飞鸭体尺与屠宰性能测定及其相关性分析

试验测定了8周龄天农飞鸭的体尺与屠宰性能,分析了各指标间的相关性。结果表明,半潜水长、胫长和宰前体重在公母鸭之间存在极显著差异(P＜0.01),体斜长、龙骨长和胫围在公母鸭之间存在显著差异(P＜0.05);屠体重、半净膛重、全净膛重、腿肌重在公母鸭之间存在极显著差异(P＜0.01),瘦肉重在公母鸭之间存在显著差异(P＜0.05)。宰前体重与体尺各指标（胸宽除外）间存在着极显著相关(P＜0.01);试验所测的9个体尺指标均与宰前体重、屠体重、半净膛重、全净膛重之间存在显著(P＜0.05)或极显著(P＜0.01)正相关;宰前体重、屠体重、半净膛重、全净膛重、胸肌重、腿肌重和瘦肉重相互之间呈强相关(P＜0.01),但体重和屠体重却与以上其它重量性状的百分率指标间无明显相关(P＞0.05)。     

QTL mapping of seedling biomass and root traits under different nitrogen conditions in bread wheat(Triticum aestivum L.)

Plant nitrogen assimilation and use efficiency in the seedling's root system are beneficial for adult plants in field condition for yield enhancement. Identification of the genetic basis between root traits and N uptake plays a crucial role in wheat breeding. In the present study, 198 doubled haploid lines from the cross of Yangmai 16/Zhongmai 895 were used to identify quantitative trait loci(QTLs) underpinning four seedling biomass traits and five root system architecture(RSA) related traits. The plants were grown under hydroponic conditions with control, low and high N treatments(Ca(NO_3)_2·4H_2 O at 0, 0.05 and 2.0 mmol L~(-1), respectively). Significant variations among the treatments and genotypes, and positive correlations between seedling biomass and RSA traits(r=0.20 to 0.98) were observed. Inclusive composite interval mapping based on a high-density map from the Wheat 660 K single nucleotide polymorphisms(SNP) array identified 51 QTLs from the three N treatments. Twelve new QTLs detected on chromosomes 1 AL(1) in the control, 1 DS(2) in high N treatment, 4 BL(5) in low and high N treatments, and 7 DS(3) and 7 DL(1) in low N treatments, are first reported in influencing the root and biomass related traits for N uptake. The most stable QTLs(RRS.caas-4 DS) on chromosome 4 DS, which were related to ratio of root to shoot dry weight trait, was in close proximity of the Rht-D1 gene, and it showed high phenotypic effects, explaining 13.1% of the phenotypic variance. Twenty-eight QTLs were clustered in 12 genetic regions. SNP markers tightly linked to two important QTLs clusters C10 and C11 on chromosomes 6 BL and 7 BL were converted to kompetitive allele-specific PCR(KASP) assays that underpin important traits in root development, including root dry weight, root surface area and shoot dry weight. These QTLs, clusters and KASP assays can greatly improve the efficiency of selection for root traits in wheat breeding programmes.     

MyoG和MEF2a基因多态性聚合效应对鸭屠宰性状的影响

【目的】探讨MyoG和MEF2a基因聚合效应对鸭屠宰性状的影响,为进一步确定与鸭屠宰性状相关的分子遗传标记提供研究基础,为鸭屠宰性状的多基因聚合育种提供依据。【方法】试验以240只三穗鸭为研究素材,扩增MyoG和MEF2a基因并进行PCR产物直接测序以检测两基因所有外显子的单核苷酸突变（SNPs）位点。运用SPSS 18.0软件中的GLM统计模型对MyoG和MEF2a基因的SNPs所对应的不同基因型与三穗鸭屠宰性状进行关联分析,根据单基因关联分析结果,将对屠宰性状存在显著影响的MyoG和MEF2a基因的多态位点利用软件PHASE 2.0构建聚合基因型,再进行聚合基因型与屠宰性状的关联分析。【结果】在试验群体中一共发现8个SNPs,其中在MyoG基因中有6个SNPs被找到,MEF2a基因中找到2个SNPs位点,在所有突变位点中,其中MyoG基因的g.2977G＞C位点发生的G/C突变使密码子由GAG变为GAC,所编码的氨基酸由谷氨酸变成天冬氨酸;而MEF2a基因中的两个多态位点,g.47915G＞A位点发生的G/A突变使密码子由GAA变为AAA,编码的氨基酸由谷氨酸变成赖氨酸,g.47918G＞A位点的G/A突变引起的密码子由GAT变成AAT,所编码的氨基酸由天冬氨酸变成天冬酰胺。剩下的5个突变位点均属于同义突变,并未引起编码氨基酸的改变。此外,进行?2适合性检验,除了MyoG基因的g.1131C＞T位点和MEF2a基因的g.47915G＞A、g.47918G＞A位点未处于Hardy-Weinberg平衡状态（P＜0.05）外,其他的突变位点均处于平衡状态。单基因关联分析结果表明,MyoG基因g.1131C＞T和g.2204G＞A突变分别对胸肌率、体重和全净膛重有着显著影响,其所对应的纯合子基因型CC、GG型为优势基因型。MEF2a基因g.47915G＞A/g.47918G＞A位点影响全净膛率,GA基因型个体属于优势基因型个体。通过挑选出与屠宰性状（胸肌率、体重、全净膛重和全净膛率）有关联的MyoG基因g.1131C＞T/g.2204G＞A位点与MEF2a基因g.47915G＞A/g.47918G＞A进行聚合效应分析,结果显示,聚合后的8种聚合基因型个体的全净膛率,在各基因型间无显著差异（P＞0.05）,TTGAGA基因型的平均值最高,其次为CCGGGA基因型;其他3个指标各基因型间差异达到了显著,其中体重和全净膛重存在正相关,都是CCGAGA基因型的平均值最高,CTGGGA基因型的平均值次之;CCGGGG基因型的胸肌率平均值最高,其次是CCGGGA基因型。结果显示,单个基因的平均值最高的基因型分别为CC、GG和GA,在两基因聚合后在4个指标中CCGGGA基因型都不是最优的组合,说明两个基因间存在互作效应。【结论】两个基因间存在互作效应,所以用单个基因分子标记进行选育可能会顾此失彼,不能收到良好的效果,但是本研究的聚合优势基因型个体偏少,有待于进一步扩大样本进行验证分析,进行更多基因的聚合效应分析。     

四倍体鸭茅产量及其构成因素的QTL定位

产量相关性状是复杂的数量性状,对鸭茅的单株产量及构成因素进行QTL分析,可提高育种中对产量性状优良基因选择的效率,同时为鸭茅遗传改良、基因克隆及分子标记辅助育种提供理论依据。以四倍体鸭茅“楷模”和“01436”为亲本杂交而成的作图群体为试验材料,于2014年对洪雅、宝兴两个不同生境下鸭茅株高、旗叶长、倒二叶长、旗叶宽、倒二叶宽、茎粗、花序长、分蘖数、单株干重等9个产量相关性状进行了表型鉴定及相关性分析。此外,在已构建的高密度鸭茅分子遗传图谱的基础上,采用MapQTL 5.0进一步对这些性状QTL定位分析。结果表明,绝大多数性状在亲本间呈显著差异且都整体表现出连续变异,符合数量性状遗传的特征;相关性分析表明,大多数产量相关性状均与干重极显著正相关,与单株干重相关性最好的依次为分蘖、株高;QTL分析发现,控制该9个农艺性状的QTL共60个,洪雅38个,宝兴22个,这些QTL分别定位于分子连锁图谱的1、2、3、4、5共5个连锁群上,单个QTL的贡献率为5.7%~24.7%,单个性状QTL个数为2~15个。其中,控制株高、花序长的QTL各12个,控制倒二叶长、茎粗的QTL各4个,控制旗叶宽、倒二叶宽的QTL各2个,控制单株干重的QTL有6个,影响分蘖的QTL为3个,与旗叶长相关的QTL最多15个。     

Beef quality traits of heifer in comparison with steer,bull and cow at various feeding environments

The present review has been focused largely on the sex type differences in beef quality among heifers, cows, steers and bulls in various feeding environments. Genetic groups, feeding systems and gender are the major factors that change carcass characteristics and fatty acid profiles of cattle. Studies identified that heifer beef has super characteristics in eating quality and a better healthy composition in fatty acids than steer, cow and bull. Diet influences the variation of fatty acid profile; particularly the level of polyunsaturated fatty acids (PUFA) interacts with breed and sex. Animals finished in pasture systems were reported to show better ratios of PUFA/ saturated fatty acids and n‐6/n‐3. Carcasses of roughage‐fed beef are lighter and have less marbling and lower quality grades but have higher cutability than carcasses of grain‐fed bulls. Heifers and cows are reported to deposit more fat than steers and bulls. Among males, lower production of testosterone by steers favors more fat thickness compared with bulls. Marbling greatly varies among cattle belonging to different sexes, and particularly, females have genetic makeup that efficiently controls deposition. The current review identified that heifers can be a premium beef brand, while steer beef currently take a large part of market share across the world.     

Identification of polymorphisms and association analysis with meat quality traits in the porcine KIAA1717 and HUMMLC2B genes

Skeletal muscle genes are potential candidates for production and meat quality. Screening a subtracted cDNA library constructed with mRNA obtained from longissimus dorsi muscles of F1 hybrids Landrace × Yorkshire and their female parents Yorkshire, we isolated two partial sequences coding for the H3-K4-specific methyltransferase (KIAA1717) and skeletal muscle myosin regulatory light chain (HUMMLC2B) genes. Database search revealed KIAA1717 and HUMMLC2B encoded proteins with SET domain and EF-hand calcium binding motif, respectively. In the present work we identified their partial polymorphisms and two SNPs, one (C1354T) at the 3′ untranslated region (UTR) of KIAA1717 and one (A345G) at the SINE (PRE-1) element of HUMMLC2B, both created/disrupted a restriction site for endonuclease Msp I. The selected pigs were genotyped at the KIAA1717 C1354T and HUMMLC2B A345G sites by means of a PCR-RFLP protocol. Significant associations were observed for the KIAA1717 C1354T polymorphic site with meat marbling (longissimus doris (p < 0.05), biceps femoris (p < 0.01)) and intramuscular fat (p < 0.01). HUMMLC2B A345G were significantly associated with meat pH (longissimus doris (p < 0.05), biceps femoris (p < 0.01)), drip loss (p < 0.01), water holding capacity (p < 0.01) and meat color value (longissimus doris (p < 0.01), biceps femoris (p < 0.05)). Further studies are needed to confirm these preliminary results.     

甜高粱主要农艺性状的主成分分析

对国内外194份甜高粱品种进行了10个主要农艺性状调查。采用主成分分析,发现穗重、生育期、生物产量、穗长、茎粗、分蘖及含糖量等7个因子为农艺性状的主成分。在甜高粱育种中应加强生物产量选择,适当考虑含糖量及生育期,但穗重、分蘖和茎粗不宜过高,并且穗长越短越好。研究结果将为甜高粱的品种改良和创新提供理论依据。     

黔东南冷凉山区优质稻农艺性状的相关性及通径分析

[目的]研究12个优质水稻(Oryza sativa L.)品种在黔东南冷凉山区主要农艺性状的相关性及通径分析。[方法]12个品种分别为临籼22、凉籼3号、德双4号、香稻82、香米德优8号、临籼22、中籼2503、中香1号、鉴真2号、昌米016、鄂中5号、滇屯502(CK)。采用随机区组试验设计,3次重复。每小区从第2行的第2株开始收取10个单株进行考种,考种项目包括株高、穗长、有效穗、总粒数、实粒数、千粒重、结实率及产量。[结果]实粒数与实际产量呈极显著正相关,相关系数为0.583 1,有效穗、总粒数和结实率与实际产量呈显著正相关,相关系数分别为0.255 4、0.548 9、0.355 2;而千粒重和穗长与产量呈显著负相关,相关系数为-0.179 0、-0.555 8。对实际产量直接贡献最大的是有效穗,通径系数为1.470 1,其次是总粒数(0.643 3)、千粒重(0.627 4)、实粒数(0.492 6)、结实率(0.208 4)。[结论]黔东南冷凉山区在选择品种和推广中要以株高适中、大穗粒多、分蘖适中为主攻目标。     

基于SNP标记的小麦籽粒性状全基因组关联分析

【目的】籽粒性状是影响小麦产量的重要因素,通过对小麦籽粒性状进行全基因组关联分析,发掘控制小麦籽粒性状显著位点,为小麦籽粒性状的遗传改良研究提供理论参考。【方法】以在新疆种植的121份小麦为材料,利用小麦50K SNP芯片,对粒长、粒宽、籽粒长宽比、籽粒面积、籽粒周长和千粒重6个性状进行基于混合线性模型MLM（Q+K）的全基因组关联分析。【结果】在不同环境间6个籽粒性状均表现出广泛的表型变异,其中千粒重变异系数最大为13.91%—17.79%,各籽粒性状遗传力为0.85—0.90。多态性信息含量PIC值为0.09—0.38,最小等位基因频率MAF值为0.05—0.50。群体结构分析表明,试验所用自然群体可分为4个亚群。GWAS结果表明,共检测到592个与6个性状显著关联位点（P<0.001）,其中,涉及6个性状的29个SNP在2个及以上的环境中被重复检测到,分布于1A（5）、1B（2）、1D、2A（5）、3B、5A、5D、6B（4）、6D、7B和7D（7）染色体上,解释9.3%—22.7%的表型变异。检测到6个与粒长稳定的关联位点,分布在1A、2A和7D染色体上,解释9.9%—22.7%的表型变异;检测到2个与粒宽稳定的关联位点,分布在3B和5D染色体上,解释9.6%—12.2%的表型变异;检测到6个与籽粒长宽比稳定的关联位点,分布在2A（2）、5A、7B和7D（2）染色体上,解释10.1%—19.4%的表型变异;检测到3个与籽粒面积稳定的关联位点,分布在1A、1B和1D染色体上,解释9.9%—18.2%的表型变异;检测到6个与籽粒周长稳定的关联位点,分布在1A（2）、2A、6D和7D（2）染色体上,解释9.3%—22.6%的表型变异;检测到6个与千粒重稳定的关联位点,分布在1B、2A和6B染色体上,解释9.7%—12.9%的表型变异。挖掘到5个控制小麦籽粒性状一因多效显著关联位点,分布在1A、2A（2）和7D（2）染色体上,解释9.9%—22.7%的表型变异。【结论】本研究材料遗传多样性丰富,在自然群体中共发现29个与6个籽粒性状在2个及以上环境中稳定显著的关联位点。