Communications in agricultural and applied biological sciences
The saddle gall midge, Haplodiplosis marginata (von Roser), has been detected in Belgium since 20... more The saddle gall midge, Haplodiplosis marginata (von Roser), has been detected in Belgium since 2010, after several decades without any reporting. It had indeed caused serious damages between 1965 and 1970. This insect is a European cereal pest whose larvae feed on stems and engender saddle-shaped depressions, resulting in yield losses. Face with the resurgence of this pest, it was decided to study its spatial distribution and, because serious damages were observed in some regions, to develop effective curative control. To date, chemical protection seems to be the only immediate solution in case of heavy emergences. Experimentation was conducted in a highly infested field (Meetkerke, Belgian Polders), according to a randomized complete blocks arrangement with four replications. Foremost, a lambdacyhalothrin-based insecticide was used to evaluate efficiency of several protection schemes, ranging between one and four spray(s). The large spread of flights observed during the 2011 spring allowed to highlight the effect of treatment date on the attack intensity and also on the galls distribution along the stem, on the different internodes: the lower internodes were protected by the early sprayings, while last sprayings induced reduction of galls number on the upper internodes. Moreover, several insecticides already registrated in cereals against aphids were compared for their efficacy against saddle gall midge. Studied pyrethroids have shown a very good efficacy, ranging between 75% and 87%, when applied twice with a 2 weeks interval. To be efficient, insecticide applications must thus be synchronized with the flights and egg-laying periods. Monitoring the phenology of flights is thus essential as part of integrated pest management against saddle gall midge.
The use of Visible/Near Infrared (Vis/NIR) spectroscopy has been evaluated to determine the optim... more The use of Visible/Near Infrared (Vis/NIR) spectroscopy has been evaluated to determine the optimal harvesting date of chicory roots. Indirect maturity parameters, such as the foliage chlorophyll content, root dry matter, sugar and nitrogen content, were measured for two hybrids during the field growing season. The root harvest date, which resulted in the highest percentage of top quality chicory heads after forcing, was chosen as the optimal harvest date. A principal component analysis indicated the presence of both a time and hybrid effect. Partial least square models were constructed to predict the indirect maturity parameters and the number of days before optimal root harvest. Correlations for cross validation between 0.75 and 0.81 were obtained for the prediction of foliage chlorophyll content. For the first time, leaf spectra were used to predict chicory root characteristics with success: root dry matter percentage had a cross validation correlation of 0.81 for the 'Mont Blanc' and 0.88 for the 'Vintor' hybrids. The prediction of root sugar and nitrogen content was poor (cross validation correlation of 0.62 and 0.74). Predicting the number of days before optimal root harvest was done reasonably accurately, with prediction errors of 8.86 d and 10.61 d for 'Mont Blanc' and 'Vintor', respectively. The visual part of the spectrum is not required in these calibration models. Data of more years and hybrids should be taken into account to make the models more robust and applicable for farmer practice.
Aechmea victoriana var discolor L. B. Foster and Aechmea dactylina Bal. are commercially propagat... more Aechmea victoriana var discolor L. B. Foster and Aechmea dactylina Bal. are commercially propagated in vitro through lateral shoot growth. A modified Murashige and Skoog medium is used which contains both BA and IAA. These growth substances were shown in the present study to synergistically stimulate the production of ethylene by the cultured plants. The stimulation of ethylene production is correlated with the outgrowth of the lateral buds. The rise in ethylene production was concluded to induce lateral shoot growth, because: (a) outgrowth of the shoots was blocked by preventing an increase in ethylene production, (b) 1-aminocyclopropane-1-carboxylic acid (ACC), the natural precursor of ethylene biosynthesis, substituted for IAA in the promotion of ethylene production and lateral bud outgrowth. Although ACC could substitute for IAA, it could not substitute for BA; therefore, cytokinins are concluded to be essential for lateral bud outgrowth in vitro in Aechmea. These results sugges...
With semi in vivo pollen tube growth assays, stigmas are pollinated in vivo and, after a fixed ti... more With semi in vivo pollen tube growth assays, stigmas are pollinated in vivo and, after a fixed time interval, the styles are isolated from the ovary and placed on culture medium in vitro. Semi in vitro pollination includes isolation of the stigma and style complex, followed by pollination and placing the stylar end on nutrient medium. After semi in vivo
The effect of cut style and placental pollination on fertilization efficiency was studied for com... more The effect of cut style and placental pollination on fertilization efficiency was studied for compatible Aechmea fasciata plants. These alternative in vitro pollination techniques resulted in lower penetration rates of the ovules by pollen tubes in comparison to pollination on the stigma. An explanation was found in the intervention of the normal pollination process,through which less pollen-pistil interactions were built
† Background and Aims The deployment of temporally separated carboxylation pathways for net CO 2 ... more † Background and Aims The deployment of temporally separated carboxylation pathways for net CO 2 uptake in CAM plants provides plasticity and thus uncertainty on how species with this photosynthetic pathway will respond to life in a higher-CO 2 world. The present study examined how long-term exposure to elevated CO 2 influences the relative contributions that C 3 and C 4 carboxylation make to net carbon gain and to establish how this impacts on the availability of carbohydrates for export and growth and on water use efficiency over the day/night cycle. † Methods Integrated measurements of leaf gas exchange and diel metabolite dynamics (e.g. malate, soluble sugars, starch) were made in leaves of the CAM bromeliad Aechmea 'Maya' after exposure to 700 mmol mol 21 CO 2 for 5 months. † Key Results There was a 60 % increase in 24-h carbon gain under elevated CO 2 due to a stimulation of daytime C 3 and C 4 carboxylation in phases II and IV where water use efficiency was comparable with that measured at night. The extra CO 2 taken up under elevated CO 2 was largely accumulated as hexose sugars during phase IV and net daytime export of carbohydrate was abolished. Under elevated CO 2 there was no stimulation of dark carboxylation and nocturnal export and respiration appeared to be the stronger sinks for carbohydrate. † Conclusions Despite the increased size of the soluble sugar storage pool under elevated CO 2 , there was no change in the net allocation of carbohydrates between provision of substrates for CAM and export/respiration in A. 'Maya'. The data imply the existence of discrete pools of carbohydrate that provide substrate for CAM or sugars for export/ respiration. The 2-fold increase in water-use efficiency could be a major physiological advantage to growth under elevated CO 2 in this CAM bromeliad.
Aims Photosynthetic plasticity in response to a range of environmental factors that include [CO 2... more Aims Photosynthetic plasticity in response to a range of environmental factors that include [CO 2 ], water availability, light intensity and temperature, is ubiquitous among plants with crassulacean acid metabolism (CAM). The present study examined how seasonal changes in light availability, as experienced by greenhouse CAM crops in northern latitude regions, influence diel carboxylation patterns and impact on carbon gain and seasonal accumulation of biomass. † Methods In the CAM bromeliad Aechmea 'Maya' integrated measurements of leaf gas exchange, diel metabolite dynamics (e.g. malate, soluble sugars and starch) and biomass accumulation were made four times a year, i.e. in winter, spring, summer and autumn. † Key Results During the brighter seasons (spring and summer) daytime Phases II and IV were dominated by C 4 carboxylation, whilst the higher diurnal uptake in the autumn and winter was characterized by equal contributions of both Rubisco and PEPC. As a consequence, net CO 2 uptake showed a significant depression at the end of the day in the darker months when supplementary illumination was turned off. Remarkable seasonal consistency was found in the amount of storage reserves available for nocturnal carboxylation, a consequence of predominantly daytime export of carbohydrate in spring and summer whilst nocturnal export was the major sink for carbohydrate in autumn and winter. † Conclusions Throughout the different seasons Aechmea 'Maya' showed considerable plasticity in the timing and magnitude of C 3 and C 4 carboxylation processes over the diel cycle. Under low PPFD (i.e. winter and autumn) it appears that there was a constraint on the amount of carbohydrate exported during the day in order to maintain a consistent pool of transient carbohydrate reserves. This gave remarkable seasonal consistency in the amount of storage reserves available at night, thereby optimizing biomass gain throughout the year. The data have important practical consequences for horticultural productivity of CAM plants and suggest a scenario for reconciling carbohydrate partitioning between competing sinks of nocturnal acidification and export for growth.
... In vitro germination test At anthesis flowers were collected from the green-house between 8.0... more ... In vitro germination test At anthesis flowers were collected from the green-house between 8.00 and 12.00 pm in eppendorf tubes with 1 ml of liquid pollen germination medium (a 20% sucrose solution with 0.001% H3BO3). ...
To cryopreserve sugar beet shoot tips using an encapsulation-dehydration technique, cold hardenin... more To cryopreserve sugar beet shoot tips using an encapsulation-dehydration technique, cold hardening of in vitro plants was needed to obtain high survival rates after freezing. Cold acclimation not only enhanced dehydration and freezing tolerance, but also induced several changes in sugar beet shoots. Plants contained greater amounts of sucrose, D-glucose and D-fructose and the fatty acid composition of lipids changed. Furthermore, the unsaturation level of membrane lipids, estimated by the (C18:2 + C18:1)/C16:0 ratio, increased after cold hardening. These changes were correlated with better survival rates after cryopreservation.
Thigmomorphogenesis is a well-studied process in agricultural crops and coniferous trees. Neverth... more Thigmomorphogenesis is a well-studied process in agricultural crops and coniferous trees. Nevertheless, the effects on both shoot and root characteristics for deciduous woody species received little attention so far. In this study, the objective was to understand the effect of aboveground flexing treatments on the development of structural, mechanical and physiological root and shoot
Aims Photosynthetic plasticity in response to a range of environmental factors that include [CO 2... more Aims Photosynthetic plasticity in response to a range of environmental factors that include [CO 2 ], water availability, light intensity and temperature, is ubiquitous among plants with crassulacean acid metabolism (CAM). The present study examined how seasonal changes in light availability, as experienced by greenhouse CAM crops in northern latitude regions, influence diel carboxylation patterns and impact on carbon gain and seasonal accumulation of biomass. † Methods In the CAM bromeliad Aechmea 'Maya' integrated measurements of leaf gas exchange, diel metabolite dynamics (e.g. malate, soluble sugars and starch) and biomass accumulation were made four times a year, i.e. in winter, spring, summer and autumn. † Key Results During the brighter seasons (spring and summer) daytime Phases II and IV were dominated by C 4 carboxylation, whilst the higher diurnal uptake in the autumn and winter was characterized by equal contributions of both Rubisco and PEPC. As a consequence, net CO 2 uptake showed a significant depression at the end of the day in the darker months when supplementary illumination was turned off. Remarkable seasonal consistency was found in the amount of storage reserves available for nocturnal carboxylation, a consequence of predominantly daytime export of carbohydrate in spring and summer whilst nocturnal export was the major sink for carbohydrate in autumn and winter. † Conclusions Throughout the different seasons Aechmea 'Maya' showed considerable plasticity in the timing and magnitude of C 3 and C 4 carboxylation processes over the diel cycle. Under low PPFD (i.e. winter and autumn) it appears that there was a constraint on the amount of carbohydrate exported during the day in order to maintain a consistent pool of transient carbohydrate reserves. This gave remarkable seasonal consistency in the amount of storage reserves available at night, thereby optimizing biomass gain throughout the year. The data have important practical consequences for horticultural productivity of CAM plants and suggest a scenario for reconciling carbohydrate partitioning between competing sinks of nocturnal acidification and export for growth.
Three ornamental bromeliads, i.e. Aechmea ‘Maya’ (CAM), Aechmea fasciata ‘Primera’ (CAM) and Guzm... more Three ornamental bromeliads, i.e. Aechmea ‘Maya’ (CAM), Aechmea fasciata ‘Primera’ (CAM) and Guzmania ‘Hilda’ (C3) were grown under greenhouse conditions at ambient (380ppm) and elevated (750ppm) CO2. The effects of long-term exposure (34 weeks) to elevated CO2 on growth and morphological traits constituting the ornamental value were assessed.Aechmea ‘Maya’ and A. fasciata ‘Primera’ showed a different growth response to elevated
... Differences in crunchiness can be attributed to the choice of hybrid, the place of origin of ... more ... Differences in crunchiness can be attributed to the choice of hybrid, the place of origin of the roots and the effect of nitrogen or calcium additions ( [Huett and Dettmann, 1988] , [Poulsen et al., 1994] and [Newman et al., 2005] ). ...
of the type of storage carbohydrate used to generate substrate for PEPC, the availability of carb... more of the type of storage carbohydrate used to generate substrate for PEPC, the availability of carbohydrate is considered to be a major limiting factor for dark CO 2 uptake and hence the expression of CAM. 4,5 Moreover the investment of resources into storage carbohydrates implies unavoidable restriction of carbohydrate partitioning to other metabolic activities, including dark respiration, growth and acclimation to abiotic stress. However, several reports relating to biomass productivity 6-8 suggest that CAM plants possess metabolic strategies that can adjust these potential conflicts of interest under different environmental scenarios and thereby optimize biomass accumulation under potentially limiting environments. The complex network of carbohydrate relations in CAM and their interplay with the environment has received relatively little coverage. Therefore, the aim of the work of Ceusters et al. 11 was to gain insight into the partitioning of carbohydrates between competing sinks such as PEP production, dark respiration, production of osmoprotectants and growth wile maintaining photosynthetic integrity and a positive carbon balance under conditions of water deprivation and during recovery from dehydration.
Background: The foundations for ethylene research were laid many years ago by researchers such as... more Background: The foundations for ethylene research were laid many years ago by researchers such as Lizada, Yang and Hoffman. Nowadays, most of the methods developed by them are still being used. Technological developments since then have led to small but significant improvements, contributing to a more efficient workflow. Despite this, many of these improvements have never been properly documented. Results: This article provides an updated, integrated set of protocols suitable for the assembly of a complete picture of ethylene biosynthesis, including the measurement of ethylene itself. The original protocols for the metabolites 1-aminocyclopropane-1-carboxylic acid and 1-(malonylamino)cyclopropane-1-carboxylic acid have been updated and downscaled, while protocols to determine in vitro activities of the key enzymes 1-aminocyclopropane-1-carboxylate synthase and 1-aminocyclopropane-1-carboxylate oxidase have been optimised for efficiency, repeatability and accuracy. All the protocols described were optimised for apple fruit, but have been proven to be suitable for the analysis of tomato fruit as well. Conclusions: This work collates an integrated set of detailed protocols for the measurement of components of the ethylene biosynthetic pathway, starting from well-established methods. These protocols have been optimised for smaller sample volumes, increased efficiency, repeatability and accuracy. The detailed protocol allows other scientists to rapidly implement these methods in their own laboratories in a consistent and efficient way.
It has been previously shown that shoot tips of in vitro plantlets of sugar beet (Beta vulgaris L... more It has been previously shown that shoot tips of in vitro plantlets of sugar beet (Beta vulgaris L. clone SES1) can be cryopreserved using the encapsulation-dehydration technique (survival rate of 37% after freezing). This article reports the influence of abscisic acid (ABA) and cold acclimation on survival after cryopreservation. When ABA was added to the multiplication medium of the plants, the survival rate of shoot tips after cryopreservation was not increased (45%). After cold acclimation of the plants, their growth pattern differed (plants became apically dominant) and the survival rate of the shoot tips after cryopreservation clearly increased (70% survival and 50% plant regeneration after freezing). This improved protocol was successfully applied to three other clones.
Communications in agricultural and applied biological sciences
The saddle gall midge, Haplodiplosis marginata (von Roser), has been detected in Belgium since 20... more The saddle gall midge, Haplodiplosis marginata (von Roser), has been detected in Belgium since 2010, after several decades without any reporting. It had indeed caused serious damages between 1965 and 1970. This insect is a European cereal pest whose larvae feed on stems and engender saddle-shaped depressions, resulting in yield losses. Face with the resurgence of this pest, it was decided to study its spatial distribution and, because serious damages were observed in some regions, to develop effective curative control. To date, chemical protection seems to be the only immediate solution in case of heavy emergences. Experimentation was conducted in a highly infested field (Meetkerke, Belgian Polders), according to a randomized complete blocks arrangement with four replications. Foremost, a lambdacyhalothrin-based insecticide was used to evaluate efficiency of several protection schemes, ranging between one and four spray(s). The large spread of flights observed during the 2011 spring allowed to highlight the effect of treatment date on the attack intensity and also on the galls distribution along the stem, on the different internodes: the lower internodes were protected by the early sprayings, while last sprayings induced reduction of galls number on the upper internodes. Moreover, several insecticides already registrated in cereals against aphids were compared for their efficacy against saddle gall midge. Studied pyrethroids have shown a very good efficacy, ranging between 75% and 87%, when applied twice with a 2 weeks interval. To be efficient, insecticide applications must thus be synchronized with the flights and egg-laying periods. Monitoring the phenology of flights is thus essential as part of integrated pest management against saddle gall midge.
The use of Visible/Near Infrared (Vis/NIR) spectroscopy has been evaluated to determine the optim... more The use of Visible/Near Infrared (Vis/NIR) spectroscopy has been evaluated to determine the optimal harvesting date of chicory roots. Indirect maturity parameters, such as the foliage chlorophyll content, root dry matter, sugar and nitrogen content, were measured for two hybrids during the field growing season. The root harvest date, which resulted in the highest percentage of top quality chicory heads after forcing, was chosen as the optimal harvest date. A principal component analysis indicated the presence of both a time and hybrid effect. Partial least square models were constructed to predict the indirect maturity parameters and the number of days before optimal root harvest. Correlations for cross validation between 0.75 and 0.81 were obtained for the prediction of foliage chlorophyll content. For the first time, leaf spectra were used to predict chicory root characteristics with success: root dry matter percentage had a cross validation correlation of 0.81 for the 'Mont Blanc' and 0.88 for the 'Vintor' hybrids. The prediction of root sugar and nitrogen content was poor (cross validation correlation of 0.62 and 0.74). Predicting the number of days before optimal root harvest was done reasonably accurately, with prediction errors of 8.86 d and 10.61 d for 'Mont Blanc' and 'Vintor', respectively. The visual part of the spectrum is not required in these calibration models. Data of more years and hybrids should be taken into account to make the models more robust and applicable for farmer practice.
Aechmea victoriana var discolor L. B. Foster and Aechmea dactylina Bal. are commercially propagat... more Aechmea victoriana var discolor L. B. Foster and Aechmea dactylina Bal. are commercially propagated in vitro through lateral shoot growth. A modified Murashige and Skoog medium is used which contains both BA and IAA. These growth substances were shown in the present study to synergistically stimulate the production of ethylene by the cultured plants. The stimulation of ethylene production is correlated with the outgrowth of the lateral buds. The rise in ethylene production was concluded to induce lateral shoot growth, because: (a) outgrowth of the shoots was blocked by preventing an increase in ethylene production, (b) 1-aminocyclopropane-1-carboxylic acid (ACC), the natural precursor of ethylene biosynthesis, substituted for IAA in the promotion of ethylene production and lateral bud outgrowth. Although ACC could substitute for IAA, it could not substitute for BA; therefore, cytokinins are concluded to be essential for lateral bud outgrowth in vitro in Aechmea. These results sugges...
With semi in vivo pollen tube growth assays, stigmas are pollinated in vivo and, after a fixed ti... more With semi in vivo pollen tube growth assays, stigmas are pollinated in vivo and, after a fixed time interval, the styles are isolated from the ovary and placed on culture medium in vitro. Semi in vitro pollination includes isolation of the stigma and style complex, followed by pollination and placing the stylar end on nutrient medium. After semi in vivo
The effect of cut style and placental pollination on fertilization efficiency was studied for com... more The effect of cut style and placental pollination on fertilization efficiency was studied for compatible Aechmea fasciata plants. These alternative in vitro pollination techniques resulted in lower penetration rates of the ovules by pollen tubes in comparison to pollination on the stigma. An explanation was found in the intervention of the normal pollination process,through which less pollen-pistil interactions were built
† Background and Aims The deployment of temporally separated carboxylation pathways for net CO 2 ... more † Background and Aims The deployment of temporally separated carboxylation pathways for net CO 2 uptake in CAM plants provides plasticity and thus uncertainty on how species with this photosynthetic pathway will respond to life in a higher-CO 2 world. The present study examined how long-term exposure to elevated CO 2 influences the relative contributions that C 3 and C 4 carboxylation make to net carbon gain and to establish how this impacts on the availability of carbohydrates for export and growth and on water use efficiency over the day/night cycle. † Methods Integrated measurements of leaf gas exchange and diel metabolite dynamics (e.g. malate, soluble sugars, starch) were made in leaves of the CAM bromeliad Aechmea 'Maya' after exposure to 700 mmol mol 21 CO 2 for 5 months. † Key Results There was a 60 % increase in 24-h carbon gain under elevated CO 2 due to a stimulation of daytime C 3 and C 4 carboxylation in phases II and IV where water use efficiency was comparable with that measured at night. The extra CO 2 taken up under elevated CO 2 was largely accumulated as hexose sugars during phase IV and net daytime export of carbohydrate was abolished. Under elevated CO 2 there was no stimulation of dark carboxylation and nocturnal export and respiration appeared to be the stronger sinks for carbohydrate. † Conclusions Despite the increased size of the soluble sugar storage pool under elevated CO 2 , there was no change in the net allocation of carbohydrates between provision of substrates for CAM and export/respiration in A. 'Maya'. The data imply the existence of discrete pools of carbohydrate that provide substrate for CAM or sugars for export/ respiration. The 2-fold increase in water-use efficiency could be a major physiological advantage to growth under elevated CO 2 in this CAM bromeliad.
Aims Photosynthetic plasticity in response to a range of environmental factors that include [CO 2... more Aims Photosynthetic plasticity in response to a range of environmental factors that include [CO 2 ], water availability, light intensity and temperature, is ubiquitous among plants with crassulacean acid metabolism (CAM). The present study examined how seasonal changes in light availability, as experienced by greenhouse CAM crops in northern latitude regions, influence diel carboxylation patterns and impact on carbon gain and seasonal accumulation of biomass. † Methods In the CAM bromeliad Aechmea 'Maya' integrated measurements of leaf gas exchange, diel metabolite dynamics (e.g. malate, soluble sugars and starch) and biomass accumulation were made four times a year, i.e. in winter, spring, summer and autumn. † Key Results During the brighter seasons (spring and summer) daytime Phases II and IV were dominated by C 4 carboxylation, whilst the higher diurnal uptake in the autumn and winter was characterized by equal contributions of both Rubisco and PEPC. As a consequence, net CO 2 uptake showed a significant depression at the end of the day in the darker months when supplementary illumination was turned off. Remarkable seasonal consistency was found in the amount of storage reserves available for nocturnal carboxylation, a consequence of predominantly daytime export of carbohydrate in spring and summer whilst nocturnal export was the major sink for carbohydrate in autumn and winter. † Conclusions Throughout the different seasons Aechmea 'Maya' showed considerable plasticity in the timing and magnitude of C 3 and C 4 carboxylation processes over the diel cycle. Under low PPFD (i.e. winter and autumn) it appears that there was a constraint on the amount of carbohydrate exported during the day in order to maintain a consistent pool of transient carbohydrate reserves. This gave remarkable seasonal consistency in the amount of storage reserves available at night, thereby optimizing biomass gain throughout the year. The data have important practical consequences for horticultural productivity of CAM plants and suggest a scenario for reconciling carbohydrate partitioning between competing sinks of nocturnal acidification and export for growth.
... In vitro germination test At anthesis flowers were collected from the green-house between 8.0... more ... In vitro germination test At anthesis flowers were collected from the green-house between 8.00 and 12.00 pm in eppendorf tubes with 1 ml of liquid pollen germination medium (a 20% sucrose solution with 0.001% H3BO3). ...
To cryopreserve sugar beet shoot tips using an encapsulation-dehydration technique, cold hardenin... more To cryopreserve sugar beet shoot tips using an encapsulation-dehydration technique, cold hardening of in vitro plants was needed to obtain high survival rates after freezing. Cold acclimation not only enhanced dehydration and freezing tolerance, but also induced several changes in sugar beet shoots. Plants contained greater amounts of sucrose, D-glucose and D-fructose and the fatty acid composition of lipids changed. Furthermore, the unsaturation level of membrane lipids, estimated by the (C18:2 + C18:1)/C16:0 ratio, increased after cold hardening. These changes were correlated with better survival rates after cryopreservation.
Thigmomorphogenesis is a well-studied process in agricultural crops and coniferous trees. Neverth... more Thigmomorphogenesis is a well-studied process in agricultural crops and coniferous trees. Nevertheless, the effects on both shoot and root characteristics for deciduous woody species received little attention so far. In this study, the objective was to understand the effect of aboveground flexing treatments on the development of structural, mechanical and physiological root and shoot
Aims Photosynthetic plasticity in response to a range of environmental factors that include [CO 2... more Aims Photosynthetic plasticity in response to a range of environmental factors that include [CO 2 ], water availability, light intensity and temperature, is ubiquitous among plants with crassulacean acid metabolism (CAM). The present study examined how seasonal changes in light availability, as experienced by greenhouse CAM crops in northern latitude regions, influence diel carboxylation patterns and impact on carbon gain and seasonal accumulation of biomass. † Methods In the CAM bromeliad Aechmea 'Maya' integrated measurements of leaf gas exchange, diel metabolite dynamics (e.g. malate, soluble sugars and starch) and biomass accumulation were made four times a year, i.e. in winter, spring, summer and autumn. † Key Results During the brighter seasons (spring and summer) daytime Phases II and IV were dominated by C 4 carboxylation, whilst the higher diurnal uptake in the autumn and winter was characterized by equal contributions of both Rubisco and PEPC. As a consequence, net CO 2 uptake showed a significant depression at the end of the day in the darker months when supplementary illumination was turned off. Remarkable seasonal consistency was found in the amount of storage reserves available for nocturnal carboxylation, a consequence of predominantly daytime export of carbohydrate in spring and summer whilst nocturnal export was the major sink for carbohydrate in autumn and winter. † Conclusions Throughout the different seasons Aechmea 'Maya' showed considerable plasticity in the timing and magnitude of C 3 and C 4 carboxylation processes over the diel cycle. Under low PPFD (i.e. winter and autumn) it appears that there was a constraint on the amount of carbohydrate exported during the day in order to maintain a consistent pool of transient carbohydrate reserves. This gave remarkable seasonal consistency in the amount of storage reserves available at night, thereby optimizing biomass gain throughout the year. The data have important practical consequences for horticultural productivity of CAM plants and suggest a scenario for reconciling carbohydrate partitioning between competing sinks of nocturnal acidification and export for growth.
Three ornamental bromeliads, i.e. Aechmea ‘Maya’ (CAM), Aechmea fasciata ‘Primera’ (CAM) and Guzm... more Three ornamental bromeliads, i.e. Aechmea ‘Maya’ (CAM), Aechmea fasciata ‘Primera’ (CAM) and Guzmania ‘Hilda’ (C3) were grown under greenhouse conditions at ambient (380ppm) and elevated (750ppm) CO2. The effects of long-term exposure (34 weeks) to elevated CO2 on growth and morphological traits constituting the ornamental value were assessed.Aechmea ‘Maya’ and A. fasciata ‘Primera’ showed a different growth response to elevated
... Differences in crunchiness can be attributed to the choice of hybrid, the place of origin of ... more ... Differences in crunchiness can be attributed to the choice of hybrid, the place of origin of the roots and the effect of nitrogen or calcium additions ( [Huett and Dettmann, 1988] , [Poulsen et al., 1994] and [Newman et al., 2005] ). ...
of the type of storage carbohydrate used to generate substrate for PEPC, the availability of carb... more of the type of storage carbohydrate used to generate substrate for PEPC, the availability of carbohydrate is considered to be a major limiting factor for dark CO 2 uptake and hence the expression of CAM. 4,5 Moreover the investment of resources into storage carbohydrates implies unavoidable restriction of carbohydrate partitioning to other metabolic activities, including dark respiration, growth and acclimation to abiotic stress. However, several reports relating to biomass productivity 6-8 suggest that CAM plants possess metabolic strategies that can adjust these potential conflicts of interest under different environmental scenarios and thereby optimize biomass accumulation under potentially limiting environments. The complex network of carbohydrate relations in CAM and their interplay with the environment has received relatively little coverage. Therefore, the aim of the work of Ceusters et al. 11 was to gain insight into the partitioning of carbohydrates between competing sinks such as PEP production, dark respiration, production of osmoprotectants and growth wile maintaining photosynthetic integrity and a positive carbon balance under conditions of water deprivation and during recovery from dehydration.
Background: The foundations for ethylene research were laid many years ago by researchers such as... more Background: The foundations for ethylene research were laid many years ago by researchers such as Lizada, Yang and Hoffman. Nowadays, most of the methods developed by them are still being used. Technological developments since then have led to small but significant improvements, contributing to a more efficient workflow. Despite this, many of these improvements have never been properly documented. Results: This article provides an updated, integrated set of protocols suitable for the assembly of a complete picture of ethylene biosynthesis, including the measurement of ethylene itself. The original protocols for the metabolites 1-aminocyclopropane-1-carboxylic acid and 1-(malonylamino)cyclopropane-1-carboxylic acid have been updated and downscaled, while protocols to determine in vitro activities of the key enzymes 1-aminocyclopropane-1-carboxylate synthase and 1-aminocyclopropane-1-carboxylate oxidase have been optimised for efficiency, repeatability and accuracy. All the protocols described were optimised for apple fruit, but have been proven to be suitable for the analysis of tomato fruit as well. Conclusions: This work collates an integrated set of detailed protocols for the measurement of components of the ethylene biosynthetic pathway, starting from well-established methods. These protocols have been optimised for smaller sample volumes, increased efficiency, repeatability and accuracy. The detailed protocol allows other scientists to rapidly implement these methods in their own laboratories in a consistent and efficient way.
It has been previously shown that shoot tips of in vitro plantlets of sugar beet (Beta vulgaris L... more It has been previously shown that shoot tips of in vitro plantlets of sugar beet (Beta vulgaris L. clone SES1) can be cryopreserved using the encapsulation-dehydration technique (survival rate of 37% after freezing). This article reports the influence of abscisic acid (ABA) and cold acclimation on survival after cryopreservation. When ABA was added to the multiplication medium of the plants, the survival rate of shoot tips after cryopreservation was not increased (45%). After cold acclimation of the plants, their growth pattern differed (plants became apically dominant) and the survival rate of the shoot tips after cryopreservation clearly increased (70% survival and 50% plant regeneration after freezing). This improved protocol was successfully applied to three other clones.
Uploads
Papers by Maurice Proft