硫对烟草叶片光合特性和叶绿素荧光参数的影响

通过液培试验,测定了不同硫营养水平(0～32 mmol/L)下烟草叶片的叶绿素含量、气体交换参数和叶绿素荧光参数.结果表明,随着硫浓度的升高,烟草叶片的Chl.a、Chl.b、总Chl的含量和Chl.a/b逐渐增加;类胡萝卜素呈先下降后升高的趋势;烟草叶片的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、胞间CO2浓度(Ci)下降显著,气孔限制值(Ls)明显升高,这表明高硫对烟草叶片的气体交换参数影响较大.随着硫浓度的升高,烟草叶片光合有效量子产量(EQY)、光合电子传递速率(ETR)、光化学淬灭(qP)都表现为先升高后降低,一般是4 mmol/L和8 mmol/L处理相对较高,浓度超过8 mmol/L以后,以上参数显著下降.非光化学淬灭(NPQ) 0,16 mmol/L和32 mmol/L处理表现相对较高,2、4、8 mmol/L处理的相对较低,2～8 mmol/L浓度的处理最适宜烟草的生长,高硫或低硫都会导致烟草EQY、ETR、qP降低和NPQ的升高.     

锰浓度对米氏凯伦藻叶绿素荧光特性及生长的影响

运用实验生态学和叶绿素荧光分析技术,研究了锰浓度(10-12-10-4mol/L)对米氏凯伦藻(Karenia mikimotoi)叶绿素荧光特性及生长的影响。单因子方差分析结果表明:锰对米氏凯伦藻的生长和叶绿素荧光参数(Fv/Fm,Fv/Fo,ΦPSⅡ,ETR,qP,NPQ)均有显著影响(P0.05);米氏凯伦藻的叶绿素相对含量和细胞密度在10-12-10-8mol/L锰浓度间随着起始锰浓度的增大而增大,在10-8-10-4mol/L锰浓度间随锰浓度的增大而降低。多重比较结果表明,10-4mol/L锰浓度组的细胞密度和叶绿素相对含量显著低于其它处理组。锰浓度对荧光参数的影响与锰浓度范围和生长时期有关,当锰浓度为10-12-10-8mol/L时,荧光参数Fv/Fm,Fv/Fo,ΦPSⅡ,ETR在第3-9天随着起始锰浓度的增加而升高,Fv/Fm和Fv/Fo在第2-7天随培养时间的延长而增加。qP值在整个培养周期内随锰浓度升高呈下降趋势,各浓度组的NPQ则呈现先下降后上升趋势。相关性分析结果表明,从第3天开始至实验结束,10-4mol/L浓度组的叶绿素相对含量与细胞密度之间均呈极显著的正相关关系(P0.01)。荧光参数(Fv/Fm、Fv/Fo)、叶绿素相对含量以及细胞密度与锰浓度的相关性则随着锰浓度范围及培养天数的不同而变化。从第4天开始至培养结束,细胞密度、叶绿素相对含量均与锰浓度(10-8-10-4mol/L)呈极显著的负相关(P0.01)。探讨了叶绿素荧光技术在赤潮藻研究中的应用。     

芳樟不同无性系叶片光合色素含量及叶绿素荧光参数分析

对18个芳樟[Cinnamomum camphora (L.) Presl]无性系叶片光合色素含量和叶绿素荧光参数进行了测定,并对各参数的相关性进行了分析;基于上述测定结果对供试的18个芳樟无性系进行了聚类分析.结果表明:芳樟不同无性系叶片叶绿素a、叶绿素b及类胡萝卜素含量分别为0.60～2.26、0.24～1.15和0.14～0.50mg· g-1,差异较大,部分无性系间叶绿素a和b以及类胡萝卜素含量差异达显著水平;其中,无性系BT2叶片的叶绿素a含量在18个无性系中最高,叶绿素b及类胡萝卜素的含量也较高.各无性系间叶片的初始荧光(Fo)、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ潜在活性(Fv/Fo)、PSⅡ电子传递情况(Fm/Fo)、光化学淬灭系数(Qp)、非光化学淬灭系数(NPQ)和PSⅡ实际光化学效率(Qy)差异明显,且部分无性系间的差异达显著水平;各无性系间的最大荧光(Fm)、可变荧光(Fv)和荧光下降比值(Rfd)差异不显著.在各叶绿素荧光参数中,Fo与Fm显著正相关;Fm与Fv、Fv/Fm、Fv/ Fo、Fm/Fo以及Fv/Fm与Fv、Fv/Fo、Fm/Fo、Qy间均存在极显著正相关,其中Fv/Fm与Fv/ Fo、Fm/Fo的相关系数均达0.98;Qp与NPQ、Rfd呈极显著正相关,与其他参数则总体上呈负相关;Qy与Fm、Fv、Fv/Fm、Fv/Fo、Fm/Fo以及Rfd与NPQ、Qp、Qy均存在显著或极显著正相关.采用欧氏距离法,可将18个无性系划分为2类:第1类包含16个无性系;第2类仅包含无性系PC5和WP1.第1类又可进一步划分为2个亚类:第1亚类仅包含无性系BY2;第2亚类共包含15个无性系,其中的BT1与BT2距离最短,光合生理特征最接近.根据研究结果,初步推断芳樟各无性系叶片的潜在光化学活性和电子传递情况共同影响PSⅡ光能转换效率;无性系116、187、BT1和MD1对光能的利用率较高;无性系BT2则具有良好的光合生理性能.     

杜鹃花类菌根真菌对桃叶杜鹃幼苗光合性能及叶绿素荧光参数的影响

【目的】研究12株杜鹃花类菌根(Ericoid mycorrhiza,ERM)真菌对2 a生桃叶杜鹃无菌实生幼苗促生效应及叶片叶绿素、光合参数和叶绿素荧光参数的影响。【方法】采用温室盆栽试验,ERM真菌菌株由野生桃叶杜鹃根系分离而得。【结果】表明接种苗侵染率较高。接种处理间在幼苗地上部分、地下部分干重与总生物量指标呈极显著差异(P<0.01)。与不接种对照相比,叶片中叶绿素a、叶绿素b、总叶绿素含量、叶片净光合速率Pn、叶片气孔导度Gs和叶片蒸腾速率Tr显著提高,而叶片胞间CO2浓度Ci则降低。接种幼苗叶片中实际量子产量ΦPSⅡ除菌株TY19、TY24和TY34低于对照外,其余均显著增加;PSⅡ电子传递速率ETR、PSⅡ最大光化学量子产量Fv/Fm、潜在活性Fv/Fo和光化学淬灭qP均显著提高;非光化学淬灭NPQ除菌株TY29外其它均高于对照,并与对照差异极显著(P<0.01)。ΦPSⅡ与Pn、Gs的相关性大于Fv/Fm、qP、NPQ;ETR与Fv/Fm、Fv/Fo、NPQ、Pn、Tr的相关性大于qP和Gs;Pn与Gs的相关性大于Tr,与Ci显著负相关(P<0.01)。【结论】通过接种处理,提高了叶片光合性能及叶绿素荧光参数,增强了植株对有效光的利用,显著增加了幼苗生物量。从综合接种效应来看,TY18、TY29、TY35、TY02、TY07和TY12是培育桃叶杜鹃菌根苗优良备选菌株。     

镉污染对烤烟光合特性、产量及其品质的影响

采用盆栽方法,研究了cd污染对烤烟叶片光合特性、烟叶品质及其产量的影响。结果表明,随着Cd处理浓度的增加,烟叶净光合速率（砌）和气孔导度（Gs）逐渐降低,胞间CO2浓度（Ci）随Cd浓度的增加逐渐增大;光系统Ⅱ活性（Fv/Fo）、最大光能转换效率（Fv／Fm）、光化学猝灭系数（qP）、非光化学猝灭系数（NPQ）、电子传递的量子产率（φps Ⅱ）和有效电子传递速率（ETR）则随Cd浓度的增加而降低;烤烟烟叶中的糖,碱比和氮,碱比升高,化学成分组成趋于不协调,不利于烟叶香吃味的形成。     

NaCl胁迫下交替呼吸途径对叶绿素含量及其荧光特性的影响

以菜豆幼苗作为试验材料,分析了NaCl胁迫下交替呼吸对叶绿素含量以及叶绿素荧光特性变化特征的影响,以探讨交替呼吸途径在逆境下的生理学作用以及植物在盐胁迫下光系统Ⅱ(PSⅡ)的调节作用机制。结果表明:(1)随着NaCl胁迫浓度(0、100、200、300mmol/L)的增高,菜豆幼苗叶片叶绿素含量显著下降,叶片光系统Ⅱ(PSⅡ)潜在最大光化学量子效率(Fv/Fm)、光适应下最大光化学效率(Fv′/Fm′)、PSⅡ光适应下实际光化学效率[Y(Ⅱ)]和光化学荧光猝灭(qP)与对照相比均显著性下降,而非光化学猝灭(NPQ)较对照组显著增加,同时交替呼吸容量在NaCl胁迫下也显著上升。(2)与单独NaCl胁迫相比,在NaCl胁迫下施加交替呼吸的抑制剂水杨基氧肟酸(SHAM)会导致菜豆幼苗叶片叶绿素含量、Fv/Fm、Fv′/Fm′、Y(Ⅱ)和qP进一步显著下降、NPQ进一步显著增加。研究认为,NaCl胁迫导致菜豆叶片光系统Ⅱ光化学效率下降和光能耗散增加,交替呼吸途径可有效缓解NaCl胁迫下菜豆叶绿素含量的减少以及光系统Ⅱ光化学反应效率的下降。     

草莓叶片光合作用对强光的响应及其机理研究

用便携式调制叶绿素荧光仪和光合仪研究了强光下草莓叶片荧光参数及表观量子效率的变化.结果表明,Fm、Fv/Fm、PSⅡ无活性反应中心数量和Q_A的还原速率在强光下降低,在暗恢复时升高;而PSⅡ反应中心非还原性Q_B的比例在强光下增加,在暗恢复时降低.上述荧光参数的变化幅度均以强光胁迫或暗恢复的前10 min最大.强光下Φ_PSII、ETR和qP先升高后降低,但qN先大幅度降低,然后小幅回升.强光处理4 h后,丰香和宝交早生的表观量子效率(AQY)分别降低了20.9%和37.5%;qE(能量依赖的非光化学猝灭)为NPQ(非光化学猝灭)的最主要成分.强光胁迫下丰香的Fo、Fm、Fv/Fm、Φ_PSII、ETR和AQY的变化幅度均明显比宝交早生小.DTT处理后,草莓叶片的Fm和Fv/Fm明显降低,Fo显著升高.可以认为,依赖叶黄素循环和类囊体膜质子梯度两种非辐射能量耗散在草莓叶片防御光损伤方面起着重要作用,丰香的光合机构比宝交早生更耐强光.     

复苏被子植物牛耳草脱水和复水期间叶黄素循环的保护作用

研究了复苏被子植物牛耳草（Boea hygrometrica(Bunge)R.Br.)离体叶片在微弱光强下（3μmol photons.m^-2.s^-1)和黑暗中叶黄素循环组分及叶绿素荧光随脱水复水的变化,结果发现：脱水期间随着光系统Ⅱ光化学效率（Fv/Fm）、实际量子产率（ΦPSⅡ）、光化学淬灭（qP）和非光化学淬灭（NPQ）值的降低,微弱光强下的对照叶片玉米黄素含量显著增加,而微弱光强下DTT处理的叶片和黑暗中的叶片都没有玉米黄素的积累,经过3d复水后,微弱光强下对照叶片的Fv/Fm,ΦPSⅡ,qP和NPQ值能完全恢复,但是微弱光强下DTT处理的叶片和黑暗中的叶片其Fv/Fm、ΦPSⅡ、qP和NPQ值能完全恢复。说明脱水的牛耳草主体叶片光系统Ⅱ的光化学活性的恢复明显受到DTT处理和黑暗的影响,因此玉米黄素可能对微弱光强下脱水的牛耳草叶片具有重要的保护作用。     

水杨酸对高温胁迫下黄瓜幼苗叶绿素荧光参数的影响

以津春3号黄瓜为试材,对其喷施0.05、0.1和0.5 mmol/L的水杨酸(SA)溶液,并进行了昼(40±1)℃/夜(30±1)℃高温胁迫处理,研究了黄瓜幼苗四叶期叶片叶绿素荧光参数变化.结果表明,高温胁迫下幼苗叶绿素荧光参数Fo、NPQ等显著升高,Fv/Fm、Fv′/Fm′等明显降低,嫁接苗的变化趋势弱于自根苗;不同浓度的SA溶液可缓解高温胁迫对黄瓜幼苗叶绿素荧光参数的影响,且以0.1 mmol/L的SA处理效果最优.     

盐胁迫对鸡爪槭幼苗生长及其叶绿素荧光参数的影响

以鸡爪槭幼苗为材料,采用盆栽方法,研究了不同盐浓度[0.042%(对照)、0.2%、0.4%和0.6%]对鸡爪槭幼苗生长的伤害和叶绿素荧光参数的影响。结果显示:当土壤NaCl含量为0.2%、0.4%和0.6%时,鸡爪槭幼苗分别表现为轻度、中度和重度盐害;叶片含水量、叶绿素a和b及叶绿素总含量均随盐浓度的增加而显著下降,花色素苷含量则表现为随盐浓度的增大而显著上升,分别比对照高出48.7%、280.3%和382.7%;叶片叶绿素荧光参数PSⅡ潜在活性(Fv/Fo)、潜在量子效率(Fv/Fm)、光化学量子产量(Yield)、光合电子传递速率(ETR)、实际光化学效率(ΦPSⅡ)和光化学猝灭系数(qP)均随着盐浓度的增大呈显著下降趋势,但非光化学猝灭系数(NPQ)在低盐胁迫时则较对照显著提高,0.2%NaCl处理时比对照显著增加33.3%,而高盐胁迫下则显著下降。研究表明,盐胁迫显著抑制了鸡爪槭幼苗叶片叶绿素合成和光合作用进行,而幼苗叶片在低盐胁迫下则可能通过增加PSⅡ反应中心非辐射热能量耗散来保护光合机构不受损害,从而表现出一定的耐盐胁迫能力。     

Spectrofluorimetric method for the determination of large chlorophyll a/b ratios

A practical spectrofluorimetric calibration method at room temperature is described for determining large chlorophyll a/b ratios on direct extracts from plant material of pigments in 80% aqueous acetone, dimethyl sulfoxide, and N,N-dimethylformamide. The method is based on the work of Boardman and Thorne [Boardman NK and Thorne SW (1971) Biochim Biophys Acta 253: 222–231] who used diethyl ether as solvent. We repeated the calibration in diethyl ether and find significantly different parameters for the calibration curve. The range of standards in this work included solutions with chlorophyll a/b ratios of 10–125 in dimethyl sulfoxide, and of 10–220 in the other solvents. Fluorescence emission spectra were found to be a highly sensitive method for assessing chlorophyll purity. We determined the limits of sensitivity for each solvent from the calibration data. The empirically determined slope of the calibration curve was shown to be related to intrinsic properties of the chlorophylls in solution; this allows predictions of the performance of the method in other solvents.     

两种生境条件下6种牧草叶绿素含量及荧光参数的比较

昆仑山前山牧场海拔较高, 策勒绿洲海拔相对较低, 两者生境差异较大。以昆仑山前山牧场和策勒绿洲边缘两种不同生境条件下生长的6种牧草: 冰草(Agropyron cristatum)、无芒雀麦(Bromus inermis)、矮生高羊茅(Festuca elata)、披碱草(Elymus dahuricus )、红豆草(Onobrychis pulchella)及和田大叶(Medicago sativa var. luxurians)为试验材料, 研究了不同生境条件下牧草叶片叶绿素含量及叶绿素荧光动力学参数的变化情况。结果显示: (1)在两种生境条件下, 昆仑山前山牧场生境生长的牧草叶绿素a、叶绿素b、总叶绿素的含量明显较高, 生长在策勒绿洲生境的牧草品种叶绿素a/b值较高; (2)昆仑山前山牧场生境牧草最大荧光、光系统II (PSII)最大光化学效率、PSII潜在活性和单位面积反应中心的数量的值明显高于策勒绿洲生境品种, 而初始荧光、单位反应中心吸收的光能、单位反应中心捕获的能量、单位反应中心耗散的能量、荧光诱导曲线初始斜率值则低于策勒绿洲生境品种。因此, 两种生境下环境因子发生了改变, 对牧草产生综合的胁迫作用; 策勒绿洲生境明显对牧草生长产生了抑制, 策勒绿洲生境牧草的色素含量降低以及PSII的机构遭到损坏, 导致反应中心一部分失活或裂解, 剩余有活性的反应中心的效率增加, 昆仑山生境则相对比较适宜牧草生长; 两种生境不同牧草叶绿素含量和叶绿素荧光参数的变化幅度不同。     

Conversion of chlorophyll b to chlorophyll a precedes magnesium dechelation for protection against necrosis in Arabidopsis

Chlorophyll is a deleterious molecule that generates reactive oxygen species and must be converted to non‐toxic molecules during plant senescence. The degradation pathway of chlorophyll a has been determined; however, that of chlorophyll b is poorly understood, and multiple pathways of chlorophyll b degradation have been proposed. In this study, we found that chlorophyll b is degraded by a single pathway, and elucidated the importance of this pathway in avoiding cell death. In order to determine the chlorophyll degradation pathway, we first examined the substrate specificity of 7‐hydroxymethyl chlorophyll a reductase. 7‐hydroxymethyl chlorophyll a reductase reduces 7‐hydroxymethyl chlorophyll a but not 7‐hydroxymethyl pheophytin a or 7‐hydroxymethyl pheophorbide a. These results indicate that the first step of chlorophyll b degradation is its conversion to 7‐hydroxymethyl chlorophyll a by chlorophyll b reductase, although chlorophyll b reductase has broad substrate specificity. In vitro experiments showed that chlorophyll b reductase converted all of the chlorophyll b in the light‐harvesting chlorophyll a/b protein complex to 7‐hydroxymethyl chlorophyll a, but did not completely convert chlorophyll b in the core antenna complexes. When plants whose core antennae contained chlorophyll b were incubated in the dark, chlorophyll b was not properly degraded, and the accumulation of 7‐hydroxymethyl pheophorbide a and pheophorbide b resulted in cell death. This result indicates that chlorophyll b is not properly degraded when it exists in core antenna complexes. Based on these results, we discuss the importance of the proper degradation of chlorophyll b.     

Accumulation of the NON‐YELLOW COLORING 1 protein of the chlorophyll cycle requires chlorophyll b in Arabidopsis thaliana

Chlorophyll a and chlorophyll b are interconverted in the chlorophyll cycle. The initial step in the conversion of chlorophyll b to chlorophyll a is catalyzed by the chlorophyll b reductases NON‐YELLOW COLORING 1 (NYC1) and NYC1‐like (NOL), which convert chlorophyll b to 7‐hydroxymethyl chlorophyll a. This step is also the first stage in the degradation of the light‐harvesting chlorophyll a/b protein complex (LHC). In this study, we examined the effect of chlorophyll b on the level of NYC1. NYC1 mRNA and NYC1 protein were in low abundance in green leaves, but their levels increased in response to dark‐induced senescence. When the level of chlorophyll b was enhanced by the introduction of a truncated chlorophyllide a oxygenase gene and the leaves were incubated in the dark, the amount of NYC1 was greatly increased compared with that of the wild type; however, the amount of NYC1 mRNA was the same as in the wild type. In contrast, NYC1 did not accumulate in the mutant without chlorophyll b, even though the NYC1 mRNA level was high after incubation in the dark. Quantification of the LHC protein showed no strong correlation between the levels of NYC1 and LHC proteins. However, the level of chlorophyll fluorescence of the dark adapted plant (F_o) was closely related to the accumulation of NYC1, suggesting that the NYC1 level is related to the energetically uncoupled LHC. These results and previous reports on the degradation of chlorophyllide a oxygenase suggest that the a feedforward and feedback network is included in chlorophyll cycle.     

Effects of nickel hyperaccumulation on physiological characteristics of Alyssum murale grown on metal contaminated waste amended soil

A pot experiment was conducted to investigate the effect of nickel concentration on physiological characteristics of Alyssum murale when grown in a soil mixed with sewage sludge (at the rate of 2.8%). Two types of sludge were used: agricultural sewage sludge (S1) and industrial sewage sludge with an increasing nickel concentration (S2, S3, and S4). Results showed that Ni in shoots was higher than Ni in roots. A. murale is able to concentrate up to 12730 mg/kg Ni in leaves. The highest dry matter yield was observed with plants grown with agricultural sewage sludge. An addition of S2 and S3 increased shoot biomass. However, application of S4 reduced 40% shoot dry weight as compared to the control Ni treatment did not affect all chlorophyll fluorescence parameters. The F(v)/F(m) ratio was stable between Ni treatments. Photosynthesis rate (A) increased with agricultural sewage sludge, but remained stable with variable Ni rates from the industrial sludge. The chlorophyll content increased with S1, S2 and S3 but it remains constant with S4 when compared to the control Therefore, high nickel concentration did not affect the function of the photosynthetic machine of A. murale.     

Recent advances in chlorophyll biosynthesis and breakdown in higher plants

Chlorophyll (Chl) has unique and essential roles in photosynthetic light-harvesting and energy transduction, but its biosynthesis, accumulation and degradation is also associated with chloroplast development, photomorphogenesis and chloroplast-nuclear signaling. Biochemical analyses of the enzymatic steps paved the way to the identification of their encoding genes. Thus, important progress has been made in the recent elucidation of almost all genes involved in Chl biosynthesis and breakdown. In addition, analysis of mutants mainly in Arabidopsis, genetically engineered plants and the application of photo-reactive herbicides contributed to the genetic and regulatory characterization of the formation and breakdown of Chl. This review highlights recent progress in Chl metabolism indicating highly regulated pathways from the synthesis of precursors to Chl and its degradation to intermediates, which are not longer photochemically active.     

Green thoughts in a green shade

The author gives an autobiographical sketch of his path to chlorophyll research, and describes some results. The discussion is largely focused on long wavelength forms of chlorophyll and how they might be generated by self-assembly. Dimers or oligomers, (Chl)_n, result from coordination interactions between the central magnesium atom of one macrocycle and nucleophilic side chains of another i.e., keto C=OMg in the case of Chl a. Coordination interactions mediated by a water molecule coordinated to Mg in one macrocycle and to a nucleophilic group in another e.g., MgO(H)HO=C keto, form aggregates with very different structures and properties; where more than one strong nucleophile or hydrogen bonding group is present in the chlorophyll, e.g., the formyl group in Chl b, the acetyl group of Bchl a, or the hydroxyethyl group of Bchl c, they may also participate in direct coordination interactions with Mg as well as hydrogen bonding to water coordinated to Mg. The magnetic resonance properties of Chl a/water aggregates have provided the basis for the special pair concept for the primary electron donor in photosynthesis. Structural information derived from small angle neutron scattering studies on chlorophyll aggregates is now providing an experimental basis for comprehensive models that integrate antenna and photoreaction center chlorophyll functions.This article was written at the invitation of Govindjee. It has been authored by a contractor of the U.S. Government under contract No. W-31-109-ENG-38. Accordingly, the U.S. Government retains a non-exclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes.     

Phosphorescence of protochlorophyll(ide) and chlorophyll(ide) in etiolated and greening bean leaves

The assignment is presented for the principal phosphorescence bands of protochlorophyll(ide), chlorophyllide and chlorophyll in etiolated and greening bean leaves measured at -196°C using a mechanical phosphoroscope. Protochlorophyll(ide) phosophorescence spectra in etiolated leaves consist of three bands with maxima at 870, 920 and 970 nm. Excitation spectra show that the 870 nm band belongs to the short wavelength protochlorophyll(ide), P627. The latter two bands correspond to the protochlorophyll(ide) forms, P637 and P650. The overall quantum yield for P650 phosphorescence in etiolated leaves is near to that in solutions of monomeric protochlorophyll, indicating a rather high efficiency of the protochlorophyll(ide) triplet state formation in frozen plant material. Short-term (2–20 min) illumination of etiolated leaves at the temperature range from -30 to 20°C leads to the appearance of new phosphorescence bands at about 990–1000 and 940 nm. Judging from excitation and emission spectra, the former band belongs to aggregated chlorophyllide, the latter one, to monomeric chlorophyll or chlorophyllide. This indicates that both monomeric and aggregated pigments are formed at this stage of leaf greening. After preillumination for 1 h at room temperature, chlorophyll phosphorescence predominates. The spectral maximum of this phosphorescence is at 955–960 nm, the lifetime is about 2 ms, and the maximum of the excitation spectrum lies at 668 nm. Further greening leads to a sharp drop of the chlorophyll phosphorescence intensity and to a shift of the phosphorescence maximum to 980 nm, while the phosphorescence lifetime and a maximum of the phosphorescence excitation spectrum remains unaltered. The data suggest that chlorophyll phosphorescence belongs to the short wavelength, newly synthesized chlorophyll, not bound to chloroplast carotenoids. Thus, the phosphorescence measurement can be efficiently used to study newly formed chlorophyll and its precursors in etiolated and greening leaves and to address various problems arising in the analysis of chlorophyll biosynthesis.Abbreviations Pchl protochlorophyll and protochlorophyllide - Chld chlorophyllide - Chl chlorophyll     

Interconversions of Chlorophylls a and b Synthesized from Exogenous Chlorophyllides a and b in Etiolated and Post-Etiolated Rye Seedlings

A comparative study of reciprocal conversions of chlorophylls a and b (Chl aand Chl b) in etiolated and post-etiolated rye seedlings (Secale cereale L.) was performed. The production of these pigments was initiated by infiltration of exogenous chlorophyllides a and b (Chlide a and b). It was shown that Chlide b, when infiltrated into etiolated rye seedlings, was esterified, producing Chl b. A major portion of Chl b (more than 80%) was transformed into Chl aduring long-term seedling dark exposure. The high rate of Chl b conversion into Chl a in the pool of pigments of exogenous origin was also observed during the lag-phase when there was no chlorophyll formation from endogenous precursors. The infiltration of Chlide a resulted in Chl a formation. The efficiency of its conversion into Chl b was low (about 1%) in the etiolated seedlings but increased during their greening. In the post-etiolated seedlings infiltrated with Chlide b, which were preliminary illuminated for 6–12 h, the Chl /Chl a ratio was almost similar in the pools of pigments synthesized from both exogenous and endogenous precursors. The rates of direct and reverse reactions responsible for the interconversion of Chl aand Chl b depended on the stage of the formation of the photosynthetic apparatus during greening of etiolated seedlings, when the particular structural components are formed in a definite sequence.     

植物叶绿素合成、分解代谢及信号调控

叶绿素(Chlorophyll, Chl)合成是决定植物光合效率的重要性状, 是决定作物产量的重要因素。参与植物Chl合成、分解代谢及信号调控的基因数目众多, 其中任何一个基因发生突变都有可能引起Chl含量的变化, 从而表现为各种叶色异常甚至导致植株死亡。自然或人工创造突变体, 对于Chl相关基因的功能分析非常必要。目前, Chl突变体己广泛应用于基础研究和生产实践。文章就该研究领域内的最新研究进展进行了概述。