活性X—3B红染料的生物富集因子及在作物体内的分配

有机染料已成为中国地表环境中重要的一大类有机污染物,采用水培和土壤两种微宇宙生态试验方法,对活性X－3B红染料的生物富集因子（BCF）及在作物体内的分配进行了研究,结果表明,在试验浓度范围内,该化合物BCF为252．1－409．4,根据这一数值和有关评判依据,可知一般生物体对该有机染料具有中等水平的富集能力,各试验作物地下部分对活性X－3B红染料的积累比地上部分至少超出10倍,尤其以根部作为食物的萝卡更为明显,从土壤－作物系统的完整性进行了比较和以地上籽实为粮食的作物来看,各作物及其不同部位对活性X－3B红染料的积累浓度大致为大豆（棕壤）＞小麦（褐土）＞水稻（水稻土）,根＞＞茎秆＞叶＞籽实（不含壳）;而从这些作物在其籽实中积累活性X－3B红染料来看,以累积量为最低的水稻籽实中的最大浓度也可达到23．33μg.kg^-1,可见,该有机染料对环境污染的生态风险不容忽视。     

活性X-3B红染料对作物生态毒理指标影响的比较研究

采用作物种子暴露实验 ,研究了小麦、白菜和水稻等 3种不同作物对活性X 3B红染料污染暴露的生态毒理学指标 .结果表明 ,小麦、白菜和水稻对活性X 3B红染料污染暴露的反应各异 ,具体表现为对3种作物的种子发芽抑制半效应浓度分别为 896 5、70 10和 75 14mg·L-1,对根伸长抑制的半效应浓度分别为 6 5 34、5 882和 45 70mg·L-1;这 3种作物在从种子萌发起至第 7天时去残余种子或种皮后的鲜生物量、干生物量均随活性X 3B红暴露浓度的增加而降低 ,但鲜生物量的降低率普遍高于干生物量的降低率 ;当作物种子暴露于高浓度 (4 5 0 0和 5 0 0 0mg·L-1)的活性X 3B红时 ,小麦生物量受该有机染料污染暴露的影响最为敏感 ,水稻其次 ,白菜最为迟钝 ;就小麦、白菜和水稻等 3种作物对活性X 3B红染料污染暴露的抗性而言 ,小麦最强 ,白菜次之 ,水稻最弱 .     

活性X-3B红染料在水-土壤-作物连续体中的迁移模型研究

进入环境的自学成才性X-3B红染料是一典型的持久性有机污染物（POPs)。它从水分室向土壤分室再到作物分室的迁移,是一连续的生态过程,基于此,从理论上对活性X-3B红染料在水-土壤两相,土壤-作物两相以及水-土壤-作物整个连续体中的迁移进行了定量描述与探讨,并采用棕壤-大豆、褐土-小麦,红壤-萝卜和水稻土-水稻等系统给予了实验论证,表明活性X-3B红染料通过吸附机制从水分室到土壤分室的迁移符合Langmuir模型。通过作物根系吸收机制从土壤分室到作物分室的迁移可以用对数化的作物-土壤积累因子（CSAF）模型予以定量描述。     

土壤类型与作物基因型对花生籽实镉积累的影响

以花生主产区的棕壤和潮土为供试土壤,以种植面积最大的白沙1016、花育22和湛油27基因型花生(Arachis hypogaea)为供试作物,采用不添加Cd(对照)和添加Cd(1.5 mg· kg-1)处理进行盆栽试验,研究土壤类型和作物基因型对花生籽实Cd积累的影响.结果表明:两种土壤对照处理的3种基因型花生籽实Cd含量均低于国家食品安全标准,而Cd处理下均高于食品安全标准.同种土壤Cd处理3种基因型花生籽实Cd含量显著高于对照,不同基因型间表现为湛油27＞白沙1016＞花育22,棕壤花生籽实Cd含量及总量均高于潮土.对照处理3种基因型花生籽实Cd生物富集系数均大于1.0,Cd处理下多小于1.0,表明花生籽实对土壤中Cd的累积能力较强,土壤Cd含量进一步增加时,其生物富集能力降低.     

土壤类型与作物基因型对花生籽实镉积累的影响

以花生主产区的棕壤和潮土为供试土壤,以种植面积最大的白沙1016、花育22和湛油27基因型花生(Arachis hypogaea)为供试作物,采用不添加Cd(对照)和添加Cd(1.5 mg·kg^-1)处理进行盆栽试验,研究土壤类型和作物基因型对花生籽实Cd积累的影响.结果表明：两种土壤对照处理的3种基因型花生籽实Cd含量均低于国家食品安全标准,而Cd处理下均高于食品安全标准. 同种土壤Cd处理3种基因型花生籽实Cd含量显著高于对照,不同基因型间表现为湛油27＞白沙1016＞花育22,棕壤花生籽实Cd含量及总量均高于潮土. 对照处理3种基因型花生籽实Cd生物富集系数均大于1.0,Cd处理下多小于1.0,表明花生籽实对土壤中Cd的累积能力较强,土壤Cd含量进一步增加时,其生物富集能力降低.     

外源磷对苗期小麦和水稻根际砷形态及其生物有效性的影响

采用土(中度砷污染土)-土根袋培养的方法研究了两个浓度的外源磷(P)对苗期小麦和水稻根际砷(As)形态分布及其生物有效性的影响.结果表明:(1)两种作物生长的土壤中各砷形态的分配比例依次为:结晶铁锰或铁铝水化氧化物结合态(45%～52%)＞无定形和弱结晶铁铝或铁锰水化氧化物结合态(26%～34%)＞专性吸附态(12%～14%)＞残渣态(4%～7%)＞非专性吸附态(0.09%～0.25%).(2)添加外源磷浓度为100 mg·kg-1与不施磷处理相比显著提高了两种作物地上部的生物量(p＜0.01).(3)苗期小麦在添加100 mg·kg-1外源磷时,不仅促进了作物生长而且抑制根中砷向地上部的转运.(4)任何磷处理下,水稻对砷的吸收能力以及由根系向地上部转移能力均高于小麦.因此,在轻中度砷污染土壤上与水稻相比更适宜种植小麦(或其他旱作植物);而在水稻种植季,可以通过添加适量磷肥(100 mg·kg-1)来减弱砷在水稻体内的累积.     

德国鸢尾对Cd胁迫的生理生态响应及积累特性

通过盆栽研究了Cd胁迫下德国鸢尾的生长状况、生态效应、生理特性及吸收和富集Cd的能力.结果表明:德国鸢尾对小于5 mg/kg的Cd有较强的耐性,适用于城区土壤修复;Cd浓度大于5 mg/kg时抑制德国鸢尾生长,降低了其生态效应.随着Cd浓度的增大,德国鸢尾根系活力、叶绿素含量和含水量逐渐降低,游离脯氨酸和可溶性糖含量先升高后降低,细胞膜透性逐渐升高.Cd在德国鸢尾体内分布为根系＞地上部分,随着Cd浓度的增大,德国鸢尾根系和地上部分Cd积累浓度逐渐升高、富集系数和转运系数逐渐降低;Cd浓度为20 mg/kg时德国鸢尾对Cd的积累量最大,为2.122 mg/plant.     

各种改性剂对重金属迁移,积累影响的研究

采用盆栽实验．研究了在不同改性措施条件下,Ｃｄ、Ｐｈ、Ｃｕ、Ｚｎ、Ａｓ多元素复合污染物对水稻、大豆生长的影响及重金属在土壤－作物系统中迁移、积累的特性．结果表明,作物根系中的离子冲量越大,对作物危害越重．酸处理对作物生长影响较大,而腐殖酸和石灰处理有利于作物的生长．改性剂对重金属迁移能力影响大小依次为酸＞腐殖酸＞石灰．作物的不同部位对重金属吸收的顺序为根＞茎叶＞籽实．重金属在土壤－作物系统中的迁移能力为Ｃｄ＞Ｚｎ＞Ｃｕ＞Ａｓ＞Ｐｂ．     

木耳菜在4种土壤中对Cs的吸收与转运研究

土壤类型是Cs污染植物修复技术的重要影响因素。采用盆栽试验,将木耳菜分别移栽在紫色土、水稻土、红壤和黄壤土中,待3叶期,分别施加不同浓度的Cs[0、20、40、80、120mg·kg~(-1) CsCl]处理10、20、30d后取样,分析木耳菜在4种土壤中对Cs的吸收与转运差异,探讨不同土壤类型、土壤pH值以及速效钾含量对木耳菜富集Cs的影响机制。结果显示:(1)不同土壤类型中木耳菜的Cs含量均与Cs施加浓度和处理时间呈显著正相关关系,植物各器官间Cs积累量大小依次为根叶茎,表明木耳菜的根、茎、叶在不同类型土壤中均能积累Cs,随着处理时间的延长,其吸收量随Cs施加浓度的增大而增加,但以根部的富集能力最强、积累量最大。(2)在不同土壤类型中和不同处理时间段,木耳菜对Cs的富集系数和转运系数均存在显著差异,其富集与转运能力随着Cs施加浓度的增大以及处理时间的延长表现为先增后减,其地下部分富集系数显著高于地上部分,且黄壤土中木耳菜对Cs的富集能力明显高于其它3种土壤。(3)土壤中的钾含量和pH值影响木耳菜对Cs的吸收和富集,与紫色土、水稻土和红壤相比,黄壤土中的速效钾含量较低,pH适中,在不同处理时间段,木耳菜在黄壤土中对Cs的富集效率都最高,表明土壤中低含量的速效钾以及适中的pH值更利于木耳菜对Cs的吸收。     

土壤中有效态镉与籽实中镉含量的关系

污水灌溉农田,在我国已有几十年的历史。未经处理的污水,长期灌溉农田,已造成各种污染物在土壤、作物中的累积。较为明显的是重金属镉对土壤、作物的污染。镉在生态系统中的迁移转化规律,土壤中全量镉与籽实中镉含量的关系,在国内外多有报道。本文主要通过盆栽试验水稻、大豆及污灌区的水稻来阐述土壤有效态镉与作物籽实中镉含量的关系。一、材料与方法1.土壤盆栽试验所需要的土壤,取材于沈阳市新民县胡台村,属非污染区草甸土,土体中游离碳酸钙全部淋     

Low cadmium (LCD), a novel gene related to cadmium tolerance and accumulation in rice

The contamination of food crops by cadmium (Cd) is a major concern in food production because it can reduce crop yields and threaten human health. In this study, knockout rice plants (Oryza sativa) tagged with the gene trap vector pGA2707 were screened for Cd tolerance, and the tolerant line lcd was obtained. The lcd mutant showed tolerance to Cd on agar plates and in hydroponic culture during early plant development. Metal concentration measurements in hydroponically grown plants revealed significantly less Cd in the shoots of lcd plants compared with wild-type (WT) shoots. When cultured in the field in soil artificially contaminated with low levels of Cd, lcd showed no significant difference in the Cd content of its leaf blades; however, the Cd concentration in the grains was 55% lower in 2009 and 43% lower in 2010. There were no significant differences in plant dry weight or seed yield between lcd and wild-type plants. LCD, a novel gene, is not homologous to any other known gene. LCD localized to the cytoplasm and nucleus, and was expressed mainly in the vascular tissues in the roots and phloem companion cells in the leaves. These data indicate that lcd may be useful for understanding Cd transport mechanisms and is a promising candidate rice line for use in combating the threat of Cd to human health.     

Analysis of Metal Element Distributions in Rice (Oryza sativa L.) Seeds and Relocation during Germination Based on X-Ray Fluorescence Imaging of Zn,Fe, K,Ca, and Mn

Knowledge of mineral localization within rice grains is important for understanding the role of different elements in seed development, as well as for facilitating biofortification of seed micronutrients in order to enhance seeds’ values in human diets. In this study, the concentrations of minerals in whole rice grains, hulls, brown rice, bran and polished rice were quantified by inductively coupled plasma mass spectroscopy. The in vivo mineral distribution patterns in rice grains and shifts in those distribution patterns during progressive stages of germination were analyzed by synchrotron X-ray microfluorescence. The results showed that half of the total Zn, two thirds of the total Fe, and most of the total K, Ca and Mn were removed by the milling process if the hull and bran were thoroughly polished. Concentrations of all elements were high in the embryo regions even though the local distributions within the embryo varied between elements. Mobilization of the minerals from specific seed locations during germination was also element-specific. High mobilization of K and Ca from grains to growing roots and leaf primordia was observed; the flux of Zn to these expanding tissues was somewhat less than that of K and Ca; the mobilization of Mn or Fe was relatively low, at least during the first few days of germination.     

Transport of Cd and Zn to seeds of Indian mustard (Brassica juncea) during specific stages of plant growth and development

The accumulation of excess Cd in the seeds of cereal and other crops compromises their commercial value and presents a potential risk to human health. Indian mustard [ Brassica juncea (L.) Czern.] is a moderate accumulator of heavy metals such as Cd and Zn, and the seeds are consumed throughout the world, particularly in the Indian subcontinent. The study here examined the transport of Cd into Indian mustard plants and to seeds as a function of external Cd and the stage of the life cycle (vegetative growth, flowering and seed set) to identify critical developmental windows where transport from roots to seeds was the greatest. Plants were also treated simultaneously with Zn to determine if Zn fertilization mitigated the transport of Cd to seeds. Plants treated with Cd during the seed set accumulated the highest concentrations of Cd, exceeding 8 mg kg⁻¹ dry weight in some instances. Cadmium accumulated during vegetative growth was not highly redistributed to seeds. No effects of Zn were observed with regard to Cd redistribution to seeds. This may be because of the relatively small Zn : Cd ratios tested. However, the results suggest that if Zn fertilization is to be used to reduce the Cd accumulation in seeds of this species, that plants should be treated during the seed set stage. As the seeds of Indian mustard consistently accumulated Cd to concentrations that exceed acceptable limits for food crops, additional study of Cd redistribution in this species is warranted.     

Pseudomonas aeruginosa inducing rice resistance againstRhizoctonia solani: Production of salicylic acid and peroxidases

Three isolates of Pseudomonas aeruginosa were used for seed treatment of rice; all showed plant growth promoting activity and induced systemic resistance in rice against Rhizoctonia solani G5 and increased seed yield. Production of salicylic acid (Sal) by P. aeruginosa both in vitro and in vivo was quantified with high performance liquid chromatography. All three isolates produced more Sal in King's B broth than in induced roots. Using a split root system, more Sal accumulated in root tissues of bacterized site than in distant roots on the opposite site of the root system after 1 d, but this difference decreased after 3 d. Sal concentration 0-200 g/L showed no inhibition of mycelial growth of R. solani in vitro, while at > or =300 g/L it inhibited it. P. aeruginosa-pretreated rice plants challenged inoculation with R. solani (as pathogen), an additional increase in the accumulation of peroxidase was observed. Three pathogenesis-related peroxidases in induced rice plants were detected; molar mass of these purified peroxidases was 28, 36 and 47 kDa. Purified peroxidase showed antifungal activity against phytopathogenic fungi R. solani, Pyricularia oryzae and Helminthosporium oryzae.     

冬季作物种植对双季稻根系酶活性及形态指标的影响

基于湖南长沙7a定位试验,以冬闲为对照,研究了冬种马铃薯、紫云英及油菜为前茬作物对早、晚稻根系酶活性、形态指标及产量的影响.结果表明,与冬闲相比,冬种作物后早、晚稻根系丙二醛(MDA)含量增加,但其根系的活性氧清除能力更强(SOD、POD和CAT活性高),能够在一定程度上缓解膜脂过氧化作用带来的伤害;冬种不同作物对早晚稻根系形态的影响表现不一.冬种马铃薯和紫云英处理在早稻生育后期的根系优势明显,并能在一定程度上促进晚稻根系生长,双季稻总产量较对照分别增加6.29％和7.76％,而冬种油菜抑制了晚稻根系生长,导致晚稻产量及双季稻总产分别降低6.31％和1.96％;相关性分析表明,灌浆期较高的根长、根数、根体积和根表面积是冬种作物改善双季稻产量的主要原因.综合来看,冬种马铃薯和紫云英对于促进双季稻根系生长,提高稻谷产量具有重要作用,而冬种油菜则不利于提高双季稻的稻谷生产力.     

四倍体野生稻快速驯化: 启动人类新农业文明

通过人工选择优良遗传变异, 将野生植物驯化为栽培作物, 以满足人类对食物的需求, 是人类发展历史中的重要事件, 推动了人类文明的持续发展。随着世界人口持续增加, 耕地面积不断减少, 灾害性天气频发, 全球粮食安全问题日趋严峻。基于作物驯化的分子机理及重要农艺性状的遗传基础, 结合高通量基因组测序和高效基因组编辑技术, 从头驯化野生植物, 创造新型作物, 将是应对这一挑战的有效策略之一。近日, 中国科学院遗传与发育生物学研究所李家洋团队联合国内外多家单位, 通过组装异源四倍体高秆野生稻(Oryza alta)基因组, 优化遗传转化体系, 利用基因组编辑技术, 使其落粒性、芒性、株型、籽粒大小及抽穗期等决定作物驯化成功与否的重要性状发生改变, 成功实现了异源四倍体高秆野生稻的从头定向驯化。该突破性研究成果证明了通过从头驯化将异源四倍体野生稻培育成未来的主粮作物, 是确保粮食安全的可行策略, 同时也为从头驯化野生和半野生植物、创制新型作物提供了重要参考。     

A golden era—pro-vitamin A enhancement in diverse crops

Numerous crops have been bred or engineered to increase carotenoid levels in an effort to develop novel strategies that address vitamin A deficiency in the developing world. The pioneering work in rice (not covered in this review) has been followed up in many additional crops, some of which are staples like rice whereas others are luxury products whose impact on food security is likely to be marginal. This review surveys the progress that has been made in carotenoid breeding and metabolic engineering, focusing on β-carotene enhancement in crops other than rice. We ask if these efforts have the potential to address vitamin A deficiency in developing countries by comparing bioavailable pro-vitamin A levels in wild type and enhanced crops to determine whether nutritional requirements can be met without the consumption of unrealistic amounts of food. The potential impact of carotenoid enhancement should therefore be judged against benchmarks that include the importance of particular crops in terms of global food security, the amount of bioavailable β-carotene, and the amount of food that must be consumed to achieve the reference daily intake of vitamin A.