Australian Journal of Plant Physiology最新文献

{"title":"Duration of the stem elongation period influences the number of fertile florets in wheat and barley.","authors":"D. Miralles, R. Richards, G. Slafer","doi":"10.1071/PP00021","DOIUrl":"https://doi.org/10.1071/PP00021","url":null,"abstract":"Yield increases in temperate cereals have been associated with increases in grain number. An experiment was conducted to investigate whether altering the duration of the stem elongation period in wheat and barley increases floret fertility and thereby grain number. A photoperiod-responsive spring wheat (UQ189) and spring barley (Arapiles) were grown in a naturally lit phytotron. Plants were grown at constant (9, 13 and 19 h) and reciprocally interchanged photoperiod [at terminal spikelet (TS, wheat) or triple mound (TM, barley)] to alter the duration of the stem elongation period. An increased duration of the late reproductive phase from TS to heading in wheat resulted in more fertile florets per spike. A similar relationship was observed in barley but only for a limited range of duration of the stem elongation period. Shorter photoperiods reduced the rate of floret development and extended the time to reach the fertile floret stage. The fact that the duration of the late reproductive phase during which the spike and stem competing for assimilates was associated with the number of fertile florets per spike suggests that extending the stem elongation period in cereals could be a way to reduce assimilate competition and thereby increase the number of fertile florets and grain yield.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74822619","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}

{"title":"Sensitivity of field-grown soybean to future atmospheric CO2: selection for improved productivity in the 21st century.","authors":"L. Ziska, J. Bunce","doi":"10.1071/PP00043","DOIUrl":"https://doi.org/10.1071/PP00043","url":null,"abstract":"Although genotypic differences among soybean (Glycine max (L.) Merr.) cultivars in their response to future CO2 partial pressures have been observed in the glasshouse, it is unclear if similar responses would occur among cultivars when grown under field conditions at normal stand densities. To determine variation in the sensitivity of soybean growth and seed yield to CO2, we grew two contrasting cultivars of the same maturity group, Ripley (semi-dwarf, determinate) and Spencer (standard, indeterminate), to reproductive maturity at ambient and elevated (30 Pa above ambient) CO2 partial pressures for two field seasons. Spencer had been previously selected in glasshouse trials as responsive to increased CO2. Significant cultivar x CO2 interaction was observed for both vegetative biomass and seed yield, with Spencer demonstrating a consistently greater yield enhancement at elevated CO2 than Ripley (60 vs 35%, respectively). Differences in CO2 sensitivity between cultivars were not evident in measurements of single leaf photosynthesis taken during anthesis, nor early or late pod-fill. Analysis of reproductive characteristics indicated that the sensitivity of the seed yield response to CO2 in Spencer was associated with the ability to form additional seed on axillary branches in response to elevated CO2. Data from this experiment suggest that screening of soybean germplasm at the glasshouse level, when combined with field trials, may be an effective strategy to begin selecting soybean lines that will maximize yield in a future, higher CO2 environment.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80731703","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}

{"title":"Rapid environmental changes that affect leaf water status induce transient surges or pauses in leaf expansion rate","authors":"J. Passioura, R. Munns","doi":"10.1071/PP99207","DOIUrl":"https://doi.org/10.1071/PP99207","url":null,"abstract":"We subjected wheat and barley plants to rapid environmental changes, and monitored leaf elongation rates for several hours thereafter. Changes in light, humidity or salinity caused sudden rises (if the leaf water status rose) or falls (if the leaf water status fell) in leaf elongation rate, followed by a recovery phase that lasted 20–60 min. After a step change in light or humidity, the growing leaf eventually resumed its original elongation rate, although the shoot water status, as monitored by leaf thickness, differed markedly. Salinity, on the other hand, produced a persistent change in leaf elongation rate, which settled down to a lower steady rate after the transient response was over. To determine whether the sudden changes in leaf elongation rate were due to changes in leaf water relations, we kept shoots fully hydrated through the environmental changes by automatically pressurising the roots to maintain leaf xylem on the point of bleeding. This annulled the environmental effects on leaf water status, and thereby largely removed the changes in leaf elongation rate. The only exception was at the dark:light transition, when the leaf elongation rate of pressurised plants rose sharply (in contrast to that of unpressurised plants, which fell), then underwent damped oscillations before settling at about its initial value. The sudden excursions of leaf growth in unpressurised plants accompanying the environmental changes were undoubtedly due to changes in leaf water status. The subsequent, generally complete, return of the leaf elongation rate to its initial value within an hour, despite the persistent change in leaf water status, suggests that a control system is operating at a time scale of tens of minutes that eventually overrides, partially or completely, the rapid effects of changes in leaf water status.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74376376","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}

{"title":"Leaf water status controls day-time but not daily rates of leaf expansion in salt-treated barley","authors":"R. Munns, Jianmin Guo, J. Passioura, G. Cramer","doi":"10.1071/PP99193","DOIUrl":"https://doi.org/10.1071/PP99193","url":null,"abstract":"Barley plants were grown in pots that would fit inside a pressure chamber, so that their shoots could be kept fully turgid by applying pressure in the chamber to bring the xylem sap of the shoot to the point of bleeding. Pressurisation increased the growth rate of NaCl-treated plants in the light period but not in the dark. The promotive effect on growth was greatest in the light period of the first day of pressurisation, but disappeared during the first night. Pressurisation promoted growth the next day during the light period, but on the second night the elongation rate was significantly lower than that of unpressurised NaCl-treated plants. This pattern of high day-time and low night-time growth then continued indefinitely. The lower night-time growth counteracted the higher day-time growth, with the result that total growth over 24 h was the same as in NaCl-treated plants that were not pressurised. Levels of total reserve carbohydrates were unaffected by pressurisation, indicating that the slower growth of the pres-surised plants during the night was not due to depletion of assimilates. These results are interpreted in the context of hormonal signals controlling growth on a 24-h basis, such that any short-term stimulation of growth arising from unusually high water status during the light period is counterbalanced by slower growth during the night.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88029219","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}

{"title":"Hypergravity-induced increase in the apoplastic pH and its possible involvement in suppression of beta-glucan breakdown in maize seedlings.","authors":"K. Soga, K. Wakabayashi, T. Hoson, S. Kamisaka","doi":"10.1071/PP00035","DOIUrl":"https://doi.org/10.1071/PP00035","url":null,"abstract":"Elongation growth of both coleoptiles and mesocotyls of maize (Zea mays L. cv. Cross Bantam T51) seedlings was inhibited under basipetal hypergravity (300 g) conditions. Hypergravity increased the pH of the apoplastic fluid of coleoptiles from 5.0 to 5.5 and mesocotyls from 5.2 to 5.7. When beta-1,3:1,4-D-glucanases (beta-glucanases) extracted from cell walls of the 1-g control coleoptiles and mesocotyls were assayed at pH 5.0 and 5.5 for coleoptiles, and at 5.2 and 5.7 for mesocotyls, respectively, the activity in the increased pH conditions was significantly lower than that in the control pH conditions. During the autolysis of the enzymically active cell wall preparations obtained from 1-g control organs, a molecular mass downshift of hemicellulosic polysaccharides occurred in cell walls. This downshift was suppressed in the increased pH conditions as compared with the control pH conditions. It was reported that hypergravity increased the molecular mass of hemicellulosic polysaccharides by decreasing the beta-glucanase activity, and thereby decreased the mechanical extensibility of cell walls in maize coleoptiles and mesocotyls. These results suggest that, in maize coleoptiles and mesocotyls, hypergravity-induced increase in the pH in the apoplastic fluid is involved in the reduction of the activity of beta-glucanases which, in turn, causes an increase in the molecular mass of hemicellulosic polysaccharides and inhibits elongation growth.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86971314","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}

{"title":"Nitrogen isotope fractionation in the fodder tree legume tagasaste (Chamaecytisus proliferus) and assessment of N2 fixation inputs in deep sandy soils of Western Australia.","authors":"M. Unkovich, J. Pate, E. C. Lefroy, D. Arthur","doi":"10.1071/PP99201","DOIUrl":"https://doi.org/10.1071/PP99201","url":null,"abstract":"Nitrogen (N) isotope fractionation and symbiotic N fixation were investigated in the shrub legume tagasaste, growing in the glasshouse and field. In a pot study of effectively nodulated plants supplied with 0, 1, 5 and 10 mM nitrate [stable isotope 15N (δ15N) of 3.45‰], the δ15N of dry matter N of fully symbiotic cultures indicated a greater isotope fractionation during distribution of N between nodules, stems, leaves and roots than for N2 fixation itself, with whole-plant δ15N being near zero (–0.46 to 0.42‰). Regardless of whether plants were field-grown, pot-cultured, fixing N2 or utilising mineral N, woody stems were depleted in 15N relative to all other plant parts. The similar orders of ranking of δ15N for plant components of the nitrate-treated and fully symbiotic plants, and a general increase in δ15N as plants were exposed to increasing concentrations of nitrate, indicated that N isotope fractionation can be accounted for, and thus not undermine 15N natural abundance as means of measuring N2 fixation inputs in tagasaste trees. In pot culture the percentage of plant N derived from the atmosphere (%Ndfa) by symbiotic N2 fixation fell from 85 to 37% when the nitrate supply was increased from 1 to 10 mM, with evidence of nitrate N being preferentially allocated to roots. δ15N natural abundance assessments of N2 fixation of 4-year-old trees of field-grown tagasaste in alley (550 trees ha-1) or plantation (2330 trees ha-1) spacing were undertaken at a study site at Moora, Western Australia, over a 2-year period of shoot regrowth (coppicing). Cumulative N yields and %Ndfa were similar for trees of alley and plantation spacing, with much less coppice N accumulation in the first compared to the second year after cutting. Scaling values from a tree to plot area basis, and using a mean %Ndfa value of 83% for all trees at the site, inputs of fixed N into current biomass plus fallen litter over the 2 years of coppicing were calculated to be 83 kg N ha-1 year-1 for the alley and 390 kg N ha-1 year-1 for the plantation spacing. Although the plantation tagasaste fixed 587 kg N ha-1 in the second year, close to the maximum value reported in the literature for any N2-fixing system, this should not be seen as typical where the trees are used for animal production, since grazing and cutting management will substantially reduce productivity and N2 fixation input.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79586739","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}

{"title":"Identification of differentially expressed genes during early development of tomato fruit. Characterisation of a novel cDNA coding for a RAD23 protein","authors":"M. Lemaire-Chamley, Johann Petit, M. Causse, P. Raymond, C. Chevalier","doi":"10.1071/PP00047","DOIUrl":"https://doi.org/10.1071/PP00047","url":null,"abstract":"Before the onset of ripening, tomato fruit development comprises three distinct phases: fruit set, a cell division phase and a cell expansion phase. In this study, we used the method of mRNA differential display in order to isolate tomato genes specifically expressed during these early phases of fruit development. Among 40 differen-tial bands, nine cDNAs were selected for further investigations based on their identification after nucleotide sequencing. We isolated the full-length cDNA corresponding to one of these fragments, coding for RAD23, a protein involved in the excision repair system, thus providing new sequence information on a poorly characterised protein in plants. All the isolated cDNAs were mapped on the tomato genome and their expression studied by northern blot and semi-quantitative RT–PCR during early fruit development and in vegetative organs of tomato plants. The sequence data are deposited in the GenBank under the accession numbers: AJ270956 (mo5-3C11/1), AJ270957 (mo5-3G12/4), AJ270958 (mo5-3G17), AJ270959 (mo5-3T12), AJ270960 (mo1-6A1), AJ270961 (mo1-6T1), AJ270962 (mo5-10G1), AJ270963 (mo6-20G1), AJ270964 (mo6-MGT2) and AJ243875 (LeRAD23-8 full-length cDNA).","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76132034","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}

{"title":"Phosphate absorption by Arabidopsis thaliana: interactions between phosphorus status and inhibition by arsenate.","authors":"G. T. Clark, J. Dunlop, H. Phung","doi":"10.1071/PP99108","DOIUrl":"https://doi.org/10.1071/PP99108","url":null,"abstract":"The effects of phosphorus status and arsenate on the absorption of phosphate by roots of intact sterile seedlings of Arabidopsis thaliana were studied by analysing the rate of depletion of phosphate from solutions initially containing 10 M KH2PO4. Depletion of phosphate from the experimental solutions was measured both chemically and by labelling with 32P. There was a substantial efflux of phosphate coincident with a rapid influx of phosphate, with efflux increasing with increasing phosphorus status. The highest rates of absorption were obtained for the plants initially grown with a high level of phosphorus but then deprived of phosphate for 5 d prior to the experiments, with the next highest rates obtained for the most phosphorus-deficient plants. Kinetic analysis suggests that changes in both the affinity and capacity of the absorption mechanism contribute to differences in the rate of phosphate influx between plants of different phosphorus status. Arsenate as 20 M KH2AsO4 inhibited phosphate influx in a manner such that all plants, regardless of their phosphorus status, had the same phosphate influx rate. This was reflected in identical values for the Michaelis constant, Km, and maximum velocity as used in Michaelis–Menten kinetics, Vmax. Arsenate had its greatest effect on phosphate movement to the shoot. The simultaneous elimination of differences in phosphate influx between plants of different phosphorus status suggest that phosphate movement to the shoot may be important in the regulation of influx by phosphorus status.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76196685","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}

{"title":"Radiation and nitrogen use at the leaf and canopy level by wheat and oilseed rape during the critical period for grain number definition","authors":"M. Dreccer, A. Schapendonk, M. Oijen, C. Pot, R. Rabbinge","doi":"10.1071/PP00019","DOIUrl":"https://doi.org/10.1071/PP00019","url":null,"abstract":"During the critical period for grain number definition, the amount of biomass produced per unit absorbed radiation is more sensitive to nitrogen (N) supply in oilseed rape than in wheat, and reaches a higher value at high N. This response was investigated by combining experimental and modelling work. Oilseed rape and wheat were grown at three levels of N supply, combined with two levels of plant density at high N supply. Canopy photosynthesis and daytime radiation use efficiency (RUEA) were calculated with a model based on observed N-dependent leaf photosynthesis and observed canopy vertical distribution of light and leaf N. In oilseed rape, RUEA was higher than in wheat and, in contrast to wheat, the sensitivity to canopy leaf N content increased from the start to the end of the critical period. These results were partly explained by the higher leaf photosynthesis in oilseed rape vs wheat. In addition, oilseed rape leaves were increasingly shaded by the inflorescence. Thus, RUEA increased because more leaves were operating at non-saturating light levels. In both species, the vertical distribution of leaf N was close to that optimising canopy photosynthesis. The results are discussed in relation to possibilities for improvement of N productivity in these crops.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80817958","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}

{"title":"Analysis of a promoter for the NADH–glutamate synthase gene in rice (Oryza sativa): cell type-specific expression in developing organs of transgenic rice plants","authors":"S. Kojima, M. Kimura, Y. Nozaki, T. Yamaya","doi":"10.1071/PP99145","DOIUrl":"https://doi.org/10.1071/PP99145","url":null,"abstract":"The entire 3.7 kbp 5´-upstream region (-2840 to +886) from the translational start codon of NADH- glutamate synthase (NADH-GOGAT, EC 1.4.1.14) gene from rice (Oryza sativa L.) or the region sequentially deleted from the 5´-end was fused with the β-glucuronidase (GUS) reporter gene. The chimeric gene was introduced into calli derived from rice scutellum via Agrobacterium tumefaciens-mediated transformation and tissue-specific GUS activity determined in T0 generations. When the entire region was fused, GUS activity was detected in vascular bundles of the developing leaf blade and in dorsal and lateral vascular bundles of developing grains. This corresponds with our previous immunodetection of NADH-GOGAT protein (Hayakawa et al., Planta 193, 455-460, 1994). A series of deletion experiments showed that a 149-nucleotide region between -142 and +7 was essential for promoter activity in the NADH-GOGAT gene.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79890085","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}