杜鹃红山茶实时定量PCR 内参基因筛选及验证

【目的】实时荧光定量PCR（quantitative real-time PCR,qRT-PCR）以高灵敏度和特异性等优点,成为基因表达分析的主要工具,而选择适合不同条件下工作的内参是qRT-PCR分析的前提。筛选得到适用于杜鹃红山茶不同器官、不同时期花瓣的qRT-PCR分析的内参基因,为后续相关基因功能研究提供可用的内参基因。【方法】选择转录延伸因子编码基因（EF1α）、α-tubulin（TUA）、β-tubulin（TUB）、Ubiquitin（UBQ）、肌动蛋白（Actin）和甘油醛-3-磷酸脱氢酶（Glyceraldehyde-3-phosphate dehydrogenase,GAPDH）6个看家基因,使用2种不同的计算程序GeNorm和NormFinder评估了6个基因表达的稳定性。进一步通过CaGASA3基因的表达模式验证了所选内参基因的适用性。【结果】在不同器官中通过GeNorm和NormFinder筛选出稳定性最好的基因,排名前2位的均为TUA和GAPDH,GAPDH基因在两种计算程序评估中稳定性均最佳。而在不同时期花瓣中,通过2种程序得出排名前2位的内参基因均为TUB和UBQ;UBQ基因在GeNorm程序评估中稳定性最好,TUB基因在NormFinder程序的评估中稳定性最佳。【结论】杜鹃红山茶不同器官中最佳内参基因为TUA和GAPDH,不同时期花瓣中最适内参基因为TUB和UBQ。     

落叶果树需冷量及其机理研究进展

落叶果树需冷量的准确估算是果树栽培尤其是果树促成栽培中的一个关键因素,直接关系到果树促成栽培的成败。综合有关文献,介绍了落叶果树需冷量的概念、估算方法、研究现状、生物学机制和存在问题。低温可以诱导休眠,休眠解除需要低温积累,从植物生理学和分子生物学角度阐述了落叶果树需冷量的机理。并对缩短落叶果树自然休眠期的可能途径从育种、施用外源化学药剂、环境调控3个方面进行了初步探讨。     

Changes in wildfire severity from maritime pine woodland to contiguous forest types in the mountains of northwestern Portugal

Large and severe wildfires are now widespread in the Mediterranean Basin. Fire severity is important to ecosystem properties and processes and to forest management but it has been neglected by wildland fire research in Europe. In this study, we compare fire severity between maritime pine (PS) woodland and other forest (OF) types, identify other variables influent on fire severity, and describe its variation. We sampled contiguous, paired stands of PS and OF cover types – including deciduous and evergreen broadleaves and short-needled mountain conifers – that burned under very high to extreme fire danger in northwestern Portugal. Data on stand characteristics and fire severity metrics were collected in plots along transects perpendicular to the PS–OF boundary. Fire severity was rated in separate for the tree canopy, understorey vegetation and forest floor layers, and then an average (composite) fire severity rating was calculated. Fire intensity inferred from stem char height (adjusted for the effects of other factors) was highest in PS, followed by deciduous broadleaved woodland and short-needled conifer forest. With a few exceptions, all fire severity ratings were significantly different between PS and OF at all sites. Most fire severity metrics and ratings were correlated. The distance for fire severity minimization did not differ between OF types (median = 21 m). Variation in composite fire severity was accounted for by a classification tree (R² = 0.44) based on cover type (contributing with 51% to the overall explanation), stand variables, aspect, distance to the PS–OF edge and fire spread pattern. Except for a more immediate decline in deciduous broadleaves, fire severity rating was not affected by OF type and tended to decrease in more mature stands and moister aspects. The fire severity moderation from PS to OF was compounded by a dominant pattern of down slope fire propagation into moister topographical positions, exacerbating the fuel effect implicit in the cover type change. The results are consistent with fire hazard and fire incidence studies and support conventional knowledge that advocates the expansion of broadleaved deciduous or evergreen forest as a means to achieve more fire-resilient ecosystems and landscapes.     

山地常绿落叶阔叶混交林更新方式对林地肥力的影响

为了解鄂西南山地常绿落叶阔叶混交林采伐迹地不同更新方式对林地土壤肥力的影响,采用典型样地法对木林子自然保护区山地常绿落叶阔叶混交林迹地3种更新方式林分的土壤进行了采样分析。结果表明:土壤容重表现出人工更新>人工促进天然更新>天然更新。土壤总孔隙度和毛管孔隙度差别不大,非毛管孔隙度人工更新林地较高。土壤自然含水量、最大持水量、毛管持水量、田间持水量等水分因子以及土壤有机质、全氮、水解氮、速效磷、速效钾和pH值等化学性质均表现出人工更新<人工促进天然更新<天然更新。3种更新方式土壤理化性质差异较大,林地土壤肥力表现出人工更新<人工促进天然更新<天然更新。     

Seasonal dynamics of foliar δ~(13)C and nutrient concentration of Chinese chastetree and spine jujube in foothill rock outcrop habitat of the southern Taihang Mountains,Central China

In this study, in situ investigation was conducted on Chinese chastetree(Vitex negundo var. heterophylla)and spine jujube(Ziziphus jujuba var. spinosa) during early, developed, and closing succession stages. Monthly data were recorded for foliar δ¹³C values and foliar N, P,and K concentrations from May to October. Foliar δ¹³C values declined with time and differences by succession stage varied by species. Older spine jujube displayed higher foliar N concentration while foliar P concentration was inversely related with N. Chinese chastetree had lower foliar K concentration than spine jujube. Foliar C/N ratio declined during the dry season and increased in the wet season. Foliar N/P ratio increased during the dry season and declined to its initial level until October, when it increased again. Foliar δ¹³C value was positively correlated with foliar N concentration. Foliar P and K concentrations were positively correlated to each other. In conclusion, the two shrubs had contrasting strategies of water use efficiency during their succession, but water use efficiency of both species was promoted by N availability and limited by P availability.     

杜鹃红山茶砧木嫁接苗成活率及生长特性研究

为筛选适合嫁接杜鹃红山茶的优良油茶砧木及最佳砧穗组合,同时研究各指标与嫁接亲和力的关系,以广西栽培面积广泛的普通油茶、高州油茶、广宁红花油茶、‘岑软2号’和‘岑软3号’5种油茶为砧木,以杜鹃红山茶为接穗开展芽苗砧嫁接试验。结果显示,嫁接成活率由高到低排序为高州油茶(83.33%)>‘岑软3号’(79.44%)>‘岑软2号’(70.00%)>普通油茶(63.33%)>广宁红花油茶(50.00%);各组合间穗砧直径比接近于1,同步生长性较好。对各指标综合进行隶属函数分析,嫁接苗生长指标由高到低排序为高州油茶>广宁红花油茶>‘岑软3号’>普通油茶>‘岑软2号’。相关性分析表明,不同砧木嫁接苗成活率与新梢生长量、根系生长量之间存在较强的相关性。综上,5种供试油茶与杜鹃红山茶均具有一定的亲和性,其中高州油茶与杜鹃红山茶砧穗亲和性最佳。     

杜鹃红山茶嫁接繁殖试验

杜鹃红山茶(Camellia azalea)属山茶科山茶属，只在阳春境内有零星分布。其花期长，花大色鲜，具有极高的科学研究价值和经济价值。作者对杜鹃红山茶进行了嫁接繁殖试验。结果表明，用油茶作砧木嫁接杜鹃红山茶，其嫁接成活率明显高于其他试验砧木；接穗以营养充足带顶芽的枝条效果好；10，11月嫁接成活率比较高。     

The bacterial community inhabiting temperate deciduous forests is vertically stratified and undergoes seasonal dynamics

Bacterial communities living in forest soils contribute to the decomposition of organic matter and the recycling of nutrients in these ecosystems and form one of the most diverse habitats on Earth. Unfortunately, due to difficulty in culturing soil bacteria, the understanding of their ecology is still limited. In the case of temperate deciduous forests, soil microbial communities face large seasonal variations in environmental conditions, such as temperature or moisture. Moreover, the supply of nutrients also differs due to seasonal processes, such as the allocation of photosynthates into soil by the roots of primary producers or the seasonal input of fresh litter. The aim of this study was to reveal how the bacterial community responds to these seasonal processes in the litter and soil of a Quercus petraea forest. Bacterial communities from litter and from the organic and mineral horizons of soil were analyzed during the four seasons of the year by 16S rRNA gene pyrosequencing. The results revealed that the composition of the bacterial community is horizon specific. The litter horizon had a higher relative abundance of Proteobacteria and Bacteroidetes than soil, while the organic and mineral horizons had a higher abundance of Acidobacteria, Firmicutes and Actinobacteria than litter. Moreover, the bacterial community was significantly affected by seasonality in all horizons. Bacterial communities in the litter showed significant differences between the vegetation season (May and July) and the autumn and winter seasons (October, February). In mineral soil, bacterial community composition was specific in the summer, when it was significantly different from all other seasons, with a larger number of taxa described as rhizosphere and mycorrhizosphere inhabitants. The results indicate that litter decomposition is the main driver of bacterial community composition in litter horizon. In contrast to reports on fungal communities, bacterial community composition in mineral soil responds to the seasonal peaks of rhizodeposition in the summer.     

杜鹃叶山茶Camellia azalea 与红山茶组10 个物种间的杂交亲和性研究

采用常规育种的方法,以杜鹃叶山茶Camellia azalea和山茶属红山茶组10个原生物种作为杂交育种亲本,设计20个杂交组合,研究其种间杂交亲和性。结果显示,杜鹃叶山茶与红山茶组原生种间反交时的杂交亲和性和育种效率要显著于正交组合。与杜鹃叶山茶进行杂交的亲和性,最好的是多齿红山茶C. polyodonta、南山茶C. semiserrata和浙江红山茶C. chekiangoleosa,其次是尖萼红山茶C. edithae、长毛红山茶C. villosa、滇山茶C. reticulata和全缘红山茶C. subintegra,较差的是厚叶红山茶C. crassissima和怒江红山茶C. saluenensis,最差的是毛蕊红山茶C. mairei。