氯钾离子共体诱导黄瓜对霜霉病抗性的研究

在黄瓜幼苗子叶期及第一真叶期用浓度为2g/kg、5g/kg、10g/kg、15g/kg、20g/kg的氯钾离子共体液进行诱导处理,可使黄瓜植株产生对霜霉病[Pseudoperonospor cubensis(Berk.et Curt.) Rostov.]的抗病性。在自然病原激发病害试验中,经2g/kg、5g/kg、10g/kg、15g/kg、20g/kg浓度的氯钾离子共体液诱导处理的植株比对照植株推迟发病3~6d,平均病株率分别比对照降低25.26%、26.63%、31.46%、39.12%和33.38%,平均病叶率分别比对照降低22.89%、28.08%、34.02%、38.36%和36.59%,平均病情指数分别比对照降低18.32%、28.97%、34.80%、35.89%和36.77%,差异达极显著水平,平均相对免疫效果分别为31.99%、43.75%、51.23%、53.43%和53.70%。在人工接种病原激发病害试验中,自诱导后第6d接种各处理浓度的平均病情指数分别比对照降低38.51%、44.86%、40.81%、43.00%和43.33%,且与对照的差异均达到极显著水平。植株产生对霜霉病诱导抗性的迟滞期为2~4d,潜育期为7~9d,诱导抗性保持的有效期达27d。氯钾离子共体液诱导处理的最佳浓度为10g/kg和15g/kg。     

N+离子注入陆地棉花粉对胚珠DNA及M1代cDNA表达的影响

通过对胚珠DNA的SSR标记分析,在DNA水平上检测氮离子束诱变后胚珠的多态性变化,结果表明,离子注入陆地棉花粉后再给雌蕊授粉,会对胚珠的DNA多态性产生影响,表明在一定程度上改变了花粉中精细胞的DNA序列;利用抑制性消减杂交(SSH)分离N+离子诱变花粉和对照正常花粉分别给雌蕊授粉后产生的M1代植株叶片间表达有差异的cDNA片段,建立差异表达cDNA文库。已测序的有50个缩减cDNA克隆,根据BLAST网络服务检索查询EMBLGen、 Bank、DDBJ和PDB的核苷酸序列数据库以及蛋白质氨基酸序列数据库,进行序列联配,结果发现52%序列在数据库中都有同源的棉属来源的EST。38个EST与其他物种已知基因部分区域的同源性为56%-100%,占总EST的76%;5条EST序列能在数据库中检索到同源性序列,但其功能（占10%）尚不清楚;9个EST能在数据库中发现为推测蛋白,占18%;4个EST在GenBank中没有查到对应的同源序列,占8%。     

Critical body residues (CBRs) for ecotoxicological soil quality assessment: copper in earthworms

The term ‘critical body residue’ (CBR) was defined as the lowest observed total body concentration of a contaminant in an organism, which is associated with the occurrence of adverse toxic effects in either individuals or populations of a defined age or stage of development. In this study, internal toxicity thresholds were determined for copper in the clitellated adult stage of earthworms (Lumbricus rubellus and Aporrectodea caliginosa). The objective was to assess the applicability of CBRs as a practical tool in soil quality assessment of contaminated sites and as a means of a sustainable protection of earthworm fauna. Laboratory studies showed that body concentrations of Cu were generally in agreement with the chemically available CaCl₂-extractable fraction in soil, but that there was also some evidence of internal pH-related homeostatic regulation. Toxicological correlates of body Cu concentrations with adverse effects on cocoon production (fecundity) suggested an approximate sublethal internal threshold of about 40 mg kg⁻¹, with mortality occurring at about 60 mg kg⁻¹. Adult L. rubellus sampled from areas with a wide range of metal pollution showed body Cu concentrations with a minimum of 8 mg kg⁻¹ and a maximum of 60 mg kg⁻¹. Beyond this apparent physiological tolerance range, environmental management directed at optimal earthworm population survival may not be sustainable in contaminated fields. Studies of L. rubellus colonizing a metal-contaminated experimental sludge-treated field showed that a reduced rate of colonization can already be associated with an average body Cu concentration of 25 mg kg⁻¹. However, in this particular field situation mixture effects of other metals that were also present in the soil and the occurrence of avoidance behaviour during colonization may have contributed to this low internal toxicity threshold. It is concluded that the CBR approach seems to be a feasible option for use as a tool in a bioavailability-based soil quality assessment, even for essential trace metals like copper, but that further insight may be needed to establish the uncertainty and reliability of the application in environmental quality assessment and decision making.     

Interactions between earthworms, trees, soil nutrition and metal mobility in amended Pb/Zn mine tailings from Guangdong, China

This paper reports research that attempts to rehabilitate toxic Pb/Zn mine tailings, in Guangdong, China, to achieve a healthy functional soil that supports sustainable vegetation. We studied the effects of the earthworm Pheretima guillelmi on the growth of a woody legume Leucaena leucocephala on Pb/Zn mine tailings diluted with varying amounts of mineral soil in pot experiments. L. leucocephala grew successfully on tailings with a 25% (w/w) soil amendment, but P. guillelmi only survived and actively burrowed with a 50% soil amendment. The presence of earthworms improved the yield of plants by 10-30%. Whilst earthworms marginally increased available N and P in soil, they increased uptake of phosphorus (by about 10%) to above-ground plant tissues. Six-month-old plants were more sensitive than 10-month plants to metal stress. P. guillelmi increased bioavailable metal concentrations in the amended spoils, accompanied by a direct increase of metal uptake by the plants. Increased metal uptake by plants was largely due to the higher dry matter production stimulated by earthworm activity, but this increased the rate of metal uptake into plants from spoil by at least 16% and as much as 53%. These results demonstrate that we should broaden the ecological context of phytoremediation by considering the plant-soil-animal interactions that influence metal mobility.     

Selenium desorption from Ca‐Kaolinite

Abstract

Toxic selenium (Se) concentrations were found recently in shallow groundwater in the west side of the San Joaquin Valley in California. The objective of the present work was to evaluate whether excessive leaching, variations in pH, and the presence of competing ions may contribute to Se solubilization and accumulation in the drainage water.

Selenium desorption from a Ca‐Kaolinite suspension deviated considerably from the corresponding adsorption isotherm. Raising the suspension pH from 5.6 to 8.7 resulted in the release of all the Se present in the system into the solution phase. Decreasing the pH from 5.6 to 3.6, reduced Se and Se concentrations in the solution by a factor of 3 and 2, respectively. When adding P at a 10:1 P‐to‐total Se molar ratio, Se and Se concentrations in the solution increased from 1.5 to 2.3 and from 2.4 to 2.6 pM, respectivley. Sulfate ions at the same, or higher, molar ratios had no apparent effect on Se solubilization.     

Sperm motility and seminal plasma characteristics in Barbus sharpeyi (Günther, 1874)

Spermatozoa concentration, ionic composition, osmolality, glucose and total protein contents of seminal plasma and sperm motility were determined in Barbus sharpeyi (Cyprinidae, Teleosotei). Spermatozoa concentration ranged from 9.77 to 20.20 × 10⁹ spermatozoa mL^?1. Osmolality (mOsmol kg^?1) and ionic contents (mM L^?1) of the seminal plasma were 274.5±9.0, 70.0±3.4 Na⁺, 28.8±0.9 K⁺, 101.7±3.1 Cl^?, 0.9±0.1 Mg²⁺ and 2.1±0.1 Ca²⁺ respectively. Total protein and glucose were 5.3±0.2 g L^?1 and 76.7±4.3 mM L^?1 respectively. Sperm motility was initiated in a hypo‐osmotic condition, composed of either an ionic (KCl or NaCl) or a non‐ionic (sucrose) activation medium. Duration of sperm motility was very short: <2 min after activation in distilled water. Percentage of motile spermatozoa was significantly higher in an activation medium containing NaCl compared with that of distilled water. An activating medium containing NaCl or KCl higher than 150 mM or sucrose higher than 275 mM totally inhibited the activation of sperm motility. Immediately after sperm activation, wave(s) propagated along the flagellum, but waves were restricted to the proximal part of the flagellum (close to the head) at 1 min post activation. Studied characteristics in the present study were compared with those of other cyprinids for understanding inter‐species differences.     

云栖竹径公园空气负离子生态效益评价

以杭州市云栖竹径公园典型植物群落毛竹纯林、常绿阔叶林及毛竹、枫香混交林为研究对象,研究3种不同植物群落空气负离子变化及其与气象因子之间的关系。研究结果表明,不同植物群落空气负离子浓度大小排序为毛竹林>毛竹+枫香混交林>常绿阔叶林,毛竹纯林具有更加强的环境气候调节效应,在改善城市气候方面发挥着重要的作用。     

Analysis of Some Divalent Metal Contents in Tobacco Expressing the Exogenous Soybean Ferritin Gene

Abstract

T2 tobacco lines overexpressing soybean ferritin in the plastids (+TPs) or apoplasm (AFs) under the regulation of CaMV 35S promoter were grown on MS nutrient solution. After 1 month growth, statuses of six major divalent‐metals (Ca, Cu, Fe, Mg, Mn, and Zn) were measured in leaves and roots. Both +TPs and AFs showed enhanced growth (max. 1.7×) in leaves than the control line. The Fe contents in leaves of +TPs and AFs were significantly larger (1.9–2.8×) than that of the control line. The other metal contents in leaves of +TPs and AFs were almost the same as or less than those of the control line. In contrast to the result of leaves, the growth enhancement in roots was not clear in +TPs, but in AFs. Also, some of the non‐ferrous metal contents in roots of +TPs and AFs were dramatically increased compared with those of the control line (Mn, 1.9–10.4×; Zn, 1.6–2.3×), whereas the differences in content of Fe, Cu, Ca, and Mg were insignificant. These results demonstrated that the ferritin overexpression in apoplasm was as effective for inducing Fe accumulation as that in plastid. Under the normal metal‐balanced condition, even if the activation of Fe uptake related enzymes leads to the accumulation of non‐specific accumulation of divalent metal ions in roots, an Fe loading/unloading system and/or an internal translocator in xylem and phloem might specifically deliver Fe to the upper part of plants.     

Salt‐Induced Regulation of Some Key Antioxidant Enzymes and Physio‐Biochemical Phenomena in Five Diverse Cultivars of Turnip (Brassica rapa L.)

A greenhouse experiment was carried out to examine the differential morpho‐physiological responses of five cultivars of turnip (Brassica rapa L.) to salt stress. Five diverse cultivars of turnip (shaljum desi surakh, shaljum purple top, shaljum golden bal, neela shaljum, and peela shaljum) were subjected for 6 weeks to varying levels of NaCl, i.e. 0, 80 and 160 mm in Hoagland’s nutrient solution in sand culture. Imposition of varying levels of salt substantially decreased shoot and root fresh and dry weights, chlorophyll contents, leaf osmotic potential, relative water contents, different gas exchange attributes, total phenolics, malondialdehyde, activities of superoxide dismutase, peroxidase catalase, and leaf and root K⁺ levels while enhanced the proline contents, membrane permeability, level of H₂O₂, leaf and root Na⁺ and Cl^? and leaf Ca²⁺ in all turnip cultivars under study. Of all cultivars, peela shaljum and neela shaljum were consistently higher in their growth than the other turnip cultivars at all salt concentrations of the growth medium. Photosynthetic capacity (A) and stomatal conductance (g_s) were higher in high biomass‐producing cultivars, i.e. peela shaljum and neela shaljum, which provide to be potential selection criteria of salt tolerance in turnip. However, the regulation of antioxidant system was cultivar‐specific under saline conditions.     

浅谈我国农田土壤重金属污染现状及修复研究

农田土壤重金属污染导致农作物重金属含量超标,这些重金属随食物链进入人体内,对人体健康造成危害。了解农田土壤重金属污染现状、重金属污染对农作物的危害,以及污染农田的治理修复,对维护人体健康具有重要意义。本文综述了我国农田土壤重金属污染现状,分析了农田土壤重金属污染可能对农作物造成的影响,概括了目前农田土壤重金属污染的主要治理方式,并分析了这些治理方式的差异性和优缺点,对未来农田土壤重金属污染治理的方向作出了展望。为该领域初学者了解该领域研究方向、发展趋势和研究热点提供了指导,也为我国农田土壤重金属污染治理的进一步研究提供参考。