We report the isolation of a banana cDNA, designated MWUGPA, encoding uridine diphosphoryl (UDP)-glucose pyrophosphorylase (UGPase, EC.2.7.7.9) that catalyses the reversible conversion between glucose 1-phosphate and UDPglucose in plants and animals. Furthermore, UGPase expression in fruit during ripening and in response to exogenous ethylene and sugars was also investigated. MWUGPA encodes a polypeptide of 467 amino acid residues and shares a high degree of sequence similarity (85–90%) with other plant UGPase homologs. In northern blot analysis, a 1.7-kb UGPase transcript was detected in both the vegetative and reproductive organs, but the former was considerably less abundant than the latter. In fruit, the level of accumulated transcripts was higher in pulp than peel at all ripening stages. Transcript abundance in both fruit tissues was relatively constant during ripen-ing, but pulp transcripts surged in the ‘more green than yellow’ category fruit when ethylene also increased. Further analysis revealed that UGPase expression in fruit was ethylene-inducible, but the response was tissue-specific, as evidenced by the promoting effect of exogenous ethylene on accumulation of UGPase transcripts in pulp but not peel. Exogenous application of sucrose and fructose also increased UGPase transcript abundance in leaf and fruit tissues, especially pulp, whereas exogenous glucose had little or no effect. The results of this study indicate that ethy-lene and soluble sugars may play a regulatory role in UGPase expression during ripening in banana fruit.
{"title":"Expression of a UDPglucose pyrophosphorylase cDNA during fruit ripening of banana (Musa acuminata)","authors":"E. Pua, S. Lim, Pei Liu, Jian-Zhong Liu","doi":"10.1071/PP00016","DOIUrl":"https://doi.org/10.1071/PP00016","url":null,"abstract":"We report the isolation of a banana cDNA, designated MWUGPA, encoding uridine diphosphoryl (UDP)-glucose pyrophosphorylase (UGPase, EC.2.7.7.9) that catalyses the reversible conversion between glucose 1-phosphate and UDPglucose in plants and animals. Furthermore, UGPase expression in fruit during ripening and in response to exogenous ethylene and sugars was also investigated. MWUGPA encodes a polypeptide of 467 amino acid residues and shares a high degree of sequence similarity (85–90%) with other plant UGPase homologs. In northern blot analysis, a 1.7-kb UGPase transcript was detected in both the vegetative and reproductive organs, but the former was considerably less abundant than the latter. In fruit, the level of accumulated transcripts was higher in pulp than peel at all ripening stages. Transcript abundance in both fruit tissues was relatively constant during ripen-ing, but pulp transcripts surged in the ‘more green than yellow’ category fruit when ethylene also increased. Further analysis revealed that UGPase expression in fruit was ethylene-inducible, but the response was tissue-specific, as evidenced by the promoting effect of exogenous ethylene on accumulation of UGPase transcripts in pulp but not peel. Exogenous application of sucrose and fructose also increased UGPase transcript abundance in leaf and fruit tissues, especially pulp, whereas exogenous glucose had little or no effect. The results of this study indicate that ethy-lene and soluble sugars may play a regulatory role in UGPase expression during ripening in banana fruit.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"152 1 1","pages":"1151-1159"},"PeriodicalIF":0.0,"publicationDate":"2000-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80404202","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}
Aspalathus linearis is a N2-fixing legume used for tea production, and grows in highly acidic soils (pH 3–5.3) of the Cederberg mountains in South Africa. Field and glasshouse studies revealed significantly higher pH in rhizosphere than non-rhizosphere soils. However, when six non-legume species were studied in adjacent fields, there were no differences in pH between rhizosphere and non-rhizosphere soils. The culture of A. linearis plants in sterile Leonard jars similarly showed a marked increase of 2.8 pH units in the nutrient solution bathing the roots of inoculated (nodulated) plants, compared to 1.5 pH units in uninoculated control. The uptake and reduction of NO3– by plants fed 2 mM NO3– also raised the rhizosphere pH by 3.5 units, a value comparable to that of the nodulated plants. The use of titrimetric methods showed that OH– and HCO3– were the components of alkalinity in the nutrient solution bathing roots of A. linearis, and were directly responsible for the increase in rhizosphere pH. These findings suggest that the ability to raise rhizosphere pH is an adaptative feature of this legume symbiosis that overcomes the adverse effects of low pH in enhancing nutrient acquisition and reducing trace element toxicity.
阿斯帕拉索是一种用于茶叶生产的固氮豆科植物，生长在南非Cederberg山脉的高酸性土壤(pH值3-5.3)中。田间和温室研究表明，根际土壤pH值显著高于非根际土壤。然而，当6种非豆科植物在邻近的农田中进行研究时，根际土壤和非根际土壤的pH值没有差异。同样，在无菌的Leonard罐子中培养线形草植株时，接种(结瘤)植株根部的营养液pH值显著增加了2.8个单位，而未接种的对照pH值为1.5个单位。饲喂2 mM NO3 -的植株对NO3 -的吸收和还原也使根际pH升高了3.5个单位，与结瘤植株的pH值相当。结果表明，OH -和HCO3 -是水杨根营养液碱度的主要组成部分，是水杨根际pH升高的直接原因。这些结果表明，提高根际pH的能力是水杨根际共生的一种适应性特征，克服了低pH的不利影响，促进了养分的获取，降低了微量元素的毒性。
{"title":"Modification of rhizosphere pH by the symbiotic legume Aspalathus linearis growing in a sandy acidic soil","authors":"M. L. Muofhe, F. Dakora","doi":"10.1071/PP99198","DOIUrl":"https://doi.org/10.1071/PP99198","url":null,"abstract":"Aspalathus linearis is a N2-fixing legume used for tea production, and grows in highly acidic soils (pH 3–5.3) of the Cederberg mountains in South Africa. Field and glasshouse studies revealed significantly higher pH in rhizosphere than non-rhizosphere soils. However, when six non-legume species were studied in adjacent fields, there were no differences in pH between rhizosphere and non-rhizosphere soils. The culture of A. linearis plants in sterile Leonard jars similarly showed a marked increase of 2.8 pH units in the nutrient solution bathing the roots of inoculated (nodulated) plants, compared to 1.5 pH units in uninoculated control. The uptake and reduction of NO3– by plants fed 2 mM NO3– also raised the rhizosphere pH by 3.5 units, a value comparable to that of the nodulated plants. The use of titrimetric methods showed that OH– and HCO3– were the components of alkalinity in the nutrient solution bathing roots of A. linearis, and were directly responsible for the increase in rhizosphere pH. These findings suggest that the ability to raise rhizosphere pH is an adaptative feature of this legume symbiosis that overcomes the adverse effects of low pH in enhancing nutrient acquisition and reducing trace element toxicity.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"42 1","pages":"1169-1173"},"PeriodicalIF":0.0,"publicationDate":"2000-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86130287","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}
Epidermal cell turgor (P) and leaf growth in Begonia argenteo-guttata L. were monitored simultaneously following changes in air humidity in order to evaluate P–growth relations. A decrease in air humidity from 70 to 5% caused a decrease in P of 0.05 MPa. This small decrease in P resulted in cessation of growth. Subsequently, growth recovered partially at constant P, indicating an increase in wall yielding to P. Notwithstanding this increase in wall yielding, the steady growth rates showed a marked dependence on P. Decreases in P of 0.05 MPa caused a 30–40% reduction in the steady rate of elongation. These results were reversible. Upon a step increase in air humidity from 5 to 70%, P and growth rate rapidly increased. Subsequently, growth declined without a corresponding decrease in P, although the rate of growth remained higher than at low humidity. The partial self-stabilization of growth following P changes and the positive relationship between steady growth rate and P are consistent with the notion that wall yielding is controlled by interactions between P and metabolism. Results are discussed in relation to biophysical factors that control growth and to present theories that accommodate variable wall yielding.
{"title":"Turgor and Cell Wall Yielding in Dicot Leaf Growth in Response to Changes in Relative Humidity","authors":"M. Serpe, M. Matthews","doi":"10.1071/PP00055","DOIUrl":"https://doi.org/10.1071/PP00055","url":null,"abstract":"Epidermal cell turgor (P) and leaf growth in Begonia argenteo-guttata L. were monitored simultaneously following changes in air humidity in order to evaluate P–growth relations. A decrease in air humidity from 70 to 5% caused a decrease in P of 0.05 MPa. This small decrease in P resulted in cessation of growth. Subsequently, growth recovered partially at constant P, indicating an increase in wall yielding to P. Notwithstanding this increase in wall yielding, the steady growth rates showed a marked dependence on P. Decreases in P of 0.05 MPa caused a 30–40% reduction in the steady rate of elongation. These results were reversible. Upon a step increase in air humidity from 5 to 70%, P and growth rate rapidly increased. Subsequently, growth declined without a corresponding decrease in P, although the rate of growth remained higher than at low humidity. The partial self-stabilization of growth following P changes and the positive relationship between steady growth rate and P are consistent with the notion that wall yielding is controlled by interactions between P and metabolism. Results are discussed in relation to biophysical factors that control growth and to present theories that accommodate variable wall yielding.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"16 1","pages":"1131-1140"},"PeriodicalIF":0.0,"publicationDate":"2000-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74761141","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}
M. C. D. Mesa, Silvia Jiménez-Bermúdez, F. Pliego-Alfaro, M. Quesada, J. Mercado
The effect of combining Agrobacterium tumefaciens infection and biolistic bombardment on the transformation of strawberry (Fragaria × ananassa Duch.) cv. Chandler, was evaluated. Bombarding leaf explants with uncoated gold particles followed by Agrobacterium infection did not improve transformation, and yielded similar percentages of shoot regeneration in the presence of kanamycin in bombarded and non-bombarded explants (7.2%). In a novel approximation, gold particles were coated with Agrobacterium cells and used to bombard leaf explants. Helium pressures of 4.5, 6.2 and 7.6 MPa and target distances of 3 and 9 cm were tested. An average of 96.2% of the explants showed β-glucuronidase (GUS) expression 15 d after bombardment, in comparison with 26.6% in explants bombarded with gold particles coated with the plasmid pGUSINT or 58.3% in non-bombarded Agrobacterium-infected explants. After 25 weeks of culture, the highest transformation frequency was obtained using a 6.2 MPa helium pressure and 3 cm target distance, yielding 69% kanamycin-resistant explants and a final transformation fre-quency of 20.7%. These values were 4.5 times higher for kanamycin-resistant explants (69% with biolistic vs 16% with Agrobacterium infection) and 2.9 times higher for transformation frequency (20.7 vs 7%,) compared with those obtained with standard Agrobacterium transformation procedures (Barcelo et al. 1998, Plant Cell, Tiss. Org. Cult. 54, 29–36). More than 15 independent transgenic plants obtained by the Agrobacterium-coated particle system were acclimatized and confirmed as transgenics by GUS activity and PCR. Segregation analysis of kanamycin resistance has been performed in seven independent lines, three of which contained a single insertion of the T-DNA.
{"title":"Agrobacterium cells as microprojectile coating: a novel approach to enhance stable transformation rates in strawberry","authors":"M. C. D. Mesa, Silvia Jiménez-Bermúdez, F. Pliego-Alfaro, M. Quesada, J. Mercado","doi":"10.1071/PP00025","DOIUrl":"https://doi.org/10.1071/PP00025","url":null,"abstract":"The effect of combining Agrobacterium tumefaciens infection and biolistic bombardment on the transformation of strawberry (Fragaria × ananassa Duch.) cv. Chandler, was evaluated. Bombarding leaf explants with uncoated gold particles followed by Agrobacterium infection did not improve transformation, and yielded similar percentages of shoot regeneration in the presence of kanamycin in bombarded and non-bombarded explants (7.2%). In a novel approximation, gold particles were coated with Agrobacterium cells and used to bombard leaf explants. Helium pressures of 4.5, 6.2 and 7.6 MPa and target distances of 3 and 9 cm were tested. An average of 96.2% of the explants showed β-glucuronidase (GUS) expression 15 d after bombardment, in comparison with 26.6% in explants bombarded with gold particles coated with the plasmid pGUSINT or 58.3% in non-bombarded Agrobacterium-infected explants. After 25 weeks of culture, the highest transformation frequency was obtained using a 6.2 MPa helium pressure and 3 cm target distance, yielding 69% kanamycin-resistant explants and a final transformation fre-quency of 20.7%. These values were 4.5 times higher for kanamycin-resistant explants (69% with biolistic vs 16% with Agrobacterium infection) and 2.9 times higher for transformation frequency (20.7 vs 7%,) compared with those obtained with standard Agrobacterium transformation procedures (Barcelo et al. 1998, Plant Cell, Tiss. Org. Cult. 54, 29–36). More than 15 independent transgenic plants obtained by the Agrobacterium-coated particle system were acclimatized and confirmed as transgenics by GUS activity and PCR. Segregation analysis of kanamycin resistance has been performed in seven independent lines, three of which contained a single insertion of the T-DNA.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"35 1","pages":"1093-1100"},"PeriodicalIF":0.0,"publicationDate":"2000-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91115090","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 spatio-temporal evolution of catalase (CAT) activity and triacylglycerol distribution was investigated in seeds and seedlings from Pinus pinaster Ait., P. pinea L. and P. radiata D. Don during germination and post-germination. The high amount of triacylglycerols contained in the whole dehydrated embryo from the three species was progressively depleted, first, in the radicle and then in hypocotyl and cotyledons during post-germinative growth. In parallel, histological localisation of CAT activity and the quantitative analysis confirmed the involvement of this enzyme in cell detoxification from peroxide released during the intense lipid breakdown. Two isozymes, CAT-1 and CAT-2, were identified during post-germinative growth. Both were particularly active in the hypocotyl and radicle, while CAT-2 was specifically active in the photosynthetic tissues. These results emphasise that CAT activity is also independent from lipid metabolism in certain tissues. The role of each isoenzyme is discussed in connection with the metabolic changes occurring during seed germination and seedling growth. Special attention is given to the role of the shoot apex in triacylglycerol storage and breakdown. Central mother cells have been shown as a specific lipid storage area of the shoot apical meristem, in contrast with the peripheral zone in which lipid reserves were always reduced.
{"title":"Histological and biochemical changes in Pinus spp. seeds during germination and post-germinative growth: triacylglycerol distribution and catalase activity","authors":"M. Jordy, Susanna Danti, J. Favre, M. Racchi","doi":"10.1071/PP00069","DOIUrl":"https://doi.org/10.1071/PP00069","url":null,"abstract":"The spatio-temporal evolution of catalase (CAT) activity and triacylglycerol distribution was investigated in seeds and seedlings from Pinus pinaster Ait., P. pinea L. and P. radiata D. Don during germination and post-germination. The high amount of triacylglycerols contained in the whole dehydrated embryo from the three species was progressively depleted, first, in the radicle and then in hypocotyl and cotyledons during post-germinative growth. In parallel, histological localisation of CAT activity and the quantitative analysis confirmed the involvement of this enzyme in cell detoxification from peroxide released during the intense lipid breakdown. Two isozymes, CAT-1 and CAT-2, were identified during post-germinative growth. Both were particularly active in the hypocotyl and radicle, while CAT-2 was specifically active in the photosynthetic tissues. These results emphasise that CAT activity is also independent from lipid metabolism in certain tissues. The role of each isoenzyme is discussed in connection with the metabolic changes occurring during seed germination and seedling growth. Special attention is given to the role of the shoot apex in triacylglycerol storage and breakdown. Central mother cells have been shown as a specific lipid storage area of the shoot apical meristem, in contrast with the peripheral zone in which lipid reserves were always reduced.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"7 1","pages":"1109-1117"},"PeriodicalIF":0.0,"publicationDate":"2000-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79459558","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}
A. Schapendonk, M. Oijen, P. Dijkstra, C. Pot, W. Jordi, G. Stoopen
In two subsequent years, an early maturing potato cultivar with low leaf area index (LAI) and a late culti- var with high LAI were grown at concentrations of 350 and 700 µL CO2 L -1 in open-top chambers. The average increase of tuber dry matter yield by elevated CO2 was 27% in 1995 and 49% in 1996. During the first weeks after planting, elevated CO2 stimulated the light-saturated rate of photosynthesis (Amax) of both cultivars by 80%. However, Amax under elevated CO2 declined to the level of the low-CO2 treatment in the course of the growing season. In 1995 this convergence due to acclimation of photosynthesis was completed within 6 weeks, but in 1996, accli- mation proceeded until the end of the growing season. Photosynthetic acclimation was accompanied by a reduced Rubisco content, and was correlated more closely with accumulation of sucrose than of starch. From fluorescence measurements it was concluded that, in contrast to the carboxylation efficiency, the efficiency of photosynthetic reactions centers was not affected by acclimation to elevated CO2. The faster photosynthetic acclimation in 1995 coincided with overall lower values of Amax, crop growth rate and growth response to elevated CO2. It is shown that the indeterminate growth pattern of potato with its large sink capacity does not preclude acclimation. The effect of acclimation on yield was quantified by computer simulations. The simulated results indicated that photosynthetic acclimation reduced the positive effect of elevated CO2 on tuber yield by 50%.
在随后的两年里，在350和700 μ L CO2 L -1的浓度下，在开顶箱中生长低叶面积指数(LAI)的早熟马铃薯品种和高叶面积指数的晚熟马铃薯品种。增加CO2对块茎干物质产量的平均提高幅度分别为1995年27%和1996年49%。在种植后的头几个星期，二氧化碳浓度升高使两个品种的光合作用光饱和率(Amax)提高了80%。然而，在生长季中，高CO2处理下的Amax逐渐下降到低CO2处理的水平。1995年，由于光合作用的驯化，这种趋同在6周内完成，但在1996年，趋同一直持续到生长季节结束。光合驯化伴随着Rubisco含量的降低，与蔗糖积累的关系比与淀粉积累的关系更密切。从荧光测量可以得出结论，与羧基化效率相反，光合反应中心的效率不受高CO2环境的影响。1995年光合驯化较快，与Amax值、作物生长率和生长对CO2升高的响应总体较低一致。结果表明，马铃薯的生长模式不确定，但其库容量大，并不妨碍驯化。通过计算机模拟量化了驯化对产量的影响。模拟结果表明，光合驯化使CO2浓度升高对块茎产量的正向影响降低了50%。
{"title":"Effects of elevated CO2 concentration on photosynthetic acclimation and productivity of two potato cultivars grown in open-top chambers","authors":"A. Schapendonk, M. Oijen, P. Dijkstra, C. Pot, W. Jordi, G. Stoopen","doi":"10.1071/PP99205","DOIUrl":"https://doi.org/10.1071/PP99205","url":null,"abstract":"In two subsequent years, an early maturing potato cultivar with low leaf area index (LAI) and a late culti- var with high LAI were grown at concentrations of 350 and 700 µL CO2 L -1 in open-top chambers. The average increase of tuber dry matter yield by elevated CO2 was 27% in 1995 and 49% in 1996. During the first weeks after planting, elevated CO2 stimulated the light-saturated rate of photosynthesis (Amax) of both cultivars by 80%. However, Amax under elevated CO2 declined to the level of the low-CO2 treatment in the course of the growing season. In 1995 this convergence due to acclimation of photosynthesis was completed within 6 weeks, but in 1996, accli- mation proceeded until the end of the growing season. Photosynthetic acclimation was accompanied by a reduced Rubisco content, and was correlated more closely with accumulation of sucrose than of starch. From fluorescence measurements it was concluded that, in contrast to the carboxylation efficiency, the efficiency of photosynthetic reactions centers was not affected by acclimation to elevated CO2. The faster photosynthetic acclimation in 1995 coincided with overall lower values of Amax, crop growth rate and growth response to elevated CO2. It is shown that the indeterminate growth pattern of potato with its large sink capacity does not preclude acclimation. The effect of acclimation on yield was quantified by computer simulations. The simulated results indicated that photosynthetic acclimation reduced the positive effect of elevated CO2 on tuber yield by 50%.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"56 1","pages":"1119-1130"},"PeriodicalIF":0.0,"publicationDate":"2000-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73181581","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. Royo, M. Abaza, R. Blanco, L. F. García del Moral
The effects on grain filling and morphometry of natural drought, late sowing and simulated drought by means of a chemical treatment with potassium iodide (KI) were compared over 3 years of field trials in triticale ( ¥ Triticosecale Wittmack) cv. Trujillo and three near-isogenic lines derived from it. Grain weight data fitted accurate to a logistic curve. The maximum rate of grain filling was the curve coefficient most sensitive to drought stress, and accounted for 7–50% of grain yield variation. Chemical treatment with KI caused greater variation in grain filling curve coefficients and grain morphometry than did a delay in the sowing date, which in turn caused greater variation than natural drought. The type and magnitude of the effects of the different kinds of stresses on grain growth and morphometry could be related to the time that elapsed from anthesis, at which time the effects were perceptible. KI reduced the maximum rate of grain filling and final grain weight by 38 and 32%, respectively, its effect being significant from 8 d after the treatment. The volume of grain was reduced 11% by KI. The impact of delayed sowing date and drought were significant 29 and 33 d after anthesis, respectively, corresponding to the end of the linear phase of the grain filling curves. Both treatments diminished grain filling duration (13% by delayed sowing, and 6% by drought, respectively), final grain weight (16 and 12%, respectively), grain volume (15% and 8%, respectively), and embryo area (8% in both cases), but neither altered the maximum grain filling rate.
{"title":"Triticale grain growth and morphometry as affected by drought stress, late sowing and simulated drought stress","authors":"C. Royo, M. Abaza, R. Blanco, L. F. García del Moral","doi":"10.1071/PP99113","DOIUrl":"https://doi.org/10.1071/PP99113","url":null,"abstract":"The effects on grain filling and morphometry of natural drought, late sowing and simulated drought by means of a chemical treatment with potassium iodide (KI) were compared over 3 years of field trials in triticale ( ¥ Triticosecale Wittmack) cv. Trujillo and three near-isogenic lines derived from it. Grain weight data fitted accurate to a logistic curve. The maximum rate of grain filling was the curve coefficient most sensitive to drought stress, and accounted for 7–50% of grain yield variation. Chemical treatment with KI caused greater variation in grain filling curve coefficients and grain morphometry than did a delay in the sowing date, which in turn caused greater variation than natural drought. The type and magnitude of the effects of the different kinds of stresses on grain growth and morphometry could be related to the time that elapsed from anthesis, at which time the effects were perceptible. KI reduced the maximum rate of grain filling and final grain weight by 38 and 32%, respectively, its effect being significant from 8 d after the treatment. The volume of grain was reduced 11% by KI. The impact of delayed sowing date and drought were significant 29 and 33 d after anthesis, respectively, corresponding to the end of the linear phase of the grain filling curves. Both treatments diminished grain filling duration (13% by delayed sowing, and 6% by drought, respectively), final grain weight (16 and 12%, respectively), grain volume (15% and 8%, respectively), and embryo area (8% in both cases), but neither altered the maximum grain filling rate.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"13 1","pages":"1051-1059"},"PeriodicalIF":0.0,"publicationDate":"2000-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85180045","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}
Effects of red light (R) and far-red light (FR), and selected photon flux densities (PFD) of photosynthetically active radiation (PAR) on seed germination in the photoblastic, primary colonising species Leptospermum scoparium J. R. et G. Forst. and the late secondary successional Melicytus ramiflorus J. R. et G. Forst. were studied. A continuous R dose response curve forL. scoparium germination was developed, unifying data from experiments using long-term exposure to PAR with those following short-term exposure to R. The threshold R dose needed to effect germination was ~0.1 mmol m –2 , and the response was saturated at 1000 mmol m –2 . Stimulation of germination by R was reversed by a subsequent exposure to FR. These features are consistent with a low-fluence response mediated by phytochrome B. FR reversal of germination was achieved at a dose two orders of magnitude lower than that of R required to induce initial germination. However, when both R and FR were provided simultaneously, the FR dose needed to even partially inhibit germination (34% compared to > 95% in controls) was two orders of magnitude higher than the R dose (R:FR ratio = 0.007). Germination in L. scoparium was also stimulated in up to 12% of seed upon diurnal exposure to FR, or by green light (~2 mol m –2 ), indicating a very-low-fluence response mediated by phytochrome A also operating in this species. In contrast, seed germination in M. ramiflorus was relatively unresponsive to R, and secondary dormancy was induced by high PFD (515 mol m –2 s –1 ).
光合有效辐射(PAR)的红光(R)和远红光(FR)及选择光子通量密度(PFD)对光致生原生定殖植物细尾草种子萌发的影响。晚期次生演替Melicytus ramiflorus J. R. et G. Forst。进行了研究。l的连续R剂量响应曲线。将长期暴露于PAR和短期暴露于R的实验数据统一起来，研究了影响萌发所需R的阈值为~0.1 mmol m -2，在1000 mmol m -2时达到饱和。这些特征与光敏色素b介导的低通量反应相一致。在比诱导初始发芽所需的R低两个数量级的剂量下，光敏色素b实现了萌发的逆转。然而，当R和FR同时提供时，甚至部分抑制发芽所需的FR剂量(34%，而对照组> 95%)比R剂量高两个数量级(R:FR比= 0.007)。白天暴露于FR或绿光(~2 mol m -2)下，高达12%的L. scoparium种子的萌发也受到刺激，这表明光敏色素a介导的极低通量响应也在该物种中起作用。相比之下，支花密叶霉种子萌发对R的响应相对较弱，高PFD (515 mol m -2 s -1)诱导其二次休眠。
{"title":"Contrasting seed germination responses to red and far-red light in Leptospermum scoparium and Melicytus ramiflorus","authors":"H. Herron, J. Clemens, D. Greer","doi":"10.1071/PP00024","DOIUrl":"https://doi.org/10.1071/PP00024","url":null,"abstract":"Effects of red light (R) and far-red light (FR), and selected photon flux densities (PFD) of photosynthetically active radiation (PAR) on seed germination in the photoblastic, primary colonising species Leptospermum scoparium J. R. et G. Forst. and the late secondary successional Melicytus ramiflorus J. R. et G. Forst. were studied. A continuous R dose response curve forL. scoparium germination was developed, unifying data from experiments using long-term exposure to PAR with those following short-term exposure to R. The threshold R dose needed to effect germination was ~0.1 mmol m –2 , and the response was saturated at 1000 mmol m –2 . Stimulation of germination by R was reversed by a subsequent exposure to FR. These features are consistent with a low-fluence response mediated by phytochrome B. FR reversal of germination was achieved at a dose two orders of magnitude lower than that of R required to induce initial germination. However, when both R and FR were provided simultaneously, the FR dose needed to even partially inhibit germination (34% compared to > 95% in controls) was two orders of magnitude higher than the R dose (R:FR ratio = 0.007). Germination in L. scoparium was also stimulated in up to 12% of seed upon diurnal exposure to FR, or by green light (~2 mol m –2 ), indicating a very-low-fluence response mediated by phytochrome A also operating in this species. In contrast, seed germination in M. ramiflorus was relatively unresponsive to R, and secondary dormancy was induced by high PFD (515 mol m –2 s –1 ).","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"62 1","pages":"1069-1076"},"PeriodicalIF":0.0,"publicationDate":"2000-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84715904","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}
M. Ellis, A. Millar, D. Llewellyn, W. Peacock, E. Dennis
Cotton (Gossypium hirsutumL.) was transformed with constructs for the over-expression of two enzymes involved in ethanol fermentation, alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC), with the goal of increasing waterlogging tolerance. Four independent transgenic lines transformed with the cotton Adh2 cDNA driven by the CaMV 35S promoter showed ectopic expression of this isozyme in leaves and up to 20-fold greater in vitro ADH activity in roots. Under conditions of O2 deficiency, excised roots from these transgenic plants showed up to 80% increase in ethanol evolution compared to untransformed roots. Conversely, one line transformed with a construct containing the Adh2 coding region in the antisense orientation showed a 65% decrease in ADH activity and a 25% decrease in ethanol production from anaerobic roots relative to untransformed cotton. Lines transformed with a rice Pdc1 cDNA driven by the CaMV 35S promoter showed high levels of expression of the transgene-encoded protein in leaves, but only very low levels of protein and no in vitro enzyme activity detectable in the roots of these plants. Roots from plants transformed with the 35S-Pdc construct did not produce more ethanol than roots from untransformed controls. We tested the ability of cotton roots to withstand low O2 treatments under hydroponic conditions. Neither the ‘ADH’ nor the ‘PDC’ transgenics showed more tolerance than the wild-type on the basis of root growth under a mild stress (5% O2), a strong stress (0% O2 with or without a 5% O2 pretreatment), or in recovery growth following these treatments. Our results show that over-expression of ADH can lead to ethanol over-production (even though the activity of this enzyme by far exceeds that of PDC, its precursor in the pathway), but this is not sufficient to increase waterlogging tolerance in cotton.
{"title":"Transgenic cotton (Gossypium hirsutum) over-expressing alcohol dehydrogenase shows increased ethanol fermentation but no increase in tolerance to oxygen deficiency.","authors":"M. Ellis, A. Millar, D. Llewellyn, W. Peacock, E. Dennis","doi":"10.1071/PP00052","DOIUrl":"https://doi.org/10.1071/PP00052","url":null,"abstract":"Cotton (Gossypium hirsutumL.) was transformed with constructs for the over-expression of two enzymes involved in ethanol fermentation, alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC), with the goal of increasing waterlogging tolerance. Four independent transgenic lines transformed with the cotton Adh2 cDNA driven by the CaMV 35S promoter showed ectopic expression of this isozyme in leaves and up to 20-fold greater in vitro ADH activity in roots. Under conditions of O2 deficiency, excised roots from these transgenic plants showed up to 80% increase in ethanol evolution compared to untransformed roots. Conversely, one line transformed with a construct containing the Adh2 coding region in the antisense orientation showed a 65% decrease in ADH activity and a 25% decrease in ethanol production from anaerobic roots relative to untransformed cotton. Lines transformed with a rice Pdc1 cDNA driven by the CaMV 35S promoter showed high levels of expression of the transgene-encoded protein in leaves, but only very low levels of protein and no in vitro enzyme activity detectable in the roots of these plants. Roots from plants transformed with the 35S-Pdc construct did not produce more ethanol than roots from untransformed controls. We tested the ability of cotton roots to withstand low O2 treatments under hydroponic conditions. Neither the ‘ADH’ nor the ‘PDC’ transgenics showed more tolerance than the wild-type on the basis of root growth under a mild stress (5% O2), a strong stress (0% O2 with or without a 5% O2 pretreatment), or in recovery growth following these treatments. Our results show that over-expression of ADH can lead to ethanol over-production (even though the activity of this enzyme by far exceeds that of PDC, its precursor in the pathway), but this is not sufficient to increase waterlogging tolerance in cotton.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"54 1","pages":"1041-1050"},"PeriodicalIF":0.0,"publicationDate":"2000-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84592566","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}
At the booting stage of development, rice (Oryza sativa L.) plants were treated with chemicals that either inhibited the action or synthesis of ethylene, or produced ethylene. Inhibitors of ethylene action (AgNO3) and synthesis [uniconazole, paclobutrazol, Co(NO3)2r promoted grain filling and quality of the kernels of the basal spikelets of the panicle, while the ethylene-releasing substance CEPA (2-chloroethylphosphonic acid) depressed these characteristics further. The inhibitors depressed the concentration of ethylene of the basal primary branches, but CEPA increased it above the control during the period of grain filling. The treatments were not effective on the superior apical spikelets of the panicle. The ethylene inhibitors improved starch synthesis in the kernels of the basal spikelets, but CEPA reduced it significantly, resulting in accumulation of soluble carbohydrates in the kernels. During the period of grain filling, sucrose synthase activity was higher than that of invertase in the kernels. Activities of sucrose synthase and invertase were higher in the apical than in the basal kernel. The ethylene inhibitors increased activities of both enzymes only in the basal kernel, whereas CEPA reduced activities significantly. Together, the results indicate that starch filling and grain quality of the basally positioned under-developed rice kernels can be affected by ethylene, and that key enzymes of sucrose metabolism are also affected in the process.
{"title":"Ethylene inhibitors enhanced sucrose synthase activity and promoted grain filling of basal rice kernels","authors":"P. Naik, P. K. Mohapatra","doi":"10.1071/PP00020","DOIUrl":"https://doi.org/10.1071/PP00020","url":null,"abstract":"At the booting stage of development, rice (Oryza sativa L.) plants were treated with chemicals that either inhibited the action or synthesis of ethylene, or produced ethylene. Inhibitors of ethylene action (AgNO3) and synthesis [uniconazole, paclobutrazol, Co(NO3)2r promoted grain filling and quality of the kernels of the basal spikelets of the panicle, while the ethylene-releasing substance CEPA (2-chloroethylphosphonic acid) depressed these characteristics further. The inhibitors depressed the concentration of ethylene of the basal primary branches, but CEPA increased it above the control during the period of grain filling. The treatments were not effective on the superior apical spikelets of the panicle. The ethylene inhibitors improved starch synthesis in the kernels of the basal spikelets, but CEPA reduced it significantly, resulting in accumulation of soluble carbohydrates in the kernels. During the period of grain filling, sucrose synthase activity was higher than that of invertase in the kernels. Activities of sucrose synthase and invertase were higher in the apical than in the basal kernel. The ethylene inhibitors increased activities of both enzymes only in the basal kernel, whereas CEPA reduced activities significantly. Together, the results indicate that starch filling and grain quality of the basally positioned under-developed rice kernels can be affected by ethylene, and that key enzymes of sucrose metabolism are also affected in the process.","PeriodicalId":8650,"journal":{"name":"Australian Journal of Plant Physiology","volume":"139 1","pages":"997-1008"},"PeriodicalIF":0.0,"publicationDate":"2000-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89481077","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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