外生菌根真菌的共生互作和宿主选择机制研究进展

外生菌根真菌作为树木的共生伙伴,是森林生态系统重要组成部分,在森林天然更新、植物抗逆性形成、协助植物吸收限制性营养等方面扮演重要角色。真菌和植物跨界共生具有复杂的分子互作过程,在共生的不同阶段有不同的分子互作机制,其调控反馈网络还有许多未知。基因组与转录组研究技术和方法的进步,为一些新的信号分子、效应蛋白以及相关通路的发现提供了可能。真菌与宿主植物之间营养转移调控对共生的影响也逐渐受到关注,营养相关的转运蛋白对共生的建立和维持提供了物质基础。真菌的宿主选择机制是值得重点关注的领域,由于外生菌根真菌的多谱系起源和演化史中存在多次宿主转换事件,真菌演化出多样的应对机制用来区分相容性宿主、不相容性宿主和非宿主。通过对不同真菌与宿主植物的组学研究,宿主选择机制研究取得了一定进展。本文对近十年来国内外的研究报道进行梳理与总结,并对未来在该领域的探索方向做出展望。     

山西糜子核心种质分子身份证构建

为快速鉴定糜子(Panicum miliaceum)资源, 建立分子标记检测平台, 以272份山西糜子核心种质为研究材料, 利用85对简单重复序列(SSR)引物, 应用ID Analysis 4.0软件, 构建DNA分子身份证。结果表明, 对85对SSR引物进行筛选, 发现20对引物组合(RYW67、RYW53、RYW37、RYW65、RYW62、RYW77、RYW5、RYW49、RYW84、RYW19、RYW11、RYW40、RYW54、RYW28、RYW31、RYW7、RYW16、RYW8、RYW9和RYW18)可区分272份材料。共检测到等位变异(Na) 60个, 平均每个位点检出3个; Shannon多样性指数(I)为0.957 8 (RYW16)-1.096 7 (RYW5), 平均值为1.055 2; 多态性信息含量(PIC)为0.604 4 (RYW77)-0.753 0 (RYW37), 平均值为0.692 1。利用20对引物构建山西糜子核心种质的字符串、条形码和二维码DNA分子身份证, 可为种质身份标识和溯源提供实践路径。     

Genome-wide RAD sequencing data suggest predominant role of vicariance in Sino-Japanese disjunction of the monotypic genus Conandron (Gesneriaceae)

Disjunct distribution is a key issue in biogeography and ecology, but it is often difficult to determine the relative roles of dispersal vs. vicariance in disjunctions. We studied the phylogeographic pattern of the monotypic Conandron ramondioides (Gesneriaceae), which shows Sino-Japanese disjunctions, with ddRAD sequencing based on a comprehensive sampling of 11 populations from mainland China, Taiwan Island, and Japan. We found a very high degree of genetic differentiation among these three regions, with very limited gene flow and a clear Isolation by Distance pattern. Mainland China and Japan clades diverged first from a widespread ancestral population in the middle Miocene, followed by a later divergence between mainland China and Taiwan Island clades in the early Pliocene. Three current groups have survived in various glacial refugia during the Last Glacial Maximum, and experienced contraction and/or bottlenecks since their divergence during Quaternary glacial cycles, with strong niche divergence between mainland China + Japan and Taiwan Island ranges. Thus, we verified a predominant role of vicariance in the current disjunction of the monotypic genus Conandron. The sharp phylogenetic separation, ecological niche divergence among these three groups, and the great number of private alleles in all populations sampled indicated a considerable time of independent evolution, and suggests the need for a taxonomic survey to detect potentially overlooked taxa.     

Poplar (Populus nigra L.) plants transformed with aBacillus thuringiensis toxin gene: insecticidal activity and genomic analysis

Insect-resistant poplar (Populus nigra L.) plants have been produced by infecting leaves withAgrobacterium tumefaciens strains carrying a binary vector containing different truncated forms of aBacillus thuringiensis (B.t.) toxin gene under a duplicated CaMV 35S promoter. Putative transgenic plants were propagated by cuttings at two experimental farms (in Beijing and Xinjiang, China). At 2–3 years after transformation, 17 of them were selected on the bases of insect-tolerance and good silvicultural traits, and evaluated for insect resistance, for the presence of theB.t. toxin DNA fragment (Southern blots and PCR) and for the expression of the transgene (western and northern blots). Somaclonal variation, as suggested by the appearance of permanent changes in the shape of the leaves, was also investigated with molecular tools (RFLP (restriction fragment length polymorphism), RAPD (random amplified polymorphic DNA) and microsatellite DNA).Bioassays withApochemia cineraius andLymantria dispar on the leaves of the selected clones showed different and, in some cases, high levels of insecticidal activity. The molecular analysis demonstrated integration and expression of the foreign gene. Somatic changes were correlated to extensive genomic changes and were quantified in dendrograms, in terms of genomic similarity. The analysis of control plants suggested that genomic changes were correlated to thein vitro culture step necessary forA. tumefaciens-mediated gene transfer, rather than to the integration of the foreign genes.Three transgenic clones (12, 153 and 192), selected for insect resistance, reduced morphological changes and promising silvicultural traits, are now under large-scale field evaluation in six different provinces in China.     

心肌电兴奋传导速度对心律失常影响的仿真研究

心电场是由心肌的电活动产生的。心肌细胞的电特性及心肌细胞间的传导关系决定了体表电位的分布及心电图的变化。心肌电兴奋传导速度则是影响心肌间兴奋传导关系的重要参数之一。由于很难通过实验方法来人为改变电兴奋传导速度,因而临床上有关该参数对心律影响的定量知识相当缺乏。本文采用真实三雏躯干模型及心脏模型,对心肌电兴奋传导速度与心律变化的关系进行定量仿真研究。结果表明,兴奋传导速度决定了整个心电图的变化,而局部普通心肌的传导速度在相当范围内变化似乎对心电图影响不明显,但传导速度超过一定范围后可能产生突变。     

广西水土保持植物材料试验研究初报

植物措施能有效地防止水土流失。本文根据水土保持植物措施的新思路和新模式,选用和配置水土保持植物材料,研究其生态经济效益。     

栝楼核糖核酸酶在RNA序列分析中的应用

栝楼核糖核酸酶（RNase TCS）对U碱基具有高度的专一性,在无脲、pH3.5、50℃时,它几乎都在-NP ↓ U-处裂解RNA.它与RNase T1,U₂和有限的碱水解一起,可用于直接的酶法RNA序列分析．     

红壤旱坡地桔园覆盖的生态效应及经济效益评价

柑桔是南方红壤地区栽培的主要果树种类,栽培面积达1126×106ｈｍ2。柑桔是一种常绿果树,生长量大,挂果期长,周年需要消耗大量的水分。我国南方红壤地区虽然雨水充沛,但降水季节分布不均,柑桔果实迅速生长的7～10月正是该地区雨水少、蒸发量大的伏秋干旱季节。经常性的伏秋干旱是制约我国柑桔产量和质量进一步提高的主要障碍因素之一。桔园夏秋进行秸秆覆盖可以降温[1]、保水[2]、防止杂草生长[3]等,但桔园应用地膜覆盖及常年连续覆盖对桔园的生态效应方面的研究较少,为此我们开展了这方面的工作,并通过连续3ａ的产量及产值分析覆盖桔园的经…     

四种水蛭抗凝血酶作用的研究

本文研究了水蛭的抗凝血酶作用,并比较了4种提取方法对抗凝作用的影响。冷浸和温浸,抗凝活性强度为菲牛蛭>日本医蛭》两种宽体金线蛭。煎煮后,前两种的活性锐碱,而两种宽体金线蛭的活性几乎不变。