生草覆盖对苹果展叶过程中光合特性的影响

为揭示生草覆盖与清耕苹果园展叶过程中光合特性的差异, 本研究采用气体交换和叶绿素荧光动力学技术分析5年龄苹果园生草覆盖和清耕条件下苹果展叶过程中光合和荧光参数的变化规律。结果表明, 展叶初期, 生草覆盖和清耕处理叶片叶绿素含量、净光合速率(Pn)、性能指数(PICS)和820 nm光吸收的振幅(ΔI)显著低于完全展开叶片(EL), Pn分别为EL的26.9%和18.4%, PICS分别为EL的67.7%和53.4%, ΔI分别为EL的35.6%和30.5%;生草覆盖处理叶片叶绿素含量、Pn、PICS和ΔI显著高于清耕处理。生草覆盖和清耕处理叶片PSⅡ功能在展叶初期已有很大程度的发育, PSⅠ功能的发育程度相对较低;生草覆盖促进了展叶初期叶片PSⅡ和PSⅠ功能的发育, 因此具有较高的光合效率。     

温度对北海道黄杨叶片光系统Ⅱ功能的影响

人工控温对北海道黄杨扦插苗叶片光系统Ⅱ的功能进行研究。结果表明:20～25℃之间是北海道黄杨叶片光系统Ⅱ作用最强的温度范围,低于或高于这一温度范围,北海道黄杨叶片的叶绿素a荧光动力学曲线发生了明显改变:FV/Fm,FV/F0值降低,导致光系统Ⅱ的原初光能转换率和潜在光合活力均受到抑制;荧光光化学猝灭系数(qP)降低,荧光非光化学猝灭系数(qN)提高,抑制了叶绿体把捕获的光能用于光合作用。     

820nm光吸收曲线技术在逆境条件下叶片光系统Ⅰ性能研究中的应用

光合作用是植物生长发育的基础,在逆境条件尤其是低温和弱光等胁迫下,叶片光系统Ⅰ(PSⅠ)性能下降引起越来越多的关注。820 nm光吸收曲线技术可以用来检测发生在PSⅠ的原初光化学反应。本文总结了利用820 nm光吸收曲线技术测定PSⅠ的光化学效率、环式电子传递能力和能量分配的基本原理,及在逆境条件下的研究成果,以期为820 nm光吸收曲线技术在其它条件下对PSⅠ性能影响提供理论和技术支撑。     

Application of chlorophyll fluorescence for the diagnosis of salt stress in tomato “Solanum lycopersicum (variety Rio Grande)”

To study the response of tomato (Solanum lycopersicum cv. Rio Grande) to salinity, the effect on plant growth, water relations, stomatal conductance and Chlorophyll fluorescence was investigated. Tomato plants were grown in peat culture under controlled conditions and submitted during 28 days to saline stress ranging from 0 to 25, 50, 100, 150 and 200 mM of NaCl. At the end of the experiment period, plant growth was significantly decreased with increasing salinity.     

高等植物光系统Ⅰ的研究(Ⅰ)──叶绿体中存在两种光系统Ⅰ

用含有ＰＥＧ的提取介质有效地提取和分离了油松、毛白杨、豌豆及菠菜的类囊体膜片，经改进了的增溶方法增溶光合色素蛋白复合物，有效地、完整地将ＰＳＩ从膜结构上溶解下来．溶解液经ＤＯＣ ＰＡＧＥ分离，均可得到迁移率相近的具光系统Ⅰ活性的两条稳定的绿带，经超速离心及不同浓度毛地黄皂苷和Ｔｗｅｅｎ ２０处理，证明它们是两种ＰＳＩ，称为ＰＳＩ １和ＰＳＩ ２．ＳＤＳ ＰＡＧＥ分析证明这两种复合物多肽种类相同，部分多肽的组成在比例上存在差异，证明在高等植物中存在两种ＰＳＩ，而且这种存在具有一定普遍性     

豌豆光系统I多肽HPCE分离特性的研究

为进一步探讨豌豆光系统I(PSⅠ)的结构与多肽组成,本研究提取了经DOC-PAGE分离的光系统I多肽,采用毛细管凝胶电泳方法,以1%的葡聚糖为毛细管凝胶线性高分子筛分基质,0.5%乙基纤维素,0.1%SDS为磷酸盐缓冲液添加剂。在35min内进行了较好地分离。所得的色谱图基线平稳、分离度较高。为进一步利用毛细管电泳技术进行蛋白复合物多肽的分离奠定了良好的基础。     

Mode of action of new diethylamines in lycopene cyclase inhibition and in photosystem II turnover

The new bleaching herbicidal compound N,N‐diethyl‐N‐(2‐undecynyl)amine (NDUA) is identified here as an inhibitor of lycopene cyclase and is compared with the known cyclase inhibitors N,N‐diethyl‐N‐[2‐(4‐chlorophenylthio)ethyl]amine (CPTA) and N,N‐diethyl‐N‐[2‐(4‐methylphenoxy)ethyl]amine (MTPA). HPLC separation of chloroplast pigments shows lycopene accumulation in NDUA treated tissue. Variation in chain length of the undecynylamine moeity of NDUA from 7 to 21 C atoms reveals an optimum of 11 to 14 C atoms for herbicidal activity. A series of seven further analogues of NDUA and CPTA reveals the structural elements necessary for inhibition of lycopene cyclase. The effect of NDUA derivatives on photosynthesis has been studied in Chlamydomonas reinhardtii. Photosynthesis is highly sensitive, particularly towards the C14 and longer chain length analogues at nanomolar concentrations. It is shown that the breakdown of photosynthesis by NDUA is due to interference with the turnover of the D1 protein of the photosystem II reaction centre that requires the continous biosynthesis of the two reaction‐centre β‐carotene moieties in the reassembly phase. The D1 protein disappearance is most marked under strong light conditions. The depletion of photosystem II occurs before total pigment bleaching. This newly recognized mechanism in herbicidal activity is also the basis for the mode of action of other lycopene cyclase inhibitors as well as phytoene desaturase inhibitors. © 2001 Society of Chemical Industry     

春季亚低温胁迫对油茶‘华硕’叶片光合生理特性的影响

为探究亚低温胁迫对油茶叶片光合生理特性的影响,以油茶‘华硕’2年生盆栽苗为试材,通过测定亚低温10 ℃/5 ℃（昼/夜）胁迫过程中油茶叶片快速叶绿素荧光诱导曲线和830 nm光吸收曲线,结合叶片超微结构观察,分析叶片叶绿素含量、光系统活性、碳同化物含量的变化。结果表明：相比于正常温度28 ℃/20 ℃（昼/夜）,亚低温胁迫处理的油茶叶片PS II与PS I活性均发生抑制;亚低温胁迫下油茶叶片光合机构电子传递链活性显著降低,导致叶片光合机构的光合性能降低;随着亚低温胁迫处理时间的延长,可溶性糖含量呈增加趋势,淀粉含量逐渐降低。因此,在亚低温胁迫下,过剩激发能会抑制油茶PS Ⅱ、PS Ⅰ的活性,导致光合电子传递活性降低,且随着胁迫时间的延长,细胞膜系统会受到显著伤害,但一定时间内,油茶叶片可以通过累积可溶性糖,维持亚低温胁迫下光系统的活性。     

水稻叶片光氧化研究进展

探讨超级粳稻品种南粳44和南粳5055对光氧化处理的光化学响应特性及其耐性机制,比较耐光氧化特性的差异,为优质超级稻的培育提供理论参考。

选用南粳44和南粳5055为试材,在抽穗10 d后取剑叶进行7 d光氧化处理,对2个粳稻品种处理前后剑叶的叶绿素荧光动力学参数进行比较和分析。

光氧化处理前,南粳44和南粳5055的叶绿素荧光动力学参数均无显著差异;光氧化处理后,2个品种的光系统Ⅱ (PSⅡ) 均受到不同程度的光抑制,PSⅡ结构和生理状态受损,光合性能下降,初始荧光(F_o)增加,最大光化学效率(F_v/F_m)和叶片光合性能指数(PI_abs)下降,PSⅡ光化学活性降低,但南粳44的光化学活性显著高于南粳5055。光氧化处理后,南粳44的单位反应中心吸收(ABS/RC)、捕获(TR_o/RC)和耗散(DI_o/RC)的能量与对照相比未显著升高,但显著低于南粳5055,说明南粳44单位面积有活性反应中心数量较高,其剑叶PSⅡ供体侧参数K相相对可变荧光(V_K)和L相相对可变荧光(V_L)分别是南粳5055的0.50倍和0.45倍,PSⅡ受体侧参数J点相对可变荧光(V_J)和I点相对可变荧光(V_I)及Q_A被还原的程度(M_o)和受体侧库的大小(S_m)分别为南粳5055的0.60倍、0.91倍、0.50倍和1.74倍,其剑叶PSⅡ供体侧电子的供应能力和受体侧Q_A向Q_B电子传递能力显著优于南粳5055;南粳44的F_v/F_m和PI_abs较南粳5055分别显著高28.24%和776.82%。

南粳44 PSⅡ的光合性能较强,可通过自身调节降低光抑制,其耐光氧化特性优于南粳5055。

     

Effects of short-term low temperatures on photosystem Ⅱ function of samara and leaf of Siberian maple (Acer ginnala) and subsequent recovery

Samara is the reproductive organ (seed) for many tree species in arid land in northwestern China. It is ecologically important in population development due to its dispersal function. However, information on its photosynthesis and effect of environmental stresses on its photosynthesis is still very limited. In the present study, responses of photosystem II (PSII) activity in samara and leaf of Siberian maple to short-term chilling/freezing and subsequent recovery potential were comparatively investigated by using polyphasic fluorescence test. The samara had more efficient photosynthesis (Fv/Fm and PIABS) and more efficient electron transport (φEo) but lower energy dissipation (DIo/RC) than leaf. Generally, the PSII performance and the electron transport for both samara and leaf were inhibited under low temperature stress, accompanied by an increase of energy dissipation in PSII reaction centers (RCs). PSII of both samara and leaf was not markedly affected by chilling and could acclimate to chilling stress. Short-term freezing could completely inhibit PSII activity in both samara and leaf, indicated by the drop of values of Fv/Fm, PIABS, φEo to zero. PSII functional parameters of short-term dark frozen samara could be largely recovered whereas those of frozen leaf could not be recovered. The higher tolerance of samara to short-term low temperature stress than leaf is of great ecological significance for seed development, population establishment of Siberian maple.