Meiotic pairing behaviour reveals differences in genomic constitution between Hystrix patula and other species of the genus Hystrix Moench (Poaceae, Triticeae)

Interspecific and intergeneric hybridizations were carried out to evaluate the genomic relationships among species of Hystrix Moench and to study the relationships between Hystrix species and Psathyrostachys huashanica Keng (2n=2x=14, Ns^h). Meiotic pairing in hybrids of Hystrix duthiei ssp. duthiei × P. huashanica (2n=3x=21), Hystrix duthiei ssp. longearistata × P. huashanica (2n=3x=21) and H. patula × P. huashanica (2n=3x=21) averaged 5.18, 5.11 and 0.29 bivalents per cell, while H. patula × H. duthiei ssp. longearistata (2n=4x=28) averaged 25.36 univalents and 1.32 bivalents per cell, respectively. The results indicate that (i) H. duthiei ssp. duthiei and H. duthiei ssp. longearistata have one set of Ns genome from Psathyrostachys; (ii) H. patula has no Ns genome; (iii) genomes of H. duthiei ssp. duthiei and H. duthiei ssp. longearistata are non-homologous to those of H. patula. The genomic relationships between H. patula and other Hystrix species are also discussed.     

华山新麦草光合特性对干旱胁迫的响应

以濒危植物华山新麦草为材料进行盆栽试验,设置3个水分梯度,研究生长指标、气体交换、叶绿素荧光参数、光合色素含量、光响应特征及丙二醛(MDA)含量.结果表明:随干旱胁迫的加剧,株高、叶宽和光合色素含量降低,根长和丙二醛(MDA)含量增加;水分胁迫导致净光合速率(PN)、气孔导度(gs)、蒸腾速率(E)、最大荧光(Fm)、光合电子传递速率(ETR)和光化学猝灭系数(qP)降低,胞间CO2浓度(Ci)、瞬时水分利用效率(WUE)、初始荧光(Fo)和非光化学淬灭系数(NPQ)升高;光系统Ⅱ最大光化学效率(Fv/Fm)不变;干旱胁迫下光响应曲线拟合结果显示,干旱胁迫造成最大光合速率和光能利用效率下降.综上表明,干旱对光系统Ⅱ的伤害是制约华山新麦草光合作用的主要原因.     

A new insight into the recycling of hyperaccumulator: synthesis of the mixed Cu and Zn oxide nanoparticles using Brassica juncea L

The mixed Cu and Zn oxide (Cu/ZnO) nanoparticles have been synthesized using Brassica juncea L. plants. The synthesized Cu/ZnO nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive spectrum (EDS). It was found that the synthesized Cu/ZnO nanoparticles were corresponding to the Cu(0.05)Zn(0.95)O structure. The shapes of the synthesized ZnO nanoparticles were nonuniform, but the CuO nanoparticles showed a spherical shape. The CuO nanoparticles entered in the structures of ZnO nanoparticles. An average size of 97 nm was obtained for Cu(0.05)Zn(0.95)O. The Cu(0.05)Zn(0.95)O nanoparticles were pure. The method for synthesis of Cu(0.05)Zn(0.95)O nanoparticles using Cu hyperaccumulator (B. juncea) plants constitutes a new insight into the recycling of hyperaccumulator and provides a novel route for further development of green nanostructure syntheses.     

Peat-assisted phytoremediation of waste foundry sands: plant growth, metal accumulation and fertility aspects

We investigated the potential of peat additions to improve plant growth and fertility and to reduce plant metal uptake in waste foundry sands (WFS) landfills. The WFS contains 78211 mg kg(-1) and 371 mg kg(-1) concentrations of Cr and Ni, respectively, and varied metal concentrations. The experiment investigated the growth of Brassica juncea plants on fertilized WFS mixed with peat at concentrations of 0, 2.5, 5, and 10% (w/w). The highest peat treatment allowed substantial plant growth and increased Ni mass in shoots, which was positively correlated to shoot biomass increments. On a concentration basis, peat additions did not increase shoot Ni values, thus suggesting that plants grown on peat-treated WFS may not increase risks to human and ecological receptors. Chromium was below detection levels in shoots for all peat treatments. Peat-treated substrates also promoted increased CEC values and higher water holding capacity, therefore improving the WFS agronomical properties. These results indicate that peat can be used as an amendment to assist in the phytoremediation of WFS landfill areas. However, there was evidence for increased mobilization of Cr and Ni in the substrate solution which can pose a threat to local groundwater.     

Accumulation, detoxification, and genotoxicity of heavy metals in Indian mustard (Brassica juncea L.)

Plants of Indian mustard (Brassica juncea L.) were exposed to different concentrations (15, 30, 60, 120 microM) of (Cd, Cr, Cu, Pb) for 28 and 56 d for accumulation and detoxification studies. Metal accumulation in roots and shoots were analyzed and it was observed that roots accumulated a significant amount of Cd (1980 microg g(-1) dry weight), Cr (1540 microg g(-1) dry weight), Cu (1995 microg g(-1) dry weight), and Pb (2040 microg g(-1) dry weight) after 56 d of exposure, though in shoot this was 1110, 618, 795, and 409 microg g(-1) dry weight of Cd, Cr, Cu, and Pb, respectively. In order to assess detoxification mechanisms, non-protein thiols (NP-SH), glutathione (GSH) and phytochelatins (PCs) were analyzed in plants. An increase in the quantity of NP-SH (9.55), GSH (8.30), and PCs (1.25) micromol g(-1) FW were found at 15 microM of Cd, however, a gradual decline in quantity was observed from 15 microM of Cd onwards, after 56 d of exposure. For genotoxicity in plants, cytogenetic end-points such as mitotic index (MI), micronucleus formation (MN), mitotic aberrations (MA) and chromosome aberrations (CA) were examined in root meristem cells of B. juncea. Exposure of Cd revealed a significant (P < 0.05) inhibition of MI, induction of MA, CA, and MN in the root tips for 24 h. However, cells examined at 24 h post-exposure showed concentration-wise recovery in all the endpoints. The data revealed that Indian mustard could be used as a potential accumulator of Cd, Cr, Cu, and Pb due to a good tolerance mechanisms provided by combined/concerted action of NP-SH, GSH, and PCs. Also, exposure of Cd can cause genotoxic effects in B. juncea L. through chromosomal mutations, MA, and MN formation.     

硫硒配施对茎瘤芥生长和营养效应的研究

以茎瘤芥品种‘涪杂1号’为材料,通过盆栽实验探讨不同浓度的硫(S)、硒(Se)配施处理对茎瘤芥干物质积累、矿质元素吸收及膨大茎营养品质的影响,为生产中合理施用硫、硒肥提供理论依据.结果表明:与对照(S0Se0,未施硫硒肥)相比,增施硫、硒肥处理均能显著提高茎瘤芥的根、膨大茎、叶片和单株干物质产量,并以S50Se1[S/Se=50(mg/kg)/1(mg/kg)]和S100Se1的处理效果较好,其单株干物质产量分别比对照显著增加32.3%和36.2%;不同硫、硒浓度配施处理对茎瘤芥13种矿质元素积累的影响不同,主要显著促进了茎、叶对氮、磷、钾、硫、硒的吸收积累,而对其它元素的影响不显著,其中茎、叶的硒含量以S50Se3处理最高,硫含量以S100Se1处理最高;各硫硒配施处理对膨大茎营养品质的影响不同,其中S50Se1和S50Se3处理能显著提高膨大茎有机硒、总氨基酸和粗蛋白含量,而对维生素C和可溶性糖含量无显著影响.可见,适宜的硫硒配施可以明显促进其对矿质元素的吸收,提高植株干物质积累,有效改善茎瘤芥膨大茎营养品质,且硫硒配施用量以S 50mg/kg、Se 1mg/kg为宜.     

Light quanta modulated characteristics of Ni uptake by Brassica juncea seedlings: the interdependence of plant metal concentration and biomass

The relationships between the concentration of metal in the growth medium, Cs, the concentration of metal absorbed by the plant, Cp, and the total biomass achieved, M, all of which are factors relevant to the efficiency of metal uptake and tolerance by the plant, have been investigated via the physiological response of Brassica juncea seedlings to Ni stress. The factorial growth experiments treated the Ni concentration in agar medium and the diurnal light quanta as independently variable parameters. Observations included the evidence of light enhancement of Ni toxicity in the root, as well as at the whole-plant level. The shoot mass index possibly is an indicator of the amount of shoot metal sequestration in B. juncea, as are the logarithmic variation of Cp with Cs and the power-law dependence of M on Cp. The sum total of these observations indicates that, for the Ni accumulating plant B. juncea, the overall metabolic allocation to either growth or metal tolerance of the plant is important. Neither a rapid biomass increase nor a high metal absorbed concentration favored the removal of high metal mass from the medium. Rather, the plants with a moderate rate of biomass growth and a moderate absorbed metal concentration demonstrated the ability to remove the maximum mass of metal from the medium. The implication of these results as related to the extant model of phyoextraction efficiency is discussed.     

不同品种芥菜对Cu胁迫响应的差异

采用水培法研究了不同品种芥菜对Cu胁迫响应的差异。结果表明:4μmol·L-1和8μmol·L-1Cu处理均抑制根和地上部生物量的积累,根受到的抑制程度大于地上部,敏感品种受到的抑制程度大于抗性品种。根中Cu积累量大于地上部,敏感品种根中Cu积累量大于抗性品种。8μmol·L-1Cu处理能明显诱导芥菜根中的MDA、Pro含量的增加及AsA含量的减少,APX、POD活性上升和GR活性下降,而不改变SOD活性。     

The ratio of leaf to total photosynthetic area influences shade survival and plastic response to light of green-stemmed leguminous shrub seedlings

Different plant species and organs within a plant differ in their plastic response to light. These responses influence their performance and survival in relation to the light environment, which may range from full sunlight to deep shade. Plasticity, especially with regard to physiological features, is linked to a greater capacity to exploit high light and is usually low in shade-tolerant species. Among photosynthetic organs, green stems, which represent a large fraction of the total photosynthetic area of certain species, are hypothesized to be less capable of adjustment to light than leaves, because of biomechanical and hydraulic constraints. The response to light by leaves and stems of six species of leguminous, green-stemmed shrubs from dry and high-light environments was studied by growing seedlings in three light environments: deep shade, moderate shade and sun (3, 30 and 100 % of full sunlight, respectively). Survival in deep shade ranged from 2 % in Retama sphaerocarpa to 74 % in Ulex europaeus. Survival was maximal at moderate shade in all species, ranging from 80 to 98 %. The six species differed significantly in their ratio of leaf to total photosynthetic area, which influenced their light response. Survival in deep shade increased significantly with increasing ratio of leaf to total photosynthetic area, and decreased with increasing plasticity in net photosynthesis and dark respiration. Responses to light differed between stems and leaves within each species. Mean phenotypic plasticity for the variables leaf or stem specific mass, chlorophyll content, chlorophyll a/b ratio, and carotenoid to chlorophyll ratio of leaves, was inversely related to that of stems. Although mean plasticity of stems increased with the ratio of leaf to total photosynthetic area, the mean plasticity of leaves decreased. Shrubs with green stems and a low ratio of leaf to total photosynthetic area are expected to be restricted to well-lit habitats, at least during the seedling stage, owing to their inefficient light capture and the low plasticity of their stems.     

西藏与周边地区芥菜型油菜农艺性状比较研究

运用典范相关分析方法,对西藏及周边地区芥菜型油菜的产量性状、主茎性状、分枝性状、角果性状等4组性状间的典范相关关系进行了比较研究.结果表明:(1)所研究的18个性状中,西藏芥菜型油菜的平均数为周边地区芥菜型油菜的1.88倍,总体变异系数比周边省份芥菜型油菜高10.22％;(2)西藏芥菜型油菜单株产量主要取决于每株角果数和千粒重,而周边省份芥菜型油菜单株产量主要取决于每株有效角果数,中国周边国家芥菜型油菜单株产量主要取决于每株有效角果数和千粒重;(3)影响西藏芥菜型油菜产量性状最重要的因素是角果性状,其次是分枝性状和主茎性状,而影响周边省份和中国周边国家芥菜型油菜产量性状最重要的因素则是主茎性状,其次是分枝性状和角果性状.