抗逆调节转录因子CBF1基因提高多年生黑麦草的抗旱能力

通过逆境诱导型启动子rd29B为驱动,分别构建出含有抗逆调节转录因子CBF1基因的表达载体pBAC122,pBAC127,其中pBAC127以CaMV35S启动子驱动的bar基因作为选择标记。用高压氦气基因枪PDS1000/He分别将表达载体导入多年生黑麦草(Lolium perenne)品种Topgun的幼胚、成熟胚和愈伤组织。经除草剂Bialaphos抗性筛选和植株再生,获得了36棵转基因植株。经PCR,Dot-blotting的分子检测,CBF1基因已整合到多年生黑麦草部分转基因株系的基因组中。用5种不同浓度的除草剂涂抹黑麦草叶片,非转基因植株表现为不抗,而转基因植株最高可以抗到135~200 mg/L。叶片脯氨酸含量测定表明,经干旱处理或使用15%PEG处理,转基因植株叶片脯氨酸含量比未处理时显著提高,部分转基因植株提高幅度明显高于非转基因植株。经过25 d人工温室干旱处理,有3棵植株显示出存活迹象,复水后,有1棵植株(C122-7)恢复正常生长。从而表明,利用逆境诱导型启动子(rd29B)来调控外源CBF1基因的表达,能显著改良黑麦草的抗旱能力。     

植物抗旱相关功能基因研究进展

综述了影响植物抗旱性的各相关功能基因的研究进展及其在抗旱基因工程上的应用现状。干旱是影响植物正常生长发育的一个最重要的逆境因子。人们对植物的抗旱性进行了多层次研究，并从各种生物中鉴别和定位了几十种与提高抗旱性相关的基因，为从分子水平上研究植物的抗旱性奠定了基础。近年来，人们发现了更多的抗旱基因，对已知抗旱基因也有了更深入的研究，并成功转化了多种不同类型的植物，提高了其抗旱能力。     

"植物细胞内pH调控系统"是适应环境逆境的一个耐性机制?

本研究把“植物细胞内pH调控系统”与植物抗逆性的关系作为研究对象,并探讨了参与植物细胞内pH调控相关的基因在碳酸盐(Na2CO3,NaHCO3)等逆境下的表达特性,其结果表明：NADP苹果酸酶(NADP—Malic Enzyme,NADP—ME)基因、磷酸烯醇式丙酮酸羧化酶(Phosphoenolpyruvate Carboxylase,PEP—Case)基因,还有细胞膜H^ —ATPase(plasmamembrane H^ —ATPase,p—H^ —ATPase)基因、液泡膜H^ —AT—Pase(vacuolar membrance H^ —ATPase,V—H^ —ATPase)基因、液泡膜H^ —PPase(vacuolar membrance H^ —PPase,V—H^ —Ppase)基因等的表达与NaCl逆境、碳酸盐逆境、外界环境pH逆境有应答关系,显示了这些基因在逆境下的表达有被强化的趋势。通过对逆境胁迫后植物根活体切片进行的pH变化趋势的观察,结果表明：植物根细胞在组织学水平上pH有明显的变化。在逆境下水稻根的组织学水平的观察,暗示了根组织有被酸性化的趋势,从而我们推测在逆境胁迫下细胞内pH发生了改变,不正常的细胞内pH会抑制细胞的生长发育,使植物受害。由此,我们提出细胞内pH调控系统是植物在长期的进化过程中获得的抗逆机制。在逆境下强化“细胞内pH调控系统”的调控能力能够提高植物的抗性。     

Changes in tolerance of soil microbial communities in Zn and Cd contaminated soils

Trace metals are present in the soil matrix in different forms, and this obscures the relationship between the amounts of metals, their biological availability and effects. Chemical methods have been devised to directly measure the biological available pools of trace metals, but such methods need to be validated against measured exposure of organisms in the soil. We studied acquired Zn- and Cd tolerance of the soil microbial community as a reporter of its exposure, and compared it with chemical determination of Zn and Cd in 10 soils differing in pH, organic matter content, texture, vegetation-/cultivation history and metal contamination. The tolerance was measured as LC₅₀ (i.e. the metal concentration which inhibits 50% of the activity) in suspensions of extracted soil bacteria, by measuring the incorporation rate of [³H] thymidine at different metal concentrations. Chemical determination of Cd and Zn in soils included total concentrations by aqua regia extractions (AR), and total concentrations in extracted pore water (PW). In addition was the ‘effective concentration’ (C_E) determined using the Diffusion Gradients in Thins films method (DGT). The LC₅₀ values correlated better with PW (r²=0.90 for Cd and r²=0.97 for Zn) and C_E (0.90 for Cd and 0.98 for Zn) compared to the correlation with AR (0.72 for Cd and 0.82 for Zn). After excluding a single extremely contaminated soil from the analysis, the correlation of LC₅₀ with AR was much poorer (r²=0.03 (ns) for Cd and r²=0.48 for Zn), whereas correlations remained significant for both PW (0.90 for Cd and 0.87 for Zn) and C_E (0.54 for Cd and 0.84 for Zn). In conclusion, PW fraction of Cd and Zn appear to be the best predictor of trace metal exposure of the soil microorganisms.     

铅锌矿尾矿坝分离节杆菌12-1对Pb~(2+)的耐受和吸附性能研究

当前铅资源的粗放式开采和使用对环境造成了严重的污染。利用微生物修复铅污染具有费用低、易操作、环境友好等优点,在水体和土壤铅污染治理中具有很好的应用前景。为了了解微生物对铅的吸附特性,本研究从铅锌矿尾矿坝分离到的一株耐铅节杆菌(Arthrobacter sp.)12-1(Gen Bank登录号:KM362724),并研究其对铅的吸附过程和作用机制。研究耐铅节杆菌12-1在含不同Pb2+浓度LB培养基中的生长情况表明,其最高可耐受800 mg/L Pb2+。在水溶液中,经24 h吸附,耐铅节杆菌12-1可将Pb2+浓度从105 mg/L降至2.17 mg/L,吸附率为97.93%。显微成像(原子力显微镜,扫描电镜)观察和能谱分析表明,耐铅节杆菌12-1吸附铅后在细胞表面形成含铅的矿物。傅立叶变换红外光谱(FT-IR)分析表明,耐铅节杆菌12-1细胞上的羧基、酰胺和磷酸基团可能参与了铅的吸附和固定过程。以上结果表明,从铅锌矿尾矿坝分离到的耐铅节杆菌12-1对铅具有较好的耐受和吸附能力,显示其在铅污染环境修复中具有潜在的应用前景。本研究为细菌修复铅污染环境的实践提供了理论基础。     

不同品种对水稻铅汞耐性和富集能力的影响

选取2种类型水稻土(黄泥土和红泥土)和9个水稻品种,通过温室盆栽试验,研究Pb(250 mg/kg)、Hg(0.6 mg/kg)污染条件下,水稻品种对水稻Pb、Hg耐性和富集能力的影响。结果表明,Pb污染处理显著降低了水稻产量,在红泥土和黄泥土中,水稻产量的降低幅度分别为3.6%~29.8%和2.3%~16.9%;Hg污染处理下,水稻产量略有下降,但差异不显著。不同品种水稻对Pb、Hg污染的耐性和富集能力差异显著。在Pb污染处理下,宁粳1号产量降幅较小,耐性较高;天协6号产量降幅较大,耐性较低;在Hg污染处理下,宁粳1号耐性较高,浙1500耐性较低。在2种类型水稻土中,特三矮2号稻米Pb的富集系数较高,对Pb污染较敏感;浙1500稻米Hg的富集系数较高,对Hg污染较敏感;宁粳1号稻米Pb、Hg的富集系数均较低,对Pb、Hg污染均不敏感。水稻品种、土壤类型和污染类型对水稻Pb、Hg耐性的影响不同,3个因子的相对贡献率分别为36.5%、18.3%和27.1%。     

Detection of tolerance of barley cultivars to infection by powdery mildew (Erysiphe graminis f.sp. hordei)

Summary Barley genotypes representing a wide range of resistance expressions and origins, from major resistance genes in modern cultivars to field resistances in landraces, were assessed for tolerance to disease under glasshouse and field conditions. A few genotypes were picked out as showing less yield loss than would be expected from the level of mildew infection. Genotypes showing more than the expected yield loss were also found. The potential use of tolerance as a breeding character is discussed.     

Bacterial salt tolerance is unrelated to soil salinity across an arid agroecosystem salinity gradient

In arid and semi-arid ecosystems, salinization is a major threat to the productivity of agricultural land. While the influence of other physical and chemical environmental factors on decomposer microorganisms have been intensively studied in soil, the influence of salinity has been less exhaustively assessed. We investigated the influence of soil salinity on soil bacterial communities in soils covering a range of salt levels. We assessed tolerance of the bacterial communities from Libyan agricultural soils forming a salinity gradient to salt (NaCl), by extracting bacterial communities and instantaneously monitoring the concentration-response to added NaCl with the Leucine incorporation technique for bacterial growth. To maximise our ability to detect differences in bacterial salt tolerance between the soils, we also repeated the assessment of bacterial growth tolerance after one month incubation with 1 or 2% added organic matter additions to stimulate microbial growth levels. We could establish clear concentration-response relationships between bacterial growth and soil salinity, demonstrating an accurate assessment of bacterial tolerance. The in situ soil salinity in the studied soils ranged between 0.64 and 2.73 mM Na (electrical conductivities of 0.74-4.12 mS cm⁻¹; cation exchange capacities of 20-37 mmol_c kg⁻¹) and the bacterial tolerance indicated by the concentration inhibiting 50% of the bacterial growth (EC₅₀) varied between 30 and 100 mM Na or between electrical conductivities of 3.0 and 10.7 mS cm⁻¹. There was no relationship between in situ soil salinity and the salt tolerance of the soil bacterial communities. Our results suggest that soil salinity was not a decisive factor for bacterial growth, and thus for structuring the decomposer community, in the studied soils.     

Long-term effects of trampling on Atlantic Heathland in Brittany (France): resilience and tolerance in relation to season and meteorological conditions

In recent decades, human trampling has become an important factor in the degradation of Atlantic heathlands. In a previous paper we showed that short-term responses of heathland to trampling were dependant on environmental parameters such as season and weather conditions (Gallet, S., Rozé, F., 2001b. Resistance of Atlantic Heathlands to trampling in Brittany (France): influence of vegetation type, season and weather conditions. Biological Conservation, 97, 189-198). Here, long term responses of experimental trampling, characterised by the resilience and the tolerance of communities and plants appear also dependant on these parameters. Dry and mesophilous heathlands are more tolerant to trampling in winter than in summer. In the case of mesophilous heathland, this is linked to high plant resilience, especially of Erica ciliaris. In summer, influence of meteorological conditions at the time of trampling depend on the species; indeed wet conditions lead to lower tolerance of Erica cinerea but to higher tolerance of E. ciliaris. Management of tourist pressure on natural or semi-natural sites must take visitors on the more tolerant communities, so it must take into account the variability of tolerance to trampling of the different types of vegetation present and needs to be adaptable to environmental conditions.     

种子引发对小麦抗盐及抗旱特性影响综述

小麦是我国北方重要粮食作物,在农业生产中经常受到干旱和盐分胁迫影响,造成减产。种子引发是在种子萌发前用天然或人工合成试剂对种子进行处理,从而提高植物抗逆性的一种简单而有效的方法。在干旱或高盐条件下,利用引发剂对小麦种子引发后,种子萌发提前,幼苗生长发育代谢增强,抗逆境相关生理指标提升,作物抗旱耐盐能力增强,最终产量及质量得到提高。本文阐述了水、有机物、植物激素、生物活性物质、生物、氧化物、无机信号物质等不同种类引发剂对小麦种子引发的作用机理和效果。并总结了种子引发的主要作用机制,如:减少植株对Na~+的吸收,增加对K~+、Ca~(2+)的吸收,减少盐分对生长造成的阻碍;促进可溶性蛋白和可溶性糖等渗透调节物质的合成和积累,细胞内维持高渗透压,有利于根系吸水;诱使胁迫条件下细胞内超氧化物歧化酶、过氧化物酶、过氧化氢酶、抗坏血酸过氧化物酶等抗氧化酶的合成增多、活性增强,有效清除活性氧,维持细胞内氧平衡;调节植物内源激素合成与运输从而使激素水平处于更加适应胁迫条件的平衡状态等。并讨论了引发剂与植物逆境生理研究之间相互补充、相互促进的关系,展望了种子引发在农业方面的发展及应用前景。