Anatomical patterns of condensed tannin in fine roots of tree species from a cool-temperate forest

Background and AimsCondensed tannin (CT) is an important compound in plant biological structural defence and for tolerance of herbivory and environmental stress. However, little is known of the role and location of CT within the fine roots of woody plants. To understand the role of CT in fine roots across diverse species of woody dicot, we evaluated the localization of CT that accumulated in root tissue, and examined its relationships with the stele and cortex tissue in cross-sections of roots in 20 tree species forming different microbial symbiotic groups (ectomycorrhiza and arbuscular mycorrhiza).MethodsIn a cool-temperate forest in Japan, cross-sections of sampled roots in different branching order classes, namely, first order, second to third order, fourth order, and higher than fourth order (higher order), were measured in terms of the length-based ratios of stele diameter and cortex thickness to root diameter. All root samples were then stained with ρ-dimethylaminocinnamaldehyde solution and we determined the ratio of localized CT accumulation area to the root cross-section area (CT ratio).Key ResultsStele ratio tended to increase with increasing root order, whereas cortex ratio either remained unchanged or decreased with increasing order in all species. The CT ratio was significantly positively correlated to the stele ratio and negatively correlated to the cortex ratio in second- to fourth-order roots across species during the shift from primary to secondary root growth. Ectomycorrhiza-associated species mostly had a higher stele ratio and lower cortex ratio than arbuscular mycorrhiza-associated species across root orders. Compared with arbuscular mycorrhiza species, there was greater accumulation of CT in response to changes in the root order of ectomycorrhiza species.ConclusionsDifferent development patterns of the stele, cortex and CT accumulation along the transition from root tip to secondary roots could be distinguished between different mycorrhizal associations. The CT in tissues in different mycorrhizal associations could help with root protection in specific branching orders during shifts in stele and cortex development before and during cork layer formation.     

Plasmid-encoded dissimilation of condensed tannin in Pseudomonas solanacearum

Pseudomonas solanacearum degrades catechin to phloroglucinolcarboxylic acid, protocatechuic acid, catechol, phloroglucinol, resorcinol and hydroxyquinol, which is plasmid-encoded. This dissimilatory plasmid, designated as pAMB1, was effectively cured by mitomycin C treatment and was transferred to a Pseudomonas sp., with a transfer frequency of 2.2 × 10⁻⁵ transconjugants/donor cell. The cured strains did not utilize catechin or its intermediates, and lacked the plasmid.     

The effects of elevated pH and high salt concentrations on tubulin

The effects of incubating phosphocellulose-purified bovine tubulin at 4 degrees C in nucleotide-free buffers at alkaline pH or at high concentrations of NaCl, KCl, (NH4)2SO4, or NH4Cl have been studied. At pH greater than or equal to 7.5 or at NaCl concentrations greater than or equal to 0.7 M, tubulin releases bound nucleotides irreversibly and loses, with apparent first-order kinetics, the ability to assemble into microtubules. In 0.1 M 1,4-piperazinediethanesulfonic acid buffer, pH 6.9, in the presence of 1.3 M NH4Cl, tubulin undergoes more rapid loss of capacity to assemble than it does in NaCl and KCl, but 1.3 M (NH4)2SO4 causes no detectable change in tubulin after 1-h incubation. Incubation at high pH or at high neutral salt concentrations also causes an apparently irreversible change in the ultraviolet difference spectrum and in the sedimentation velocity profile of tubulin. At elevated salt concentrations a decrease of approximately 10% in the molar ellipticity within the wavelength range 220-260 nm is observed. The changes that occur during 1-h exposure to pH 8.0 can be completely prevented by including 1 mM guanosine 5'-triphosphate (GTP) or 4 M glycerol in the buffer, but those which occur at pH 9.0 cannot be prevented by these additions. In 1 M NaCl when the ratio of bound guanine nucleotide to tubulin reaches approximately 1.0, tubulin loses the abilities to assemble into microtubules and to bind colchicine. The rate of loss of nucleotide in 2 M NaCl is decreased in the presence of 1 mM GTP, and tubulin is protected almost completely from 1 M NaCl-induced loss of GTP (and retains the ability to exchange [3H]GTP as well) in the presence of bound colchicine. Investigators who anticipate exposing tubulin to buffers of elevated pH or high concentrations of chaotropic salts should be extremely cautious in interpreting the resulting data unless they can demonstrate that irreversible alteration of the protein has not occurred.     

Seasonality affects leaf nutrient and condensed tannin concentration in southern African savannah browse

Trees that maintain some leaves throughout dry seasons become important ruminant browse depending on nutritive and antinutritive values. Leaves from seven tree species that maintained some leaves during the dry season were collected during dry and wet seasons and analysed for nutritive and antinutritive values. Neutral detergent fibre of leaves was either not different or less (P ≤ 0.05) during the dry season as compared to the wet season depending on species. Acid detergent fibre was either not different or greater (P ≤ 0.05) during the dry season as compared to the wet season. Crude protein and condensed tannins (CT) were either not different or less (P ≤ 0.05) during the dry season than during the wet season for the seven species. The biological activity (protein‐binding ability; PB) of the CT was highly species specific and was either not different between seasons, more bioactive during the wet season, or more bioactive during the dry season depending on the species. Based on combinations of low fibre, high protein and potentially beneficial levels of bioactive CT, Senegalia caffra, Vachellia karoo and Searsia lancea may be the most promising dry‐season browse of the species studied.     

施肥对短枝木麻黄幼苗总酚和可溶性缩合单宁含量的影响

研究了施用氮肥和磷肥对短枝木麻黄幼苗总酚(total phenolics,TP)和可溶性缩合单宁(extractable condensed tannin,ECT)含量的影响,探讨短枝木麻黄单宁形成的养分效应.结果表明:施加氮肥使短枝木麻黄幼苗小枝的TP和ECT含量显著降低,支持碳氮平衡假说和生长分化平衡假说,但对氮含量没有显著影响,从而导致TP/N和ECT/N降低;施加磷肥对TP和ECT含量没有显著影响;随着处理时间的延长,短枝木麻黄幼苗小枝TP含量升高了9.91%～14.32%,而ECT含量降低了14.32%～298.88%;TP或ECT与有机物质含量的关系则相反,表明不同类型单宁的合成途径不同,但由于TP和ECT均与氮含量无显著相关性,故不支持蛋白质竞争模型;在贫瘠土壤条件下,TP/N和ECT/N的水平较高,有利于提高短枝木麻黄的防御水平,降低凋落物的分解率,减少养分损失,从而保持较高的生产力.     

The phenolics and a hydrolysable tannin polyphenol oxidase of Medinilla magnifica

The production of viable meristem cultures of Medinilla magnifica has proved to be very difficult. This may be due, in part, to a pronounced ‘browning’ response of the tissues on cutting. For this reason the phenolic compounds and the hydrolysable-tannin polyphenol oxidase from Medinilla were studied. The distribution of the compounds was: simple phenols 19% , flavonoids 5% , hydrolysable tannins 69% , condensed tannins 7%. Amongst the simple phenols and phenolic acids, the following were identified: phloroglucinol, p-hydroxybenzoic acid, vanillic acid, protocatechuic acid, gallic acid (both in free and bound form the most abundant simple phenol), syringic acid, trans-p-coumaric acid, trans-ferulic acid and trans-caffeic acid. No kaempferol or quercetin or their derivatives were detected but condensed tannins are present. Methods for the extraction, fractionation and quantitative determination of phloroglucinol and the phenolic acids, as well as correction factors for losses during the extraction, alkali treatment and derivatization, are presented in a supplementary publication. With regard to the hydrolysable tannin polyphenol oxidase activity of Medinilla stems, the enzyme(s) is rather specific since at neither of its two pH optima (6 and 7) could a classical polyphenol oxidase activity be detected. The enzyme was strongly inhibited by 2-mercaptoethanol. Preliminary experiments have further shown that in addition to the hydrolysable tannins of the tissue, the ferrous ions of the medium, and oxygen together with the hydrolysable tannin polyphenol oxidase could play a role in the browning response. Ways to overcome this difficulty have been suggested.     

Effects of NaOH treatment on condensed tannin contents and gas production kinetics of tree leaves

Effects of NaOH treatment on the crude protein (CP), condensed tannin (CT) and in vitro gas production kinetics of leaves of Arbutus andrachne, Glycyrrhiza glabra L. and wheat straw were determined. Wheat straw, which is tannin-free, was used as the standard. The NaOH treatment was completed by pulverization of samples with 0, 20, 40, 60 and 80 g/L of NaOH solution in the proportion of 1 L of solution to 1 kg of sample. Gas production was determined at 3, 6, 12, 24, 48, 72 and 96 h of incubation. NaOH treatment linearly decreased (P<0.001) the CT contents of leaves of Arbutus andrachne and Glycyrrhiza glabra L. whereas NaOH treatment had no effect on the CP contents of Arbutus andrachne, Glycyrrhiza glabra L. and wheat straw. The 80 g/L NaOH treatment reduced the CT content of leaves of Arbutus andrachne and Glycyrrhiza glabra L. by 59.6% and 86.7%, respectively. NaOH treatment linearly decreased (P<0.01) gas production rate of Arbutus andrachne although it linearly increased (P<0.01) gas production rate of wheat straw. In contrast, NaOH treatment had no effect on gas production rate of leaves of Glycyrrhiza glabra L. NaOH treatment linearly decreased (P<0.001) potential gas production of leaves of Arbutus andrachne and Glycyrrhiza glabra L. whereas NaOH treatment linearly increased (P<0.001) potential gas production of wheat straw. Treatment with NaOH can be used to improve the nutritive value of tannin-free forages such as straw, but not for tannin-containing leaves.     

落叶松针叶内缩合单宁含量与树龄及家系的关系

为了研究树龄、家系和生长时期对落叶松组成抗性的影响,在7和8月采集落叶松针叶,对比分析了长白73-26(Larix olgensis 73-26)和73-28(L.olgensis 73-28),杂种日5×兴9(L.kaempferi 5×L.gmelinii9)和日3×兴2(L.kaempferi 3×L.gmelinii2)4个家系的不同年龄落叶松针叶内缩合单宁含量。结果表明:落叶松针叶内缩合单宁含量,受树龄×家系,树龄×家系×生长时期的交互效应影响差异显著。在幼龄林、中龄林和近熟林3个年龄等级中,幼龄林显著高于其他林龄,在4个家系中,杂种家系显著高于长白家系;同时,在落叶松生长旺盛的7月显著高于生长缓慢的8月,说明落叶松在7月组成抗性相对较强,幼龄林和杂种家系的组成抗性相对较强。因此,建议多种植抗性较强的杂种落叶松,同时在8月以后加强对中龄和近熟林木的防虫监护。     

The distribution of 67Zn and 207Pb applied to white spruce foliage at ambient concentrations under different pH regimes

A stable isotope tracer technique was used to evaluate the translocation of trace metals applied to white spruce (Picea glauca) foliage at ambient concentrations under different pH regimes. Simulated rainfall (0.1 ml) containing ⁶⁷Zn (102 ng ml⁻¹) or ²⁰⁷Pb (184 ng ml⁻¹) was applied to needles, at the mid-point of 1-year-old shoots, twice daily for a 30-day period, in rainfall adjusted to pH 4.0 or 6.0. One week after the final application, the distribution of the excess ⁶⁷Zn and ²⁰⁷Pb within the 3-year-old seedlings was assessed. All of the applied ⁶⁷Zn was found in the application segment, in both pH treatments. The majority (∼99%) of the excess ²⁰⁷Pb in white spruce remained in the application segment, although translocation of Pb away from the application zone occurred, and was significantly enhanced when ²⁰⁷Pb was applied in rainfall at pH 4.0 compared with pH 6.0. Most of the translocated ²⁰⁷Pb moved towards the shoot tip, but the amount of excess ²⁰⁷Pb in plant tissues decreased sharply with increasing distance from the application area. Even though metal application rates were in the upper range of ambient levels recorded in rain or fog, very small increases in Pb concentration were found in any plant section away from the application zone, suggesting foliar uptake is not a major pathway of Zn and Pb accumulation in white spruce.     

Effects of cotton condensed tannin on feeding and digestion in the cotton pest, Heliothis zea

Condensed tannin of cotton incorporated into an artificial diet caused growth inhibition in H. zea larvae whose susceptibility was dependent upon the concentration of the dietary tannin, and also upon the size of the feeding larvae.Larvae feeding on tannin-treated diet exhibited both decreased protease and invertase activities in the midgut caecal wall, as well as lowered total protein and sugar levels in the haemolymph as compared to controls. These differences, however, had no effect on assilimation and efficiency of conversion of digested matter into animal biomass and therefore may be secondary effects. Ultimately, inhibition of growth is attributed to a reduction in food consumption.     

剪叶损伤与昆虫取食对兴安落叶松(Larix gmelinii)针叶中缩合单宁诱导作用的差异

单宁是植物内与抗虫性相关的重要次生代谢物质.为了研究昆虫取食及剪叶诱导对兴安落叶松(Larix gmelinii)针叶内缩合单宁含量的影响,用剪叶法和落叶松毛虫(Dendrolimus superans)幼虫取食处理5年生兴安落叶松苗,以香草醛-盐酸法测定其剩余健康针叶内缩合单宁含量的变化.结果表明:(1)处理后1～10d,剪叶4枝75%,8枝50%、75%,12枝25%、50%、75%及虫伤4枝75%的兴安落叶松健康针叶内的缩合单宁含量均明显高于对照(P<0.01),15d时,剪叶8枝75%,12枝50%的兴安落叶松针叶内的缩合单宁含量仍高于对照(P<0.05),说明剪叶与虫伤处理均能诱导缩合单宁含量增加.(2)剪叶4枝75%,8枝50%,12枝25%、75%的处理之间,诱导的缩合单宁含量差异不显著(P>0.05).剪叶8枝75%,12枝50%诱导缩合单宁含量增加幅度比其它剪叶处理大,且诱导持续时间长.说明剪叶程度虽能影响缩合单宁含量,但二者并不呈线性关系.(3)剪叶4枝75%在5d时诱导缩合单宁含量最高,虫伤4枝75%在10d时诱导缩合单宁含量最高,说明剪叶诱导的缩合单宁含量高峰早于虫伤处理.但处理后1～10d,剪叶及虫伤4枝75%的落叶松针叶内缩合单宁含量均明显高于对照(P<0.01或P<0.05),之后与对照差异不显著(P>0.05),说明在受到诱导处理后,兴安落叶松产生应激反应,使其针叶内缩合单宁含量在一定时间内先增加,后逐渐恢复到正常水平.由上可见,可以采取适当的损伤处理取得与昆虫取食相似的兴安落叶松抗性反应.     

Inhibitory effects of tannin on human salivary alpha-amylase

Here, we first report on the effectiveness and specificity of tannin inhibition of 2-chloro-4-nitrophenyl-4-O-β-d-galactopyranosylmaltoside hydrolysis that is catalyzed by human salivary α-amylase (HSA). Tannin was gallotannin in which quinic acid was esterified with 2-7 units of gallic acid. A number of studies establish that polyphenols—like tannins—may prevent oral diseases, e.g., dental caries. Kinetic analyses confirmed that the inhibition of hydrolysis is a mixed non-competitive type and only one molecule of tannin binds to the active site or the secondary site of the enzyme. Since Dixon plots were linear, product formation could be excluded from the enzyme-substrate-inhibitor complex (ESI). Kinetic constants calculated from secondary plots and non-linear regression are almost identical, thereby confirming the suggested model. Kinetic constants (K_EI=9.03 μg mL⁻¹, K_ESI=47.84 μg mL⁻¹) show that tannin is as an effective inhibitor of HSA as acarbose and indicate a higher stability for the enzyme-inhibitor complex than ESI.     

Differential effects of H2S on cytoplasmic and nuclear thiol concentrations in different tissues of Brassica roots

H₂S-fumigation experiments with the sulphur-demanding plant Brassica oleracea L. (hybrid curly kale) were carried out to modulate glutathione levels in root tip cells. Plants were exposed in small fumigation cabinets to 0.4 μl l^–1 H₂S for 96 h. The data obtained by HPLC analysis of bimane-labeled thiols showed a slight increase of glutathione contents of about 20% in the roots of H₂S fumigated plants. The histochemical non-destructive assay for the determination of glutathione in single cells of whole plant organs was carried out for the first time by the use of monochlorobimane (BmCl) in situ to give a fluorescent GSH–bimane conjugate, followed by a fixation procedure. A significant increase of the fluorescence signal after the H₂S treatment was localized in the cytoplasm as well as in the nucleoplasm of root meristem cells.     

Influence of benzyladenine on condensed tannin formation and callus growth in cultures from sainfoin (Onobrychis viccifolia Scop.) cotyledons

Cotyledons from aseptically grown seedlings of sainfoin (Onobrychis viciifolia Scop.) were used as explant material to grow callus tissue for periods of 21 and 31 days. The formation of cells containing condensed tannins was induced by adding a range of BAP concentrations to an mB5 culture medium containing 2,4-D. After 21 days the fresh weight of calli treated with BAP was much greater than the control and appeared highest at the 0.6 mg/L level. Fresh weight was reduced at high BAP levels (2 to 8 mg/L) but still remained well above the control. The formation of tannin-filled cells was genotype-specific but occurred in all treatments with BAP. After 21 days in culture, fresh weight and tannin formation increased with the BAP level at the lower BAP concentrations. After 31 days, the growth rate slowed in the control and the lower BAP concentration, but continued at a high rate in the remaining treatments; the number of tannin-filled cells appeared to decline. The results show that in sainfoin callus culture, BAP induces the formation of condensed tannin, a secondary metabolite, and concomitantly produces a high growth rate.Abbreviations BAP 6-benzylaminopurine - KIN kinetin - PAR photosynthetically active radiation Contribution No. 974 of Agriculture Canada, Research Station, 107 Science Cres., Saskatoon, Saskatchewan, S7N 0X2 Canada