The anti-photooxidation of anthocyanins-rich leaves of a purple rice cultivar

In the leaf of rice (Oryza sativa L.) cultivar Yunnan purple rice, the anthocyanins with an obvious absorption peak at 530nm were distributed in the cells of upper and lower epidermis, bulliform tissue and bristle. The maximal photosynthetic oxygen evolution rate and chlorophyll content in flag leaves were 28% and 23%, respectively, more than the common green leaf rice cultivar Chijiaoruanzhan. Higher chlorophyll content is probably one of the physiological adaptations for enhancing light harvesting capacity of the antenna in photosystems in this cyanic leaves species. Upon the photooxidation of leaf segments mediated by methyl viologen in weak light for 3 days, the distinct bleaching of anthocyanins in purple rice was associated with the reduction of scavenging ability to DPPH · free radical ability and the increase in membrane leakage rate. But almost no changes in contents of flavonoids and total phenolics were observed. Chlorophyll fluorescence parameters Fv/Fo, qP and ϕ_PSII decreased with the increase in NPQ and DES of xanthophylls cycle after photooxidation treatment. Green rice leaves showed more decrease in DPPH · scavenging rate and more increase in cell membrane leakage rate but showed a trace of anthocyanins during photooxidation. It is suggested that anthocyanin may be a beneficial and primary antioxidant in sun cyanic rice leaves against oxidative stress induced by environmental adversity. And photooxidation could induce different changing patterns of anthocyanins between the tested purple and green rice leaves.     

在光氧化条件下不同类型高产稻的叶绿素荧光特性和膜脂过氧化特点

用不同类型高产稻(Oryza sativa L.)粳稻9516、具有粳型成分的两系法亚种间杂交稻培矮64/E32、两优培九(培矮64/9311)和籼型杂交稻X07S/紫恢100、冈优881、汕优63为材料,研究了孕穗期叶片在光氧化条件下的叶绿素荧光特性和膜脂过氧化表现.光氧化处理后,与籼型杂交稻比较,粳稻和具有粳型组分的亚种间杂交稻的PSⅡ原初光化学效率(Fv/Fm)、PSⅡ的线性电子传递的量子效率(ΦPSⅡ)和光化学猝灭系数(qP)下降的较少;超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)诱导的活性较高,活性氧 (O(-)/()2、H2O2)和丙二醛(MDA)的产生积累较少,叶绿素和蛋白质含量下降较少,表现出耐光氧化特性,这与在自然条件下生育后期叶绿素含量变化相一致.相关分析表明它们的耐光氧化特性与结实率密切相关,说明耐光氧化品种抗早衰,有利籽粒充实.这些结果启示我们:从超高产育种出发,兼顾杂种优势利用和抗早衰两方面考虑,在母本不育系中引入粳型成分是一个值得重视的育种策略.     

Antioxidant activities of red versus green leaves in Elatostema rugosum

Anthocyanin biosynthesis in leaves increases under stresses which also generate reactive oxygen species (ROS). In the present study the hypothesis that red leaves are better equipped to scavenge ROS than green leaves was tested. Antioxidants in leaf extracts from red and green morphs of Elatostema rugosum were identified, and activities quantified using enzymatic and α,α‐diphenyl‐β‐picrylhydrazyl (DPPH) assays and cyclic voltammetry. Red leaves from E. rugosum held greater amounts of superoxide dismutase, catalase, anthocyanins, and hydroxycinnamic acids, were significantly more effective at scavenging DPPH radicals, and produced higher voltammetric currents than green leaves. Anthocyanins contributed to the antioxidant pool more than all other constituent phenolics. Anthocyanin concentrations, and antioxidant activities declined with leaf age. Purified anthocyanin fractions displayed oxidative activities at both pH 7·0 and pH 5·5. Implications of the antioxidant potential of anthocyanin in its cytoplasmic and vacuolar locations are discussed.     

超高产水稻组合‘培矮64S/E32’的耐光氧化特性及其机理

甲基紫精（MV）介导的光氧化导致两个水稻品种‘汕优63’(目前我国大面积推广的杂交水稻)和‘培矮64S/E32’（新培育的超高产杂交水稻）细胞电解质渗漏率都增加,前者增加的量大于后者,显示‘培矮64S/E32’的细胞膜系统受光氧化的伤害小。光氧化条件下,‘培矮64S/E32’仍能维持较高的光合放氧能力（Amax、Φi）、PSⅡ活性（Fv/Fm、ΦPSⅡ）和叶绿素荧光猝灭系数（qP、NPQ）,而且光氧化引起‘培矮64S/E32’这些参数的下降幅度也小。另外,光氧化导致了两个水稻品种抗氧化酶SOD和APX活性增加,‘培矮64S/E32’增加的幅度约为‘汕优63’的3倍。结果表明超高产水稻具有更强的耐光氧化能力。     

NaCl-induced Senescence in Leaves of Rice (Oryza sativa L.) Cultivars Differing in Salinity Resistance

The influence of NaCl on senescence-related parameters (proteinand chlorophyll concentrations, membrane permeability and chlorophyllfluorescence) was investigated in young and old leaves of fiverice cultivars differing in salt resistance. NaCl hastened thenaturally-occurring senescence of rice leaves which normallyappears during leaf ontogeny: it decreased chlorophyll and proteinconcentrations and increased membrane permeability and malondialdehydesynthesis. Such an acceleration of deteriorative processes affectedall leaves in salt-sensitive cultivars while it was more markedin oldest than in youngest leaves of salt-resistant genotypes.NaCl-induced senescence also involved specific modifications,such as an increase in basal non-variable chlorophyll fluorescence(F ₀) recorded in all cultivars or a transient increase in solubleprotein concentration recorded in salt-resistant genotypes only.Alteration of membrane permeability appeared as one of the firstsymptoms of senescence in rice leaves and allowed discriminationamong cultivars after only 7 d of stress. In contrast, F _v/F _mratio (variable fluorescence/maximal fluorescence) was thesame for all cultivars during the first 18 d of stress and thuscould not be used for identifying salt-resistant rice exposedto normal light conditions. Relationships between parametersinvolved in leaf senescence are discussed in relation to salinityresistance of rice cultivars. Chlorophyll concentration; chlorophyll fluorescence; electrolyte leakage; magnesium; malondialdehyde; membrane permeability; NaCl; Oryza sativa L.; protein; rice; salinity resistance; senescence; UV absorbing substances     

Effect of transient accumulation of anthocyanin on leaf development and photoprotection of Fagopyrum dibotrys mutant

Changes in pigments contents, leaf area, leaf dry mass per unit area (LMA), photosynthetic rate and chlorophyll a fluorescence were investigated in developing leaves of Fagopyrum dibotrys Hara. mutant. Anthocyanins transiently accumulate below the upper epidermis during leaf ontogeny of this mutant. Red leaves possessed lower Chl content, LMA, photosynthetic rate and apparent carboxylation efficiency than green leaves. However, content of anthocyanins declined and above mentioned parameters increased during further leaf development. In both red and green leaves, chronic photoinhibition did not take place according to variable to maximum chlorophyll fluorescence ratio (F_v/F_m). Red leaves had higher non-photochemical quenching (NPQ) and higher PS 2 efficiency.     

Characteristics of gas exchange and chlorophyll fluorescence in red and green leaves of Begonia semperflorens

To determine the effects of leaf colour on gas exchange and chlorophyll fluorescence, two genotypes of Begonia semperflorens with green leaves or red leaves were compared. The red leaves showed a high accumulation of anthocyanins and high absorbance at 282 and 537 nm while the green leaves exhibited a higher net photosynthetic rate and lower thermal dissipation of light energy. It seems likely that anthocyanins in the vacuoles restricted the absorption of green light to the chloroplasts, leading to a decrease in the efficiency of excitation capture by open PS 2 centres, photochemical quenching and CO₂ assimilation.     

Relationship of photosynthetic efficiency and seed-setting rate in two contrasting rice cultivars under chilling stress

Low temperature during the vegetative stage affects rice (Oryza sativa L.) seed-setting rate in Heilongjiang province at Northeast China. However, little is known about changes of the photosynthetic rate and physiological response in contrasting rice cultivars during chilling periods. In this study, two rice cultivars with different chilling tolerance were treated with 15°C from June 27 to July 7. The chilling-susceptive cultivar, Longjing11 (LJ11), showed a significant decrease in a ripening rate and seed-setting rate after being treated for four days, whilst chilling-tolerant cultivar, Kongyu131 (KY131), was only slightly affected after 4-d treatment. The photosynthetic activities, chlorophyll contents, and antioxidative enzyme activities in LJ11 decreased significantly along with the chilling treatment. The decrease in ß-carotene contents might play a role as it could cause direct photooxidation of chlorophylls and lead to the inhibition of the photosynthetic apparatus. In the meantime, no significant damage was found in leaves of KY131 from June 27 to July 11. In conclusion, the chilling-tolerance mechanism of rice is tightly related to the photosynthetic rate, metabolism of reactive oxygen species, and scavenging system in the vegetative stage.     

Ultraviolet-B-Responsive Anthocyanin Production in a Rice Cultivar Is Associated with a Specific Phase of Phenylalanine Ammonia Lyase Biosynthesis

Seedlings of 17 rice (Oryza sativa L.) cultivars were classified on the basis of anthocyanin pigmentation into three groups: an acyanic group with 9 cultivars, a moderately cyanic group with 5 cultivars, and a cyanic group with 3 cultivars. Seedlings of the cyanic group were deep purple in color, possessing copious amounts of anthocyanin in shoots. Sunlight (SL)-mediated anthocyanin and phenylalanine ammonia lyase (PAL) induction in a cyanic cultivar, purple puttu, was compared with an acyanic cultivar, black puttu. A brief exposure of dark-grown purple puttu seedlings to SL induced anthocyanin formation during a subsequent dark period with a peak at 24 h. The magnitude of SL-mediated anthocyanin induction is age dependent, the 4-d-old seedlings being the most responsive to SL. The anthocyanin induction in purple puttu seedlings is mediated exclusively by the ultraviolet-B (UV-B) component of SL. The SL-triggered anthocyanin induction was reduced by about 30% by a terminal far-red light pulse and was restored by a red light pulse, indicating the role of phytochrome in modulation of anthocyanin level. The SL-mediated induction of PAL showed two peaks, one at 4 h and the other at 12 h. Whereas the first PAL peak (4 h) was induced by phytochrome and was seen in both cultivars, the second PAL peak (12 h) was inducible by UV-B only in the cyanic purple puttu cultivar.     

Differential stomatal closure by abscisic acid in epidermal strips of green and pigmented leaves or leaf parts

Response of stomata in epidermal strips from green leaves ofTradescantia sillamontana and anthocyanin-rich purple leaves ofT. virginiana and from green and pigmented regions ofPedilanthus tithymaloides leaves, to ABA have been compared. Stomata from anthocyanin-rich leaves or leaf parts appeared to be relatively insensitive to ABA as compared to those from green leaves or leaf parts. Observations indicate the possibility of the involvement of endogenous anthocyanins in antagonising ABA in preventing the stomatal opening.     

Antioxidation of Anthocyanins in Photosynthesis Under High Temperature Stress

Chlorophyll fluorescence and antioxidative capability in detached leaves of the wild type Arabidopsis thaliana L. ecotype Landsberg erecta （Ler） and three mutants deficient in anthocyanins biosynthesis （tt3, tt4, and tt3tt4） were investigated during treatment with temperatures ranging 25-45 ℃. In comparison with the wild type, chlorophyll fluorescence parameters Fv/Fm, φps,, electron transport rate （ETR）, Fv/Fo and qP in three anthocyanin-deficient mutants showed a more rapidly decreasing rate when the temperature was over 35 ℃. Non-photochemical quenching （NPQ） in these mutants was almost completely lost at 44 ℃, whereas the content of heat stable protein dropped and the rate of the membrane leakage increased. Fo-temperature curves were obtained by monitoring Fo levels with gradually elevated temperatures from 22 ℃ to 72 ℃ at 0.5 ℃/min. The inflexion temperatures of Fo were 45.8 ℃ in Ler, 45.1℃ in tt3, 44.1℃ in tt4 and 42.3 ℃ in tt3tt4, respectively. The temperatures of maximal Fo in three mutants were 1.9-3.8℃ lower than the wild type plants. Meanwhile, three mutants had lower activities of superoxide dismutase （SOD） and ascorbate peroxidase （APX） and an inferior scavenging capability to DPPH （1.1-diphenyl-2-picrylhy.drazyl） radical under heat stress, and in particular tt3tt4 had the lowest antioxidative potential. The results of the diaminobenzidine-H2O2 histochemical staining showed that H2O2 was accumulated in the leaf vein and mesophyll cells of mutants under treatment at 40 ℃, and it was significantly presented in leaf cells of tt3tt4. The sensitivity of Arabidopsis anthocyanins-deficient mutants to high temperatures has revealed that anthocyanins in normal plants might provide protection from high temperature injury, by enhancing its antioxidative capability under high temperature stress.     

枫香变红过程中叶片组织结构、光合特性及色素含量变化研究

枫香(Liquidambar formosana)因其叶片入秋后逐渐变红而极具观赏价值,是优良的景观生态树种。为了解枫香叶片结构变化与叶色的关系,该文通过连续监测枫香叶片变红过程中组织结构、光合特性及色素含量的变化,分析叶片结构与其光合特性和色素的关系。结果表明：(1)叶片变色过程中,表皮细胞均为椭圆形,紧密排列,未观察到明显的细胞变异,表面未附着绒毛和蜡质,且上表皮细胞与栅栏组织细胞间排列紧密,未出现较大的气室。(2)随着叶片逐渐变红,叶片结构变化显著,其中叶片、上表皮、栅栏组织和海绵组织厚度及气孔开度均逐渐减小,而气孔器长和宽、单个气孔器面积则逐渐增大。(3)随着叶片结构的变化,其叶绿素含量逐渐减少,致使净光合速率逐渐减小,在出现光破坏时,叶片通过在栅栏组织细胞液泡内合成花色苷来自我保护,而大量的花色苷致使叶片表面呈现红色。综上认为,叶绿素含量降低,花色素苷大量积累是导致枫香叶片变红的直接原因,而枫香叶色变红则是其一系列生理结构特征综合作用的结果。     

Pigment variation and transcriptional response of the pigment synthesis pathway in the S2309 triple-color ornamental kale (Brassica oleracea L. var. acephala) line

Ornamental kale is popular because of its colorful leaves and few studies have investigated the mechanism of color changes. In this study, an ornamental kale line (S2309) with three leaf colors was developed. Analysis of the anthocyanin, chlorophyll, and carotenoid contents and RNA-seq were performed on the three leaf color types. There was less chlorophyll in the white leaves and purple leaves than in the green leaves, and the anthocyanin content was greatest in the purple leaves. All the downregulated DEGs related to chlorophyll metabolism were detected only in the S2309_G vs. S2309_W comparison, which indicated that the decrease in chlorophyll content was caused mainly by the inhibition of chlorophyll biosynthesis during the leaf color change from green to white. Moreover, the expression of 19 DEGs involved in the anthocyanin biosynthesis pathway was upregulated. These results provide new insight into the mechanisms underlying the three-color formation.     

Association of red coloration with senescence of sugar maple leaves in autumn

We evaluated the association of red coloration with senescence in sugar maple (Acer saccharum Marsh.) leaves by assessing differences in leaf retention strength and the progression of the abscission layer through the vascular bundle of green, yellow, and red leaves of 14 mature open-grown trees in October 2002. Computer image analysis confirmed visual categorization of leaves as predominantly green, yellow or red, and chemical quantification of leaf pigment concentrations verified that leaf color reflected underlying differences in leaf biochemistry. Significantly lower chlorophyll concentrations within red and yellow leaves indicated that senescence was more advanced in leaves from these color categories relative to green leaves. Among leaf types, only red leaves contained high concentrations of anthocyanins. There were significant differences in leaf retention capacity among color categories, with the petioles of green leaves being the most firmly attached to twigs, followed by red and then yellow leaves. Microscopic analysis indicated that yellow leaves had the most advanced extension of the abscission layer through the vasculature, with green and red leaves having significantly less abscission layer progression than yellow. A more limited progression of the abscission layer through vascular bundles may be evidence of delayed leaf senescence that could extend resorption of mobile leaf constituents. Together, results from this study suggest an association between leaf anthocyanin content and functional delays in senescence.     

Protection mechanisms against excess light in the resurrection plants Craterostigma wilmsii and Xerophyta viscosa

Mechanisms of avoidance and protection against light damage were studied in the resurrection plants Craterostigma wilmsii and Xerophyta viscosa.In C. wilmsii, a combination of both physical and chemical changes appeared to afford protection against free radical damage. During dehydration leaves curled inwards, and the abaxial surface became exposed to light. The tissue became purple/brown in colour, this coinciding with a three-fold increase in anthocyanin content and a 30% decline in chlorophyll content. Thus light-chlorophyll interactions are progressively reduced as chlorophyll became masked by anthocyanins in abaxial layers and shaded in the adaxial layers. Ascorbate peroxidase (AP) activity increased during this process but declined when the leaf was desiccated (5% RWC). During rehydration leaves uncurled and the potential for normal light-chlorophyll interaction was possible before full hydration had occurred. Superoxide dismutase (SOD) and glutathione reductase (GR) activities increased markedly during this stage, possibly affording free radical protection until full hydration and metabolic recovery had occurred.In contrast, the leaves of X. viscosa did not curl, but light-chlorophyll interactions were minimised by the loss of chlorophyll and dismantling of thylakoid membranes. During dehydration, free radical protection was afforded by a four-fold increase in anthocyanin content and increased activities of AP, GR and SOD. These declined during rehydration. It is suggested that potential free radical damage may be avoided by the persistence of anthocyanins during the period of thylakoid membrane re-assembly and full chlorophyll restitution which only occurred once the leaves were fully rehydrated.     

外源施加AsA和MeJA对乙烯利诱导水稻叶片衰老的影响

以野生型水稻(Oryza sativa)株系中花11(ZH-11)及其抗坏血酸合成关键酶基因GLDH下调株系(GI-2)为材料,研究了外源抗坏血酸(AsA)与茉莉酸甲酯(MeJA)对乙烯利诱导下水稻叶片早衰现象的影响。结果表明,外源AsA提高了水稻GI-2中的抗坏血酸含量、Rubisco含量及叶绿素的含量,减缓了其光合特性参数的下降速率,但对水稻ZH-11没有显著影响。外源MeJA降低了两株系的抗坏血酸、Rubisco及叶绿素含量,加快了叶内光合特性参数的下降速率,且对ZH-11的影响大于GI-2。因此,外源AsA处理能有效缓解乙烯利诱导的水稻叶片早衰现象,使叶片的衰老进程得以延缓,而外源MeJA作用相反。     

紫花含笑花被呈色过程中色素含量与超微结构的变化特征

为了探究色素含量以及细胞结构在紫花含笑花被呈色过程中的作用机理,该研究以绿色和紫色花被为材料,测定其花被色素含量,运用逐步回归方程分析花被呈色与色素含量的关系,采用石蜡切片及超薄切片技术观察花被细胞超显微结构变化。结果表明:(1)在紫花含笑花被呈色过程中,紫色花被表面明度L^*值降低,a^*值上升,b^*值降低;花被花青素苷的积累量以及类胡萝卜素和类黄酮等含量增加,同时伴随着叶绿素的降解及其含量降低。(2)a^*与花青素、类黄酮、类胡萝卜素等色素含量以及花青素/类黄酮、花青素/叶绿素呈显著正相关关系,b^*与叶绿素含量和花青素/类胡萝卜素呈显著正相关关系。(3)在细胞结构上,随着花被由绿转紫,其上表皮细胞由扁平型向圆锥凸起型变化,单个细胞长宽比增大,细胞垂周壁出现褶皱,紫色花被上表皮结构向增加入射光吸收面积变化;液泡体积增大与叶绿体向有色体转化是主要的细胞器变化。研究发现,花被呈色是多因素作用的结果,花青素含量的产生与积累以及类胡萝卜素和类黄酮等含量增加辅助增色可能是紫花含笑呈紫色的主要...     

LED光质及光周期对香子含笑幼苗生长和光合特性的影响

香子含笑(Michelia gioii)为我国珍贵阔叶树种,在用材、香料、景观等方面具有重要价值。为了进一步培育优良苗木和开发利用其非木质资源,该研究将香子含笑幼苗放置在由2个光周期(12、16 h·d^-1)和4种光质(R:B=8:1、R:B=6:1、R:B:P:G =8:1:1:1、R:B:P:G=6:1:1:1,其中R、B、P、G分别代表红光、蓝光、紫光、绿光)两两组合成、光照强度一致的8个光照条件下生长。结果表明:(1)香子含笑幼苗的苗高和地径增长量、叶长宽比、最大净光合速率、暗呼吸速率及光补偿点在12 h·d^-1光周期R:B=6:1光质下最高,叶面积和叶绿素含量在16 h·d^-1光周期R:B:P:G=6:1:1:1光质下最高。(2)16 h·d^-1光周期处理下的苗高增长量、叶面积、质量指数、叶绿素a+b含量、叶绿素a/b比值、类胡萝卜素含量和光饱和点均高于12 h·d^-1光周期。(3)在红蓝组合光质基础上添加紫、绿光提高了幼苗的质量指数,并影响光合色素的合成和积累;(4)光质R:B=6:1与R:B=8:1相比,更具有促进香子含笑幼苗苗高、地径、叶片生长及提高光合作用的潜力。综上结果认为,对于促进香子含笑幼苗生长和进行光合作用,光周期为 16 h·d^-1光质为R:B:P:G=6:1:1:1光照条件的潜力较大,其次是光周期为12 h·d^-1光质为R:B=6:1的光照条件。     

普通野生稻和武育粳8号剑叶光合功能衰退的比较

以武育粳 8号 (Wuyujing8)和普通野生稻 (Oryza.sativaL .f.spontaneaRoschev .)为材料 ,比较了它们剑叶光合功能衰退的进程。结果表明 ,在剑叶一生中 ,武育粳 8号剑叶的叶绿素含量和光合速率都高于普通野生稻 ,光合速率的最高值前者为 2 3 .5 μmolCO2 m 2 ·S 1,后者为 1 5 .5 μmolCO2 m 2 ·S 1。前者剑叶光合速率的高值持续期比后者长近 2 0d ,其叶源量是后者的 2 .8倍。武育粳 8号剑叶叶绿素含量最大值的SPAD值为 5 0 .1 ,而普通野生稻最大值的SPAD值为 42 .7。在可溶性蛋白质的基础上 ,核酮糖 1 ,5 二磷酸羧化酶比活性二者之间没有太大区别。内肽酶活力上升落后于光合功能的衰退。在光合功能衰退的早期 ,内肽酶的活力仅有小幅度提高 ,但在叶片衰老的末期升高幅度则较大。这说明内肽酶主要在光合功能衰退的后期即不可逆衰退期才发挥较大作用。     

Strength of winter leaf redness as an indicator of stress vulnerable individuals in Pistacia lentiscus

Leaf anthocyanins are believed to afford protection against photoinhibition, yet the dependence of protection on actual anthocyanin concentrations has not been investigated. To that aim, non-invasive optical methods (spectral reflectance and chlorophyll fluorescence) were used to assess the levels of anthocyanins and chlorophylls as well as photosystem II photochemical efficiency in hundreds of leaves from the mastic tree (Pistacia lentiscus), which displays in the field a continuum of leaf tints during winter from fully green to fully red. Contrary to expectations based on the photoprotective hypothesis, the strength of leaf redness was positively correlated to the extent of mid-winter chronic photoinhibition and negatively correlated to leaf chlorophyll contents. Hence, a photoprotective role for anthocyanins is not substantiated. Instead, we argue that winter leaf redness may be used reliably, quickly and non-invasively to locate vulnerable individuals in the field.