Accelerating Strawberry Seed Germination by Fungal Infection

Germination of strawberry seed was accelerated by natural andartificial infections of Ulocladium charatarum and other fungi,including the Arthrinium state of Apiospora montagnei and aCladosporium sp. Germination was variously promoted by fungiboth in light and darkness, on damp filter paper, water andmalt agar plates and on horticultural compost. Germinated seedlingswere apparently undamaged by these infections, although whencultured on malt agar the seedlings were overgrown by the fungus.Several other fungi promoted germination, but three of themlater killed the seedlings. Germination of seed of all threecultivars that were tested was promoted by fungal infectionwhich probably promoted germination by hastening breakdown ofthe seed coat. Strawberry, Fragaria ananassa Duch., germination, fungus     

云南东部山区不同类型次生林群落谱系结构特征

以云南东部山区4种群落39个样方调查的205个物种数据为基础,分析群落谱系结构,以推断植被恢复过程中的群落构建机制。结果表明:(1)不同恢复方式所形成的华山松林、水冬瓜林以及次生常绿阔叶林均呈现谱系聚集格局,表现出生境过滤作用的主导性;(2)在处于森林恢复初期的火棘灌丛中,草本植物在大尺度上呈现随机格局,可能是生境过滤与竞争排斥双重作用的结果;(3)群落过去的状态或经历(如农耕、砍伐等)所形成的影响可能一直存在,从而使得恢复的群落谱系结构在生境过滤作用下更加趋向于聚集;(4)不同生活型植物的谱系结构具有差异,反映出植物群落构建的主导因素会因植物生活型不同而具有差异。     

Evolutionary pattern of the regulatory network for flower development:Insights gained from a comparison of two Arabidopsis species

Previous studies on Arabidopsis thaliana and other model plants have indicated that the development of a flower is controlled by a regulatory network composed of genes and the interactions among them.Studies on the evolution of this network will therefore help understand the genetic basis that underlies flower evolution.In this study,by reviewing the most recent published work,we added 31 genes into the previously proposed regulatory network for flower development.Thus,the number of genes reached 60.We then compared the composition,structure,and evolutionary rate of these genes between A.thaliana and one of its allies,A.lyrata.We found that two genes (FLC and MAF2) show 1∶ 2 and 2∶ 2 relationships between the two species,suggesting that they have experienced independent,post-speciation duplications.Of the remaining 58 genes,35 (60.3％) have diverged in exon-intron structure and,consequently,code for proteins with different sequence features and functions.Molecular evolutionary analyses further revealed that,although most floral genes have evolved under strong purifying selection,some have evolved under relaxed or changed constraints,as evidenced by the elevation of nonsynonymous substitution rates and/or the presence of positively selected sites.Taken together,these results suggest that the regulatory network for flower development has evolved rather rapidly,with changes in the composition,structure,and functional constraint of genes,as well as the interactions among them,being the most important contributors.     

综述与专论：表观遗传修饰调控阿尔茨海默病的研究进展

阿尔茨海默病（Alzheimer’s disease,AD）是一种临床上常见的以进行性认知功能障碍和记忆减退为主要特征的神经退行性疾病。近些年研究发现，表观遗传修饰如DNA修饰、组蛋白修饰、RNA修饰及非编码RNA在Aβ沉积、Tau蛋白过度磷酸化、神经再生、突触可塑性和认知功能中发挥不同程度的调控作用，进而改善或加剧AD病理进程。临床数据表明表观遗传修饰的改变与AD风险呈显著相关性，运用药物、物理刺激、si RNA等干预手段在AD动物模型中改变表观遗传修饰水平可改善AD病理和认知能力。本文综述了不同的表观遗传修饰在AD中的调控作用，为进一步理解AD的表观遗传学机制及通过干预表观遗传修饰改善或治疗AD的可行性提供理论依据。     

七叶一枝花种质资源在福建地区的适应性评价

针对南方低山丘陵区种植重楼存在资源混杂及可借鉴文献少等的问题，本文对搜集的120份重楼种质资源在福建省的物候期、病害发生和农艺性状进行观测，并对生长较好的资源采用HPLC法对重楼皂苷进行测定，利用主成分分析和权重评分法开展七叶一枝花种质资源适应性评价。结果表明搜集到的西南地区包括云贵川重楼资源在福建省的生育期不完整，物候期及农艺性状等指标较差，而另外有49份表现良好的为七叶一枝花资源，其中符合《中国药典》重楼皂苷含量的占55%。七叶一枝花资源的病害、农艺性状和重楼皂苷含量存在着广泛的变异，南方低山丘陵区种植重楼应选择当地或相似经纬度及地形地貌地区的七叶一枝花优异资源。七叶一枝花种质资源的评价，是以适应性、有效成分及农艺性状为主成分来进行权重评分，总得分越高则适应性越强。     

1975—2018年南四湖流域景观生态风险时空变化及其驱动因素研究

研究区域的景观生态风险变化趋势及其驱动因素,可以更加科学地保护和开发流域生态系统。以南四湖流域1975—2018年9期土地利用数据为基础,借助ArcGIS 10.2和Fragstats 4.2等软件计算景观生态指数,并构建景观生态风险评估模型,通过空间自相关性分析,探究南四湖流域自改革开放40年来生态风险的时空变化,并用地理探测器定量研究驱动因子的贡献量。研究结果表明:流域最大斑块指数不断减小,景观破碎化加剧,且与景观生态风险指数呈正相关;而平均分维数、香浓多样性和香浓均匀度与生态风险指数呈负相关。在空间上,生态风险指数具有较强集聚性,东部草地和林地区域主要是高值区,湖区北部以及西部耕地和建设用地则主要是低值区;总体上,研究区大部分为低风险和较低风险区,且生态风险平均值不断降低;地理探测器分析表明,海拔和人为干扰度因子贡献量在35%以上,对生态风险有显著的解释力。据此,以后应减少人类行为对南四湖流域生态系统的干预,降低流域的景观生态风险,实现经济、社会和生态的可持续发展。