彭凤; 路承凯; 梁岗
|铁（Fe）是植物生长发育所必需的营养元素而镉（Cd）是对植物有害的元素，且植 物对 Fe 和 Cd 的吸收存在拮抗作用。OsIMA 是一类正调控水稻 Fe 吸收的一类小肽，其过表 达可以促进 Fe 的积累。为探究 OsIMA 是否参与水稻对 Cd 胁迫的适应性，该研究以水稻为 研究材料，利用荧光定量PCR 分析了OsIMA 基因的表达水平，通过遗传转化和CRISPR/Cas9 基因编辑技术构建了 OsIMA1 过表达植物和 ima1 突变体植物，评估了 OsIMA1 过表达和突 变体植物在 Cd 逆境条件下的株高，并用利用电联耦合等离子体质谱法测量了根和地上部的 Fe 和 Cd 含量。结果表明：（1）Cd 处理后，OsIMA1 和 OsIMA2 的转录水平上调。（2）OsIMA1 过表达植物比野生型植物对 Cd 胁迫更耐受。（3）ima1 功能缺失突变体比野生型植物对 Cd 胁迫更敏感。（4）Cd 含量检测发现，OsIMA1 过表达植株根系的 Cd 含量较高，而 ima1 突 变体植株地上部的 Cd 含量较高。综上所述，OsIMA1 通过限制 Cd 从根向地上部的转运以 增强水稻对 Cd 逆境的适应能力，该研究为定向培育耐 Cd 作物提供了理论依据。|
董燕平; 王斌; 韦玉莲; 何凤; 陆芳; 李冬兴; 黄甫昭; 郭屹立; 向悟生; 李先琨
|为研究喀斯特季节性雨林优势树种对异质性生境条件的适应策略，以广西弄岗原生性 森林7 个优势树种为对象，测定各树种成年个体叶片微形态指标及生长季光合生理特征，探 讨树种叶片结构功能对喀斯特峰丛山地异质性生境的响应规律。结果表明：（1）沿喀斯特 地貌部位的洼地-中坡-山顶生境梯度，树木的叶片紧密度、栅栏组织厚度、角质层厚度、上 表皮厚度等9 个微形态指标呈现显著上升趋势，叶片疏松度呈现显著下降趋势；（2）沿洼 地-中坡-山顶生境梯度，树木的光补偿点、暗呼吸效率、最大蒸腾速率等呈现显著上升趋势； 而最大水分利用效率、最大胞间CO2 浓度、表观量子效率等呈现显著下降趋势；（3）叶片 紧密度与光合能力、蒸腾能力等相关指标表现为显著正相关；叶片疏松度与这两类指标表现 为显著负相关。综上所述，喀斯特季节性雨林优势树种叶片功能性状存在光合效率和耐旱性 之间的权衡，洼地生长的树木具有显著的弱光适应特征，中坡生长的树木表现较广的生境适 应范围，山顶分布的树种受强光、高温和裸岩限制，表现出较强的干旱适应特征以及保守的 生态适应策略。|
张华敏; 张新岭; 尹守恒; 王利亚; 李冰冰
|葱属植物是被子植物最大的属之一，包括大蒜、洋葱、大葱、韭菜等多种具有独特辛 辣风味的蔬菜作物。S-烷(烯)基半胱氨酸亚砜是葱属植物特有的次生代谢产物，是葱属植物 各种挥发性含硫化合物的前体物质，赋予葱属植物独特的辛辣风味和药用价值。因此，研究 葱属植物 S-烷(烯)基半胱氨酸亚砜的代谢途径具有重要意义。在葱属植物中已发现了 7 种 S- 烷(烯)基半胱氨酸亚砜，这些 S-烷(烯)基半胱氨酸亚砜主要在叶片中经谷胱甘肽途径合成， 然后转运到鳞茎等贮藏器官的细胞质中积累。目前，关于葱属植物 S-烷(烯)基半胱氨酸亚砜 降解的研究较多，而 S-烷(烯)基半胱氨酸亚砜生物合成的研究较少。S-烷(烯)基半胱氨酸亚 砜是植物硫代谢的下游产物，上游还涉及含硫化合物的吸收、转运、半胱氨酸和谷胱甘肽的 代谢等过程，这些代谢过程的变化也可能影响 S-烷(烯)基半胱氨酸亚砜生物合成。今后应加 强两方面的研究，一是继续克隆鉴定 S-烷(烯)基半胱氨酸亚砜生物合成途径中的关键酶基因 并研究其功能；二是加强葱属植物硫代谢的研究，为研究 S-烷(烯)基半胱氨酸亚砜生物合成 的调控奠定基础。这些研究将为深入解析葱属植物 S-烷(烯)基半胱氨酸亚砜的代谢途径和利 用分子育种技术调控葱属植物的风味提供参考。|
宋述灵; 易伶俐; 张李龙; 陈琳; 余泽平; 宋庆妮; 栾丰刚; 方熊; 刘骏
|木质藤本是森林物种多样性维持的组成部分，然而近年来热带、亚热带森林，尤其是 次生林内木质藤本数量的过度增加给森林的恢复和健康发展造成威胁，这一现象却未得到太 多关注。至今国内尚未有研究对森林木质藤本过多的现象、增加机制与生态效应进行综合认 识。该文梳理国内外相关文献，从木质藤本数量增加的机制与生态效应进行分析和总结，以 期为森林管理和恢复等方面的宏观决策提供科学依据。综合相关研究认为：（1）木质藤本数 量的增加与气象干旱、大气 CO2 浓度上升、自然干扰和森林破碎化有关。在环境变化的情 况下，木质藤本在形态、行为、生理等方面比树木更具优势，表现为更快的生长速率、更强 的繁殖力、可塑性和高效的资源获取力。（2）木质藤本主要是通过遮荫胁迫、资源竞争和机 械压力与损伤等方式对树木造成影响。（3）木质藤本过度增加在个体水平上会阻碍树木生长、 生殖并引起树木死亡，在群落水平上会改变物种组成、降低多样性，在生态系统水平上会降 低森林碳储量、改变碳、矿质养分和水分循环过程等。综合以上研究建议结合野外长期监测 与控制实验开展木质藤本种群动态变化与环境变化关系、森林干扰对木质藤本生长的影响、 木质藤本对环境变化的响应及适应机理、木质藤本数量过度增加的生态效应评价研究。同时， 应积极探索合理的森林木质藤本管控方法。|
贾凯; 刘俊; 耿晓桐; 张耀洲; 肖颖
|为确定细叶十大功劳叶中总生物碱大孔树脂分离纯化的最佳工艺条件及抗氧化活性，通 过比较6 种大孔吸附树脂对总生物碱的静态吸附和解吸附效果，优选出最佳树脂并考察其动态 纯化总生物碱的工艺条件，采用DPPH 法对纯化前后的总生物碱抗氧化性能进行评价。结果表 明：（1）AB-8 型大孔吸附树脂纯化效果最好，其最佳工艺条件为上样浓度50 mg·mL-1（生药 浓度）、上样量26 BV、上样液流速2 BV·h-1；吸附完成后，先以3 BV 水洗，再以4 BV 50% 乙醇洗脱，在此条件下得到的总生物碱含量由13.33%提高到56.64%。（2）各样品对DPPH 自由基的清除能力为对照品Vc（IC50=10.39 μg·mL-1）＞总生物碱纯化品（IC50=39.08 μg·mL-1） ＞总生物碱粗品（IC50=55.28 μg·mL-1）。AB-8 型大孔吸附树脂可有效富集细叶十大功劳叶中 总生物碱有效部位，细叶十大功劳叶中总生物碱具有一定的抗氧化活性。|
WANG Ziyi; LIU Xiaohong; WANG Keyi; ZENG Xiaomin; ZHANG Yu; GE Wensen; KANG Huhu; LU Qiangqiang
Abstract: A knowledge of the tree-ring stable nitrogen isotope ratio (δ15N) can deepen our understanding of forest ecosystem dynamics by indicating the long-term availability, cycling and sources of nitrogen (N). However, the radial mobility of N blurs the interannual variations in the long-term N records. Previous studies of the chemical extraction of tree rings before analysis had produced inconsistent results and it is still unclear whether it is necessary to pre-treat wood samples from specific tree species to remove soluble N compounds before determining the δ15N values. We compared the effects of pre-treatment with organic solvents and hot ultrapure water on the N concentration and δ15N of tree rings from endemic Qinghai spruce (Picea crassifolia) growing in the interior of the central Qilian Mountains, China, during the last 60 a. We assessed the effects of different preparation protocols on the removal of the labile N compounds and investigated the need to pre-treat wood samples before determining the δ15N values of tree rings. Increasing trends of the tree-ring N concentration were consistently observed in both the extracted and unextracted wood samples. The total N removed by extraction with organic solvents was about 17.60%, with a significantly higher amount in the sapwood section (P<0.01). The δ15N values of tree rings decreased consistently from 1960 to 2019 in both the extracted and unextracted wood samples. Extraction with organic solvents increased the δ15N values markedly by about 5.2‰ and reduced the variations in the δ15N series. However, extraction with hot ultrapure water had little effect, with only a slight decrease in the δ15N values of about 0.5‰. Our results showed that the radial pattern in the inter-ring movement of N in Qinghai spruce was not minimized by extraction with either organic solvents or hot ultrapure water. It is unnecessary to conduct hot ultrapure water extraction for the wood samples from Qinghai spruce because of its negligible effect on the removal of the labile N. The δ15N variation trend of tree rings in the unextracted wood samples was not influenced by the heartwood–sapwood transition zone. We suggest that the δ15N values of the unextracted wood samples of the climate-sensitive Qinghai spruce could be used to explore the ecophysiological dynamics while focusing on the long-term variations.
SU Yuan; GONG Yanming; HAN Wenxuan; LI Kaihui; LIU Xuejun
Abstract: Litter decomposition is an important component of the nutrient recycling process and is highly sensitive to climate change. However, the impacts of warming and increased precipitation on litter decomposition have not been well studied, especially in the alpine grassland of Tianshan Mountains. We conducted a manipulative warming and increased precipitation experiment combined with different grassland types to examine the impact of litter quality and climate change on the litter decomposition rate based on three dominant species (Astragalus mongholicus, Potentilla anserina, and Festuca ovina) in Tianshan Mountains from 2019 to 2021. The results of this study indicated there were significant differences in litter quality, specific leaf area, and leaf dry matter content. In addition, litter quality exerted significant effects on litter decomposition, and the litter decomposition rate varied in different grassland types. Increased precipitation significantly accelerated the litter decomposition of P. anserina; however, it had no significant effect on the litter decomposition of A. mongholicus and F. ovina. However, warming consistently decreased the litter decomposition rate, with the strongest impact on the litter decomposition of F. ovina. There was a significant interaction between increased precipitation and litter type, but there was no significant interaction between warming and litter type. These results indicated that warming and increased precipitation significantly influenced litter decomposition; however, the strength was dependent on litter quality. In addition, soil water content played a crucial role in regulating litter decomposition in different grassland types. Moreover, we found that the litter decomposition rate exhibited a hump-shaped or linear response to the increase of soil water content. Our study emphasizes that ongoing climate change significantly altered litter decomposition in the alpine grassland, which is of great significance for understanding the nutrient supply and turnover of litter.
ZHANG Yu; ZHANG Mingjun; QU Deye; WANG Shengjie; Athanassios A ARGIRIOU; WANG Jiaxin; YANG Ye
Abstract: Caragana korshinskii Kom. and Tamarix ramosissima Ledeb. are pioneer shrubs for water and soil conservation, and for windbreak and sand fixation in arid and semi-arid areas. Understanding the water use characteristics of different pioneer shrubs at different ages is of great importance for their survival when extreme rainfall occurs. In recent years, the stable isotope tracing technique has been used in exploring the water use strategies of plants. However, the widespread δ2H offsets of stem water from its potential sources result in conflicting interpretations of water utilization of plants in arid and semi-arid areas. In this study, we used three sets of hydrogen and oxygen stable isotope data (δ2H and δ18O, corrected δ2H_c1 based on SW-excess and δ18O, and corrected δ2H_c2 based on −8.1‰ and δ18O) as inputs for the MixSIAR model to explore the water use characteristics of C. korshinskii and T. ramosissima at different ages and in response to rainfall. The results showed that δ2H_c1 and δ18O have the best performance, and the contribution rate of deep soil water was underestimated because of δ2H offset. During the dry periods, C. korshinskii and T. ramosissima at different ages both obtained mostly water from deeper soil layers. After rainfall, the proportions of surface (0–10 cm) and shallow (10–40 cm) soil water for C. korshinskii and T. ramosissima at different ages both increased. Nevertheless, there were different response mechanisms of these two plants for rainfall. In addition, C. korshinskii absorbed various potential water sources, while T. ramosissima only used deep water. These flexible water use characteristics of C. korshinskii and T. ramosissima might facilitate the coexistence of plants once extreme rainfall occurs. Thus, reasonable allocation of different plants may be a good vegetation restoration program in western Chinese Loess Plateau.
DONG Jianhong; ZHANG Zhibin; LIU Benteng; ZHANG Xinhong; ZHANG Wenbin; CHEN Long
Abstract: Rapid industrialization and urbanization have led to the most serious habitat degradation in China, especially in the loess hilly area of the Yellow River Basin, where the ecological environment is relatively fragile. The contradiction between economic development and ecological environment protection has aroused widespread concern. In this study, we used the habitat quality of Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST-HQ) model at different scales to evaluate the dynamic evolution characteristics of habitat quality in Lanzhou City, Gansu Province of China. The spatiotemporal variations of habitat quality were analyzed by spatial autocorrelation. A Geographical Detector (Geodetector) model was used to explore the driving factors that influencing the spatial differentiation of habitat quality, including natural factors, socio-economic factors, and ecological protection factors. The results showed that the habitat quality index of Lanzhou City decreased from 0.4638 to 0.4548 during 2000–2018. The areas with reduced the habitat quality index were mainly located in the Yellow River Basin and Qinwangchuan Basin, where are the main urban areas and the new economic development areas, respectively. The spatial distribution of habitat quality presented a trend of high in the surrounding areas and low in the middle, and showed a significant positive spatial autocorrelation. With the increase of study scale, the spatial distribution of habitat quality changed from concentrated to dispersed. The spatial differentiation of habitat quality in the study area was the result of multiple factors. Among them, topographic relief and slope were the key factors. The synergistic enhancement among these driving factors intensified the spatial differentiation of habitat quality. The findings of this study can provide a scientific basis for land resources utilization and ecosystem restoration in the arid and semi-arid land.
WANG Kun; WANG Xiaoxia; FEI Hongyan; WAN Chuanyu; HAN Fengpeng
Abstract: Robinia pseudoacacia L. (RP) restoration has increased vegetation cover in semi-arid regions on the Loess Plateau of China, but ecological problems have also occurred due to RP restoration, such as reduced soil moisture. Further, it is still uncertain how microbial diversity, composition and assembly processes change with RP restoration in semi-arid regions. Therefore, amplicon sequencing of small subunit ribosomal ribonucleic acid (16S rRNA) and internal transcribed spacer (ITS) genes was performed to study soil bacterial and fungal diversity, composition and assembly processes at four study sites with different stand ages of RP plantations (Y10, RP plantation with stand ages less than 10 a; Y15, RP plantation with stand ages approximately 15 a; Y25, RP plantation with stand ages approximately 25 a; and Y40, RP plantation with stand ages approximately 40 a) along a 40-a chronosequence on the Loess Plateau. The diversity of soil bacteria and fungi increased significantly during the restoration period from 10 to 15 a (P<0.05). However, compared with Y15, bacterial diversity was lower at Y25 and Y40, and fungal diversity remained stable during the restoration period between 25 and 40 a. The relative abundances of Proteobacteria and Ascomycota increased during the restoration period from 10 to 15 a. Conversely, after 15 a of restoration, they both decreased, whereas the relative abundances of Actinomycetes, Acidobacteria and Basidiomycota gradually increased. The variations in soil bacterial communities were mainly related to changes in soil total nitrogen, nitrate nitrogen and moisture contents, while soil fungal communities were mainly shaped by soil organic carbon and nitrate nitrogen contents. Bacterial communities were structured by the heterogeneous selection and stochastic process, while fungal communities were structured primarily by the stochastic process. The RP restoration induced an increase in the relative importance of heterogeneous selection on bacterial communities. Overall, this study reveals the changes in microbial diversity, community composition and assembly processes with RP restoration on the Loess Plateau and provides a new perspective on the effects of vegetation restoration on soil microbial communities in semi-arid regions.