造礁石珊瑚共生虫黄藻离体培养方法的优化

【目的】开发一种高效地从造礁石珊瑚中分离、培养共生虫黄藻的技术方法,为珊瑚共生虫黄藻藻种资源储备和生理功能研究积累基础。【方法】首先采用微孔滤网过滤法和密度梯度离心法从造礁石珊瑚组织中直接分离或富集共生虫黄藻细胞,然后用改良的L1培养基在96孔板上对所得细胞进行离体培养,最后进行单细胞分离、培养和(或)平板划线培养获得单克隆虫黄藻细胞系。对所得虫黄藻单克隆藻株进行聚合酶链式反应-限制性内切酶片段长度多态性(polymerase chainreaction-restrictionfragmentlengthpolymorphism,PCR-RFLP)分析,结合内转录间隔区2(internal transcribed spacer2,ITS2)和大亚基(large subunit,LSU)测序进行物种鉴定及系统发育分析。【结果】采用上述方法从涠洲岛的霜鹿角珊瑚(Acropora pruinose)和西沙群岛的丛生盔形珊瑚(Galaxea fascicularis)及柔枝鹿角珊瑚(Acropora tenuis)中分离、培养得到3个虫黄藻株系,编号分别为AP21C1、GF21D1和AT21A...     

黄柳与垂柳的耐热性和耐旱性比较研究

 作为一种优良的固沙植物,黄柳（Salix gordejevii）主要分布于内蒙古科尔沁沙地和浑善达克沙地,在流动沙丘边缘和半流动沙丘生长最多,属于灌木型先锋植物。实验对黄柳的耐热性和耐旱性与垂柳（Salix babylonica）进行了比较研究。两种植物的离体叶片在6个温度（即25、30、35、40、45、50 ℃）下处理1 h;在6个水势梯度（即0、-0.25、-0.5、-0.75、-1.0、-1.25 MPa）下处理24 h后,测定了其含水量、膜透性、光系统Ⅱ的最大光化学效率（由Fv/Fm计算）等参数。黄柳叶片在温度处理和干旱处理中均能保持比垂柳较高的含水量;45 ℃以下的温度对两种植物叶片的膜透性没有明显影响,但高于45 ℃的温度（本实验中为50 ℃）使黄柳和垂柳叶片膜透性剧增,且黄柳增大更多;干旱处理造成两种植物叶片膜透性增大,且垂柳的总是大于黄柳的;低于35 ℃的温度对Fv/Fm没有影响,高于40 ℃的温度使两种植物叶片的Fv/Fm明显降低,且黄柳的极显著地小于垂柳的;干旱处理总使两种植物叶片的Fv/Fm降低,当渗透势小于-0.75 MPa时,黄柳的Fv/Fm显著地大于垂柳的。这些结果说明黄柳的耐旱性比垂柳强,其耐热性比垂柳差。就光合器官而言,黄柳、垂柳耐热性和耐旱性的差别主要是由于通过光系统Ⅱ的电子传递对高温和干旱的敏感性不同造成的。     

浑善达克沙地不同光合途径植物叶片气体交换和水势特征(英文)

以生长于浑善达克沙地上的C3植物白榆(Ulmus pumila)、C4植物沙米(Agriophyllum pungens)和CAM植物钝叶瓦松(Orostachys malacophyllus)3种不同光合途径植物为材料,测定了它们生长期叶片的光合气体交换参数、叶绿素荧光参数和水势,探讨它们对生长环境的生理响应特征.结果表明,白榆和沙米的净光合速率、气孔导度均高于钝叶瓦松,特别是在夏季高温(>40℃)和强光照(>2 100 μmol·m-2·s-1)条件下表现得更加明显.白榆和沙米的光合速率、叶片水势都发生了严重的午休现象,其白天光合速率的降低主要是由于气孔关闭造成的.钝叶瓦松的叶片水势在3种植物中最高,但是白天的光合速率很低;其Fv/Fm值在14:00最低,一天中此时光系统II受伤害最大;CAM物种瓦松的碳固定仅发生在夜间.研究发现,C3植物白榆和C4植物沙米比CAM植物钝叶瓦松对热和高光照有着更强的忍耐力,瓦松固定碳主要发生在生长最快的阶段;CAM植物瓦松为了能够在夏季强光和高温条件下生存,它必须进行高强度的呼吸,仅在早晨和夜间进行碳固定.     

NaCl对小麦光合功能的伤害主要是由离子效应造成的

采用荧光动力学的方法来区分盐胁迫中的渗透因素和离子因素。用五种等渗Hogland培养液 (分别含 (NaCl,KCl,NaNO3,KNO3和PEG)对冬小麦处理两星期。结果 ,与对照相比 ,NaCl处理引起PSII受体侧电子库 (CA/Fo)变小 ,PSII活性 (Fv/Fo)、原初光能转化效率 (Fv/Fm)、量子产量 (Yield)与荧光化学猝灭系数 (qP)下降 ,但使QB_非还原性PSII反应中心含量增加。然而 ,等渗的PEG处理并不产生类似的伤害。这表明渗透因素不是盐胁迫对光合作用造成伤害的主要原因。同时 ,KNO3处理对光合作用不产生伤害。由于NaCl和NaNO3处理均造成受体侧电子库变小 ,PSII活性和原初光能转化效率下降 ,并使QB_非还原性PSII反应中心增加 ,而等渗的PEG和KCl处理并不产生类似的伤害 ,这暗示Na 可能是盐胁迫影响光合作用的主要毒害离子     

干旱对白皮松幼苗针叶生理特性的影响

试验目的是研究栽植前和栽植后干旱致使白皮松（Pinus bungeana Zucc.）针叶的生理特性的改变,了解白皮松造林前后能够适应的干旱范围,为白皮松科学造林提供理论依据。试验中模拟白皮松容器苗造林前后可能遇到的干旱胁迫,研究栽植前容器苗分别为B1：75%～80%（正常浇水）、B2：55%～60%（轻度干旱）、B3：35%～40%（严重干旱）和栽植后土壤相对含水量分别为A1：75%～80%、A2：55%～60%、A3：35%～40%、A4：15%～20%（极严重干旱）对白皮松针叶的生理指标的影响。结果表明：栽植前白皮松容器苗经B3处理后,针叶电解质渗透率增加,叶绿素含量和PSII最大光化学效率（Fv/Fm）显著降低,表明针叶受到一定伤害。栽植后如果正常浇水,这些影响将消除,如果遭遇栽植后干旱,B3处理的受害程度不比B1和B2处理深。栽植后白皮松经A3和A4处理4周后,针叶的电解质渗透率增加,Fv/Fm降低,表明白皮松针叶受到伤害。白皮松容器苗造林在栽植前遭到适当干旱胁迫时不会影响造林后的表现。但应避免栽植后初期4周以上严重干旱胁迫。     

风力胁迫对具鞘微鞘藻结皮光合活性的影响

抵抗风力胁迫是荒漠藻类适应干旱区环境的重要生物学机制,也是藻结皮能够拓殖流沙的必要条件之一,但有关藻类对风力胁迫的响应机理国内外尚无研究报道。以具鞘微鞘藻(Microcoleus vaginatus Gom.)人工结皮为实验对象,研究了不同强度风力吹蚀对结皮含水量、藻类活力、生物量、及其光合活性的影响。结果表明:不论低于当地起沙风(3m/s)还是高于起沙风(5m/s和7m/s)的风力吹蚀,结皮中藻类生物量均明显下降,而且结皮生物量的变化与风速大小和吹蚀时间呈线性关系(y=14.78+0.035a-1.48b,a风速,b时间,r2=0.79)。进一步分析发现,风力吹蚀后结皮中藻类活力并没有降低但主要光合色素和天线色素的含量普遍降低,叶绿素荧光(Fv/Fm)、表观电子传递速率(ETR)和净光合速率(Pn)明显下降,并且风速越大,降幅越大。这些结果说明风力胁迫对藻结皮生长和光合活性的影响主要是通过影响光合色素代谢合成和电子传递速率引起的,对其生命力没有明显影响。     

Effects of winter cold stress on photosynthesis and photochemical efficiency of PSII of the Mediterranean <Emphasis Type="Italic">Cistus albidus</Emphasis> L. and <Emphasis Type="Italic">Quercus ilex</Emphasis> L.

This study examined the photosynthetic and growth performances of potted plants of Cistus albidus L. and Quercus ilex L. submitted either to natural Mediterranean winter conditions or to mild greenhouse conditions. Plants grown outdoors exhibited lower light and CO₂-saturated CO₂ assimilation rates (A_sat) and apparent quantum yield (_i) than those indoors. Until mid-winter, C. albidus had higher A_sat than Q. ilex, but differences disappeared after a period of severe cold. Maximal photochemical efficiency of PSII (Fv/Fm) measured predawn was higher in C. albidus than in Q. ilex, and decreased throughout the season in outdoor plants. Fv/Fm also decreased at light saturation (A_sat) in both species. Fv/Fm was correlated with photosynthetic capacity and efficiency (quantum yield), but the resulting regression slopes were different between the two species. At the physiological level, C. albidus seemed to cope better with cold stress than Q. ilex. However, winter stress induced reduction of leaf absorptance, increased leaf mass per area, extensive leaf damage and high plant mortality in C. albidus. This suggests that the high performance of C. albidus leaves is not likely to be maintained for long periods of cold stress, and may therefore depend on continuous leaf replacement. Quercus ilex showed a conservative behaviour, with low net assimilation rates but greater leaf and plant survival than C. albidus.     

Increased exposure to UV-B radiation during early development leads to enhanced photoprotection and improved long-term performance in Lactuca sativa

Plant responses to solar UV radiation are numerous and have often been considered from a perspective of negative outcomes for plant productivity. In this study, we used two experimental approaches consisting of: (1) field-based spectrally modifying filters in addition to (2) controlled indoor exposure to UV-B, to examine the effects of UV radiation on growth and photosynthetic performance of lettuce (Lactuca sativa L.) seedlings. Various aspects of growth were affected in plants grown under a UV-inclusive environment compared to a UV-depleted environment, including reductions in leaf expansion, increases in leaf thickness and the rate of net photosynthesis. After transplantation to a uniform field environment, lettuce plants initially propagated under the UV-inclusive environment exhibited higher harvestable yields than those from a UV-depleted environment. In controlled conditions, photosynthetic rates were higher in plants grown in the presence of UV-B radiation, and relative growth of plants pre-acclimatized to UV-B was also increased, in addition to higher maximum photochemical efficiency of photosystem II (PSII) (F(v) /F(m) ) following subsequent exposure to high photosynthetically active radiation (PAR) and temperature stress. Our findings are discussed within the context of sustainability in agriculture and the paradigm shift in photobiology which such beneficial responses to UV radiation could represent.     

利用Fv/Fm检测锥状施克里普藻 N和P限制的局限

通过测定缺N和缺P的锥状施克里普藻(Scrippsiella trochoidea)在分别添加充足的NO3-N、PO4-P后,光系统Ⅱ(PSⅡ)最大光化学量子产量(Fv/Fm)的变化,来检验Fv/Fm能否用来检测锥状施克里普藻N、P限制的情况。实验表明,锥状施克里普藻分别在不加N、P元素的f/2-Si培养基培养过程中,缺N组叶绿素a(Chla)浓度先升高,在原培养液N耗尽后快速下降;缺P组Chla开始时升高,在原培养液P耗尽后缓慢下降。两组藻液Fv/Fm比值保持相对稳定,短时间内未见明显降低。当分别向藻液中重新添加充足的N和P后,缺N组藻液添加N后Chla浓度48h内明显上升,缺P组藻液添加P后Chla浓度48h内没有明显变化,两种培养液中Fv/Fm均未见明显升高。结果证明,利用Fv/Fm不能够快速检测锥状施克里普藻N、P限制的情况,该法在检测浮游植物营养盐胁迫时具有局限性。