牡丹花枝不同发育时期各器官乙烯释放和ACC含量的变化

以牡丹( Paeonia suffruticosa) 品种‘胡红’为试材, 测定了不同发育时期花枝以及不同器(花瓣、雌蕊、雄蕊、花托、花萼、茎、叶柄、叶) 的乙烯释放量和ACC含量的变化。花的乙烯释放量变化类型主要取决于花瓣, 花朵衰老时花托和雄蕊是乙烯释放的主要部位。雄蕊在初开期有一明显的乙烯释放高峰。花朵开放过程中花瓣的ACC含量缓慢减少, 进入衰老期ACC含量又有快速上升的趋势; 而茎的ACC含量一直处于下降趋势。叶柄和叶片的ACC含量在花朵的整个开放过程中变化不大。结果提示器官之间乙烯和ACC梯度在花朵开放和衰老前后起着重要的调节作用, 而乙烯和ACC在花器不同部位间的运输及分配上有差异。     

氮、磷养分添加对高寒草甸土壤酶活性的影响

本试验以典型的青藏高原高寒矮嵩草草甸(Kobresia humilis meadow)为研究平台,以表征土壤碳、氮、磷、硫养分循环的6种土壤酶为研究对象,研究土壤酶以及土壤速效养分在4年氮、磷养分添加的累积效应下的变化规律,分析和评价氮、磷养分添加对土壤养分循环方面的影响。试验结果为:氮、磷养分添加改变了土壤中速效养分的含量;氮添加与010 cm土层中的碱性磷酸酶活性有正效应,磷添加抑制了010 cm土层中的碱性磷酸酶活性;氮、磷养分添加均抑制了010 cm土层中的脲酶活性;氮添加抑制了2个土层中的纤维素酶活性;芳基硫酸酯酶活性和蔗糖酶活性没有表现出显著差异性;1020 cm土层中的几丁质酶活性在氮、磷养分添加处理下均增强,其中磷添加对几丁质酶活性的增幅最显著。结果表明:外源添加的氮在调控磷的矿化方面有促进作用,磷的添加对氮素的释放也有一定的作用;青藏高原高寒草甸受磷限制的程度可能更大。     

基于相对迁移率的节节麦高分子量谷蛋白亚基组成分析

高分子量谷蛋白亚基(HMW-GS)是影响小麦烘烤品质的重要因素。新的HMW-GS变异类型的发现和利用,有助于优质小麦品种的培育。然而,目前HMW-GS新变异类型众多、对照标准材料多样,导致传统数字命名系统分辨率严重降低。本研究通过利用HMW-GS的条带与中国春1Dx2条带的迁移率比值作为相对迁移率来表示亚基类型,进而提高HMW-GS的分辨率,并且不需要除中国春以外的其它对照材料。在158份节节麦中,成功检测到了64种亚基类型和127种亚基组合。对这些亚基组合进行聚类分析,结果显示在遗传相似系数(GS)为0.003的水平上可将其划分为9个类群。上述结果表明,本研究采用的基于相对迁移率的亚基表示方法,能有效区分SDS-PAGE胶上距离较近的蛋白条带,可为麦类作物HMW-GS变异类型的发掘提供新的手段。     

利用RNA-seq筛选调控当归抽薹主要候选基因

当归提前抽薹严重影响产量,而当归抽薹分子遗传机理尚不清楚。本研究利用RNA-seq技术对连续五代抽薹当归的叶片、茎段、种子、根进行测序,对所有组装后的Unigenes进行功能注释,寻找调控当归抽薹主要候选基因。结果表明:在当归的叶片、根、种子、茎段转录本中分别得到7.1、7.63、7.23、6.59 Gb数据,通过Nr、Nt、Swissprot、KEGG、KOG、Interpro、GO、Intersection、Overall等蛋白数据库进行蛋白质预测,分别预测了71 024、59 931、49 694、51 832、55 320、46 908、35 598、17 133、79 161个蛋白。所有转录本中80.13%预测蛋白与胡萝卜同源。在KEGG通路中共有2 666个差异表达的基因参与植物信号传导;与拟南芥、胡萝卜、芥菜中参与调控开花相关基因比对,共筛选出56条候选基因,将56条候选基因在NCBI中进行核酸比对,得到与直接控制抽薹AP1转录因子同源的Unigene45683_All、激活AP1转录因子的整合子FT和FD同源的Unigene11264_All、参与拟南芥光周期调控基因CO (CONSTANS)的同源基因Unigene4344_All、在芥菜中促进抽薹整合因子SOC1的表达的AGL24或直接作用于抽薹决定基因LFY的同源基因Unigene46836_All、Unigene7820_All、CL10006.Contig2_All。因此,上述候选基因很有可能参与调控当归抽薹相关分子机制。本研究筛选到与当归抽薹相关的候选基因,有助于了解当归抽薹相关分子机制,为挖掘控制当归抽薹相关基因提供理论依据。     

Haplotype variations of gene Ppd-D1 in Aegilops tauschii and their implications on wheat origin

The Ppd-D1 controlling photoperiod response is an important gene for wheat adaptation since it affects heading time. In the present study, three haplotypes, i.e. haplotype I without deletion, haplotype II with a 24?bp deletion, and haplotype III with two deletions of 24 and 15?bp, were identified in the upstream of the coding region in 80 Ae. tauschii accessions. The haplotype distribution was related to subspecies taxon. All typical ssp. tauschii accessions had haplotype I, whereas all ssp. strangulata had haplotype III. The three haplotypes were observed in Ae. tauschii with morphologically intermediate forms between the two typical subspecies. Present results supported that ssp. strangulata or intermediate form was the D-genome donor of common wheat since only haplotype III were found in wheat. Moreover, a 16?bp deletion in exon 8 of gene Ppd-D1 exists in common wheat. However, none of Ae. tauschii accessions analyzed had the 16?bp deletion.     

Nitrogen deposition impacts on the amount and stability of soil organic matter in an alpine meadow ecosystem depend on the form and rate of applied nitrogen

The effects of atmospheric nitrogen (N) deposition on carbon (C) sequestration in terrestrial ecosystems are controversial. Therefore, it is important to evaluate accurately the effects of applied N levels and forms on the amount and stability of soil organic carbon (SOC) in terrestrial ecosystems. In this study, a multi‐form, small‐input N addition experiment was conducted at the Haibei Alpine Meadow Ecosystem Research Station from 2007 to 2011. Three N fertilizers, NH₄Cl, (NH₄)₂SO₄ and KNO₃, were applied at four rates: 0, 10, 20 and 40 kg N ha^?1 year^?1. One hundred and eight soil samples were collected at 10‐cm intervals to a depth of 30 cm in 2011. Contents and δ¹³C values of bulk SOC were measured, as well as three particle‐size fractions: macroparticulate organic C (MacroPOC, > 250 µm), microparticulate organic C (MicroPOC, 53–250 µm) and mineral‐associated organic C (MAOC, < 53 µm). The results show that 5 years of N addition changed SOC contents, δ¹³C values of the bulk soils and various particle‐size fractions in the surface 10‐cm layer, and that they were dependent on the amounts and forms of N application. Ammonium‐N addition had more significant effects on SOC content than nitrate‐N addition. For the entire soil profile, small additions of N increased SOC stock by 4.5% (0.43 kg C m^?2), while medium and large inputs of N decreased SOC stock by 5.4% (0.52 kg C m^?2) and 8.8% (0.85 kg C m^?2), respectively. The critical load of N deposition appears to be about 20 kg N ha^?1 year^?1. The newly formed C in the small‐input N treatment remained mostly in the > 250 µm soil MacroPOC, and the C lost in the medium or large N treatments was from the > 53 µm POC fraction. Five years of ammonium‐N addition increased significantly the surface soil POC:MAOC ratio and increased the instability of soil organic matter (SOM). These results suggest that exogenous N input within the critical load level will benefit C sequestration in the alpine meadow soils on the Qinghai–Tibetan Plateau over the short term.     

Nutrient limitation of alpine plants: Implications from leaf N : P stoichiometry and leaf δ15N

Nitrogen (N) deposition can affect grassland ecosystems by altering biomass production, plant species composition and abundance. Therefore, a better understanding of the response of dominant plant species to N input is a prerequisite for accurate prediction of future changes and interactions within plant communities. We evaluated the response of seven dominant plant species on the Tibetan Plateau to N input at two levels: individual species and plant functional group. This was achieved by assessing leaf N : P stoichiometry, leaf δ¹⁵N and biomass production for the plant functional groups. Seven dominant plant species—three legumes, two forbs, one grass, one sedge—were analyzed for N, P, and δ¹⁵N 2 years after fertilization with one of the three N forms: NO$ _3^- $ , NH$ _4^+ $ , or NH₄NO₃ at four application rates (0, 7.5, 30, and 150 kg N ha^–1 y^–1). On the basis of biomass production and leaf N : P ratios, we concluded that grasses were limited by available N or co‐limited by available P. Unlike for grasses, leaf N : P and biomass production were not suitable indicators of N limitation for legumes and forbs in alpine meadows. The poor performance of legumes under high N fertilization was mainly due to strong competition with grasses. The total above‐ground biomass was not increased by N fertilization. However, species composition shifted to more productive grasses. A significant negative correlation between leaf N : P and leaf δ¹⁵N indicated that the two forbs Gentiana straminea and Saussurea superba switched from N deficiency to P limitation (e.g., N excess) due to N fertilization. These findings imply that alpine meadows will be more dominated by grasses under increased atmospheric N deposition.     

草地生态系统健康研究述评

阐述了草地生态系统健康的研究进展、存在问题和发展趋势,重点介绍了评价的指标体系和方法,包括结构功能指标体系法、综合指标体系及10多种方法的特点和适用情况.同时对于指标的筛选、权重的确定、标准的划分等难重点问题给出了建议.提出了用多种方法来评价同一研究对象来进行比较和矫正的观点,并强调形成集自然、经济、社会、人类健康为一...     

两种高寒植被长波辐射的气候学特征及比较

地球边界层热量来源是地表吸收太阳短波辐射后再以长波辐射形式加热的结果,而边界层生物活动与近地表热量息息相关,讨论长波辐射的变化特征对生态系统的物质流动及能量交换具有重要意义。以2003年对高寒矮嵩草草甸、金露梅灌丛两种植被类型观测的资料,比较分析了两种植被类型地面长波辐射（ULR）、大气逆辐射（DLR）以及地面有效长波辐射（ELR）的变化特征。结果表明,高寒矮嵩草草甸、金露梅灌丛ULR、DLR以及ELR均具有明显的日、月变化。其中矮嵩草草甸、金露梅灌丛的ULR月平均日变化在北京时间14∶00最高,凌晨最低;DLR在16∶00-18∶00最高,凌晨最低;ELR在8∶00最低,14∶00最高。月变化中,两种植被类型区ULR、DLR的最低值出现在1-2月,较高值出现在7-9月,而ELR变化趋势比较复杂。总体而言,金露梅灌丛的DLR、ULR变化值明显比矮嵩草草甸的高。     

青藏铁路格唐段高海拔地区植被恢复研究——I高寒草原植被现状与恢复基本途径探讨

青藏铁路的修建加强了西藏与内地的联系,对其经济发展、社会稳定具有重要的意义。但在修建过程中不可避免地对沿线的局部植被生态系统造成不同程度影响和破坏,如何尽快恢复植被生态系统至关重要。对青藏铁路青海境内的高海拔的气候条件及现有植被状况作了统计调查,提出尊重科学,因地制宜的指导原则,恢复与重建的工作一起抓:一方面要增强环保意识,加强管理,综合治理;另一方面通过原有草皮回植,科学管理以及异地繁殖当地草种等途径尽快提高地表覆盖度和植物种群多样性,以期达到最佳的生态效应。