Isomers of rhodoxanthin in reddish brown leaves of gymnosperms and effect of daylight intensity on the contents of pigments during autumnal coloration

The major red carotenoids in autumnal, colored leaves were analyzed in seven species and one variety that belong to two families of gymnosperms. The red carotenoids in leaves of all species and variety were rhodoxanthin, which was separated into three geometric isomers, (6Z, 6′Z)-rhodoxanthin, (6Z)-rhodoxanthin and (all E)-rhodoxanthin. The effects of daylight intensity on the content and composition of the leaf pigments of autumnal coloration were studied with leaves ofCryptomeria japonica (evergreen) andTaxodium distichum (deciduous) grown under different grades of shade. Histological observation showed that many reddish particles of rhodoxanthin were observed inside chromoplasts on the sunny side of a leaf at the early stage of coloration and that the content of the reddish particles was decreased toward the shady side from the sunny side of a leaf. The transition from chloroplasts to chromoplasts was observed and cells at different stage of coloration independently existed in the mesophyll tissue of a leaf. The content of rhodoxanthin became maximum when the daylight intensity was 4.1–7.4 MJ m^?2 day^?1 and the daily mean temp. was below 8.1 C inCryptomeria, and 3.1–8.3 MJ m^?2 day^?1 and 13.4 C inTaxodium.     

Eco-physiological studies on the response of taxodiaceous conifers to shading,with special reference to the behaviour of leaf pigments

The composition of leaf pigments was studied in 32 species of gymnosperms. In 19 species belonging to four families, both evergreen and deciduous leaves turned to reddish brown in late autumn and winter. The red pigment detected in these leaves proved to be rhodoxanthin. The colouring was due to the disappearance of chloroplast pigments and the subsequent synthesis of rhodoxanthin. Neither qualitative nor quantitative differences were recognised in the chloroplast-derived pigments of green leaves between the species with and without the ability to produce rhodoxanthin. Unlike green leaves in which ca. 10% of total carotenoid content was α-carotene, reddish brown leaves scarcely contained α-carotene. Changes in pigment composition during the reddish colouring of leaves and their regreening were studied in detail and discussed.     

Photosynthetic acclimation to low temperature by western red cedar seedlings

Imposition of low, but above freezing, temperatures resulted in a gradual increase in the cold hardiness of western red cedar seedlings. This was associated with a decrease in the maximum rates of photosynthetic CO₂ fixation and O₂ evolution, and changes in chlorophyll a fluorescence transients which indicated that photoinhibition had occurred. Maximum photosynthetic rates declined approximately 40% during cold hardening. The leaves changed colour from green to red-brown during the hardening process. The colour change was due to the synthesis of large amounts of the carotenoid rhodoxanthin. Lutein levels doubled, while chlorophyll declined slightly. Dehardening resulted in the rapid recovery of photosynthesis to control levels, the rapid disappearance of rhodoxanthin, and the return of lutein levels to control. It is suggested that rhodoxanthin accumulation at low temperature functions to decrease the light intensity reaching the photosynthetic apparatus. The combination of photoinhibition and rhodoxanthin synthesis probably serves to protect the photosynthetic capacity of the seedlings at low temperature.     

Impact of specific environmental characteristics of the site of origin (shady,sunny) on anthocyanin and flavonol contents of replanted plants at common cyclamen (<Emphasis Type="Italic">Cyclamen purpurascens</Emphasis> Mill.)

The value of plant provenance (plant origin) is well-known phenomena in woody plants, but less is known in herbaceous plants (perennials). This study with common cyclamen (Cyclamen purpurascens Mill.) was conducted to reveal the importance of specific environmental site properties of plant origin for plant growth and plant quality in the next years. The plants were observed in years 2013 and 2014, more than 10 years after removing and replanting them from the original sites. Morphological characteristics of plants were evaluated by measuring the length and the width of plant rosettes, whereby plants originated from different sites did not show any significant differences. Additionally, the pigment composition, flavonol and anthocyanin content of plant leaves were evaluated. Plants removed from sunny sites showed significantly lower chlorophyll values (total chlorophyll, chlorophyll a) in the both observed years; lower carotenoid and total pigment values were measured only in year 2013. The prevailing anthocyanin in cyclamen leaves was malvidin-3,5-diglucoside with 57.28 µg l^?1 FW in the year 2013 and with 103.68 µg l^?1 FW in the year 2014. Plants originated from the sunny sites accumulated in 2013 significantly more malvidin-3,5-diglucoside in comparison with plants from shady sites of origin. The major substances from the flavonol group were quercetin-3-O-rutinoside and quercetin-dirhamnosyl-glucoside in both analysed years. The cyclamen leaves originated from sunny sites contained in 2013 significant more quercetin-dirhamnosyl-glucoside than cyclamen leaves from shady sites. The results of the study show that different stress parameters (irradiation and water supply in specific year) have a significant impact on the morphological and also internal parameters of cyclamen leaves.     

Cretaceous coleopteran larva fed on a female fructification of extinct gymnosperm

A fossil coleopteran larva was found in a permineralized female fructification of a new extinct gymnosperm from the Late Cretaceous of Japan. The fossil provides the firstin situ evidence that the insects used some gymnosperm fructification as foods as well as pupation sites before they started using angiosperm fruits.     

Lipids produced by Epicoccum nigrum in submerged culture

1. The lipids of the red mycelium of the fungus Epicoccum nigrum Link were investigated. Four carotenoid pigments were isolated and identified as beta-carotene, gamma-carotene, rhodoxanthin and torularhodin. 2. For the first time rhodoxanthin was isolated as a fungal metabolite. 3. Linoleic acid was the major fatty acid in the total lipids. 4. Ergosterol was present in the lipids in the non-esterified form.     

基于叶绿素荧光成像及荧光参数分布特征的叶片光合异质性定量分析

植物叶片光合作用具有高度的空间异质性,叶绿素荧光成像技术为叶片光合异质性的研究提供了便利,但叶片光合异质性的定量分析并没有得到广泛应用。本文利用Imaging PAM叶绿素荧光成像系统,获得中亚热带地区越冬期小叶榕(Ficus microcarpa)阳生叶和阴生叶的叶绿素荧光参数图像,并利用仪器的分析软件对其进行分析,定量比较了阳生叶和阴生叶的光合异质性特征。研究发现：越冬期小叶榕阳生叶的光合异质性和光抑制程度明显高于阴生叶,变异系数可作为光合异质性的定量指标。低温强光导致阳生叶坏死率(P_LN)达4.30%,并有53.30%的区域处于严重光抑制(0v/F_m<0.627),但仍有42.27%的区域仅为轻度光抑制(0.627≤F_v/F_m<0.800)。而低温弱光并未造成阴生叶坏死和严重光抑制。通过对光系统Ⅱ(PSⅡ)的实际光合效率(Y(Ⅱ))、调节性能量耗散的量子产额(Y(NPQ))和非调节性能量耗散的量子产额(Y(NO))荧光参数异质性的定量分析表明,阳生叶...     

Molecular and functional studies of tilapia (Oreochromis mossambicus) NMDA receptor NR1 subunits

The Pin-tailed Manakin (Ilicura militaris) is a small, sexually dimorphic, frugivorous suboscine songbird (Pipridae; Passeriformes; Aves) endemic to the Atlantic Forest of Brazil. A variant individual of this species was recently described in which the red patches that characterise the male's Definitive plumage were replaced by orange-yellow ones. We show here that the pigments in the feathers of the colour variant are common dietary carotenoids (zeaxanthin, beta-cryptoxanthin), not carotenoids synthesised by birds, lending support to the suggestion that the individual is a colour mutant lacking the capability to transform yellow dietary pigments into the red pigments normally present in these feathers. By comparison, the yellow crown feathers of a close relative, the Golden-winged Manakin (Masius chrysopterus), contained predominantly endogenously produced epsilon-caroten-3'-ones. Surprisingly, the normal-coloured feathers of the male Pin-tailed Manakin owe their red hue to rhodoxanthin, an unusual carotenoid more commonly found in plants, rather than 4-keto-carotenoids typically found in red plumages and found lacking in previously characterised bird colour variants. The implication is that birds, like the tilapia fish, may be able to synthesise this unusual pigment endogenously from dietary precursors. A newly described carotenoid, 6-hydroxy-epsilon,epsilon-carotene-3,3'-dione, here named piprixanthin, present in the red feathers of the Pin-tailed Manakin, provides a plausible intermediate between epsilon,epsilon-carotene-3,3'-dione (canary-xanthophyll B), a bright yellow pigment found in this and other songbirds, and rhodoxanthin. It is apparent that pigeons (Columbidae, Columbiformes) also have the capability to produce rhodoxanthin, and a structurally related pigment, endogenously. The ability to synthesise rhodoxanthin might have arisen at least twice in birds.     

Circadian Rhythms of Leaf and Stomatal Movements in Gymnosperm Species

It is generally accepted that various physiological, morphological and gene expression phenomena are under the control of a circadian clock, and that this time keeping mechanism is universally present. Although such endogenously regulated phenomena have first been documented in plants more than 250 years ago and much work has been accumulated particularly in the past 70 years, it was not obvious from the literature whether such time keeping mechanisms exist in gymnosperms. Two prominent parameters were investigated in several gymnosperm species which have been demonstrated to be under the control of a circadian clock in many plants: (i) leaf movement and (ii) stomata movement. In young plants of Pinus sylvestris, Picea abies, Taxus baccata, Araucaria angustifolia, Araucaria heterophylla and Ginkgo biloba leaf oscillations could be recorded for about 5 days. However, compared to angiosperm plants, the amplitude was small. The period length under free running conditions (constant temperature and continuous light) was characteristic for the species. Stomatal movement was observed in Ginkgo biloba leaves by electron microscopy. Stomata were open at noon and closed at midnight under normal day/night conditions (LD) as well as under constant light conditions (LL), indicating that stomatal aperture is under circadian control in the gymnosperm Ginkgo biloba. Online recordings of stomata conductance however, exhibited diurnal but not circadian oscillations of net CO₂-exchange in G. biloba leaves. Our results show that a circadian clock controls leaf and stomatal movements in gymnosperm species indicating that endogenous time keeping mechanisms are present.     

Photoprotective role of rhodoxanthin during cold acclimation in Cryptomeria japonica

To examine the role of rhodoxanthin in long‐term acclimation to low temperatures, we monitored seasonal changes in pigment composition, photosynthesis, chlorophyll fluorescence and the level of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) in needles of wild‐type and mutant forms of Cryptomeria japonica. In winter, rhodoxanthin accumulated in sun‐exposed needles of wild‐type plants, but not in those of the mutant. The level of chlorophyll decreased in both types of plant in winter. In contrast, the level of the xanthophyll cycle pool increased in both cases. The level of the pool in the mutant was twice that in the wild type in winter, on a Chl basis, even though the levels in both were similar in summer. The synthesis of rhodoxanthin might be triggered by photo‐inhibitory conditions, as suggested by the sustained elevated levels of zeaxanthin (Z) and antheraxanthin (A). In the wild type and the mutant, the quantum yield of CO₂ fixation (φ), the photosynthetic capacity, the photochemical efficiency of photosystem II (PSII), the photochemical quenching and the level of Rubisco in summer were similar. However, all these values for the wild type were higher than those for the mutant in winter. The non‐photochemical quenching (NPQ) in the mutant in winter increased rapidly even under low light conditions due to the high sustained levels of Z and A. In contrast, in the wild type, the conversion of Z via A to rhodoxanthin prevented the rapid increase in NPQ to maintain the relatively high level of φ. These findings suggest that rhodoxanthin might play an important photoprotective role in long‐term acclimation to cold. The dynamic regulation of the amount of rhodoxanthin relative to the level of the xanthophyll cycle pool might act to maintain an appropriate balance between light absorption, photosynthesis and the thermal dissipation of energy due to excess absorbed light in winter.     

Bi-directional acclimation of <Emphasis Type="Italic">Cycas micronesica</Emphasis> leaves to abrupt changes in incident light in understory and open habitats

Leaf gas-exchange responses to shadefleck–sunfleck and sun–cloud transitions were determined for in situ Cycas micronesica K.D. Hill plants on the island of Guam to add cycads to the published gymnosperm data. Sequential sunfleck–shadefleck transitions indicated understory leaves primed rapidly but open field leaves primed slowly. Time needed to reach 90% induction of net CO₂ assimilation (P_N) was 2.9 min for understory leaves and 13.9 min for open field leaves. Leaf responses to sun–cloud transitions exhibited minimal adjustment of stomatal conductance, so P_N rapidly returned to precloud values following cloud–sun transitions. Results indicate bi-directional leaf acclimation behavior enables mature C. micronesica trees to thrive in deep understory conditions in some habitats and as emergent canopy trees in other habitats. These data are the first nonconifer gymnosperm data; the speed of gas-exchange responses to rapid light transitions was similar to some of the most rapid angiosperm species described in the literature.     

Cytokinins in the Leaves of Ginkgo biloba: I. The Complex in Mature Leaves

Cytokinin conjugates of zeatin, ribosylzeatin, and their respective dihydro derivatives tentatively have been identified as the major cytokinins present in mature Ginkgo biloba L. leaves. Ribosylzeatin was present in higher levels than zeatin and dihydrozeatin. No evidence could be found that 6-(2,3,4-trihydroxy-3-methylbutylamino)purine occurs as a metabolite in the mature leaves. From the available evidence, it is concluded that cytokinin conjugates are probably the major metabolites formed in the leaves of this deciduous gymnosperm.     

The role of pigment system of an evergreen dwarf shrub Ephedra monosperma in adaptation to the climate of Central Yakutia

Adaptive reactions of the pigment system in assimilating shoots of evergreen dwarf shrub Ephedra monosperma J.G. Gmel. ex C.A. Mey. were studied under natural conditions of Central Yakutia. Seasonal changes in the content and ratio of green and yellow pigments were revealed; their relation to the stage of plant development and formation of cold tolerance was shown. The decrease in chlorophyll content started in September when the natural photoperiod became shorter and the air temperature lower; the chlorophyll concentration in winter was 30% lower than in summer. The content of β-carotene decreased twofold. The xanthophyll cycle pigments increased in content and deepoxidation level by a factor of 1.7 and 3.6, respectively. In peripheral cells of assimilating parenchyma, accumulation of a secondary carotenoid, rhodoxanthin was noted. In the period of active plant growth (from June to August), rhodoxanthin was absent, while its concentration in shoots in winter was 75 μg/g dry wt. It is concluded that changes in the pigment pool reflect structural and functional reorganization of photosynthetic machinery and are an indispensable part of the intricate process of plant hardening. Activation of energy-dissipating and antioxidant pigment systems, together with accumulation of the light-screening secondary carotenoid rhodoxanthin, promote the retention of photosynthetic apparatus and the survival of Ephedra monosperma plants under extreme conditions of cryolithozone of Yakutia.     

Evaluation of diel patterns of relative changes in cell turgor of tomato plants using leaf patch clamp pressure probes

Relative changes in cell turgor of leaves of well‐watered tomato plants were evaluated using the leaf patch clamp pressure probe (LPCP) under dynamic greenhouse climate conditions. LPCP changes, a measure for relative changes in cell turgor, were monitored at three different heights of transpiring and non‐transpiring leaves of tomato plants on sunny and cloudy days simultaneously with whole plant water uptake. Clear diel patterns were observed for relative changes of cell turgor of both transpiring and non‐transpiring leaves, which were stronger on sunny days than on cloudy days. A clear effect of canopy height was also observed. Non‐transpiring leaves showed relative changes in cell turgor that closely followed plant water uptake throughout the day. However, in the afternoon the relative changes of cell turgor of the transpiring leaves displayed a delayed response in comparison to plant water uptake. Subsequent recovery of cell turgor loss of transpiring leaves during the following night appeared insufficient, as the pre‐dawn turgescent state similar to the previous night was not attained.     

Are red leaves photosynthetically active?

At irradiances close to those representing a sunny day, red and green leaves of poinsettia (Euphorbia pulcherrima) showed only minor differences in their photosynthetic capacities despite the strong differences in their pigment composition. However, contrarily to green leaves, red leaves did not show inhibition of photosynthesis at high irradiances, because anthocyanins protected chloroplasts from photoinhibition.     

Circadian Rhythms of Leaf and Stomatal Movements in Gymnosperm Species

It is generally accepted that various physiological, morphological and gene expression phenomena are under the control of a circadian clock, and that this time keeping mechanism is universally present. Although such endogenously regulated phenomena have first been documented in plants more than 250 years ago and much work has been accumulated particularly in the past 70 years, it was not obvious from the literature whether such time keeping mechanisms exist in gymnosperms. Two prominent parameters were investigated in several gymnosperm species which have been demonstrated to be under the control of a circadian clock in many plants: (i) leaf movement and (ii) stomata movement. In young plants of Pinus sylvestris, Picea abies, Taxus baccata, Araucaria angustifolia, Araucaria heterophylla and Ginkgo biloba leaf oscillations could be recorded for about 5 days. However, compared to angiosperm plants, the amplitude was small. The period length under free running conditions (constant temperature and continuous light) was characteristic for the species. Stomatal movement was observed in Ginkgo biloba leaves by electron microscopy. Stomata were open at noon and closed at midnight under normal day/night conditions (LD) as well as under constant light conditions (LL), indicating that stomatal aperture is under circadian control in the gymnosperm Ginkgo biloba. Online recordings of stomata conductance however, exhibited diurnal but not circadian oscillations of net CO₂-exchange in G. biloba leaves. Our results show that a circadian clock controls leaf and stomatal movements in gymnosperm species indicating that endogenous time keeping mechanisms are present.     

Aerial Dispersal of Epiphytic Bacteria over Bean Plants

Plant canopies are strong sources of bacterial aerosols during sunny days when the leaves are dry. Bacterial concentration, upward flux, and deposition onto exposed petri plates were measured over snap beans during three growing seasons. A net upward flux of bacteria occurred only during the warm part of sunny days, not at night when leaves were wet with dew or when a thermal inversion was present. Aerosol source strength was positively correlated with wind speed. Upward fluxes were higher on days after rain than on days when the soil was dry. Other unidentified sources of variability in source strength probably exist. Canopy-level deposition, apparently due to intermediate-scale transport of bacteria in fairly concentrated clouds, can occur in the early evening.     

喀斯特退化天坑阴坡阳坡壳斗科植物的功能性状特征

喀斯特退化天坑的负地形生境中阴坡和阳坡的局域环境具有显著差异,导致植物群落类型差异明显。本研究以云南沾益退化天坑深陷塘为例,探究退化天坑阴坡与阳坡壳斗科植物功能性状特征,有助于揭示天坑的物种多样性保护库价值。结果表明: 阴坡土壤营养物质含量高于阳坡,阴坡壳斗科植物的叶面积、比叶面积和叶干重显著大于阳坡,叶厚度显著小于阳坡,叶干物质含量小于阳坡;阴坡壳斗科植物功能性状的主要环境影响因子是土壤全钾和土壤含水量,全磷是阳坡的主要环境影响因子。阴坡的叶功能性状变异程度小于阳坡,主要是以改变叶干重增加植物体内光合速率和碳积累能力的方式适应阴坡生境;阳坡通过保持较小比叶面积,增加叶面积变异程度来获得更多的资源。退化天坑深陷塘阴坡植物群落演替速度明显快于阳坡,壳斗科植物优势在阴坡逐渐减小,在阳坡仍是优势建群种。     

Occurrence of endodermis with a casparian strip in stem and leaf

It is well known that an endodermis with casparian strip always occurs in roots, but few people are aware that it also occurs in stems and leaves of some vascular plants. The rather sparse literature on endodermis in aerial organs was last included in a review in 1943. The present compilation, which does not consider hydathodes, nectaries, or other secretory structures, emphasizes distribution of cauline and foliar endodermis with casparian strip. It occurs unevenly among major taxa: quite common in rhizomes and leaves among pteridophyte groups, with exceptions; absent in gymnosperm stems but found in leaves at least among some conifers; in stems of at least 30 mostly herbaceous angiosperm families, but far less common in leaves, where it is mostly reported from petioles. Etiolation can induce casparian strips in stems and petioles of some herbaceous plants, but results from leaf blades are questionable. There are recent reports of an endodermis with casparian strip in leaves of both woody and herbaceous taxa. The physiological function, if any, of a casparian strip in aerial organs remains unknown.