夏蜡梅天然群体表型变异及分布特征

选取夏蜡梅自然分布区8个群体,对花部、叶部、果部和种子的22个性状进行了系统调查与分析,以揭示夏蜡梅天然群体的表型变异特征及变异规律。结果显示:夏蜡梅天然群体存在丰富的表型变异,20个表型性状在群体间与群体内差异均达到极显著水平(P0.01),平均变异系数为12.15%(6.40%～45.87%),平均表型分化系数为41.87%(1.14%～85.07%),群体内变异(58.13%)大于群体间变异(41.87%);夏蜡梅花色(外被片颜色)表现为白、浅粉、粉、粉红4种类型,不同群体间各花色比例各有不同;各表型性状与生态因子间相关性分析结果显示,22个表型性状中有8个和生态因子呈显著相关。通过表型性状UPGMA聚类分析可以将8个群体划分为4个类群,表型性状分化体现为连续性的地理分布格局。     

川西北地区康定柳天然群体表型多样性研究

为揭示川西北乡土灌木树种康定柳天然群体的遗传变异规律,采用变异系数、巢式方差分析、聚类和相关分析等方法,研究四川阿坝州康定柳5个天然群体雌、雄性类群叶片表型变异程度和变异规律,分析群体间和群体内的表型多样性。结果表明：康定柳叶片表型性状在群体间和群体内均存在极其丰富的多样性,叶片表型性状平均变异系数为18.97%,雌、雄性类群间表型分化系数平均为27.32%和21.51%,小于群体内,表明康定柳天然群体叶片表型性状在群体内的多样性大于群体间;叶片表型变异系数从大到小依次为巴西（19.49%）、红星（19.42%）、壤塘（19.05%）、阿坝（18.94%）、红原（17.98%）,巴西群体的表型多样性最丰富,而红原群体的最低。利用群体间欧氏距离进行UPGMA聚类分析,5个群体间雌、雄性类群聚为3类。     

顶坛花椒结实性状表型多样性分析

以贵州花江峡谷地区特有经济树种顶坛花椒为研究对象,按海拔、坡向因素选取3个群体32个单株,调查了9个结实性状,采用多重比较、变异系数、相关分析、聚类分析等方法,分析顶坛花椒结实性状的多样性及群体间和群体内的变异特征和变异规律。结果表明,顶坛花椒结实性状在群体间和群体内均存在丰富的变异。3个群体9个性状的平均变异系数为29.81%（17.36%~50.96%）,9个形态性状的平均变异系数由大到小的顺序依次为果穗果粒密度（47.56%）>果穗果粒数（44.43%）>枝条结果部位长度（33.71%）>果穗宽（28.75%）>果枝直径（25.21%）>果穗长（24.61%）>果枝长宽比（22.54%）>果穗长宽比（21.23%）>果枝果穗密度（20.20%）,表明果枝果穗密度和果穗长宽比较为稳定,而果穗果粒密度和果穗果粒数稳定性较低。相关分析表明,果穗性状和枝条性状间无显著相关关系。聚类分析表明,顶坛花椒结实性状的变异无空间特异性。为顶坛花椒种质资源的评价、利用及遗传改良提供了依据。     

绒山羊绒毛品质遗传研究进展

绒毛品质不仅影响绒山羊养殖的经济效益,还影响绒毛纺织品的质量。近年来,随着产绒量的提高,绒毛品质有下降趋势,为了提高生产效益,在生产过程中提高绒毛品质势在必行。绒毛品质是绒山羊育种中重要的选择参数,而控制绒毛品质的主要性状是数量性状,通过数量遗传学和分子遗传学寻找控制数量性状的主效基因,从而研究其生长机理和控制绒毛生长的基因的表达机制。作者综述了近年来有关绒毛品质的研究成果,其中包括通过表型选择来提高绒毛品质,且找到控制绒毛品质性状的HOX、BMP、KAP基因和色素基因等,还有寻找控制目标性状相应的QTL和对不同序列的SNPs进行GWAS分析,通过基因型的选择来提高绒毛品质,这些研究为提高绒毛品质奠定了理论基础,也为今后研究绒毛品质的遗传因素提供借鉴。     

基于花表型性状的梨种质资源多样性研究

对"国家果树种质兴城梨、苹果圃"内保存的梨13个种625份资源的花器官11个表型性状进行数据采集,分析了花表型性状的分布频率、变异系数、Simpson指数和Shannon-weaver指数,并对每花序花朵数、雄蕊数、柱头数、花冠直径在5个栽培种的种群内和种群间多样性进行了比较分析,对脆肉和软肉梨进行了聚类分析。结果表明:(1)梨花器官表型多样性丰富,以白色花蕾、紫红色花药、柱头高于花药和花柱基部无茸毛等类型居多,分别占相对应描述符分布频率的50.56%、47.52%、63.20%和80.96%。(2)花药颜色的Simpson指数和Shannon-weaver指数较高,分别为0.719和2.351,多样性最为丰富,并新发现深红色和深紫色花药两种类型资源。(3)每花序花朵数、雄蕊数、花冠直径和柱头数的平均变异系数分别为19.50%、15.12%、13.74%和8.50%,表明柱头数性状的遗传稳定性高于另外3个性状。(4)根据花冠直径分布统计分析,提出了5级数值分级指标与参照品种。(5)梨花4个表型性状在种群内和种群间差异均达到极显著水平,种群内和种群间表型分化系数VST分别为72.97%和27.03%,表明种群内变异更为丰富。(6)聚类分析显示,196个脆肉梨地方品种可划分为5类,72个软肉型秋子梨可划分为4类。     

Phenotypic and phylogenetic studies associated with the crucifer white leaf spot pathogen,Pseudocercosporella capsellae,in Western Australia

Pseudocercosporella capsellae (white leaf spot disease) is an important disease on crucifers. Fifty‐four single‐conidial isolates collected from Brassica juncea (Indian mustard), B. napus (oilseed rape), B. rapa (turnip), and Raphanus raphanistrum (wild radish) across Western Australia were investigated for differences in pathogenicity and virulence using cotyledon screening tests, genetic differences using internal transcribed spacer (ITS) sequencing and phylogenetic analysis, and growth rates on potato dextrose, V8 juice and malt extract agars. All isolates from the four crucifer hosts were pathogenic on the three test species: B. juncea, B. napus and R. raphanistrum, but showed differences in levels of virulence. Overall, isolates from B. juncea, B. napus and B. rapa showed greatest virulence on B. juncea, least on R. raphanistrum and intermediate virulence on B. napus. Isolates from R. raphanistrum showed greatest virulence on B. juncea, least on B. napus and intermediate virulence on R. raphanistrum. Growth and production of a purple‐pink pigment indicative of cercosporin was greatest on malt extract agar and cercosporin production on V8 juice agar was positively correlated with virulence of isolates on B. juncea and B. napus. ITS sequencing and phylogenetic analysis showed that isolates collected from B. napus, B. juncea and B. rapa, in general and with few exceptions, had a high degree of genetic similarity. In contrast, isolates from R. raphanistrum were clearly differentiated from isolate groups collected from Brassica hosts. Pseudocercosporella capsellae reference isolates from other countries generally grouped into a single separate cluster, highlighting the genetic distinctiveness of Western Australian isolates.     

Phenotypic trait of Crassostrea hongkongensis♀× C. angulata♂ hybrids in southern China

The Hong Kong oyster (Crassostrea hongkongensis) and the Portuguese oyster (Crassostrea angulata) are important aquaculture species in southern China. To understand the potential feasibility of hybridization between the two species, two‐by‐two factorial cross‐experiments were conducted in Shenzhen (Guangdong province). An asymmetry in fertilization was revealed: C. hongkongensis eggs could be fertilized by C. angulata sperm, but the reciprocal cross was not possible. The fertilization and hatching success in the C. hongkongensis females × C. angulata males (HA) cross was lower than the two intraspecific crosses. Moreover, hybrid larvae had a slower growth rate than those from parental progenies due to genome incompatibility. However, the size of the spat and adult growth were greater than those of the two parental progeny, with obvious heterosis during the grow‐out stage. The survival advantage of hybrids was examined at all times. The surprising finding was that all hybrids were completely fertile, meaning they could produce normal and functional gametes. Genetic analysis by molecular markers was applied to confirm that the HA spat were true hybrids. Our results revealed that the interspecific hybridization between C. hongkongensis and C. angulata is completely successful in one direction. Furthermore, hybrids are viable, fast growing and completely fertile, which provides a promising method for the genetic improvement of oysters as a new aquaculture stock in southern China.     

云南香格里拉特有易危植物中甸刺玫的表型多样性

 利用形态学指标对云南香格里拉县现存的中甸刺玫（Rosa praelucens Byhouwer）3 个天然居 群、1 个由引种植株构成的“引种”群体和1 个由零星散生在农家的植株所构成“农家”群体进行了表型 多样性研究。结果表明：（1）和平村天然居群的植株最高,花最大,果实最大,种子数量最多且百粒质 量最大。乃司村天然居群的叶片小叶数最多,叶片连叶柄最长,果梗最长,但果实最小,种子百粒质量 最轻。联合村天然居群的花色最红且变异最丰富。“农家”群体的植株冠幅最大,花瓣数最多且变异最丰 富。“引种”群体的株高、冠幅、小叶片和花径等的均值最小但变异系数较大,花色最淡,种子数最少。 （2）中甸刺玫种内存在着丰富的表型变异,23 个表型性状的变异系数均值为22.88%,平均表型分化系 数为69.56%,群体间的变异是其表型变异的主要来源。（3）目前引种的植株和自然散生在农家庭院的植 株主要分别从乃司村和联合村人为地直接或间接采集并单独保存下来。基于中甸刺玫的表型多样性及变 异特征,应尽可能地保护较多的居群;从资源利用的角度则应尽量保护群体的完整性以保存其群体内所 蕴藏的观赏性状。     

Inferring phenotypic causal structure among farrowing and weaning traits in pigs

Direct selection for litter size or weight at weaning in pigs is often hindered by external interventions such as cross‐fostering. The objective of this study was to infer the causal structure among phenotypes of reproductive traits in pigs to enable subsequent direct selection for these traits. Examined traits included: number born alive (NBA), litter size on day 21 (LS21), and litter weight on day 21 (LW21). The study included 6,240 litters from 1,673 Landrace dams and 5,393 litters from 1,484 Large White dams. The inductive causation (IC) algorithm was used to infer the causal structure, which was then fitted to a structural equation model (SEM) to estimate causal coefficients and genetic parameters. Based on the IC algorithm and temporal and biological information, the causal structure among traits was identified as: NBA → LS21 → LW21 and NBA → LW21. Owing to the causal effect of NBA on LS21 and LW21, the genetic, permanent environmental, and residual variances of LS21 and LW21were much lower in the SEM than in the multiple‐trait model for both breeds. Given the strong effect of NBA on LS21 and LW21, the SEM and causal information might assist with selective breeding for LS21 and LW21 when cross‐fostering occurs.