Young leaves of three grape cultivars having different surface characteristics (cv. Athiri, pubescent; cv. Soultanina, glabrous green; and cv. Fraoula, glabrous red-brown) only during the early stages of their development, were used to investigate the potential, differential effect of a trichome layer or a pigmented epidermis on the light microenvironment within the mesophyll. The penetration of forward propagated 310, 360 and 430 nm radiation into the leaf tissues was monitored using a quartz fibre-optic microprobe. The mesophyll of the young leaves of Athiri was much better protected from ultraviolet-A, ultraviolet-B and high visible radiation compared to the other two cultivars. Abaxial, as well as adaxial trichome layers attenuated almost all incident radiation at 310 nm and 360 nm and a considerable part of the blue light (430 nm). No significant differences in light attenuation from epidermal and mesophyll layers between the other two cultivars were observed. The adaxial epidermis of young and dehaired leaves of cv. Athiri was largely ineffective in absorbing the incident ultraviolet- B radiation. In addition, the dehaired lamina of such leaves exhibited 80% lower relative concentration of ultraviolet-absorbing compounds per leaf surface area, compared to leaves of similar ontogenetic stage in the cv. Soultanina. It is proposed that the occurrence of a dense trichome layer in young leaves, besides other proposed functions, may play a protective role against not only ultraviolet radiation damage, but also against high insolation. This protection could be advantageous under stress conditions during leaf development.
{"title":"Different leaf surface characteristics of three grape cultivars affect leaf optical properties as measured with fibre optics: possible implication in stress tolerance","authors":"G. Karabourniotis, J. Bornman, V. Liakoura","doi":"10.1071/PP98052","DOIUrl":"https://doi.org/10.1071/PP98052","url":null,"abstract":"Young leaves of three grape cultivars having different surface characteristics (cv. Athiri, pubescent; cv. Soultanina, glabrous green; and cv. Fraoula, glabrous red-brown) only during the early stages of their development, were used to investigate the potential, differential effect of a trichome layer or a pigmented epidermis on the light microenvironment within the mesophyll. The penetration of forward propagated 310, 360 and 430 nm radiation into the leaf tissues was monitored using a quartz fibre-optic microprobe. The mesophyll of the young leaves of Athiri was much better protected from ultraviolet-A, ultraviolet-B and high visible radiation compared to the other two cultivars. Abaxial, as well as adaxial trichome layers attenuated almost all incident radiation at 310 nm and 360 nm and a considerable part of the blue light (430 nm). No significant differences in light attenuation from epidermal and mesophyll layers between the other two cultivars were observed. The adaxial epidermis of young and dehaired leaves of cv. Athiri was largely ineffective in absorbing the incident ultraviolet- B radiation. In addition, the dehaired lamina of such leaves exhibited 80% lower relative concentration of ultraviolet-absorbing compounds per leaf surface area, compared to leaves of similar ontogenetic stage in the cv. Soultanina. It is proposed that the occurrence of a dense trichome layer in young leaves, besides other proposed functions, may play a protective role against not only ultraviolet radiation damage, but also against high insolation. This protection could be advantageous under stress conditions during leaf development.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87726314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The regeneration potential of ageing calli initiated from isolated scutella of immature embryos was increased in nine elite Australian cultivars (QT7208, QT9685, QT7709, Kennedy, Lang, Sunvale, Giles, Petrie and Veery) of wheat (Triticum aestivum L.). Firstly, the effects of 4–32 h of dehydration stress on regeneration of 4- to 20-week old calli were evaluated. Cultivars such as Veery, Kennedy and Sunvale showed significant improvement in regeneration from calli up to 12-weeks old that had undergone 16 h of dehydration stress. Secondly, 4- to 20-week old callus cultures were treated with 0.05–5 mM spermidine to evaluate its effect on regeneration. While spermidine had a negative effect on regeneration from 4-week old calli at all tested concentrations (as compared with untreated controls), there was a 3–50% improvement in the regeneration ability of older calli (16- to 20-week old) of all cultivars. Finally, exogenous application of 1 mM spermidine to 16-week old cultures, in combination with 16 h dehydration stress, improved plant regeneration by 10–65% in all nine cultivars.
{"title":"Enhanced shoot regeneration in nine Australian wheat cultivars by spermidine and water stress treatments","authors":"H. Khanna, G. Daggard","doi":"10.1071/PP01115","DOIUrl":"https://doi.org/10.1071/PP01115","url":null,"abstract":"The regeneration potential of ageing calli initiated from isolated scutella of immature embryos was increased in nine elite Australian cultivars (QT7208, QT9685, QT7709, Kennedy, Lang, Sunvale, Giles, Petrie and Veery) of wheat (Triticum aestivum L.). Firstly, the effects of 4–32 h of dehydration stress on regeneration of 4- to 20-week old calli were evaluated. Cultivars such as Veery, Kennedy and Sunvale showed significant improvement in regeneration from calli up to 12-weeks old that had undergone 16 h of dehydration stress. Secondly, 4- to 20-week old callus cultures were treated with 0.05–5 mM spermidine to evaluate its effect on regeneration. While spermidine had a negative effect on regeneration from 4-week old calli at all tested concentrations (as compared with untreated controls), there was a 3–50% improvement in the regeneration ability of older calli (16- to 20-week old) of all cultivars. Finally, exogenous application of 1 mM spermidine to 16-week old cultures, in combination with 16 h dehydration stress, improved plant regeneration by 10–65% in all nine cultivars.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76265349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigates the response to elevated CO2 partial pressure (pCO2) of C4grasses belonging to different biochemical subtypes (NAD–ME and NADP–ME), and taxonomic groups (main Chloroid assemblage, Paniceae and Andropogoneae). Seventeen C4 grasses were grown under well-watered conditions in two glasshouses maintained at an average dailyppCO2 of 42 (ambient) or 68 (elevated) Pa. Elevated pCO2 significantly increased plant water-use efficiency (WUE; dry matter gain per unit water transpired) in 12 out of the 17 C4 grasses, by an average of 33%. In contrast, only five species showed a significant growth stimulation. When all species are considered, the average plant dry mass enhancement at elevated pCO2 was 26%. There were no significant subtype (or taxa) × pCO2 interactions on either WUE or biomass accumulation. When leaf gas exchange was compared at growth pCO2 but similar light and temperature, high pCO2-grown plants had similar CO2 assimilation rates (A) but a 40% lower stomatal conductance than their low pCO2-grown counterparts. There were no signs of either photosynthetic or stomatal acclimation in any of the measured species. We conclude that elevated pCO2 improved WUE primarily by reducing stomatal conductance.
{"title":"Plant water use efficiency of 17 Australian NAD-ME and NADP-ME C₄ grasses at ambient and elevated CO₂ partial pressure","authors":"O. Ghannoum, S. Caemmerer, J. Conroy","doi":"10.1071/PP01056","DOIUrl":"https://doi.org/10.1071/PP01056","url":null,"abstract":"This study investigates the response to elevated CO2 partial pressure (pCO2) of C4grasses belonging to different biochemical subtypes (NAD–ME and NADP–ME), and taxonomic groups (main Chloroid assemblage, Paniceae and Andropogoneae). Seventeen C4 grasses were grown under well-watered conditions in two glasshouses maintained at an average dailyppCO2 of 42 (ambient) or 68 (elevated) Pa. Elevated pCO2 significantly increased plant water-use efficiency (WUE; dry matter gain per unit water transpired) in 12 out of the 17 C4 grasses, by an average of 33%. In contrast, only five species showed a significant growth stimulation. When all species are considered, the average plant dry mass enhancement at elevated pCO2 was 26%. There were no significant subtype (or taxa) × pCO2 interactions on either WUE or biomass accumulation. When leaf gas exchange was compared at growth pCO2 but similar light and temperature, high pCO2-grown plants had similar CO2 assimilation rates (A) but a 40% lower stomatal conductance than their low pCO2-grown counterparts. There were no signs of either photosynthetic or stomatal acclimation in any of the measured species. We conclude that elevated pCO2 improved WUE primarily by reducing stomatal conductance.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82165071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Audran, S. Liotenberg, M. Gonneau, Helen M. North, A. Frey, Karine Tap-Waksman, N. Vartanian, A. Marion-Poll
Abscisic acid (ABA) is involved in seed development and plant adaptation to environmental stresses. ABA is synthesized from cleaved xanthophylls and zeaxanthin epoxidase (ZEP) is the enzyme responsible for the conversion of zeaxanthin to violaxanthin. In this study, we have characterized the ABA1 gene (AtZEP) of Arabidopsis thaliana L. and show that this complements the aba1 mutant, defective in zeaxanthin epoxidation. The molecular basis for two aba1 mutant alleles has been determined and the reduction in their AtZEP transcript levels correlates with the molecular defect identified. As AtZEP mRNA abundance was not affected in two other ABA-deficient mutants (aba2 and aba3) and in two ABA-insensitive mutants (abi1 and abi2), no feedback regulation of ABA biosynthesis seems to occur at the level of ZEP transcription. Steady state transcript levels increased in roots during rapid water stress as well as progressive drought stress, providing evidence that zeaxanthin epoxidation contributed to the regulation of ABA biosynthesis in roots and consequently to the plant adaptive response to hydric stress. In seeds in situ hybridization analysis detected AtZEP mRNA in the embryo cells from the globular stage to desiccation phase. In contrast, expression of AtZEP in maternal tissues was specific to the maturation phase. These results are discussed in relation to the role of ABA both in response to drought stress and in seed development.
{"title":"Localisation and expression of zeaxanthin epoxidase mRNA in Arabidopsis in response to drought stress and during seed development","authors":"C. Audran, S. Liotenberg, M. Gonneau, Helen M. North, A. Frey, Karine Tap-Waksman, N. Vartanian, A. Marion-Poll","doi":"10.1071/PP00134","DOIUrl":"https://doi.org/10.1071/PP00134","url":null,"abstract":"Abscisic acid (ABA) is involved in seed development and plant adaptation to environmental stresses. ABA is synthesized from cleaved xanthophylls and zeaxanthin epoxidase (ZEP) is the enzyme responsible for the conversion of zeaxanthin to violaxanthin. In this study, we have characterized the ABA1 gene (AtZEP) of Arabidopsis thaliana L. and show that this complements the aba1 mutant, defective in zeaxanthin epoxidation. The molecular basis for two aba1 mutant alleles has been determined and the reduction in their AtZEP transcript levels correlates with the molecular defect identified. As AtZEP mRNA abundance was not affected in two other ABA-deficient mutants (aba2 and aba3) and in two ABA-insensitive mutants (abi1 and abi2), no feedback regulation of ABA biosynthesis seems to occur at the level of ZEP transcription. Steady state transcript levels increased in roots during rapid water stress as well as progressive drought stress, providing evidence that zeaxanthin epoxidation contributed to the regulation of ABA biosynthesis in roots and consequently to the plant adaptive response to hydric stress. In seeds in situ hybridization analysis detected AtZEP mRNA in the embryo cells from the globular stage to desiccation phase. In contrast, expression of AtZEP in maternal tissues was specific to the maturation phase. These results are discussed in relation to the role of ABA both in response to drought stress and in seed development.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84605743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Musrur Rahman, A. Grover, W. Peacock, E. Dennis, M. Ellis
A transgenic approach was taken to manipulate the levels of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) in rice, in order to investigate whether alteration of ethanol fermentation can affect anaerobic tolerance. A line transformed with an antisense Adh1 construct had only 4–8% of the ADH activity of untransformed plants. This line showed reduced ethanol production and coleoptile growth under anoxia. Mature plants had reduced survival when submerged in water and exposed to anoxia, suggesting that ADH plays an essential role in seed germination and plant survival in the absence of O2. A transgenic line transformed with a cotton Adh2 cDNA in the sense orientation relative to a constitutive promoter, showed 3–4-fold more ADH activity than either untransformed controls, or a flooding-tolerant rice variety (FR13A), both in air and under hypoxia. However, ethanol production by this line was only slightly higher than that of untransformed controls, and there was no increase in survival following anoxia treatments. Three independent transgenic lines containing the ricePdc1 cDNA driven by an anaerobically-inducible promoter (6XARE) showed an increase in PDC1 polypeptide in shoots, but not in roots or endosperm. A moderate increase in PDC activity and ethanol production was observed in shoots of these lines under anaerobic conditions, as well as decreased survival of shoots when submerged and exposed to anoxia. F1 plants containing both the PDC and ADH constructs showed levels of anoxia-tolerance similar to those of untransformed plants. These results suggest that over-production of PDC may be toxic to rice plants because of increased acetaldehyde. Consistent with this view, acetaldehyde levels were appreciably higher in plants over-producing PDC, compared with untransformed plants, or hybrid lines containing both the PDC and ADH constructs.
{"title":"Effects of manipulation of pyruvate decarboxylase and alcohol dehydrogenase levels on the submergence tolerance of rice","authors":"Musrur Rahman, A. Grover, W. Peacock, E. Dennis, M. Ellis","doi":"10.1071/PP00137","DOIUrl":"https://doi.org/10.1071/PP00137","url":null,"abstract":"A transgenic approach was taken to manipulate the levels of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) in rice, in order to investigate whether alteration of ethanol fermentation can affect anaerobic tolerance. A line transformed with an antisense Adh1 construct had only 4–8% of the ADH activity of untransformed plants. This line showed reduced ethanol production and coleoptile growth under anoxia. Mature plants had reduced survival when submerged in water and exposed to anoxia, suggesting that ADH plays an essential role in seed germination and plant survival in the absence of O2. A transgenic line transformed with a cotton Adh2 cDNA in the sense orientation relative to a constitutive promoter, showed 3–4-fold more ADH activity than either untransformed controls, or a flooding-tolerant rice variety (FR13A), both in air and under hypoxia. However, ethanol production by this line was only slightly higher than that of untransformed controls, and there was no increase in survival following anoxia treatments. Three independent transgenic lines containing the ricePdc1 cDNA driven by an anaerobically-inducible promoter (6XARE) showed an increase in PDC1 polypeptide in shoots, but not in roots or endosperm. A moderate increase in PDC activity and ethanol production was observed in shoots of these lines under anaerobic conditions, as well as decreased survival of shoots when submerged and exposed to anoxia. F1 plants containing both the PDC and ADH constructs showed levels of anoxia-tolerance similar to those of untransformed plants. These results suggest that over-production of PDC may be toxic to rice plants because of increased acetaldehyde. Consistent with this view, acetaldehyde levels were appreciably higher in plants over-producing PDC, compared with untransformed plants, or hybrid lines containing both the PDC and ADH constructs.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81856338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydrated leaves of the resurrection grass Sporobolus stapfianus Gandoger are not desiccation tolerant, but moderate to severe drought stress can induce their desiccation tolerance while the leaves remain attached to drying intact plants. Free-cell suspensions prepared from fully turgid leaves of S. stapfianus were also found to be desiccation-sensitive. In this study a sensitive assay was developed to determine the effect of exogenous substances on the protoplasmic drought tolerance (PDT) of cell suspensions. Suspended cells were incubated with a wide variety of individual plant growth substances over a range of concentrations. After the incubation, the protoplasmic drought tolerance at each concentration of each substance was determined osmotically. Brassinolide (BR) and methyljasmonic acid (MJA), applied separately, gave the greatest effect — each improved PDT by approximately 6 MPa, compared with controls incubated without growth substances. Exogenous abscisic acid (ABA) improved the PDT of S. stapfianus only slightly (about 1 MPa). Salicylic acid (SA), 1-aminocyclopropane–1-carboxylic acid (ACC), ethephon, gibberellic acid (GA), kinetin (KN) andN 6 -(2-isopentyl)adenine (2ip) each improved PDT by ca 1.5 MPa. Indoleacetic acid (IAA) had no effect, and zeatin (ZN) had a deleterious effect on PDT. Incubation of suspended cells in combinations of two growth substances (MJA with ABA, ACC, BR, GA, IAA or KN; BR with ABA) produced no evidence of synergism, or in most cases, even of additive effects of the tested substances. ABA, BR and MJA (applied separately) stimulated the synthesis of numerous specific proteins. Each growth substance stimulated the synthesis of differing proteins, with four exceptions. This investigation raises the possibility that BR and MJA may play a role in a chain of events which leads eventually to the induction of desiccation tolerance in leaves of S. stapfianus. The effects on cell PDT observed in this study, while large, were insufficient to account for the remarkable improvement observed in the PDT of S. stapfianus leaves attached to drying plants.
{"title":"Effects of growth substances on the protoplasmic drought tolerance of leaf cells of the resurrection grass, Sporobolus stapfianus","authors":"H. Ghasempour, E. M. Anderson, D. Gaff","doi":"10.1071/PP00096","DOIUrl":"https://doi.org/10.1071/PP00096","url":null,"abstract":"Hydrated leaves of the resurrection grass Sporobolus stapfianus Gandoger are not desiccation tolerant, but moderate to severe drought stress can induce their desiccation tolerance while the leaves remain attached to drying intact plants. Free-cell suspensions prepared from fully turgid leaves of S. stapfianus were also found to be desiccation-sensitive. In this study a sensitive assay was developed to determine the effect of exogenous substances on the protoplasmic drought tolerance (PDT) of cell suspensions. Suspended cells were incubated with a wide variety of individual plant growth substances over a range of concentrations. After the incubation, the protoplasmic drought tolerance at each concentration of each substance was determined osmotically. Brassinolide (BR) and methyljasmonic acid (MJA), applied separately, gave the greatest effect — each improved PDT by approximately 6 MPa, compared with controls incubated without growth substances. Exogenous abscisic acid (ABA) improved the PDT of S. stapfianus only slightly (about 1 MPa). Salicylic acid (SA), 1-aminocyclopropane–1-carboxylic acid (ACC), ethephon, gibberellic acid (GA), kinetin (KN) andN 6 -(2-isopentyl)adenine (2ip) each improved PDT by ca 1.5 MPa. Indoleacetic acid (IAA) had no effect, and zeatin (ZN) had a deleterious effect on PDT. Incubation of suspended cells in combinations of two growth substances (MJA with ABA, ACC, BR, GA, IAA or KN; BR with ABA) produced no evidence of synergism, or in most cases, even of additive effects of the tested substances. ABA, BR and MJA (applied separately) stimulated the synthesis of numerous specific proteins. Each growth substance stimulated the synthesis of differing proteins, with four exceptions. This investigation raises the possibility that BR and MJA may play a role in a chain of events which leads eventually to the induction of desiccation tolerance in leaves of S. stapfianus. The effects on cell PDT observed in this study, while large, were insufficient to account for the remarkable improvement observed in the PDT of S. stapfianus leaves attached to drying plants.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84860421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigated the distribution of aluminium (Al) in the root tips of the Al-tolerant forage legume,Lotus pedunculatus Cav., a species that also accumulates condensed tannin (proanthocyanidin) in the roots and leaves. Clonal cuttings were grown in low ionic-strength nutrient solutions containing Al at levels that were either stimulatory or inhibitory (5–60µM ). The X-ray microanalysis of treated root apices revealed Al deposits at all Al concentrations. In freeze-fractured root samples from high Al concentrations (30 and 60 M ), deposits were found very close to the root tip. These deposits were predominantly composed of Al, phosphorus (P) and silicon (Si). At low Al concentrations (10 µM ), epoxy-embedded root samples were examined and Al deposits were also found near the meristematic areas. At lower concentrations (10 µM ), Al was found associated with P. In all osmium-fixed samples from high and low Al concentrations, Al was generally found in association with osmium-binding vacuoles. Because of the established high affinity of osmium for condensed tannin, the hypothesis is developed that condensed tannins possibly bind and detoxify Al in the root apices of L. pedunculatus.
{"title":"Possible involvement of condensed tannins in aluminium tolerance of Lotus pedunculatus.","authors":"P. Stoutjesdijk, P. Sale, P. Larkin","doi":"10.1071/PP01012","DOIUrl":"https://doi.org/10.1071/PP01012","url":null,"abstract":"We investigated the distribution of aluminium (Al) in the root tips of the Al-tolerant forage legume,Lotus pedunculatus Cav., a species that also accumulates condensed tannin (proanthocyanidin) in the roots and leaves. Clonal cuttings were grown in low ionic-strength nutrient solutions containing Al at levels that were either stimulatory or inhibitory (5–60µM ). The X-ray microanalysis of treated root apices revealed Al deposits at all Al concentrations. In freeze-fractured root samples from high Al concentrations (30 and 60 M ), deposits were found very close to the root tip. These deposits were predominantly composed of Al, phosphorus (P) and silicon (Si). At low Al concentrations (10 µM ), epoxy-embedded root samples were examined and Al deposits were also found near the meristematic areas. At lower concentrations (10 µM ), Al was found associated with P. In all osmium-fixed samples from high and low Al concentrations, Al was generally found in association with osmium-binding vacuoles. Because of the established high affinity of osmium for condensed tannin, the hypothesis is developed that condensed tannins possibly bind and detoxify Al in the root apices of L. pedunculatus.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80243830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effects of cold-induced photoinhibition on chlorophyll and carotenoid dynamics and xanthophyll cycling in Eucalyptus nitens (Deane and Maiden) Maiden were assessed between planting and 32 weeks after planting. The seedlings were fertilised or nutrient-deprived (non-fertilised) before planting and shaded or not shaded after planting. The experimental site was 700 m a.s.l., which is considered marginal for establishment of E. nitens plantations in Tasmania due to low mean annual minimum temperatures. Low temperature–high light conditions caused a reduction in variable to maximal chlorophyll fluorescence ratio (F v /F m ), which was more pronounced in non-fertilised than in fertilised seedlings. Shadecloth shelters alleviated this depression. Except in shaded fertilised seedlings, F v /F m did not recover to the level before planting until after 20 weeks. Total chlorophyll content was initially reduced in shaded treatments but subsequently increased with increasing temperatures and F v /F m. Total xanthophyll content and xanthophylls per unit chlorophyll remained relatively constant in fertilised seedlings but decreased in non-fertilised seedlings within 2 weeks after planting. Total xanthophyll and xanthophylls per unit chlorophyll subsequently recovered in non-shaded, non-fertilised seedlings with increasing temperatures and F v /F m. Diurnal [yield and non-photochemical quenching (NPQ) and seasonal (F v /F m) variation in chlorophyll fluorescence parameters were not reflected in xanthophyll cycling during the period of most severe photoinhibition. This result may indicate that chlorophyll–xanthophylls protein complexes form in winter-acclimated E. nitens foliage as have been demonstrated to occur in Eucalyptus pauciflora Sieb. ex Spreng. (Gilmore and Ball 2000, Proceedings of the National Academy of Sciences USA 97, 11098–11101).
研究了冷诱导光抑制对桉树(Deane and Maiden)的叶绿素和类胡萝卜素动态及叶黄素循环的影响。幼苗在种植前施肥或不施肥，种植后遮荫或不遮荫。实验地点为海拔700米，由于年平均最低气温较低，因此被认为是塔斯马尼亚州建立沙狐猴种植园的边缘。低温-强光条件导致叶绿素荧光变异性与最大变异性比值(F v /F m)的降低，在未受精的幼苗中比在受精的幼苗中更为明显。遮阳棚减轻了这种压抑。除遮荫施肥的幼苗外，直到20周后，fv / fm才恢复到种植前的水平。在遮荫处理下，总叶绿素含量最初降低，但随后随着温度和F /F m的升高而增加。在播种后2周内，施肥幼苗的总叶黄素含量和单位叶绿素叶黄素含量保持相对稳定，而未施肥幼苗的总叶黄素含量则有所下降。在光照抑制最严重的时期，叶绿素荧光参数的日产量、非光化学猝灭(NPQ)和季节性(fv /F m)变化并未反映在叶黄素循环中。这一结果可能表明，叶绿素-叶黄素蛋白复合物在冬季适应的黑桫椤叶片中形成，这种复合物已被证实发生在少叶桉中。Spreng交货。(Gilmore and Ball 2000，美国国家科学院院刊97,11098-11101)。
{"title":"Cold-induced photoinhibition and foliar pigment dynamics of Eucalyptus nitens seedlings during establishment","authors":"D. Close, C. Beadle, M. Hovenden","doi":"10.1071/PP01039","DOIUrl":"https://doi.org/10.1071/PP01039","url":null,"abstract":"The effects of cold-induced photoinhibition on chlorophyll and carotenoid dynamics and xanthophyll cycling in Eucalyptus nitens (Deane and Maiden) Maiden were assessed between planting and 32 weeks after planting. The seedlings were fertilised or nutrient-deprived (non-fertilised) before planting and shaded or not shaded after planting. The experimental site was 700 m a.s.l., which is considered marginal for establishment of E. nitens plantations in Tasmania due to low mean annual minimum temperatures. Low temperature–high light conditions caused a reduction in variable to maximal chlorophyll fluorescence ratio (F v /F m ), which was more pronounced in non-fertilised than in fertilised seedlings. Shadecloth shelters alleviated this depression. Except in shaded fertilised seedlings, F v /F m did not recover to the level before planting until after 20 weeks. Total chlorophyll content was initially reduced in shaded treatments but subsequently increased with increasing temperatures and F v /F m. Total xanthophyll content and xanthophylls per unit chlorophyll remained relatively constant in fertilised seedlings but decreased in non-fertilised seedlings within 2 weeks after planting. Total xanthophyll and xanthophylls per unit chlorophyll subsequently recovered in non-shaded, non-fertilised seedlings with increasing temperatures and F v /F m. Diurnal [yield and non-photochemical quenching (NPQ) and seasonal (F v /F m) variation in chlorophyll fluorescence parameters were not reflected in xanthophyll cycling during the period of most severe photoinhibition. This result may indicate that chlorophyll–xanthophylls protein complexes form in winter-acclimated E. nitens foliage as have been demonstrated to occur in Eucalyptus pauciflora Sieb. ex Spreng. (Gilmore and Ball 2000, Proceedings of the National Academy of Sciences USA 97, 11098–11101).","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90108905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fiona M. McAlister, W. R. Lewis-Henderson, Colin L. D. Jenkins, J. Watson
A perennial ryegrass (Lolium perenne L.) cDNA library was screened with a PCR-amplified cad DNA fragment generated from ryegrass cDNA template using degenerate oligonucleotide primers. A full-length cDNA (LpeCad1) was isolated and confirmed to encode a cinnamyl alcohol dehydrogenase (CAD) enzyme by expression of activity in Escherichia coli. The recombinant enzyme catalyses conversion of coniferaldehyde and sinapaldehyde with similar efficiency, and apparent K m values below 10 µM were determined for these substrates, whereas weak substrate inhibition occurs above this concentration. The predicted perennial ryegrass CAD was very similar (88–87percnt; amino acid sequence identity) to the only other monocotyledonous plant CAD sequences available, those of maize and sugarcane, respectively. Southern blot hybridization analysis indicated that there may be two or three cad genes, or alleles, in perennial ryegrass. The ryegrass LpeCad1 gene resembles the maize cadgene in showing strong expression in root and stem tissues, but is also expressed at lower levels in shoot, leaf sheath, leaf blade and floral tissues.
{"title":"Isolation and expression of a cinnamyl alcohol dehydrogenase cDNA from perennial ryegrass (Lolium perenne)","authors":"Fiona M. McAlister, W. R. Lewis-Henderson, Colin L. D. Jenkins, J. Watson","doi":"10.1071/PP00046","DOIUrl":"https://doi.org/10.1071/PP00046","url":null,"abstract":"A perennial ryegrass (Lolium perenne L.) cDNA library was screened with a PCR-amplified cad DNA fragment generated from ryegrass cDNA template using degenerate oligonucleotide primers. A full-length cDNA (LpeCad1) was isolated and confirmed to encode a cinnamyl alcohol dehydrogenase (CAD) enzyme by expression of activity in Escherichia coli. The recombinant enzyme catalyses conversion of coniferaldehyde and sinapaldehyde with similar efficiency, and apparent K m values below 10 µM were determined for these substrates, whereas weak substrate inhibition occurs above this concentration. The predicted perennial ryegrass CAD was very similar (88–87percnt; amino acid sequence identity) to the only other monocotyledonous plant CAD sequences available, those of maize and sugarcane, respectively. Southern blot hybridization analysis indicated that there may be two or three cad genes, or alleles, in perennial ryegrass. The ryegrass LpeCad1 gene resembles the maize cadgene in showing strong expression in root and stem tissues, but is also expressed at lower levels in shoot, leaf sheath, leaf blade and floral tissues.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77119927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Hanba, Shin-Ichi Miyazawa, H. Kogami, I. Terashima
We examined the changes in leaf anatomy and some physiological characteristics during leaf expansion and maturation. Three deciduous tree species having different types of shoot phenology, maple (Acer mono Maxim.; ‘flush’ type), alder (Alnus japonica(Thunb.) Steud.; ‘successive’ type), and Japanese poplar (Populus maximowiczii A. Henry; ‘successive’ type), were studied. Leaf CO 2 assimilation rate at high irradiance (P max) and CO 2 transfer conductance inside the leaf (g i) varied significantly with leaf development. There were strong positive relationships between P max) and g i for all of the species. The variations in g i were partly related to those in the surface area of chloroplasts facing the intercellular airspaces, while some other factors that related to liquid phase conductance may also contribute to the variation in g i . The developments of mesophyll cells were accompanied by the concomitant increase in chloroplast and Rubisco content in Alnus and Populus (successive types).
研究了叶片膨大和成熟过程中叶片解剖结构和一些生理特性的变化。三种不同枝条物候类型的落叶乔木:枫;' flush '型)，桤木(Alnus japonica(Thunb.)Steud。“连续”型)和日本杨树(Populus maximowiczii A. Henry;“连续”型)进行了研究。高辐照下叶片co2同化速率(P max)和叶片内co2传递导率(gi)随叶片发育变化显著。所有种属的pmax)与gi呈极显著正相关。gi的变化部分与叶绿体面对细胞间隙表面积的变化有关，而其他一些与液相电导有关的因素也可能导致gi的变化。桤木和杨木(连续型)叶肉细胞的发育伴随着叶绿体和Rubisco含量的增加。
{"title":"Effects of leaf age on internal CO2 transfer conductance and photosynthesis in tree species having different types of shoot phenology","authors":"Y. Hanba, Shin-Ichi Miyazawa, H. Kogami, I. Terashima","doi":"10.1071/PP00102","DOIUrl":"https://doi.org/10.1071/PP00102","url":null,"abstract":"We examined the changes in leaf anatomy and some physiological characteristics during leaf expansion and maturation. Three deciduous tree species having different types of shoot phenology, maple (Acer mono Maxim.; ‘flush’ type), alder (Alnus japonica(Thunb.) Steud.; ‘successive’ type), and Japanese poplar (Populus maximowiczii A. Henry; ‘successive’ type), were studied. Leaf CO 2 assimilation rate at high irradiance (P max) and CO 2 transfer conductance inside the leaf (g i) varied significantly with leaf development. There were strong positive relationships between P max) and g i for all of the species. The variations in g i were partly related to those in the surface area of chloroplasts facing the intercellular airspaces, while some other factors that related to liquid phase conductance may also contribute to the variation in g i . The developments of mesophyll cells were accompanied by the concomitant increase in chloroplast and Rubisco content in Alnus and Populus (successive types).","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84185037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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