Root Morphology and Zn2+ Uptake Kinetics of the Zn Hyperaccumulator of Sedum alfredii Hance

Root morphology and Zn2 uptake kinetics of the hyperaccumulating ecotype (HE) and nonhyperaccumulating ecotype (NHE) of Sedum alfredii Hance were investigated using hydroponic methods and the radiotracer flux technique. The results indicate that root length, root surface area, and root volume of NHE decreased significantly with increasing Zn2 concentration in growth media, whereas the root growth of HE was not adversely affected, and was even promoted, by 500 μmol/L Zn2 . The concentrations of Zn2 in both ecotypes of S. alfredii were positively correlated with root length, root surface area and root volumes, but no such correlation was found for root diameter. The uptake kinetics for 65Zn2 in roots of both ecotypes of S. alfredii were characterized by a rapid linear phase during the first 6 h and a slower linear phase during the subsequent period of investigation. The concentration-dependent uptake kinetics of the two ecotypes of S. alfredii could be characterized by the Michaelis-Menten equation, with the Vmax for 65Zn2 influx being threefold greater in HE compared with NHE, indicating that enhanced absorption into the root was one of the mechanisms involved in Zn hyperaccumulation. A significantly larger Vmax value suggested that there was a higher density of Zn transporters per unit membrane area in HE roots.     

Structural Analysis of Peptides of PSⅡ Light-harvesting Complexes in Siphonous Green Algae,Codium fragile

Peptide composition and arrangement of 4 major light harvesting complexes LHCP1-3 and LHCP3′isolated from siphonous green algae （Codium fragile (Sur.) Hariot.） were investigated. LHCP1 showed five main peptides, 34.4, 31.5, 29.5, 28.2 and 26.5 kD in SDS PAGE, the 34.4 and 31.5 kD peptides were never found in higher plants. LHCP3 contained the other four kinds of LHCP1 peptides except 34.4 kD, while LHCP3′consisted of only 28.2 and 26.5 kD peptides. We found that 34.4, 28.2 and 26.5 kD peptides were easy to decompose from LHCP 1 when subjected to SDS PAGE without pretreatment. They might be located at the exterior of LHCP1, while the 31.5 and 29.5 kD peptides were at the central part. The 28.2 and 26.5 kD peptides often occurred in CPa, the center complex of PSⅡ. They are possibly the LHCⅡ peptides tightly associated with CCⅡ. According to the results described above, a peptide map of LHCP1 was sketched.     

Organic Materials Could Improve the Phytoremediation Efficiency of Soil Potentially Hazardous Metal by <i>Sedum alfredii</i> Hance

Soil potentially hazardous metal (PHM) is continually attracting public attention worldwide, due to its highly toxic properties and potentially huge damage to human being through food chain. Phytoremediation is an effective and eco-friendly way in remediation technology. A pot experiment was carried out to investigate the effect of different organic materials (biogas residue (BR), mushroom residue (MR), and bamboo-shoot shell (BS)) application on phytoremediation of two PHM-contaminated soils (Fuyang soil as ‘heavily-polluted soil’ and Wenzhou soil as ‘moderately-polluted soil’, respectively) by Sedum alfrecdii Hance. The results indicated: 1) for moderately-polluted soil, the 5% BR treatment had the strongest activation to Cu and Zn, for heavily-polluted soil, 1% BS treatment had the highest activation effect for Cu, Zn, Pb and Cd. 2) the above-ground biomass of Sedum alfredii Hance increased with the addition rate of organic materials. 3) for Cd uptake of Sedum alfredii Hance in moderately-polluted soil, only 1% BS treatment had a better accumulation effect, compared to the control, for Zn element, MR treatments were weaker than the control, while other treatments were better than the control, of which 5% BR, 1% BS and 5% BS accumulated more Zn element by 39.6%, 32.6% and 23.8%, respectively; in heavily-polluted soil, the treatments of 5% BS, 1% BR and 5% BR accumulated more Cd than the control by 12.9%, 12.8% and 6.2%, respectively, the treatments with organic materials addition promoted Zn accumulation in shoots of Sedum alfredii Hance, and the best treatment was 5% BS. Therefore, an appropriate application rate of BS and BR could improve the remediation efficiency for Zn/Cd contaminated soils by Sedum alfredii Hance.     

Light period of Crassulacean Acid Metabolism: Control of carbon transfer from malic acid to carbohydrates by CO2 concentration

In the CAM plants, Kalanchoë tubiflora (Harvey) Hasset, Sedum morganianum E. Walth and Sedum rubrotinctum R. T. Clausen, the effects of CO₂ concentrations on the light-dependent ¹⁴C transfer from the nocturnally synthetized [14C]-malic acid to starch have been studied. CO₂ concentrations up to 5 × 103 μ1 1–1 did not inhibit this carbon transfer. Higher CO₂ concentrations, however, were increasingly inhibitory. At 104 μl 1–1 CO₂, the carbon transfer was practically prevented.
The malic acid consumption in the light showed the same response to CO₂ concentrations as the [^l4C]-transfer. Photosynthesis itself was not inhibited by the CO₂ concentrations applied. It is assumed that, during phase III of CAM, light controls the internal CO₂ concentration via photosynthesis; and that the internal CO2 concentration then controls the rate of malate decarboxylation.     

Floral morphology,micromorphology and palinology of selected Sedum s.l. species (Crassulaceae)

Sedum L. (Crassulaceae) is a large and taxonomically difficult genus whose delimitation and classification are under debate. Due to the controversial results of previous cytological, morphological, and molecular studies, further investigations are needed in order to gain a shared taxonomy of the current recognized species clades. In the present paper, morphological and micromorphological features of 23 selected Mediterranean species of Sedum s.l. – collected from exsiccata or fresh specimens throughout Italy – were investigated, in order to provide additional data toward their classification above species level. In particular, the study focused on flower structure and morphology, floral epidermal surfaces and pollen morphology. The distribution pattern of the examined microcharacters across the species revealed a wide range of variation and different combinations of the single characters. NMDS analysis allowed individuating discrete groups that showed a general consistency with the current systematic delimitation of species groups. Our study also evidenced for the first time the wide morphological variability of nectaries and of the glandular indumentum, not previously investigated in detail. In addition, we proposed the combined use of floral diagrams and floral formulae as valuable tools in studying the variability of flower structure at genus level.     

塔里木河流域胡杨和灰叶胡杨克隆分株空间分布格局

以叶尔羌河下游阿瓦提县天然胡杨和灰叶胡杨混交林、塔里木河上游农一师16团天然灰叶胡杨林和塔里木河中游轮台县天然胡杨林为对象,研究胡杨和灰叶胡杨克隆分株种群的空间分布格局.结果表明: 8种不同取样尺度(5 m×5 m、5 m×10 m、5 m×15 m、10 m×10 m、10 m×15 m、15 m×15 m、15 m×20 m、20 m×20 m)下,3个研究区2物种克隆分株种群的空间分布格局均表现为集群分布,表明集群分布是研究区胡杨和灰叶胡杨克隆分株种群空间分布格局的基本属性;在5 m×5 m尺度上,3个研究区2物种克隆分株种群均表现出负二项参数最小、Cassie指标和聚块性指标最大、聚集强度最大的分布特征.     

莎车巴旦姆物候期对气象条件的响应及花期预测模型

利用莎车县农业气象试验站2008—2013年巴旦姆物候期和同期气象观测资料,分析了巴旦姆物候期的变化特征以及气温、日照时数对物候期的影响.结果表明：巴旦姆花期之前的物候期始日之间均呈正相关,与花期之后的物候期始日的相关性大多较小,花芽膨大早迟与休眠期、生长期天数分别呈极显著的正相关和负相关.以果实成熟期为界,气温对之前、之后物候期间隔日数的影响分别为负相关和正相关,日照时数与物候期间隔日数大多为正相关.果实成熟 叶变色始期间隔日数对平均最高气温以及花序出现 开花末期、叶变色始期 落叶末期间隔日数对日照时数存在明显的响应.当巴旦姆休眠期符合日平均气温-3.0～-7.5 ℃的天数满30 d后,经过17～28 d将进入花芽萌动期.花芽萌动期、开花始期、叶变色始期和落叶末期的始日分别与首个候平均气温≥4 ℃且候平均最高气温≥12 ℃、春季侯平均气温≥14 ℃且侯平均最高气温≥22 ℃、秋季首个侯平均气温≤10 ℃且侯平均最高气温≤18 ℃和冬季首个侯平均气温≤1.9 ℃的候序一一对应.利用偏最小二乘法回归分析,建立巴旦姆盛花期始日预测模型,经过检验模型效果较好.     

高浓度O3对城市蒙古栎凋落叶分解和养分释放的影响

采用开顶箱(OTCs)模拟法和分解袋法,以O₃自然浓度(40 nmol·mol^-1)为对照,研究高浓度O₃(约120 nmol·mol^-1)对城市自然环境下生长的10年生蒙古栎凋落叶分解和养分释放的影响,分解时长达150 d.结果表明：高浓度O₃未对蒙古栎凋落叶的分解产生显著影响.高浓度O₃抑制了蒙古栎凋落叶C、K释放,分解150 d,高浓度O₃处理K残留率为23.9%,显著高于对照(17.1%).高浓度O₃在分解前期(0～60 d)抑制了凋落叶N、木质素的释放,在分解后期(60～150 d)起促进作用.高浓度O₃处理与对照木质素/N变化趋势一致且无显著差异.除分解中期(60 d)外,对照P残留率始终高于高浓度O₃处理.C/P变化趋势与P相反,在整个分解过程中,高浓度O₃处理C/P高于对照,而且C、N、K残留率以及C/N与凋落叶干质量剩余率呈显著正相关.因此,高浓度O₃将对蒙古栎林的营养循环产生一定影响.