Resistance-related physiological response of rice leaves to the compound stress of enhanced UV-B radiation and Magnaporthe oryzae

An enhanced UV-B radiation (5.0?kJ?m^?2) was supplied before, during, and after Magnaporthe oryzae infection. The effects of single and compound stress of the UV-B radiation and M. oryzae on the resistance physiology and gene expression of rice leaves were examined. Results revealed that UV-B radiation given before M. oryzae infection (UV-B?→?M.) significantly increased the pathogenesis-related proteins (PRs) activities of phenylalanine ammonialyase (PAL), lipoxygenase (LOX), chitinase (CHT), and β-1,3-glucanase, the resistance-related substances (flavonoids and total phenols) content, and resistance-related genes (OsPAL and OsCHT) expression, thereby improving the disease resistance of rice leaves. Simultaneous exposure to UV-B radiation and M. oryzae (UV-B/M.) significantly increased the OsLOX2 expression and the PRs activities. Exposure to UV-B radiation after M. oryzae infection (M.?→?UV-B) decreased the flavonoid content, did not improve the PRs activity, and increased OsLOX2 expression. Compound treatments of UV-B?→?M., UV-B/M., and M.?→?UV-B reduced the disease index by 62.3%, 40.2%, and 26.6%, respectively, indicating UV-B radiation inhibited the occurrence of M. oryzae disease, but its inhibitory effect weakened when it was provided after M. oryzae infection. Hence, rice responded to the compound stress of UV-B radiation and M. oryzae through a resistance-related physiological mechanism associated with the sequence of stress occurrence.     

Spatial variation in landscape‐level CO2 and CH4 fluxes from arctic coastal tundra: influence from vegetation,wetness, and the thaw lake cycle

Regional quantification of arctic CO₂ and CH₄ fluxes remains difficult due to high landscape heterogeneity coupled with a sparse measurement network. Most of the arctic coastal tundra near Barrow, Alaska is part of the thaw lake cycle, which includes current thaw lakes and a 5500‐year chronosequence of vegetated thaw lake basins. However, spatial variability in carbon fluxes from these features remains grossly understudied. Here, we present an analysis of whole‐ecosystem CO₂ and CH₄ fluxes from 20 thaw lake cycle features during the 2011 growing season. We found that the thaw lake cycle was largely responsible for spatial variation in CO₂ flux, mostly due to its control on gross primary productivity (GPP). Current lakes were significant CO₂ sources that varied little. Vegetated basins showed declining GPP and CO₂ sink with age (R² = 67% and 57%, respectively). CH₄ fluxes measured from a subset of 12 vegetated basins showed no relationship with age or CO₂ flux components. Instead, higher CH₄ fluxes were related to greater landscape wetness (R² = 57%) and thaw depth (additional R² = 28%). Spatial variation in CO₂ and CH₄ fluxes had good satellite remote sensing indicators, and we estimated the region to be a small CO₂ sink of ?4.9 ± 2.4 (SE) g C m^?2 between 11 June and 25 August, which was countered by a CH₄ source of 2.1 ± 0.2 (SE) g C m^?2. Results from our scaling exercise showed that developing or validating regional estimates based on single tower sites can result in significant bias, on average by a factor 4 for CO₂ flux and 30% for CH₄ flux. Although our results are specific to the Arctic Coastal Plain of Alaska, the degree of landscape‐scale variability, large‐scale controls on carbon exchange, and implications for regional estimation seen here likely have wide relevance to other arctic landscapes.     

Litter dynamics of evergreen deciduous broad-leaved mixed forests and its influential factors in Shennongjia,China

凋落物是陆地生态系统的重要组成部分, 凋落物动态特征可以反映出生态系统的存在状况以及环境对植被的影响作用。为探究北亚热带常绿落叶阔叶混交林凋落物产量及现存量的动态及其影响因素, 该研究观测了神农架地区一处典型植被2009-2015年的凋落物产量及现存量, 据此分析其动态特征及其与气象因素的关系。研究结果表明: 该森林凋落物平均年产量及现存量分别为5.94 t·hm ^-2和10.46 t·hm ^-2, 2009至2014年均无明显年际变化趋势, 但在2015年均显著降低, 且当年倒春寒天数显著高于其他年份; 季节动态变化呈现双峰型, 峰值分别出现在3-5月和10月; 凋落物月产量与当月的前第1-4个月的月平均气温正相关, 与当月的前第8-10个月的月平均气温负相关, 且与当月的前第6-7及第10个月的月平均相对湿度负相关; 凋落物产量季节性指数平均值为0.032, 与年平均气温显著正相关。可见, 长时间倒春寒现象会显著影响凋落物年产量及现存量, 月平均气温和相对湿度对凋落物产量季节动态的影响有明显的滞后性, 且年平均气温对北亚热带主要森林类型的凋落物产量季节性指数有显著影响。     

Cultivar and Rhizobium strain effect on nitrogen fixation and transport inPhaseolus vulgaris L.

The effects of Rhizobium strain and its interaction with plant cultivar were examined in glasshouse-grownPhaseolus vulgaris in two experiments where the physiological attributes defining the symbiotic efficiency were determined. Strains of Rhizobium significantly affected nodulation, rates of N accumulation, partitioning of N within the mature shoot and remobilizaton of the N stored in the vegetative organs to the seeds. The most efficient symbiosis (strain CO5 with Negro Argel), in comparison with the least efficient symbiosis (strain 127 K-17 with Venezuela-350) showed higher rates of C₂H₂ reduction from flowering to mid pod fill stage, evolved less hydrogen from nodules and showed higher rates of N transport as well as higher percentages of ureide-N in the xylem sap. At maturity, the best cultivar/strain association exceeded the total N accumulated in the seed and the harvest index of the poorest symbiosis in 88% and 20%, respectively. The other symbiotic combinations were intermediate in all characteristics. Nitrogen accumulation in plant shoot showed highly significant correlation with acetylene reduction rates, nodule relative efficiency, total N transport in the xylem sap and percentage of N transported as ureides.     

黄渤海甲壳类的分类多样性

为了解黄渤海甲壳类的分类多样性特征, 我们统计了2010-2015年中国水产科学研究院黄海水产研究所调查捕获的黄渤海甲壳类(软甲纲: 十足目与口足目)物种名录。结合历史文献, 进一步系统整理得到黄渤海甲壳类物种总名录。基于这2个名录, 应用分类阶元包含指数(the inclusion index at taxonomic level, TINCL_i)、平均分类差异指数(average taxonomic distinctness index, Δ⁺)和分类差异变异指数(variation in taxonomic distinctness index, Λ⁺)研究了其分类多样性特征。结果显示: 2010-2015年调查名录中, 甲壳类共93种, 隶属于2目39科66属, 其中10种为新分布种; 对虾科、藻虾科、长臂虾科、梭子蟹科和弓蟹科的物种数最多, 合计占总物种数的38.71%; TINCL_i分别为1.41种/属和2.38种/科; Δ⁺和Λ⁺分别为50.25和35.20。总名录中, 甲壳类共228种, 隶属于2目53科123属, 其中藻虾科、豆蟹科、对虾科、弓蟹科和鼓虾科的物种数最多, 合计占总物种数的30.70%; TINCL_i分别为1.85种/属和4.30种/科, Δ⁺和Λ⁺分别为50.18和30.87。对虾科的相对丰富度指数(the relative richness index, R_r)最高(100), 其次是梭子蟹科(71.43)和长臂虾科(62.50), 豆蟹科最低(6.25)。黄渤海甲壳类的平均分类差异指数(Δ⁺)明显小于鱼类(P < 0.05)。2010-2015年调查的Δ⁺计算值高于理论值, 且在理论值的95%置信区间内, 说明黄渤海甲壳类群落正处在中等程度的干扰中。     

Environmental,geographical and time-related impacts on avian malaria infections in native and introduced populations of house sparrows (Passer domesticus), a globally invasive species

Aim

The increasing spread of vector-borne diseases has resulted in severe health concerns for humans, domestic animals and wildlife, with changes in land use and the introduction of invasive species being among the main possible causes for this increase. We explored several ecological drivers potentially affecting the local prevalence and richness of avian malaria parasite lineages in native and introduced house sparrows (Passer domesticus) populations.

Location

Global.

Time period

2002–2019.

Major taxa studied

Avian Plasmodium parasites in house sparrows.

Methods

We analysed data from 2,220 samples from 69 localities across all continents, except Antarctica. The influence of environment (urbanization index and human density), geography (altitude, latitude, hemisphere) and time (bird breeding season and years since introduction) were analysed using generalized additive mixed models (GAMMs) and random forests.

Results

Overall, 670 sparrows (30.2%) were infected with 22 Plasmodium lineages. In native populations, parasite prevalence was positively related to urbanization index, with the highest prevalence values in areas with intermediate urbanization levels. Likewise, in introduced populations, prevalence was positively associated with urbanization index; however, higher infection occurred in areas with either extreme high or low levels of urbanization. In introduced populations, the number of parasite lineages increased with altitude and with the years elapsed since the establishment of sparrows in a new locality. Here, after a decline in the number of parasite lineages in the first 30 years, an increase from 40 years onwards was detected.

Main conclusions

Urbanization was related to parasite prevalence in both native and introduced bird populations. In invaded areas, altitude and time since bird introduction were related to the number of Plasmodium lineages found to be infecting sparrows.     

基于地形梯度的岩溶槽谷区土地利用空间格局分析

揭示当前多因素驱动机制下岩溶槽谷区典型地貌单元在地形梯度上土地利用分布的一般规律与差异性特征具有重要意义。以2017年landsat TM高清影像和30 m×30 m DEM（Digital Elevation Model）为数据源,并结合实地调查,通过地形位分布指数、土地利用多样性指数、土地利用程度指数及土地利用相对合理性指数指标计算,探讨岩溶槽谷区地形梯度的土地利用类型空间分布共同特征与差异。结果表明：（1）岩溶槽谷区土地利用类型呈现山坡（高地形位）-槽坝（低地形位）两种分布格局特色存在,且土地利用类型在地形梯度上主要以低、中、高3种地形位组合模式;（2）土地利用类型在地形梯度上呈现梯度效应,表现出各自分布特征与差异;（3）岩溶槽谷区土地利用多样性、土地利用程度和土地利用合理性在地形梯度上分布格局既存在一些共同性特征,又存在各自差异性;（4）地形梯度土地利用特征差异性是受自然因素、社会经济因素、政策因素共同作用的结果。     

Impact of Land-Use Patterns on Chemical Properties of Trace Elements in Soils of Rural,Semi-Urban,and Urban Zones of the Niger Delta,Nigeria

The study of the concentrations of Cr, Zn, Cd, Pb, Ni, and Cu in soils under different land uses in rural, semi-urban, and urban zones in the Niger Delta was carried out with a view to providing information on the effects of the different land uses on the concentrations of trace elements in soils. Our results indicate significant variability in concentrations of these metals in soils under different land uses in rural, semi-urban, and urban zones. The maximum concentrations of metals in the examined soil samples were 707.5 mg.kg^?1, 161.0 mg.kg^?1, 2.6 mg.kg^?1, 59.6 mg.kg^?1, 1061.3 mg.kg^?1, and 189.2 mg.kg^?1 for Cr, Zn, Cd, Pb, Ni, and Cu, respectively. In the rural zone, the cassava processing mill is a potent source of Ni, Cr, Cu, and Zn while agricultural activities are a source of Cd, and automobile emissions and the use of lead oxide batteries constitute the major sources of Pb. In the urban zone, soils around the wood processing mill showed elevated concentrations of Cu, Cr, Zn, and Ni, while soils around automobile mechanic works and motor parks showed elevated levels of Pb. Elevated Cd concentrations were observed in soils under the following land uses: urban motor park, playground, welding and fabrication sheds, and metallic scrap dump. The contamination/pollution index of metals in the soil follows the order: Ni > Cd > Cr > Zn > Cu > Pb. The multiple pollution index of metals at different sites were greater than 1, indicating that these soils fit into “slight pollution” to “excessive pollution” ranges with significant contributions from Cr, Zn, Cd, Ni, and Cu.     

基于生理指标与籽粒产量关系的小麦品种抗冻性分析

以20个冬小麦品种为材料进行盆栽试验,对其在低温胁迫条件下功能叶超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性,丙二醛（MDA）、可溶性蛋白、可溶性糖含量以及籽粒产量、千粒重和籽粒形态性状进行测定.结果表明：拔节初期麦苗经-4 ℃低温胁迫后,不同品种冬小麦籽粒形态性状和产量性状均发生变化,绝大多数小麦品种籽粒长宽比、圆度和不育小穗数均增加,籽粒等效直径和面积及千粒重和籽粒产量均下降.通径分析表明,拔节初期低温处理后,功能叶SOD活性和可溶性糖含量是影响籽粒产量的主导因素,其中SOD活性对籽粒产量的直接影响较大,直接通径系数为-0.578.以籽粒产量下降的百分数作为小麦抗冻性评价的标准,可将20个小麦品种划分为3类：强抗冻类型的济麦19、济麦20、良星99、山农1135、山农8355、泰山23、泰山9818、汶农6号和烟农21,弱抗冻类型的临麦2号、潍麦8号、烟农19和淄麦12号,而其余7个品种属中度抗冻类型.苗期综合评价值（D值）与籽粒产量下降的百分数之间呈显著负相关(r=-0.512*),说明小麦苗期抗冻性强有利于获得较高的籽粒产量.苗期是小麦抗冻性鉴别选择的重要时期.