间作两个生态气候区的龙葵和少花龙葵促进茄子幼苗生长且降低镉吸收

Soil contamination by heavy metals is a serious environmental problem worldwide,and reduction of heavy metal accumulation in vegetables grown on contaminated land is a matter of urgency.A pot experiment was conducted to study the effects of intercropping with the Cd hyperaccumulators Solanum nigrum and Solanum photeinocarpum from two ecoclimatic regions,Ya'an and Chengdu,Sichuan Province,China,on the growth and cadmium (Cd) uptake of eggplant (Solanum melongena L.).The biomass,photosynthetic pigment contents,and activities of antioxidant enzymes of eggplant were enhanced by intercropping.The biomass of eggplant was the highest after intercropping with S.photeinocarpum from Ya'an,but did not differ significantly from that after intercropping with S.nigrum from Chengdu.The shoot Cd content of eggplant was significantly reduced by intercropping with the hyperaccumulators,which ranked as follows:S.nigrum from Chengdu ＞ S.nigrum from Ya'an ＞ S.photeinocarpum from Chengdu ＞ S.photeinocarpum from Ya'an,with the decreases being 19.60％,14.36％,9.66％,and 6.42％,respectively,as compared with the control.The lowest shoot Cd content and translocation factor of eggplant were attained after intercropping with S.nigrum from Chengdu.Therefore,it was feasible to intercrop eggplant with S.nigrum and S.photeinocarpum on Cd-contaminated soil.     

An effective planting model to decrease cadmium accumulation in rice grains and plants: Intercropping rice with wetland plants

Cadmium (Cd) pollution affects plant growth and poses a serious threat to food safety and human health.Cadmium-contaminated rice is assumed to be the main source of Cd exposure to humans,with grave health risks.Phytoremediation is an efficient,cost-effective,and eco-friendly approach to minimize Cd accumulation in rice.However,research on the effect of rice intercropping with wetland plants that exhibit great capacity for phytoremediation in decreasing Cd concentrations in paddies is limited.A p...     

高镉累积水稻对镉污染农田的修复潜力

为探究高镉累积水稻品种扬稻6号和玉珍香对镉污染农田土壤的修复潜力,通过大田小区试验,测定6个不同生育期(返青、分蘖、孕穗、齐穗、蜡熟、完熟)5个部位(根、茎0～10 cm、茎10～20 cm、茎20 cm以上和谷)稻草的镉含量,开展高镉累积水稻镉累积规律、移除时间和移除高度研究.结果表明,水稻扬稻6号和玉珍香各部位镉含...     

Mechanisms of cadmium accumulation in rice grains and molecular breeding for its reduction

ABSTRACT

Cadmium (Cd) has an important impact on agriculture, as the excessive consumption of this element from contaminated food crops leads to toxicity in humans. Rice is the greatest source of dietary Cd intake in populations consuming rice as a staple food. Therefore, reducing the Cd concentration of rice grains for diminishing the potential risk of Cd for human health is a major challenge. This review summarizes the main achievements on Cd accumulation in rice by our research group. Using a positron-emitting tracer imaging system, we succeeded to visualize differences in real-time Cd dynamics from roots to panicles in rice varieties with different Cd accumulation abilities. Several loci or genes responsible for Cd accumulation in rice were found through quantitative trait loci (QTLs) analysis. Using the QTL qCdp7 responsible for efficiently extracting Cd from paddy soils, practical rice varieties for Cd-phytoextraction were developed by DNA marker-assisted breeding. A rice variety named ‘Koshihikari Kan No.1? carrying a mutant allele of OsNramp5 for reducing Cd concentration in rice grains was produced by mutant breeding with ion-beams, and breeding programs have been implemented to transfer this allele into many Japanese rice varieties by DNA marker-assisted breeding. Growing low-Cd varieties aerobically would be a feasible way to simultaneously reduce inorganic arsenic and Cd concentrations in rice grains. These results provide basis for reducing Cd concentration in rice through breeding new varieties.     

外源Cd在不同品种水稻组织中的细胞分布和化学形态特征研究

采用水培试验,以低镉(Cd)积累水稻品种‘D83A/R527’和高Cd积累水稻品种‘辐优838’为供试材料,设置3个Cd浓度(5μmol·L~(-1)、10μmol·L~(-1)、25μmol·L~(-1))处理,从Cd亚细胞及化学形态分布角度研究了不同基因型水稻品种的Cd积累特性,为探讨水稻对Cd的吸收积累生理机制提供科学依据。结果表明:(1)水稻‘D83A/R527’的根系和茎叶Cd含量及根系-茎叶转移系数均显著低于‘辐优838’(P0.05)。(2)两水稻根系各亚细胞组分中Cd含量表现为可溶部分(F3)细胞壁(F1)细胞器(F2),茎叶表现为细胞壁(F1)可溶部分(F3)细胞器(F2);‘D83A/R527’根系和茎叶细胞壁Cd的质量分数(36.76%~51.75%)高于‘辐优838’(31.29%~49.07%)。(3)两水稻品种Cd化学形态含量均表现为氯化钠提取态(F_(NaCl)-Cd)醋酸提取态(F_(HAc)-Cd)去离子水提取态(F_W-Cd)乙醇提取态(F_E-Cd)盐酸提取态(F_(HCl)-Cd);随Cd处理浓度的增加,‘D83A/R527’根系F_E-Cd和F_W-Cd(活性态Cd)质量分数逐渐下降(24.75%~18.34%),‘辐优838’活性态Cd逐渐上升(27.18%~28.68%),茎叶F_(HAc)-Cd和F_(HCl)-Cd(惰性态Cd)质量分数(32.41%~38.98%)逐渐上升且高于‘辐优838’(28.44%~31.22%),‘D83A/R527’根系和茎叶F_(NaCl)-Cd质量分数(32.71%~51.17%)均高于‘辐优838’(32.14%~47.63%)。综上,‘D83A/R527’水稻幼苗Cd积累量低;与‘辐优838’相比,‘D83A/R527’水稻幼苗根系和茎叶细胞壁质量分数较高,"活性态"Cd质量分数较低,"惰性态"Cd则更高,表明‘D83A/R527’水稻对Cd有更强的固持能力。     

Zn accumulation and subcellular distribution in the Zn hyperaccumulator Sedurn alfredii Hance

Zn accumulation and subcellular distribution in leaves of the hyperaccumulating ecotype （HE） and non-hyperaccumulating ecotype （NHE） of Sedum alfredii Hance were studied using radiotracer and gradient centrifugation techniques. Leaf Zn accumulation in the HE of S. alfredii was 18.5-26.7 times greater than that in the NHE when the plants were grown at 1-500μmol Zn L-1. Leaf section uptake of 65Zn was highly dependent on external Zn levels. Greater 65Zn uptake in HE was noted only at external Zn levels 〉 100μmol L-1. Zinc subcellular distribution in the leaves of the two ecotypes of S. alfredii was： cell wall 〉 soluble fraction 〉 cell organelle. However, more Zn was distributed to the leaf cell wall and soluble fractions for HE than for NHE. In the leaf of HE, 91%-94% of the Zn was found in the cell walls and the soluble fraction and only 6%-9% Zn was distributed in the cell organelle fraction. For NHE, about 20%-26% Zn was recovered in the cell organelle fraction. In stems, Zn distribution to the ceil wail fraction was approximately two fold greater in the HE than that in the NHE. For the hyperaccumulating ecotype of S. alfredii, the cell wall and the vacuole played a very important role in Zn tolerance and hyperaccumulation.     

植物对镉毒害的形态和生理响应研究进展

Cadmium (Cd) contamination has posed an increasing challenge to environmental quality and food security.In recent years,phytoremediation has been particularly scrutinized because it is cost-effective and environmentally friendly,especially the use of metal-hyperaccumulating plants to extract or mine heavy metals from polluted soils.Under Cd stress,responses of hyperaccumulator and non-hyperaccumulator plants differ in morphological responses and physiological processes such as photosynthesis and respiration,uptake,transport,and assimilation of minerals and nitrogen,and water uptake and transport,which contribute to their ability to accumulate and detoxify Cd.This review aims to provide a brief overview of the recent progresses in the differential responses of hyperaccumulator and non-accumulator plants to Cd toxicity in terms of growth and physiological processes.Such information might be useful in developing phytoremediation technology for contaminated soils.     

氮对超积累植物东南景天生长和镉积累的影响

通过水培试验,研究了氮素水平对超积累植物东南景天植株生长和镉吸收积累的影响。结果表明,在一定范围内供氮（4.0-16.0 mm ol/L）能明显促进东南景天的生长,随着氮素水平的升高,地上部和根系的生物量也提高,在供氮水平为16.0 mm ol/L时达到最大值,而当供氮水平≥32.0 mm ol/L时,东南景天的生长受到严重的抑制,其地上部和根系的生物量开始下降,各项根系形态的指标（包括根系长度、根系表面积、根系直径、根系体积）均有所降低。氮对东南景天体内镉积累有一定的促进作用,随着氮素用量的增加,体内镉含量逐渐升高,与生物量不同,镉含量在氮水平32.0 mm ol/L条件下达到最大。研究结果表明,适当提高营养液氮素水平,有利于东南景天的生长和镉吸收,为进一步利用东南景天修复镉污染土壤,提高修复效率提供科学依据。     

不同磷水平下玉米和小麦植株亚细胞中镉的积累

Corn and wheat plants were grown in a nutrient culture solution at four levels of phosphorus (0,0.12,0.60 and 3.0mmol L^-1) and two levels of cadmium(0 and 4.0umol L^-1) in greenhouse for a 18-day period.The concentrations of phosphorus and cadmium in cell wall,cytoplasm and vacuoles of roots and leaves were examined by cell fractionation techniques.With increasing phosphorus in medium,the contents of P in cell wall,cytoplasm and vacuoles of corn and wheat roots and leaves increased.The highest content of P was observed in cell wall,next in vacuoles,and the lowest in cytoplasm.The wheat subcellular fractions in both roots and leaves hab higher concentrations of phosphorus than those of corn.Increasing phosphorus in medium significantly inhibited the intracellular Cd accumulation in both species,However,at P concentration up to 3.0mmol L^-1,the Cd content in cell wall was increased.Increasing phosphorus resulted in reduction of the subcellular Cd content in cell wall was increased.Increasing phosphorus resulted in reduction of the subcellualr Cd content in corn and wheat leaves.Compared with corn,the wheat roots had a higher Cd content in the cell wall and vacuoles and a lower in cytoplasm,while in leaf subcellular fractions the wheat cell had a higher Cd content in its vacuoles and a lower one in its cytoplasm,The results indicate that phosphorus may be involved in sequestration of Cd ionic activity in both cell wall and vaculoes by forming insoluble Cd phosphate.     

Intercropping of Sonchus asper and Vicia faba affects plant cadmium accumulation and root responses

The cadmium(Cd)pollution of farmland soil is serious in the world.The present study investigated the effects of intercropping Vicia faba and the hyperaccumulator Sonchus asper on the Cd accumulation and root responses(morphology and secreted organic acids)of plants grown on soil from a mining area in Yunnan Province,China,under different Cd stress levels(0,50,100,and 200 mg kg^-1).Intercropping increased the biomass of both S.asper and V.faba,as well as the Cd accumulation and Cd trans...     

混种凤仙花嫁接后代对葡萄幼苗生长及镉积累的影响

采用盆栽试验,以凤仙花未嫁接、同株嫁接、异株同苗嫁接、异株异苗嫁接后代与葡萄幼苗混种,研究在镉胁迫下混种凤仙花嫁接后代对葡萄幼苗生长及镉积累的影响。结果表明,与葡萄幼苗单种相比,混种凤仙花嫁接后代提高了葡萄幼苗的生物量、光合色素含量、抗氧化酶活性、可溶性蛋白及可溶性糖含量,并显著降低了葡萄幼苗根系及地上部分的镉含量;混种凤仙花嫁接后代显著增加了土壤pH值并降低土壤的有效态镉含量。其中,混种异株异苗株凤仙花嫁接后代促进葡萄幼苗生长和降低土壤镉积累的效果最好。与葡萄单种相比,混种异株异苗株凤仙花嫁接后代葡萄幼苗根系和地上部分的生物量分别增加了47.25%和23.16%;葡萄幼苗根系及地上部分的镉含量显著低于葡萄单种和其它嫁接处理;土壤的有效态镉含量较葡萄单种降低了10.02%。本研究中葡萄幼苗混种的凤仙花嫁接后代均可应用于葡萄园镉污染土壤的修复,且最佳材料是凤仙花异株异苗嫁接后代。     

锌镉超富集植物滇苦菜中碳酸酐酶对镉的响应

A number of higher plants are able to hyperaccumulate cadmium(Cd). However, it is unknown whether cadmium(Cd) plays a biological functional role in the carbonic anhydrase(CA) of hyperaccumulators. A hydroponic experiment was conducted to explore the potentially physiological function of Cd in CA and the accumulation and tolerance of Cd in the Zn/Cd hyperaccumulator Picris divaricata Vant. P. divaricata was exposed to nutrient solutions with six Cd concentrations(0, 5, 10, 25, 50 and 75 μmol L~(-1)). After 12 d, plants were harvested for the analysis of plant biomass, Cd concentration and CA activity. The Cd concentrations in plant increased with the increasing Cd in nutrient solution, reaching 640 and 3 100 mg kg~(-1) in shoot and root, respectively, at the 75 μmol L~(-1) Cd treatment. Meanwhile, plant growth was enhanced by the Cd treatments at 5–25 μmol L~(-1), but it was significantly inhibited when the plants were exposed to solutions with higher Cd concerntrations(50 and 75 μmol L~(-1)). Exposure to Cd significantly increased the CA activity in P. divaricata, which reached a maximum value of 21.27 U mg~(-1) proteins at the 25 μmol L~(-1)Cd treatment, and the CA activity and shoot Cd concentration were positively correlated at solutions Cd of ≤ 25 μmol L~(-1). Moreover, two protein bands appeared on the denatured gel electrophoresis of purified CA, indicating that P. divaricata may have CA isomers with their respective molecular weights at around 60 and 55 k Da, at least one of which is Cd-bound. In addition, trace amounts of Cd in purified CA significantly increased with the supplied Cd concentration in nutrient solution(5–25 μmol L~(-1)). The results suggested that Cd may play a biological role by enhancing the activities and forming the active Cd-specific CA in the hyperaccumulator P. divaricata.     

Cadmium and zinc accumulation by the hyperaccumulator Thlaspi caerulescens from soils enriched with insoluble metal compounds

Abstract

The clay mineralogy of seven Dystrandepts developed on basalts in Northland (New Zealand), the French Massif Central and Western Oregon (U.S.A.) was determined by selective dissolution—differential infrared spectroscopy in combination with chemical, X-ray diffrac tion, electron microscopic and thermogravimetric analyses. Of 14 soil samples, 6 from Northland and Cantal (French Massif Central) contained allophane and imogolite, whereas the remaining 8 did not. Allophane-like constituents and/or “alumina” were found in all the samples, and opaline silica was present in three A₁ horizons. The contents of 2 : 1–2 : 1 : 1 layer silicates and their intergrades varied somewhat among the samples. Predominant volcanic glass shards in the Northland Dystrandepts and quartz in the Western Oregon Dystrandepts indicated that their parent materials were not restricted to basalt.     

Effects of calcium on cadmium uptake and transport in the tree species Gamblea innovans

The effect of calcium (Ca) on cadmium (Cd) accumulation in plants was investigated using Gamblea innovans Sieb. & Zucc., a deciduous tree species that is an accumulator plant for Cd and zinc (Zn). Saplings of G. innovans were grown for 3 months and fed with solutions containing only Ca (+Ca), both Ca and Cd (Ca+Cd), or only Cd (+Cd). The Ca concentration in roots was higher in both treatments containing Cd alone (+Cd) and Ca+Cd compared to roots treated with Ca alone (+Ca). In addition, the Cd concentration in roots was higher in the Ca+Cd treatment than the Cd treatment. This showed that the presence of Ca²⁺ in the rhizosphere relates with Cd uptake into roots. The result that the transport of Cd from roots through stem to leaves was suppressed by Ca treatment indicates that the presence of Ca regulates Cd transport from the roots. A clear correlation between Cd and Zn concentrations in leaves suggests a possibility that the Cd treatment accelerates the transport of Zn into leaves via the same protein transporter in this species.     

镉胁迫下不同生态型富集植物混种樱桃幼苗对土壤酶活性的影响

[目的]研究镉胁迫条件下,两种生态型(矿山和农田)富集植物与樱桃幼苗混种对土壤酶活性的影响,为镉污染区樱桃科学生产提供参考。[方法]将甜心樱桃和那翁樱桃幼苗分别与两种生态型的镉富集植物小飞蓬、龙葵、马唐混种,测定土壤过氧化氢酶、土壤脲酶和土壤蔗糖酶活性。[结果]甜心樱桃混种矿山生态型马唐的土壤过氧化氢酶和土壤脲酶活性均最高,分别较甜心樱桃单种提高了41.07%和57.53%。那翁樱桃混种农田生态型小飞蓬的土壤过氧化氢酶活性最高,混种矿山生态型马唐的土壤脲酶活性最高。樱桃幼苗混种两种生态型富集植物后,只有甜心樱桃混种农田生态型小飞蓬、那翁樱桃混种矿山生态型马唐、那翁樱桃混种农田生态型马唐提高了土壤蔗糖酶活性。[结论]镉胁迫条件下,与樱桃混种以提高土壤酶活性的首选材料是矿山生态型马唐,其次为农田生态型小飞蓬。     

Effects of cadmium stress on seedlings of various rangeland plant species (Avena fatua L., Lathyrus sativus L., and Lolium temulentum L.): Growth,physiological traits,and cadmium accumulation

A pot culture experiment was performed to study the effect of cadmium stress (Cd stress) on seedling growth, physiological traits, and remediation potency of Avena fatua, Lathyrus sativus, and Lolium temulentum. The seedlings of these native rangeland plant species were treated with 0, 2, 4, and 6 mM cadmium nitrate concentrations. Based on the results of analysis of variance (p < 0.05), the shoot height, shoot dry weight, root length, root dry weight, root: shoot ratio, total chlorophyll content, soluble sugars, and protein contentof A. fatua, L. sativus, and L. temulentum significantly decreased with increased cadmium concentrations. Generally, translocation factor (TF) and tolerance index (TI) decreased significantly as the concentration of cadmium increased. The maximum TF and TI of studied plants in various concentrations of Cd were observed in L. temulentum followed by L. sativus and A. fatua. The root concentration factor (RCF) values of all studied plants were higher than 1 under different cadmium concentrations. Our results indicate that Lolium temulentum could be labeled as an accumulator of Cd asthe values of TF and RCF are greater than 1. A. fatua and L. sativus showed a potential to be used in the phytoremediation of Cd-contaminated soils.     

Cadmium accumulation in Crassocephalum crepidioides (Benth.) S. Moore (Compositae) in heavy-metal polluted soils and Cd-added conditions in hydroponic and pot cultures

Abstract

We have identified Crassocephalum crepidioides (Benth.) S. Moore (Compositae) as a cadmium (Cd)-accumulator plant in a heavy-metal polluted environment. In soil polluted with Cd, 5.7–17.5 mg kg^?1 Cd, concentrations in the above-ground plant tissues were measured as 14.6–78.6 mg kg^?1 with transfer factors in the above-ground plant tissues (concentration in above-ground tissues/soil concentration) of 1.5–6.0. No other toxic heavy metals or plant micronutrients were found to have accumulated into the above-ground plant tissues. In a hydroponic culture with 1 µmol L^?1 Cd added to Hoagland's nutrient solution, Cd concentration in the above-ground plant tissues was 121.0 mg kg^?1, with a transfer factor of more than 1000. In a pot culture carried out for 9 weeks in a greenhouse, the highest Cd concentration in the above-ground plant tissues, 121.2 mg kg^?1, was found in a treatment with 5 mg kg^?1 Cd, whereas the highest Cd content in an above-ground plant tissue, 106.1 µg, was found in a treatment with 2 mg kg^?1 Cd. These results clearly showed that C. crepidioides is a Cd accumulator. In all samples, the Cd concentration in the above-ground plant tissues was higher than that in the roots. The results obtained in the present study show that this plant has a strong potential for use in phytoremediation in farm fields contaminated with Cd.