外源NO对镉胁迫下水稻幼苗抗氧化系统和微量元素积累的影响

重金属污染已成为世界范围的主要问题之一,其中镉(Cd)毒害的范围最广.Cd污染影响植物的生长和发育.一氧化氮(NO)作为植物体内的一种活性信号因子,参与了植物对各种胁迫的应答.为了探讨外源NO对Cd胁迫下水稻苗期生理生化响应的调节作用,以粳稻和籼稻为材料,采用营养液水培的方法,研究外源NO供体硝普钠(SNP)对100μmol/L Cd胁迫下2个水稻基因型(ZF802和ZH11)幼苗生长、抗氧化酶系统和微量元素吸收的影响.结果表明,1.5 mmol/L SNP能明显缓解Cd胁迫对两种水稻幼苗生长的抑制作用,提高幼苗对Cd的耐性.尽管存在一定的基因型差异,但外源NO能使两个基因型叶片中的超氧化物歧化酶(SOD)和过氧化物酶(POD)活性下降,降低了叶片中丙二醛(MDA)含量,从而缓解Cd对水稻幼苗的毒害.另外,外源NO影响Cd胁迫下水稻幼苗地上部和根部Cd和微量元素的积累,这种影响的程度与水稻的品种有关,具有显著的基因型差异,且机制较复杂.     

有机物料对污染土壤上水稻生长和重金属吸收的影响

采用盆栽试验,研究了施用有机碳源、菜籽饼和猪粪对污染土壤上水稻生长和重金属吸收特性的影响.结果表明： 施用菜籽饼和猪粪均能缓解重金属对水稻的毒害作用,促进水稻生长,显著增加地上部生物量和籽粒产量,降低糙米中重金属浓度;而有机碳源抑制水稻生长.与施用化肥相比,施用菜籽饼和猪粪处理的水稻籽粒产量分别增加128.3%和67.9%;施用菜籽饼处理的糙米Cd、Cu和Zn浓度分别降低47.6%、35.2%和21.5%,施用猪粪处理分别降低9.5%、21.2%和9.3%.土壤中DTPA提取态重金属浓度与水稻地上部生物量和重金属积累总量呈显著负相关.     

不同种类镁肥对烤烟中微量元素含量和产质量的影响

针对福建武平烟区土壤酸化严重,土壤有效镁含量偏低导致烟叶镁含量低的问题,研究了3 种不同镁肥对土壤和烤后烟叶中微量元素含量以及烤烟产质量的影响。结果表明,施用不同镁肥后均能显著提高土壤交换镁的含量,但不同镁肥对提高土壤交换镁含量的时效不同。各处理土壤其它中微量元素含量以施用硫酸镁的土壤较高,施用氢氧化镁的土壤偏低。烤后烟叶的镁含量以氧化镁处理最高,其次为氢氧化镁。施用镁肥会影响烟叶其它中微量元素的含量,其中施用氢氧化镁会导致中上部烟叶钙铁含量轻度缺乏,而施用硫酸镁会导致烟叶中锌锰含量过高。各处理中以氧化镁处理烟叶化学成分含量最适宜,且经济性状最优。因此,在福建武平烟区建议施用氧化镁,既可以防止烤烟生育前期有效镁的淋失,又可以提高烟叶的产量和质量。     

镉胁迫对金银花叶片含水量及微量元素吸收积累的影响

采用土培试验方法,研究了不同浓度镉(Cd)胁迫下金银花的叶片含水量和体内微量元素含量的变化。结果表明:随着Cd处理浓度的增加,叶片含水量呈先上升后下降的变化趋势。在100和200mg·kg-1Cd处理下,叶片含水量分别为70.4%和65.3%,与对照相比虽有所降低,但并未表现出显著差异。从整体上看,Cd胁迫促进了根中Fe含量增加,而Mn、Cu和Zn含量均有所下降;与对照相比,叶中Cu含量降低,Fe、Mn和Zn含量均在低浓度Cd处理下增加,随着Cd处理浓度的增加而降低。     

植物营养中新的必要,有益和毒害元素

至今为止,将近一个半世纪的研究,证明了18种化学元素是植物生命活动所必需的营养物质,其中的氯和钠在本世纪SO年代才被发现它们是植物的必需营养元素。进入SO年代又确认了镍是植物必需的微量营养元素。在植物体内已发现几乎含有化学元素周期表中自然存在的全部化学元素,这些化学元素存在于植物体内是来源于它们的生活环境——形成土壤的母质,以及环境的污染。在植物体内的化学元素,基本上可分为3类：（1）植物生命活动必需的,这些化学元素组成了植物体,成为植物体的结构物质,或参与植物生命活动中的新陈代谢活动。（2）虽然是非…     

根区通氧状况对水稻幼苗生长及吸收镉的影响

采用水培的方法研究了根区通氧状况对水稻根系结构、根系泌氧、根表铁膜生成以及水稻耐受、吸收Cd的影响.水培条件下,根区氧处理对水稻幼苗的生长产生了一定的影响,缺氧条件下的水稻根的伸长量降低,生物量增加,直径增粗,根系泌氧量增加,并降低幼苗对Cd的吸收.当培养溶液Cd2+浓度为1.0 mg/L时,缺氧处理相对于通氧处理,根表吸附的Cd降低了85 5%,地下部分吸收的Cd降低了35%,转运到地上部分的Cd降低了58%.根表铁膜对Cd的吸收和转运也有一定的抑制作用,但其作用因环境中Cd2+浓度和根区通氧状况而异.在根区通氧充分的培养条件下,水稻幼苗铁膜对较高浓度Cd2+(1.0 mg/L)的吸收和转运起着重要的作用,DCB-Cd占根系吸收Cd的50%,茎叶对Cd的吸收显著降低(p<0.05).研究表明在缺氧胁迫下,根系结构本身(如根表通透性降低)是影响水稻吸收Cd的重要因素.     

重金属镉对水稻根毛细胞钾离子吸收过程的影响

重金属镉进入植物体后会引起一系列的毒害反应,然而迄今为止有关镉毒害的机制并不明了。本研究综合使用了膜电势测定、非损伤微测和膜片钳等电生理学实验技术,检测了镉对水稻根毛细胞钾离子吸收过程的影响。研究结果显示,外源施用50μmol·L-1 CdCl2能明显造成水稻根毛细胞膜的去极化,抑制根毛细胞质膜内向K＋通道活性,同时诱导外向K＋通道开放,导致根系内K＋外渗,进而降低了水稻根部K＋含量。通过上述影响,镉扰乱了水稻根系对钾离子的吸收过程,造成钾元素缺失,成为植物体镉毒害作用的机理之一。     

镉胁迫对姬松茸生长和镉吸收累积的影响

利用外源镉添加的袋栽试验,系统研究了镉对姬松茸J37和J1两菌株农艺性状、子实体产量、氨基酸和镉含量的影响,以求为低富集镉的姬松茸品种选育和安全栽培提供科学依据。结果表明外源镉添加对姬松茸J37和J1品种子实体的农艺性状的影响各异,两菌株单个子实体重量、子实体高度、菌盖直径、菌盖厚度和菌柄直径等均与外源镉浓度具有显著的负相关性,其中子实体重量与外源镉浓度间的相关性最大;15 mg/kg镉水平是两菌株农艺性状发生显著变化的敏感点。不同镉水平下J37菌株单个子实体重量比J1菌株高10.9%—36.6%,表现为较强镉耐受性。姬松茸J37与J1菌株子实体产量、氨基酸和镉含量均随着潮次的增加而降低,子实体产量和氨基酸含量随着外源镉水平增加而降低,而镉含量随外源镉水平增加而增加。与外源镉0mg/kg处理相比,当外源镉水平达15 mg/kg时,J1和J37子实体总产量分别下降23.4%和13.4%以上,J1和J37子实体镉含量分别提高51.5%、13.7%以上,且J1子实体镉含量已达到食品卫生标准的临界值。当外源镉水平达到35 mg/kg时,J1和J37子实体产量分别下降45%、32%以上,J1和J...     

水稻中镉积累对粘虫的影响

水稻中重金属积累如何影响水稻害虫尚不清楚,本文拟探讨镉积累的水稻对粘虫Mythimna separata幼虫的影响。通过测定不同浓度氯化镉处理的水稻以及人工饲料对粘虫幼虫生长发育的影响,并进一步研究了氯化镉处理水稻中粘虫诱导的防御化合物含量的变化。研究表明水稻叶片中镉的积累导致粘虫幼虫生长减慢、死亡率上升。不同浓度镉处理可以显著提高粘虫诱导的酚胺类化合物对香豆酰腐胺、阿魏酰腐胺、肉桂酰腐胺以及阿魏酰胍丁胺的含量。不同浓度镉添加的人工饲料对粘虫幼虫的存活率无显著影响,而粘虫幼虫取食1 μM和10 μM氯化镉添加的人工饲料后体重反而高于取食未含镉的人工饲料。综上所述,镉积累提高了水稻中粘虫诱导的防御化合物的含量以及水稻对粘虫的抗性,研究结果有利于加深水稻与不同环境胁迫关系的认识。     

Influence of cadmium and nickel on growth,net photosynthesis and carbohydrate distribution in rice plants

Six day old rice seedlings (Oryza sativa L. cv. Bahía) were grown for 5 or 10 days in a nutrient solution with either Cd (0.01, 0.1 mmol/l) or Ni (0.1, 0.5 mmol/l). Both Cd and Ni reduced the length of shoots and roots depending on the concentration and type of ion tested. On the other hand, the dry weight to fresh weight ratio was increased by heavy metal treatments, especially in the aerial part of 0.5 mmol/l Ni treated plants. The application of 0.1 mmol/l Cd and 0.5 mmol/l Ni to the seedlings produced an inhibition of the transport of carbohydrate reserves from the seeds from which plants were developing, to the rest of the plant. Net photosynthesis was also inhibited in treated plants. However, the total carbohydrate content in the shoots of these plants was higher than in controls. Thus, the starch, soluble sugars and sucrose content in the shoots of 0.5 mmol/l Ni treated plants was respectively up to 2.6, 2.8 and 4 times greater compared to controls. The distribution of assimilates between organs was also affected by the treatment: the carbohydrate content increased in the stem and second leaf but it was not affected or decreased in the root and third leaf. Although less evident, the effect of Cd on carbohydrate distribution and content was similar to that of Ni. The possible mechanisms involved in the abnormal carbohydrate accumulation and distribution are discussed.Abbreviations 0 DT plants at day zero of treatment - 5 DT five days treated plants - 10 DT ten days treated plants - DW dry weight - FW fresh weight     

CO2浓度升高对不同品种水稻镉吸收和根形态的影响

为了探讨CO2浓度升高下不同水稻品种荣优398 (RY)和粤杂889(YZ)吸收重金属Cd差异性的原因,利用水培试验研究了不同浓度Cd处理下两种水稻吸收Cd的差异及根形态的变化特征.结果表明:低Cd处理(5、10、20 μmol·L-1)显著增加水稻生物量;当Cd浓度高于50 μmol·L-1时,Cd胁迫效果开始显现,水稻生物量减少.CO2浓度升高显著增加了水稻的生物量,增加了YZ茎Cd含量而降低了RY茎Cd含量.在5～200 μmol·L-1的Cd浓度下,CO2浓度升高增加了YZ活性根在总根长中的比例,降低了RY活性根的比例.CO2浓度升高下不同水稻品种根形态的变化是导致其对Cd吸收差异性的原因之一.     

Effect of acidulation of high cadmium containing phosphate rocks on cadmium uptake by upland rice

Little information is available in literature on Cd uptake by crops from either phosphate rock (PR) or partially acidulated PR (PAPR). The purpose of this greenhouse experiment was to study the effect of acidulation of two PRs having high Cd content (highly reactive North Carolina PR and low-reactive Togo PR) on Cd uptake by upland rice. The degrees of acidulation with H₂SO₄ were 100% for North Carolina PR (NC-single superphosphate [SSP]) and 50% or 100% for Togo-PR (i.e., Togo PAPR or Togo-SSP). Separation of the confounding effect between P uptake and Cd uptake from various P sources was made by adding 200 mg P/kg as KH₂PO₄ to all the treatments. Rates of Cd added from various P sources were 50–400 µg Cd/kg. Upland rice (Oryza sativa L.) was grown on two acid soils (Hartsells, pH 5.0 and Waverly, pH 5.6) to maturity.The results show that Cd uptake by rice grains followed the order of NC-SSP> NC-PR and Togo SSP> Togo PAPR> Togo PR. The results also showed that most of the Cd uptake was retained in rice roots and straw. Total uptake of Cd, Ca, and P by rice plant (root, straw, and grain) was higher from NC-PR than from Togo-PR. Cd concentration in rice grains showed no significant difference between NC-PR and Togo-PR, whereas Cd concentrations in root and straw were higher with NC-PR than that with Togo-PR. There was a significant relationship between total Cd uptake by rice plant and Cd extracted by DTPA from soils treated with various P sources at 400 µg Cd/kg.     

玉米与番茄间作对土壤镉吸收的影响

为探究间作对作物吸收重金属镉(Cadmium,Cd)的影响,以Cd相对高积累番茄(中蔬4号)和相对低积累玉米(金珠蜜甜玉米)为试验材料,在Cd 3.70 mg/kg的污染水平下以单作、限制性间作、间作3种种植方式进行了盆栽试验,研究间作后作物各部位Cd积累差异及其形成原因。结果表明,番茄和玉米间作和限制性间作所产番茄根、茎、叶中Cd含量均有所提高(叶中Cd含量从13.52mg/kg分别升高至24.94mg/kg和27.30mg/kg);与未种植作物的对照组相比,非单作条件下番茄根围土壤的pH有所下降,酸性磷酸酶活性上升,而脲酶活性下降,且间作组变化幅度较大;间作还能改变作物根围微生物种群结构,提高对重金属吸收有促进作用的微生物种群的丰度,最终实现Cd高积累番茄对Cd的吸收能力提高。研究结果可为利用间作模式修复土壤重金属污染和保障食品安全提供参考。     

OsNRAMP1 transporter contributes to cadmium and manganese uptake in rice

Rice is a major dietary source of the toxic metal, cadmium (Cd). Previous studies reported that the rice transporter, OsNRAMP1, (Natural resistance-associated macrophage protein 1) could transport iron (Fe), Cd and arsenic (As) in heterologous yeast assays. However, the in planta function of OsNRAMP1 remains unknown. Here, we showed that OsNRAMP1 was able to transport Cd and manganese (Mn) when expressed in yeast, but did not transport Fe or As. OsNRAMP1 was mainly expressed in roots and leaves and encoded a plasma membrane-localized protein. OsNRAMP1 expression was induced by Cd treatment and Fe deficiency. Immunostaining showed that OsNRAMP1 was localized in all root cells, except the central vasculature, and in leaf mesophyll cells. The knockout of OsNRAMP1 resulted in significant decreases in root uptake of Cd and Mn and their accumulation in rice shoots and grains, and increased sensitivity to Mn deficiency. The knockout of OsNRAMP1 had smaller effects on Cd and Mn uptake than knockout of OsNRAMP5, while knockout of both genes resulted in large decreases in the uptake of the two metals. Taken together, OsNRAMP1 contributes significantly to the uptake of Mn and Cd in rice, and the functions of OsNRAMP1 and OsNRAMP5 are similar but not redundant.     

Role of the iron transporter OsNRAMP1 in cadmium uptake and accumulation in rice

The heavy metal cadmium (Cd) is toxic to humans, and its accumulation in rice grains is a major agricultural problem. Rice has seven putative metal transporter NRAMP genes, but microarray analysis showed that only OsNRAMP1 is highly up-regulated by iron (Fe) deficiency. OsNRAMP1 localized to the plasma membrane and transported Cd as well as Fe. OsNRAMP1 expression was observed mainly in roots and was higher in the roots of a high-Cd-accumulating cultivar (Habataki) than in those of a low-Cd-accumulating cultivar (Sasanishiki). The amino acid sequence of OsNRAMP1 in the Sasanishiki and Habataki cultivars was found to be 100% identical. These results suggest that OsNRAMP1 participates in cellular Cd uptake and that the differences observed in Cd accumulation among cultivars are because of differences in OsNRAMP1 expression levels in roots.     

不同生长调节物质对水稻生长及镉积累的影响

比较脱落酸(ABA)、乙烯利(ETH)、水杨酸(SA)和茉莉酸甲酯(MeJ A)4种植物生长调节物质(PGR)对水稻生长及籽粒镉(Cd)积累的影响差异。试验采用重金属污染土种植水稻,于分蘖期、灌浆期各进行1次PGR叶面喷施处理,分析灌浆期叶片光合指标,丙二醛(MDA)含量以及收获期各部位生物量和Cd含量。结果表明:(1)低浓度ABA(5mg/L)可维持水稻正常产量;高浓度ABA(15mg/L)则导致产量下降。ETH对水稻地上部生长和单株产量有显著抑制作用,SA和MeJ A(0.56mg/L)均可保证地上部正常生长,维持正常产量。(2)外施4种PGR均抑制灌浆期叶片气孔开放,降低蒸腾速率和光合速率,抑制效果最明显的是高浓度MeJ A(0.56mg/L)。(3)在供试浓度范围内SA、低浓度ABA(5mg/L)以及高浓度MeJ A均可降低灌浆期叶片MDA含量,减少质膜过氧化水平。(4)4种PGR均可降低水稻籽粒Cd含量,其中低浓度ABA(5mg/L)抑制籽粒Cd积累的效应最佳。相关性分析结果表明,PGR抑制籽粒积累Cd的效应与地上部向籽粒转运Cd的调控机制有关,与蒸腾速率无显著相关关系。(5)综上所述,低浓度ABA(5mg/L)处理对水稻产量无影响,且籽粒Cd含量降低程度最大。适当浓度的PGR可降低水稻籽粒Cd含量,在中低度重金属污染农田生态修复实践中具有一定的应用前景,但必须精确控制PGR的处理时间和处理浓度,避免出现抑制生长和降低产量的负效应。     

转座因子对水稻同义密码子使用偏性的影响

利用635个包含完整转座因子插入的粳稻CDS序列,对转座因子如何影响基因编码区的碱基组成及基因的表达水平,进而对基因同义密码子的使用偏性产生影响进行了详细分析。结果表明:转座因子插入极显著地影响到基因编码区的同义密码子使用但并非唯一因素;转座因子对不同基因的表达水平具有多重影响,有的基因表达被抑制,有的反而增强,但总的来说它减少了基因表达水平对同义密码子使用的影响程度。