三角梅苞叶色彩参数和色素含量分析及蓝色转基因受体的筛选北大核心CSCD

三角梅作为重要的观赏植物颜色繁多,但缺乏稀有的蓝色。为筛选适合的蓝色转基因受体,明确不同品种三角梅苞片吸收利用DHM(二氢杨梅素)合成甜菜色素途径竞争产物(类黄酮色素)的潜在能力,该研究对红色、白色、黄色和紫色4大花色6个品种的三角梅苞片进行离体诱导培养,测定诱导培养后苞片色彩参数及色素含量变化,并进行相关性分析。结果显示:(1)三角梅苞片红绿色相值(a*)是决定苞片呈色的主要色彩参数,其色彩主要由甜菜色素和黄酮类色素决定,并以甜菜红素的影响最大。(2)除白色品种三角梅苞片中黄酮类色素含量大于甜菜色素含量外,其余品种苞片发育中甜菜色素含量均呈上升趋势,黄酮类色素呈下降趋势。(3)甜菜色苷含量与苞片a*值呈显著正相关关系,同时与苞片黄蓝色相值(b*)呈显著负相关关系;总黄酮含量与苞片b*值呈显著正相关关系,与苞片a*值呈极显著负相关关系。(4)经DHM体外诱导培养后,苞片总黄酮含量及占比在4个品种三角梅(‘新加坡大白’、‘宝老橙’、‘中国丽人’、‘黄蝶’)中明显升高,但各品种苞片总甜菜色素含量及占比均下降,并以‘新加坡大白’苞片中总黄酮含量上升幅度最大(65.77%),含量占比变化(增加26.91%)也为6个品种中最大。(5)灰色关联度综合分析显示,白色品种‘新加坡大白’与灰色关联度分析拟定的参考品种关联度最高(0.7444),表明三角梅品种中‘新加坡大白’可考虑作为蓝色转基因三角梅的受体品种。     

DNA methylation as a possible mechanism affecting ability of natural populations to adapt to changing climate

Environmentally induced epigenetic variation has been recently recognized as a possible mechanism allowing plants to rapidly adapt to novel conditions. Despite increasing evidence on the topic, little is known on how epigenetic variation affects responses of natural populations to changing climate. We studied the effects of experimental demethylation (DNA methylation is an important mediator of heritable control of gene expression) on performance of a clonal grass, Festuca rubra, coming from localities with contrasting temperature and moisture regimes. We compared performance of demethylated and control plants from different populations under two contrasting climatic scenarios and explored whether the response to demethylation depended on genetic relatedness of the plants. Demethylation significantly affected plant performance. Its effects interacted with population of origin and partly with conditions of cultivation. The effects of demethylation also varied between distinct genotypes with more closely related genotypes showing more similar response to demethylation. For belowground biomass, demethylated plants showed signs of adaptation to drought that were not apparent in plants that were naturally methylated. The results suggest that DNA methylation may modify the response of this species to moisture. DNA methylation may thus affect the ability of clonal plants to adapt to novel climatic conditions. Whether this variation in DNA methylation may also occur under natural conditions, however, remains to be explored. Despite the significant interactions between population of origin and demethylation, our data do not provide clear evidence that DNA methylation enabled adaptation to different environments. In fact, we obtained stronger evidence of local adaptation in demethylated than in naturally‐methylated plants. As changes in DNA methylation may be quite dynamic, it is thus possible that epigenetic variation can mask plant adaptations to conditions of their origin due to pre‐cultivation of the plants under standardized conditions. This possibility should be considered in future experiments exploring plant adaptations.     

Using unmanned aerial vehicle‐based multispectral,RGB and thermal imagery for phenotyping of forest genetic trials: A case study in Pinus halepensis

The assessment of genetic differentiation in functional traits is fundamental towards understanding the adaptive characteristics of forest species. While traditional phenotyping techniques are costly and time‐consuming, remote sensing data derived from cameras mounted on unmanned aerial vehicles (UAVs) provide potentially valid high‐throughput information for assessing morphophysiological differences among tree populations. In this work, we test for genetic variation in vegetation indices (VIs) and canopy temperature among populations of Pinus halepensis as proxies for canopy architecture, leaf area, photosynthetic pigments, photosynthetic efficiency and water use. The interpopulation associations between vegetation properties and above‐ground growth (stem volume) were also assessed. Three flights (July 2016, November 2016 and May 2017) were performed in a genetic trial consisting of 56 populations covering a large part of the species range. Multispectral (visible and near infrared wavelengths), RGB (red, green, blue) and thermal images were used to estimate canopy temperature and vegetation cover (VC) and derive several VIs. Differences among populations emerged consistently across flights for VC and VIs related to leaf area, indicating genetic divergence in crown architecture. Population differences in indices related to photosynthetic pigments emerged only in May 2017 and were probably related to a contrasting phenology of needle development. Conversely, the low population differentiation for the same indices in July 2016 and November 2016 suggested weak interpopulation variation in the photosynthetic machinery of mature needles of P. halepensis. Population differences in canopy temperature found in July 2016 were indicative of variation in stomatal regulation under drought stress. Stem volume correlated with indices related to leaf area (positively) and with canopy temperature (negatively), indicating a strong influence of canopy properties and stomatal conductance on above‐ground growth at the population level. Specifically, a combination of VIs and canopy temperature accounted for about 60% of population variability in stem volume of adult trees. This is the first study to propose UAV remote sensing as an effective tool for screening genetic variation in morphophysiological traits of adult forest trees.     

Dynamic investigation and modeling of the nitrogen cometabolism in Methylococcus capsulatus ( Bath)

The methanotrophic bacterium Methylococcus capsulatus is capable of assimilating methane and oxygen into protein-rich biomass, however, the diverse metabolism of the microorganism also allows for several undesired cometabolic side-reactions to occur. In this study, the ammonia cometabolism in Methylococcus capsulatus is investigated using pulse experiments. Surprisingly Methylococcus capsulatus oxidizes ammonia to nitrate through a yet unknown mechanism and fixes molecular nitrogen even at a high dissolved oxygen tension. The observed phenomena can be modeled using 14 ordinary differential equations and 18 kinetic parameters, of which 6 were revealed by Morris screening to be identifiable from the experimental data. Monte Carlo simulations showed that the model was robust and accurate even with uncertainty in the parameter values as confirmed by statistical error analysis.     

Fatty acids differentiate consumers despite variation within prey fatty acid profiles

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The sentineling—Foraging trade‐off in dominant and subordinate Arabian babblers

Many cooperative breeders forage under predation risks, sentineling is a central activity, and groupmates have to balance between sentineling and foraging. The optimal balance between sentinel activity and foraging may differ among dominant and subordinate individuals, as dominants are more efficient foragers. Two theoretical models pertain to this balance and predict when individuals with different foraging abilities should switch between the two activities on the basis of their energetic state. In one of these models, individuals must attain a critical energetic level by dusk to pass the night, and in the second model fitness is monotonically increasing with the energetic state. We tested these models in the cooperatively breeding Arabian babbler, Turdoides squamiceps. We measured the length of sentinel bouts and the gaps between them both in natural conditions and following experimental feeding. Following feeding ad libitum, subordinates expanded their sentinel bouts significantly more than dominants in comparison with natural conditions. These findings are consistent with the first model, but not with the second. In the experiment, we measured the mass of mealworms consumed by each individual following a sentinel bout relative to its body mass. This ratio was larger for subordinates, indicating that they ended their sentinel bouts at a lower energetic state than dominants. This finding is consistent with the second model, but not with the first. Immediately after eating ad libitum, in 62% of the cases the first behavior performed by the babblers was a new sentinel bout, but in 17% it was a mutual interaction with a groupmate, indicating that social interactions also play a role in the trade‐off vis‐à‐vis sentinel activity.     

Impact of increased predation risk on vigilance behaviour in a gregarious waterfowl,the Egyptian goose Alopochen aegyptiaca

Vigilance is amongst the most universal of anti‐predator strategies and commonly declines with increasing group size. We experimentally manipulated predation risk in a system with a known relationship between group size and vigilance levels to explore whether this relationship changes in response to elevated predation risk. We investigated the vigilance levels of Egyptian geese Alopochen aegyptiaca at eight golf courses in the western Cape, South Africa, to assess the perception of and reaction to predation risk. We manipulated predation risk by introducing trained Harris's hawks Parabuteo unicintus where avian predation was otherwise low or absent. The study confirmed the typical reduction in vigilance with group size on control sites, where the risk of predation is low. However, at experimental sites with elevated predation risk, a positive relationship between vigilance and group size was observed. We hypothesize that the mechanism for this relationship might be linked to social information transfer via copying behaviour and manipulation to induce vigilance. Thus, larger groups will have a higher probability of containing individuals with experience of elevated predation risk and their increased vigilance behaviour is copied by naïve individuals. This prediction is based on the intended outcome of introducing avian predation to make the geese feel less safe and to eventually leave the site as a management tool for controlling nuisance geese.     

管氏肿腿蜂对锈色粒肩天牛的防治试验

利用管氏肿腿蜂进行了防治锈色粒肩天牛幼虫的试验,结果表明:锈色粒肩天牛幼虫的寄生死亡率可达40%~70%,而且幼虫的寄生死亡率随着放蜂量的增加而提高,按虫蜂比1∶1、1∶5和1∶10分别放蜂,寄生死亡率依次为35.4%、48.3%和68.9%;最佳放蜂时间为8月中旬,此时放蜂的校正寄生率为55.67%,明显地高于7月份和9月份。     

Tree identity and diversity directly affect soil moisture and temperature but not soil carbon ten years after planting

1. Soil C is the largest C pool in forest ecosystems that contributes to C sequestration and mitigates climate change. Tree diversity enhances forest productivity, so diversifying the tree species composition, notably in managed forests, could increase the quantity of organic matter being transferred to soils and alter other soil properties relevant to the C cycle.
2. A ten‐year‐old tree diversity experiment was used to study the effects of tree identity and diversity (functional and taxonomic) on soils. Surface (0–10 cm) mineral soil was repeatedly measured for soil C concentration, C:N ratio, pH, moisture, and temperature in twenty‐four tree species mixtures and twelve corresponding monocultures (replicated in four blocks).
3. Soil pH, moisture, and temperature responded to tree diversity and identity. Greater productivity in above‐ and below‐ground tree components did not increase soil C concentration. Soil pH increased and soil moisture decreased with functional diversity, more specifically, when species had different growth strategies and shade tolerances. Functional identity affected soil moisture and temperature, such that tree communities with more slow‐growing and shade‐tolerant species had greater soil moisture and temperature. Higher temperature was measured in communities with broadleaf‐deciduous species compared to communities with coniferous‐evergreen species.
4. We conclude that long‐term soil C cycling in forest plantations will likely respond to changes in soil pH, moisture, and temperature that is mediated by tree species composition, since tree species affect these soil properties through their litter quality, water uptake, and physical control of soil microclimates.