Physiological acclimation strategies of riparian plants to environment change in the delta of the Tarim River,China

The occurrence and development of riparian forests, which were mainly dominated by mesophytes species related closely with surface water. Since there was no water discharged to the lower reaches of Tarim River in the past three decade years, the riparian forests degrade severely. The groundwater table, the saline content of the groundwater, as well as the content of free proline, soluble sugars, plant endogenous hormones (abscisic acid (ABA), and cytokinins (CTK)) of the leaves and relative rates of sap flow of the Populus euphratica Oliv. (arbor species), Tamarix ramosissima Ldb. (bush species), and Apocynum venetum L. (herb species) were monitored and analyzed at the lower reaches of the Tarim River in the study area where five positions on a transect were fixed at 100 m intervals along a sampling direction from riverbank to the sand dunes before and after water release. The physiological responses and acclimation strategies of three species to variations in water and salinity stress were discussed. It was found that A. venetum population recovered to groundwater table ranging from −1.73 to −3.56 m, and when exposed to saline content of the groundwater ranging from 36.59 to 93.48 m mol/L; P. euphratica appeared to be more sensitive to the elevation of groundwater table than the A. venetum and T. ramosissima at groundwater table ranging from −5.08 to −5.80 m, and when exposed to saline content of the groundwater ranging from 42.17 to 49.55 m mol/L. T. ramosissima tended to be the best candidate species for reclamation in this hyper-arid area because it responded to groundwater table ranging from −1.73 to −7.05 m, and when exposed to saline content of the groundwater ranging from 36.59 to 93.48 m mol/L. These results explained the distribution patterns of desert vegetation in the lower reaches of the Tarim River. Understanding the relationships among ecological factors variables, physiological response and acclimation strategies of plant individuals could provide guidance to sustainable management, reclamation and development of this and similar regions.     

Nickel effects on growth and antioxidative enzymes activities in desert plant Zygophyllum xanthoxylon （Bunge） Maxim

One-month old Zygophyllum xanthoxylon seedlings were grown under five different Ni concentrations (0, 50, 150, 450 and 900 mg/kg). Growth parameters, tissues Ni accumulation, soluble protein content, photosynthetic pigment content, lipid peroxidation, antioxidative enzyme activities, and proline content were studied after one month of Ni exposure. The significant reduction in fresh biomass in the shoot and roots was detected at high Ni concentrations (≥450 mg/kg), whereas dry biomass was not significantly affected in both organs by any of the Ni doses tested. The Ni contents in the shoots and roots increased in a dose-dependent manner, and Ni contents in roots were higher than that in shoots at all treatments. The high Ni doses elevated soluble protein contents in leaves and roots. No visible symptoms of chlorosis were observed in leaves of plants grown in presence of Ni. Malondialdehyde (MDA) contents significantly increased in leaves and roots at high Ni treatments (≥450 mg/kg), indicating that Ni induces oxidative stress. Enzyme activities might play a central role in cellular protection against the Ni induced oxidative stress. Proline contents proportionally increased with the elevated Ni concentrations. Zygophyllum xanthoxylon revealed moderate Ni tolerance under tested culture conditions, and could be used as tools for revegetation for erosion control in moderate Ni contaminated sites.     

增强的UV-B辐射对地木耳中抗逆性物质的影响

实验室条件下模拟兰州地区夏至臭氧层衰减12％、20％和40％时增强的UV-B辐射2.54kJ·m-2·d-1(T1)、4.25 kJ·m-2· d-1 (T2)和8.35 kJ·m-2·d-1(T3),研究了不同强度的UV-B辐射对陆生蓝藻地木耳（Nostoc commune）中的的抗逆性物质光合色素（叶绿素a、类胡...     

Proline with or without Hydroxyproline Influences Collagen Concentration and Regulates Prolyl 4-Hydroxylase α(I) Gene Expression in Juvenile Turbot(Scophthalmus maximus L.)

This study was conducted to investigate the effect of dietary proline(Pro), and Pro and hydroxyproline(Hyp) in combination on the growth performance, total Hyp and collagen concentrations of tissues, and prolyl 4-hydroxylase α(I)(P4H α(I)) gene expression in juvenile turbot feeding high plant protein diets. A diet containing 50% crude protein and 12% crude lipid was formulated as the basal and control, on which other two protein and lipid contents identical experimental diets were formulated by supplementing the basal with either 0.75% Pro(Pro-0.75) or 0.75% Pro and 0.75% Hyp(Pro+Hyp). Four groups of fish in indoor seawater recirculating systems, 35 individuals each, were fed twice a day to apparent satiation for 10 weeks. The results showed that dietary Pro and Hyp supplementation had no significant effect on growth performance and feed utilization of juvenile turbot(P 0.05). Total Hyp and collagen concentrations in muscle were significantly increased when dietary Pro and Hyp increased(P 0.05), and fish fed diet Pro+Hyp showed significantly higher free Hyp content in plasma than those fed other diets(P 0.05). The expression of P4 H α(I) gene in liver and muscle was significantly up regulated in fish fed diet Pro-0.75 in comparison with control(P 0.05); however the gene was significantly down regulated in fish fed diet Pro+Hyp in muscle in comparison with fish fed diet Pro-0.75(P 0.05). It can be concluded that supplement of crystal L-Pro and L-Hyp to high plant protein diets did not show positive effects on growth performance of juvenile turbot, but enhanced total collagen concentrations in muscle.     

不同冬小麦对盐处理和干旱胁迫交互作用响应的差异性分析

通过对抗逆性不同的6个烟台冬小麦品种在盐处理和干旱胁迫交互作用进程中叶片相对含水量（RWC）,膜脂过氧化产物（MDA）和抗氧化酶活力（SOD,POD,CAT）及渗透调节物含量（脯氨酸,可溶性蛋白）的分析,以了解不同冬小麦品种对盐处理和干旱胁迫交互作用响应的生理调节差异。研究表明,在水分供应充足条件下盐处理10 d,6个品种冬小麦生长良好并和对照没有差异,但在干旱胁迫中盐处理组较对照MDA含量低,RWC和抗氧化酶活力和渗透调节物含量均高,且叶片萎蔫较对照出现晚。但经盐处理的6个冬小麦品种对干旱胁迫响应有差异。在长期干旱(12 d),抗旱性强的品种RWC（81%）明显高于抗旱性弱的（62%）,前者叶片MDA含量较后者低30%,抗旱性强的品种抗氧化酶活力和渗透调节物含量略低于抗旱性弱的品种,但是差异不明显。在盐处理和干旱胁迫交互作用下,盐离子自身可作为渗透调节物既增加了土壤的持水力又提高了细胞保水力而使冬小麦耐旱性增强。抗旱性强的冬小麦品种对盐处理反应敏感且保水性强,细胞膜脂过氧化程度较低,故耐旱力高,抗旱性弱的品种则相反。研究进一步表明,在未来干旱地区实施适度的盐水灌溉可提高冬小麦的耐旱力,但选择抗旱力强的冬小麦品种是实施这一农业耕作措施的关键。     

干旱胁迫下的胡杨脯氨酸累积特点分析

以塔里木河下游的主要乔木-胡杨为研究样本，结合野外地下水位临测资料，详细分析了塔里木河下游干旱胁迫环境下胡杨体内脯氨酸的累积与变化。分析研究表明，胡杨体内的脯氨酸含量与塔里木河下游地下水位变化存在密切，脯氨酸含量随地下水位降低而增加，二者相关系数达0．913；在不同地下水位埋深条件下。脯氨酸含量的增加幅度有差异；胡杨体内的脯氨酸含量随干旱胁迫的加深而积累，是胡杨对干旱逆境的一种反应。表明塔里木河下游胡杨的生长发育已受到严重的干旱胁迫。     

阿拉善荒漠区几种抗旱植物游离氨基酸和游离脯氨酸的分布特征

以阿拉善荒漠区生长的多浆旱生植物梭梭(Haloxylon ammodendron)和霸王(Zygophyllum xanthoxylum)、少浆旱生植物白沙蒿(Artemisia sphaerocephala)和柠条(Caragana korshinskii)、中旱生植物沙米(Agriophyllum squarrosu)和绵蓬(Corispermum mongolicum)为材料, 对其游离氨基酸成分及游离脯氨酸的分布特征进行了比较研究。结果表明, 供试植物根中的总游离氨基酸含量均低于茎和叶中的总游离氨基酸含量, 其中叶中的游离氨基酸总量最高; 不同植物中的主要氨基酸组成不相同, 同一植物的不同部位主要氨基酸组成也不尽相同。少浆旱生植物体内大量积聚游离脯氨酸, 其整株中的游离脯氨酸是中旱生植物的6.0~16.0倍, 是多浆旱生植物的1.8~25.0倍。白沙蒿植株的根到茎、茎到叶, 总游离氨基酸含量以2.0倍和5.7倍的增幅增加, 其中游离脯氨酸含量增加最明显, 增幅达3.0倍和10.5倍。柠条植株也表现出同样的趋势。可见, 大量积累游离氨基酸, 特别是游离脯氨酸是少浆旱生植物适应干旱荒漠生境的重要机制。从根到茎、由茎到叶, 中旱生植物沙米和绵蓬与多浆旱生植物梭梭和霸王总游离氨基酸含量增幅都并不十分显著; 二者中的游离脯氨酸积累不占主导地位。故中旱生植物和多浆旱生植物并不主要依靠积累脯氨酸来调节渗透势确保水分的供应。     

不同pH处理对菹草(Potamogeton crispus L.)Cr6+毒害效应的影响

对Cr⁶⁺胁迫条件下不同pH处理对菹草无菌苗元素、光合色素、活性氧、丙二醛、抗氧化酶、脯氨酸(Pro)及多胺(PAs)含量的影响进行研究,以探讨不同pH处理影响水生植物Cr⁶⁺毒害效应的机制.结果表明:(1)偏酸性pH处理加剧菹草对铬的蓄积,而pH为7.0时Cr⁶⁺胁迫所造成的矿质元素失衡有所减弱;(2)Cr⁶⁺胁迫下pH为6.0~8.0的处理延缓了菹草的失绿症状,促进了光合色素的合成;(3)Cr⁶⁺胁迫下菹草超氧化物歧化酶、过氧化氢酶的活性在pH为6.0和7.0的处理组诱导程度最小;(4)Cr⁶⁺胁迫下pH为6.0和7.0处理的菹草Pro含量显著提高;(5)pH为4.0和5.0的处理使腐胺(Put)含量显著提高,而pH为6.0和7.0的处理则促进亚精胺(Spd)含量及游离态(Spd+Spm)/Put比值上升,精胺(Spm)含量总体趋势为随pH值升高而逐步上升,仅在pH为4.0和5.0的处理组中低于Cr⁶⁺胁迫对照组.因此,pH条件可影响菹草对铬及营养元素的积累,抗氧化酶、Pro、PAs代谢等生理生化过程,导致铬毒性效应差异.在pH为6.0~7.0的范围内,菹草能调节抗氧化酶系统,较有效地清除体内活性氧,提高机体中Pro、PAs含量及游离态(Spd+Spm)/Put比值,减轻膜系统脂质过氧化,维持机体内矿质元素平衡,致使毒性效应达到最小程度.     

镍胁迫对菹草(Potamoge toncrispus L.)活性氧及脯氨酸代谢的影响

本文以组织培养技术培养的菹草无菌苗为实验材料,研究了不同浓度(0、0.05、0.10、0.15、0.20 mmol/L)Ni2+胁迫对菹草过氧化氢(H2O2)、超氧阴离子(O2.-)和丙二醛(MDA)的含量、抗氧化系统、脯氨酸代谢途径的影响.结果显示:(1)Ni2+胁迫影响了活性氧水平,主要表现为H2O2和O2.-的大量积累;MDA含量也随着Ni2+浓度的升高呈上升趋势;(2)随着Ni2+浓度的升高,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性及还原型谷胱甘肽(GSH)、非蛋白巯基(NP-SH)含量均表现为先升后降趋势;抗坏血酸(AsA)含量变化不明显;植物络合素(PCs)则表现为上升趋势;(3)脯氨酸代谢关键酶在Ni2+胁迫下表现为:鸟氨酸转氨酶(OAT)活性在0～0.10 mmol/L Ni2+胁迫下高于对照组;吡咯啉-5-羧酸合成酶(P5CS)活性在Ni2+大于0.10 mmol/L时,显著增加;脯氨酸脱氢酶(ProDH)活性无显著变化;脯氨酸(Pro)含量则均显著高于对照组.以上结果表明,Ni2+胁迫提高了活性氧的水平,加重了膜脂过氧化的程度,干扰了抗氧化系统的内在平衡;此外,低浓度Ni2+胁迫下菹草脯氨酸积量主要依赖于鸟氨酸途径,而高浓度下则主要依靠谷氨酸途径.     

外源鸟氨酸对菹草(Potamogeton crispus L.)抗镉胁迫能力的影响

本文以组织培养技术培养的菹草无菌苗为实验材料,研究了2 mmol/L外源鸟氨酸(L-Orn)对40μmol/L镉(Cd)胁迫下菹草体内Cd含量、光合色素水平、超氧阴离子(O·-2)产生速率、过氧化氢(H2O2)、丙二醛(MDA)与可溶性蛋白含量以及脯氨酸和多胺代谢的影响.结果显示:(1)在单一Cd胁迫下,菹草体内的Cd大量积累,达到335.00μg/g,并诱导了明显的氧化胁迫,具体表现为O·-2产生速率以及H2O2和MDA含量显著升高,可溶性蛋白以及光合色素含量明显下降.外源L-Orn的添加很大程度上抑制了菹草体内Cd的积累,Cd含量降至232.50μg/g,并降低了活性氧(ROS)水平,减轻了膜脂过氧化程度,减缓了光合色素和可溶性蛋白的分解.(2)在单一Cd胁迫下,伴随着吡咯啉-5-羧酸合成酶(P5CS)活性的增加和脯氨酸脱氢酶(ProDH)活性的下降,菹草体内的脯氨酸含量轻微增加,仅为对照组的1.91倍,而外源L-Orn显著增强了P5CS和δ-鸟氨酸转氨酶(OAT)的活性,使脯氨酸含量大幅度升高,为对照组的8.36倍.(3)单一Cd胁迫分别通过激活精氨酸脱羧酶(ADC)、鸟氨酸脱羧酶(ODC)和多胺氧化酶(PAO)的活性,使腐胺(Put)的含量增加,亚精胺(Spd)和精胺(Spm)含量减少.而施用外源L-Orn后,ADC和ODC的活性进一步增强,Put的含量大幅增加,并促进Put向Spd和Spm的转化,同时PAO的活性下降,使Spd和Spm含量增加,从而使总多胺含量增加.由此可见,外施L-Orn可通过抑制Cd的进入和参与调节脯氨酸以及多胺代谢,抑制ROS的积累、膜脂过氧化、光合色素以及蛋白质的分解,一定程度上增强菹草对Cd胁迫的抗性.