimulating hormone(FSHR),and inhibinα(INHA),were determined in granulosa cells.Results showed that CTSD was expressed in corpus luteum,follicle,and granulosa cells.Notably,CTSD expression in the monotocous group was significantly higher than that in the polytocous group.In addition,CTSD knockdown could improve granulosa cell proliferation,inhibit cell apoptosis,and significantly elevate the expression of proliferating cell nuclear antigen(PCNA)and B cell lymphoma 2(Bcl-2),but it lowered the expression of Bcl-2-associated X(Bax)and caspase-3.Furthermore,CTSD knockdown significantly reduced the ratios of cells in the G0/G1 and G2/M phases but substantially increased the ratio of cells in the S phase.The expression levels of cyclin D2 and cyclin E were elevated followed by the obvious decline of cyclin A1 expression.However,the expression levels of BMPR-IB,FSHR,and INHA clearly increased as a result of CTSD knockdown.Hence,our findings demonstrate that CTSD is an important factor affecting the litter size trait in goats by regulating the granulosa cell proliferation,apoptosis,cell cycle,and the expression of candidate genes of the prolific trait.

Insertion/deletion variants within the IGF2BP2 gene identified in reported genome-wide selective sweep analysis reveal a correlation with goat litter size

Insulin-like growth factor 2 m RNA-binding protein 2(IGF2 BP2,also called IMP2)plays an essential role in the development and maturation of germ cells and embryos and is a candidate gene for goat litter size,based on a previous genomewide selective sweep analysis.In this study,the m RNA expression level of IGF2 BP2 was found to be significantly higher in a single-lamb group than in a multi-lamb group.Insertions/deletions(indels)within the goat IGF2 BP2 gene,including P4-Ins-13 bp and P5-Del-12 bp,were verified in 918 Shaanbei White Cashmere(SBWC)female goats.The minor allelic frequencies(MAFs)of P4-Ins-13 bp and P5-Del-12 bp loci were 0.349 and 0.295,respectively.Analysis using the Chi-square(χ^(2))test showed that the genotype(χ^(2)=14.479,P=0.006)distribution of P4-Ins-13 bp was significantly different between the single-lamb and multi-lamb groups.Correlation analysis demonstrated that P4-Ins-13 bp was significantly associated with goat litter size(P=0.022),and individual goats with the homozygous deletion/deletion(DD)genotype produced more litters than other goats.Therefore,considered as a potential molecular marker significantly related to lambing traits,the P4-Ins-13 bp mutation of the goat IGF2 BP2 gene can be used in goat breeding with practical molecular marker-assisted selection(MAS)to optimize female reproduction and improve economic efficiency in the goat industry.

The combined genotypes effect of ESR and FSHβ genes on litter size traits in five different pig breeds

Estrogen receptor (ESR) and Follicular-stimula-ting hormone beta subunit (FSHβ) genes were chosen as candidates to determine whether they control litter size and some other reproductive traits in swine. 269 sows from five different pig breeds were genotyped by an established PCR-RFLPs protocol at both ESR and FSHβ loci. The effects of both ESR and FSHβ on pig reproductive traits, including total number born (TNB) and number born alive (NBA), are analyzed by SAS software (version 6.12). These computation results demonstrated that both ESR locus and FSHβ locus are the major genes influencing litter size in pigs. The sows of BBBB combined genotype of ESR and FSHβ loci generally produce 1.85-3.01 TNB and 2.0-3.0 NBA more than those of ABAA combined genotype. The notable effect of ESR locus and FSHβ locus on litter size of pigs have made it possible to improve the pig reproduction by Marker-assisted selection (MAS). Moreover, introgression of the beneficial alleles into commercial pig breeding lines,

FSHβsubunit gene is associated with major gene controlling litter size in commercial pig breeds

An insertion fragment in porcine FSHβ subunit gene was cloned by PCR. Sequencing data show that the insertion is a retroposon of 292 bp siting in intronⅠ at the site between +809 and +810 base. Based on these results, a PCR programme was created to genotype animal individuals in different pig breeds at FSHβ locus and polymorphism of FSHβ gene was analyzed. With the combination of genotype and litter size of sows, it was demonstrated that FSHβ locus is closely associated with major gene controlling litter size in commercial pig breeds, such as Yorkshire, Landrace, Durco. Averagely the AA sows give more 1.5 piglets than BB sows do per litter.

Contribution of soil fauna to the degradation of recalcitrant components in Cinnamomum camphora foliar litter in different-sized gaps in Pinus massoniana plantations

Forest gaps are important in forest dynamics and management, but little is known about how soil fauna influence the degradation of recalcitrant litter components in different-sized forest gaps. This investigation uses litterbags with two different mesh sizes (0.04 and 3 mm) to control the meso- and microfauna entering the bags to quantify the contribution of soil fauna to the degradation of recalcitrant components (including condensed tannins, total phenol, lignin and cellulose) during litter decomposition. The experiment was conducted in seven different forest gap sizes in Pinus massoniana plantations over 1 year. One closed-canopy site (CC) and forest gap sizes of 100, 225, 400, 625, 900, 1225 and 1600 m^2 were created in a P. massoniana plantation in the Sichuan basin of China;the CC was treated as the control. Cinnamomum camphora foliage from local native trees was used in all forest gap experiments. We found the following:(1) Gap size had significant effects on the degradation rates (E) of condensed tannins and lignin and on the contributions of soil fauna;medium-sized gaps also presented high degradation rates. Soil fauna obviously contributed to the degradation of recalcitrant foliar litter components in medium-sized gaps.(2) The highest contribution to degradation (40.98%) was recorded for lignin, and the lowest contribution (0.29%) was recorded for condensed tannins. The results indicate that medium-sized gaps (900 m^2) were conducive to the degradation of recalcitrant litter components by soil fauna.

饲料中不同蛋黄粉添加量对孔雀鱼繁殖力的影响

本文以孔雀鱼为试验材料,研究了饲料中不同蛋黄粉添加量对孔雀鱼繁殖周期和产仔量的影响。结果表明,饲料中蛋黄粉添加量越高,孔雀鱼繁殖周期越短,处理1(饲喂基础饲料+2%蛋黄粉)、处理2(饲喂基础饲料+4%蛋黄粉)、处理3(饲喂基础饲料+8%蛋黄粉)与CK(饲喂基础饲料)之间差异均显著(P<0.05),但处理1、2、3之间差异不显著(P>0.05);随着饲养时间延长和饲料中蛋黄粉添加量增多,孔雀鱼产仔量增多,处理1、2、3的第3次产仔量均显著高于CK(P<0.05),但处理1、2、3之间差异不显著(P>0.05);处理2的孔雀鱼总产仔量显著高于处理1(P<0.05),虽然处理3的孔雀鱼总产仔量最高,但其与处理2之间差异不显著(P>0.05)。可见,在饲料中添加蛋黄粉可缩短孔雀鱼繁殖周期,提高孔雀鱼产仔量,最适添加量为4%。

miR-23a/27a/24基因簇g.65307469G>A突变对大白猪产仔数和启动子活性的影响

[目的]本文旨在研究大白猪miR-23a/27a/24基因簇启动子突变位点多态性与产仔数性状的关系及潜在机制,为母猪繁殖性状的分子育种提供新的潜在遗传标记。[方法]利用混池测序技术筛选猪miR-23a/27a/24基因簇启动子突变位点,直接测序法对大白猪群体(n=345)miR-23a/27a/24基因簇突变位点进行基因分型,计算遗传多样性;用线性模型对突变位点多态性与产仔数性状进行关联性分析;构建不同等位基因类型启动子载体,转染猪卵巢颗粒细胞,通过检测荧光素酶活性分析突变对启动子活性的影响;用生物信息学方法预测不同等位基因类型启动子潜在结合的差异转录因子,用荧光素酶活性分析差异转录因子对不同等位基因类型启动子活性的影响。[结果]在猪miR-23a/27a/24基因簇启动子-648 nt(Chr.2,65307469 nt)处发现1个新的G/A突变,命名为g.65307469G>A。在大白猪群体中发现3种基因型(GG、GA和AA),其中GG为优势基因型(89.57%),G等位基因为优势等位基因(94.64%)。关联性分析发现,GA基因型母猪的总产仔数(TNB)比GG基因型母猪每胎高0.56头(P<0.05)。荧光素酶活性分析结果显示G等位基因类型启动子活性显著高于A等位基因类型(P<0.05)。在不同等位基因类型启动子间发现1个潜在结合的差异转录因子死亡相关蛋白1(THAP1),成功构建猪THAP1基因过表达载体,共转试验结果显示转录因子THAP1对不同等位基因类型启动子活性均无显著影响(P>0.05)。[结论]miR-23a、miR-27a和miR-24是大白猪产仔数性状的候选基因,g.65307469G>A突变抑制miR-23a/27a/24基因簇的启动子活性,但与转录因子THAP1无关。

基于全基因组重测序解析皮山红羊群体遗传结构及产羔数候选基因研究

[目的]皮山红羊是分布于新疆和田地区的新发现多羔性地方绵羊品种。本研究基于全基因组重测序技术从基因组水平上了解皮山红羊的群体遗传结构及产羔性状受选择信号区域,并对候选基因进行验证。[方法]选择30只连续产2~3羔的经产皮山红羊母羊为高繁组(high fertility, HF),30只连续产单羔的经产皮山红羊母羊为低繁组(low fertility, LF),对这两个群体进行全基因组重测序。应用主成分分析(PCA)、系统进化树、群体遗传结构及全基因组扫描(Fst&θπ)等综合分析法确定候选区域,进一步筛选皮山红羊产羔性状候选基因。采用飞行质谱分型技术对候选基因进行分型验证。[结果]皮山红羊高、低繁殖组群体连锁不平衡(LD)分析衰减曲线相似,系统进化树显示两组群体分化程度不明显。PCA结果显示,两个群体明显聚成一簇,个别个体离群,其位置及相互关系符合进化树结构以及群体结构结果。设置同时达到Top 1%Z(Fst)值和θπ值的窗口为候选区域,共注释229个强选择信号,HF和LF组注释基因分别为86和143个,其中筛选到42个可能与繁殖性状相关的候选基因,如MARF1、CHGA、BMPR1B、IMMP2L、CDK14、ZDHHC3、CCDC71、DSCAML1、LIMK2、P2RY14等。经GO与KEGG通路分析发现,GO功能显著富集在钠离子跨膜转运蛋白活性的调控、凋亡过程的调控、钠离子通道调节剂活性、G蛋白偶联受体结合、G蛋白偶联嘌呤核苷酸受体活性等条目,KEGG显著富集通路主要与信号传递、信号通路、物质代谢等通路有关。分型结果表明,MARF1基因有11个SNPs位点在皮山红羊群体中真实存在,其中,g.14023542 T>A、g.14036507 A>G、g.14046123 C>T位点与群体平均产羔数显著关联,且前2个突变位点呈现强连锁关系(r2>0.3),g.14023542 T>A位点TT基因型具有最多的平均产羔数(1.901±0.675)。[结论]皮山红羊高繁组和低繁组两个群体遗传背景相似,具有一定程度的分化,但分化不明显。MARF1、CHGA、BMPR1B、IMMP2L、CDK14、ZDHHC3、CCDC71、DSCAML1、LIMK2、P2RY14等基因可能是影响皮山红羊产羔性状的候选基因。MARF1基因的3个SNPs位点可作为皮山红羊产羔性状潜在分子选育标记。