Meloidogyne hispanica n. sp. (Nematoda: Meloidogynidae), the 'Seville Root-Knot Nematode'

Meloidogyne hispanica n. sp. is described and illustrated from specimens obtained from peach rootstock, Prunus persica silvestris Batsch, from the Seville district of Spain. The perineal pattern of the female is oval shaped to rectangular with low dorsal arch and often widely spaced lateral lines with fringe-like striae. The stylet, 14.1 μm long, has broad, distinctly set off knobs. Males have a high, rounded head cap that slopes posteriorly. Labial disc and medial lips are fused to form elongate lip structures. The robust styler, 23.5 μm long, has large, rounded knobs that are slightly set off from the shaft. Mean second-stage juveniles length is 392.6 μm. The truncate head region is generally not annulated. The distinctly rounded and raised labial disc and the crescent-shaped medial lips form dumbbell-shaped lip structures. The stylet, 11.1 μm long, has rounded, posteriorly sloping knobs. The slender tail, 46.4 μm long, has large irregular-sized annules in the posterior region and ends in a bluntly rounded tip. Tomato was a good host; tobacco, pepper, and watermelon were poor hosts; cotton and peanut were nonhosts. Meloidogyne hispanica n. sp. reproduces by mitotic parthenogenesis and has a somatic chromosome number of 2n = 33-36. The esterase pattern is unique among Meloidogyne species.     

京津水源区小流域土壤侵蚀空间模拟

针对京津水源区生态环境脆弱、水土流失空间分异大、突发性强等问题,以河北省平泉县东北沟典型小流域为例,采用GIS技术与CSLE模型对其土壤侵蚀进行二维空间模拟及侵蚀规律研究,并对模型模拟精度进行验证.结果表明:模型确定性系数>0.85,模拟结果可信度高;小流域侵蚀模数为2359.24t·km-2·a-1,属于轻度侵蚀,侵蚀主要源于15°以上坡面,占侵蚀总量的92.1%;土壤侵蚀模数随坡度先逐渐增加,当坡度>45°时,土壤侵蚀模数有减小的趋势;土壤侵蚀模数空间异质性显著,坡耕地侵蚀模数最大,为6112.90tkm-2·a-1;荒草地占总面积33.2%,侵蚀量却达总量的74.9% ;59.3%的侵蚀来自阳坡和半阳坡,而阴坡半阴坡仅占流域侵蚀量的16.2%.研究为利用CSLE模型对小流域土壤侵蚀进行空间模拟提供技术范例,为京津水源区土壤侵蚀规律研究及水土保持生态建设提供科学参考.     

Über zwei diploide,in Südwest-Anatolien endemische Arten aus dem Komplex derVeronica cymbalaria (Scrophulariaceae)

Veronica lycica Lehm. is a distinct, diploid member of theVeronica cymbalaria group, endemic in Lycia (S.W. Anatolia). Closely related is the newV. stamatiadae M. Fischer etW. Greuter which is also diploid and seems to be restricted to the small Greek island Ro close to the South coast of Lycia. The chromosome numbers for both species are reported for the first time (2n = 18).

Untersuchungen über den PolyploidkomplexVeronica cymbalaria agg., II. — Der erste Beitrag dieser Serie:Fischer (1975).     

Development and characterization of novel microsatellite markers in the Asiatic lion (Panthera leo persica)

All cat species, except domestic cats, are either threatened or endangered. The Asiatic lion (Panthera leo persica), a critically endangered species, is driven to a single habitat zone in Gir forests in India for its survival. The present status of this big cat compels us to acquire deeper knowledge of its genetic variability and phylogenetic relationships. Here we report the isolation of highly polymorphic microsatellite loci from a partial genomic library of the Asiatic lion. These loci were characterized and have shown high levels of variation ranging from six to 11 alleles per locus in the population studied.     

Paraphyly of Veronica (Veroniceae; Scrophulariaceae): Evidence from the Internal Transcribed Spacer (ITS) Sequences of Nuclear Ribosomal DNA

Veronica (Veroniceae; Scrophulariaceae) and segregated genera, such as Hebe from New Zealand has been debated intensively in the past. We conducted an analysis of sequence data from the internal transcribed spacer region of nuclear ribosomal DNA (ITS) to evaluate the validity of segregate genera and the monophyly of Veronica. According to the results presented here, Veronica is paraphyletic, with the Hebe complex, Synthyris, and Paederota nested within the larger Veronica clade. Pseudolysimachion is in a basal polytomy of the expanded Veronica clade in the strict consensus tree and might be nested within Veronica as well. Clades within Veronica do not correspond to sections traditionally recognized. This study provides a first estimation of the phylogeny of Veroniceae using molecular data and can serve as a starting point for future investigations of Veronica and relatives. Received 24 July 2000/ Accepted in revised form 19 October 2000     

弱光对三年生油桃源叶韧皮组织超微结构的影响

以日光温室内栽培的三年生油桃"早红艳"(Prunus persica L. var. nectarine Ait "Zao Hong Yan")为试材,利用透射电子显微镜(TEM)技术首次对处于正常光照条件和弱光条件下的源叶的韧皮组织进行了超微结构观察,重点研究了叶片超微结构对弱光的响应.结果表明:在正常光照条件下,油桃源叶各级叶脉的筛管和伴胞的平均直径均比弱光条件下的大,表明光能影响细胞的发育,而弱光抑制了细胞的生长.在正常光照下的伴胞具有致密的细胞质,内含丰富的线粒体、内质网、多泡体、囊泡和质体,而弱光下的伴胞明显液泡化,同时含有少量的线粒体和内质网.在弱光条件下也观察到叶绿体基粒片层边缘紊乱,筛孔处于阻塞状态.在弱光下,邻近维管束鞘细胞的叶肉细胞内积累了大量的淀粉粒和少量的线粒体.淀粉粒的积累可能是由于光合同化产物的生产与输出之间的不平衡,这一观察结果有力地支持了大部分叶片是在光照条件下输出其大部分同化产物的观点.在筛管/伴胞、伴胞/韧皮薄壁细胞、韧皮薄壁细胞/韧皮薄壁细胞和韧皮薄壁细胞/维管束鞘细胞之间的胞间连丝密度都在弱光条件下下降,在正常光照强度下支脉筛管/伴胞和韧皮薄壁细胞/维管束鞘细胞之间可以观察到胞间连丝,而在弱光下几乎观察不到胞间连丝的存在,所以同化物的运输在弱光条件下可能以质外体运输为主,而在正常光照强度下,共质体运输可能是主要的运输方式.这些研究结果证明,日光温室内油桃通过源叶韧皮组织超微结构的变化对弱光做出适应性响应.     

基于流式细胞术和K-mer分析的银缕梅属(Parrotia C.A.Mey.)植物基因组大小测定

金缕梅科(Hamamelidaceae)银缕梅属(Parrotia C.A.Mey.)仅包含银缕梅(Parrotia subaequalis(H.T.Chang)R.M.Hao&H.T.Wei)和波斯铁木(Parrotia persica(DC.)C.A.Mey.)两种落叶阔叶乔木,其中银缕梅是我国华东地区特有的Ⅰ级濒危珍稀保护植物,属东亚第三纪孑遗成分;其姊妹种波斯铁木则间断分布于伊朗北部,属北极第三纪孑遗植物类群。本研究首次利用流式细胞术和K-mer分析方法对银缕梅属两姊妹种的基因组大小进行了测定,建立和优化了以萝卜(Raphanus sativus L.‘Saxa’)为内标、WPB(Woody plant buffer)为细胞核解离液的两种植物单倍体基因组的DNA含量(DNA C值)流式测定的适宜体系,旨在为金缕梅科银缕梅属植物的全基因组测序、基因组学研究、种质资源开发和利用以及物种保育等提供前期基础数据参考;同时也可为金缕梅科其他属、种的基因组大小测定提供借鉴。主要研究结果如下:(1)通过流式测定银缕梅基因组大小约为971.45±13.91 Mb,波斯铁木基因组大小约为890.52±24.69 Mb;(2)K-mer分析估测银缕梅基因组大小为951.70 Mb,杂合率为1.740%,重复序列比例为77.50%;波斯铁木基因组大小为858.50 Mb,杂合率为0.695%,重复序列占74.30%;(3)银缕梅属于高杂合和高重复基因组,波斯铁木则属于微杂合和高重复基因组。本研究的结果为银缕梅属植物后续基于DNA三代高通量测序技术的全基因组测序、组装及去冗余处理等工作提供了重要的数据参考。     

The devil is in the detail: Nonadditive and context‐dependent plant population responses to increasing temperature and precipitation

In climate change ecology, simplistic research approaches may yield unrealistically simplistic answers to often more complicated problems. In particular, the complexity of vegetation responses to global climate change begs a better understanding of the impacts of concomitant changes in several climatic drivers, how these impacts vary across different climatic contexts, and of the demographic processes underlying population changes. Using a replicated, factorial, whole‐community transplant experiment, we investigated regional variation in demographic responses of plant populations to increased temperature and/or precipitation. Across four perennial forb species and 12 sites, we found strong responses to both temperature and precipitation change. Changes in population growth rates were mainly due to changes in survival and clonality. In three of the four study species, the combined increase in temperature and precipitation reflected nonadditive, antagonistic interactions of the single climatic changes for population growth rate and survival, while the interactions were additive and synergistic for clonality. This disparity affects the persistence of genotypes, but also suggests that the mechanisms behind the responses of the vital rates differ. In addition, survival effects varied systematically with climatic context, with wetter and warmer + wetter transplants showing less positive or more negative responses at warmer sites. The detailed demographic approach yields important mechanistic insights into how concomitant changes in temperature and precipitation affect plants, which makes our results generalizable beyond the four study species. Our comprehensive study design illustrates the power of replicated field experiments in disentangling the complex relationships and patterns that govern climate change impacts across real‐world species and landscapes.