Fertilizer boron (B) and molybdenum (Mo) were provided to contrasting cultivars of subirrigated p... more Fertilizer boron (B) and molybdenum (Mo) were provided to contrasting cultivars of subirrigated pot chrysanthemums at approximately 6–100% of current industry standards in an otherwise balanced nutrient solution during vegetative growth, and then all nutrients were removed during reproductive growth. Two experiments were conducted for each nutrient in a naturally lit greenhouse using a randomized complete block split-plot design. Boron (0.313–5.00 µmol L−1) or Mo (0.031–0.500 µmol L−1) was the main plot, and cultivar was the sub-plot. Petal quilling was observed with leaf-B of 11.3–19.4 mg kg−1 dry mass (DM), whereas Mo deficiency was not observed with leaf-Mo of 1.0–3.7 mg kg−1 DM. Optimized supplies resulted in leaf tissue levels of 48.8–72.5 mg B kg−1 DM and 1.9–4.8 mg Mo kg−1 DM. Boron uptake efficiency was more important than B utilization efficiency in sustaining plant/inflorescence growth with decreasing B supply, whereas Mo uptake and utilization efficiencies appeared to hav...
Moderate levels of zinc (3.50, 1.75 or 0.875 μmol·L−1 Zn) or copper (0.75, 0.38 or 0.19 μmol·L−1 ... more Moderate levels of zinc (3.50, 1.75 or 0.875 μmol·L−1 Zn) or copper (0.75, 0.38 or 0.19 μmol·L−1 Cu), in combination with a complete suite of other essential nutrients, were supplied up to flower bud break only, to two cultivars of subirrigated, potted, pinched chrysanthemums. Market-quality plants were produced with sufficient leaf-zinc or leaf-copper even though the delivery of the respective nutrient could be reduced by 75% compared with an industry standard. These results are interpreted as evidence for improved uptake efficiency with decreasing Zn or Cu delivery. Our modified delivery practice could contribute to low-input production of floricultural crops.
Postharvest deterioration can result in qualitative and quantitative changes in the marketability... more Postharvest deterioration can result in qualitative and quantitative changes in the marketability of horticultural commodities, as well as considerable economic loss to the industry. Low temperature and controlled atmosphere conditions (low O2 and elevated CO2) are extensively employed to prolong the postharvest life of these commodities. Nevertheless, they may suffer from chilling injury and other physiological disorders, as well as excessive water loss and bacterial/fungal decay. Research on the postharvest physiological, biochemical, and molecular responses of horticultural commodities indicates that low temperature/controlled atmosphere storage is associated with the promotion of γ-aminobutyrate (GABA) pathway activity, with or without the accumulation of GABA, delaying senescence, preserving quality and ameliorating chilling injury. Regardless of whether apple fruits are stored under low temperature/controlled atmosphere conditions or room temperature, elevated endogenous GABA ...
Polyamines (PAs) are ubiquitous aliphatic amines that play important roles in growth, development... more Polyamines (PAs) are ubiquitous aliphatic amines that play important roles in growth, development, and environmental stress responses in plants. In this study, we report that exogenous application of spermine (Spm) is effective in the induction of resistance to gray mold disease, which is caused by the necrotrophic fungal pathogen Botrytis cinerea, on tomato (Solanum lycopersicum), bean (Phaseolus vulgaris), and Arabidopsis thaliana. High throughput transcriptome analysis revealed a priming role for the Spm molecule in the genus Arabidopsis, resulting in strong upregulation of several important defense-associated genes, particularly those involved in systemic-acquired resistance. Microscopic analysis confirmed that Spm application potentiates endogenous defense responses in tomato leaves through the generation of reactive oxygen species and the hypersensitive response, which effectively contained B. cinerea growth within the inoculated area. Moreover, co-application of Spm and salic...
Academic scientists face an unpredictable path from plant biology research to real-life applicati... more Academic scientists face an unpredictable path from plant biology research to real-life application. Fundamental studies of γ-aminobutyrate and carotenoid metabolism, control of Botrytis infection, and the uptake and distribution of mineral nutrients illustrate that most academic research in plant biology could lead to innovative solutions for food, agriculture, and the environment. The time to application depends on various factors such as the fundamental nature of the scientific questions, the development of enabling technologies, the research priorities of funding agencies, the existence of competitive research, the willingness of researchers to become engaged in commercial activities, and ultimately the insight and creativity of the researchers. Applied research is likely to be adopted more rapidly by industry than basic research, so academic scientists engaged in basic research are less likely to participate in science commercialization. It is argued that the merit of Discovery...
Greenhouse floriculture operations pose significant environmental risk due to extensive inputs of... more Greenhouse floriculture operations pose significant environmental risk due to extensive inputs of fertilizer, especially nitrogen and phosphorus (P). Recent evidence shows that the use efficiency for nitrogen or sulphur is markedly improved in subirrigated potted chrysanthemums (Chrysanthemum morifolium Ramat.) by supplying a moderate level of the nutrient during vegetative growth, and removing the entire nutrient suite at the onset of reproductive growth, without adverse effects on plant quality. Here, two split-plot experiments were conducted with subirrigated, potted, disbudded chrysanthemums grown in a peat:perlite mixture under greenhouse conditions (high- or low-ambient light) with inorganic orthophosphate (Pi) treatment (2.6 mmol L−1 Pi supplied during the vegetative and reproductive stages, and 2.6, 1.95, or 1.3 mmol L−1 Pi supplied during the vegetative stage only) as the main plot and cultivar (‘Olympia’ and ‘Covington’) as the subplot. Market quality plants with sufficien...
Polyamines represent a potential source of 4-aminobutyrate (GABA) in plants exposed to abiotic st... more Polyamines represent a potential source of 4-aminobutyrate (GABA) in plants exposed to abiotic stress. Terminal catabolism of putrescine in Arabidopsis thaliana involves amine oxidase and the production of 4-aminobutanal, which is a substrate for NAD+-dependent aminoaldehyde dehydrogenase (AMADH). Here, two AMADH homologs were chosen (AtALDH10A8 and AtALDH10A9) as candidates for encoding 4-aminobutanal dehydrogenase activity for GABA synthesis. The two genes were cloned and soluble recombinant proteins were produced in Escherichia coli. The pH optima for activity and catalytic efficiency of recombinant AtALDH10A8 with 3-aminopropanal as substrate was 10.5 and 8.5, respectively, whereas the optima for AtALDH10A9 were approximately 9.5. Maximal activity and catalytic efficiency were obtained with NAD+ and 3-aminopropanal, followed by 4-aminobutanal; negligible activity was obtained with betaine aldehyde. NAD+ reduction was accompanied by the production of GABA and β-alanine, respectiv...
1-Methylcyclopropene (1-MCP) delays ethylene-meditated ripening of apple (Malus domestica Borkh.)... more 1-Methylcyclopropene (1-MCP) delays ethylene-meditated ripening of apple (Malus domestica Borkh.) fruit during controlled atmosphere (CA) storage. Here, we tested the hypothesis that 1-MCP and CA storage enhances the levels of polyamines (PAs) and 4-aminobutyrate (GABA) in apple fruit. A 46-week experiment was conducted with "Empire" apple using a split-plot design with four treatment replicates and 3°C, 2.5 kPa O2, and 0.03 or 2.5 kPa CO2 with or without 1 μL L(-1) 1-MCP. Total PA levels were not elevated by the 1-MCP treatment. Examination of the individual PAs revealed that: (i) total putrescine levels tended to be lower with 1-MCP regardless of the CO2 level, and while this was mostly at the expense of free putrescine, large transient increases in soluble conjugated putrescine were also evident; (ii) total spermidine levels tended to be lower with 1-MCP, particularly at 2.5 kPa CO2, and this was mostly at the expense of soluble conjugated spermidine; (iii) total spermi...
Background The ubiquitous, non-proteinaceous amino acid GABA (γ-aminobutyrate) accumulates in pla... more Background The ubiquitous, non-proteinaceous amino acid GABA (γ-aminobutyrate) accumulates in plants subjected to abiotic stresses such as chilling, O2 deficiency and elevated CO2. Recent evidence indicates that controlled atmosphere storage causes the accumulation of GABA in apple (Malus x domestica Borkh.) fruit, and now there is increasing interest in the biochemical mechanisms responsible for this phenomenon. Here, we investigated whether this phenomenon could be mediated via Ca2+/calmodulin (CaM) activation of glutamate decarboxylase (GAD) activity. Results GAD activity in cell-free extracts of apple fruit was stimulated by Ca2+/CaM at physiological pH, but not at the acidic pH optimum. Based on bioinformatics analysis of the apple genome, three apple GAD genes were identified and their expression determined in various apple organs, including fruit. Like recombinant Arabidopsis GAD1, the activity and spectral properties of recombinant MdGAD1 and MdGAD2 were regulated by Ca2+/Ca...
Subirrigation systems are popular for reducing nutrient usage in indoor floricultural production.... more Subirrigation systems are popular for reducing nutrient usage in indoor floricultural production. Two open subirrigation experiments were conducted in a commercial setting using multiple chrysanthemum cultivars and up to 75% less N–P–K than industry standards. The lowest N–P–K levels supplied in the nutrient solution (in mmol·L−1: 5.4 N, 0.71−0.97 P, 1.9−4.1 K) up to bud break, were associated with acceptable leaf N–P–K levels [4.5−5.4% dry matter (DM), 0.23−0.60% DM, and 3.3−5.6% DM, respectively]. These findings validate our modified delivery practice and the use of lower N–P–K inputs in the production of subirrigated pot chrysanthemums.
Industry standards for nutrient delivery to greenhouse-grown ornamentals are typically in excess ... more Industry standards for nutrient delivery to greenhouse-grown ornamentals are typically in excess of the plant’s needs and can be reduced without causing adverse effects. Previous studies have reduced the level of specific nutrients or suite of nutrients over the entire crop cycle or at the onset of reproductive growth. Here, two split-plot experiments (four blocks each) were conducted with subirrigated, potted, disbudded chrysanthemums (Chrysanthemum morifolium Ramat.) grown under greenhouse conditions with sulphate treatment (2.25 mmol L−1 S supplied continuously over the crop cycle in experiment 2 only and 2.25, 1.125, or 0.5625 mmol L−1 S interrupted at inflorescence emergence) as the main plot and cultivar (‘Olympia’ and ‘Covington’) as the sub-plot. Morphological characteristics of plants with fully-expanded inflorescences were unaffected by decreasing S delivery over the crop cycle. Dry mass (DM) yields and S budgets revealed that supply-based S use and S uptake efficiencies i...
g-Aminobutyric acid transaminase (GABA-T) catalyses the breakdown of GABA to succinic semialdehyd... more g-Aminobutyric acid transaminase (GABA-T) catalyses the breakdown of GABA to succinic semialdehyde. In this report, three GABA-T isoforms were identified in the tomato (Solanum lycopersicum L.) plant. The deduced amino acid sequences of the three isoforms are highly similar over most of their coding regions with the exception of their N-terminal regions. Transient expression of the individual full-length GABA-T isoforms
The authors describe the development of gamma aminobutyrate (GABA) as a potential control agent i... more The authors describe the development of gamma aminobutyrate (GABA) as a potential control agent in plant invertebrate pest systems. The evidence indicates that GABA accumulation in plants in response to biotic and abiotic stresses is mediated via the activation of glutamate decarboxylase. More applied research, based on the fact that GABA acts as an inhibitory neurotransmitter in invertebrate pests, indicates that ingested GABA disrupts nerve functioning and causes damage to oblique-banded leafroller larvae, and that walking or herbivory by tobacco budworm and oblique-banded leafroller larvae stimulate GABA accumulation in soybean and tobacco, respectively. In addition, elevated levels of endogenous GABA in genetically engineered tobacco deter feeding by tobacco budworm larvae and infestation by the northern root-knot nematode. It is concluded that genetically engineered crop species overexpressing glutamate decarboxylase and having high GABA-producing potential may be an alternat...
Fertilizer boron (B) and molybdenum (Mo) were provided to contrasting cultivars of subirrigated p... more Fertilizer boron (B) and molybdenum (Mo) were provided to contrasting cultivars of subirrigated pot chrysanthemums at approximately 6–100% of current industry standards in an otherwise balanced nutrient solution during vegetative growth, and then all nutrients were removed during reproductive growth. Two experiments were conducted for each nutrient in a naturally lit greenhouse using a randomized complete block split-plot design. Boron (0.313–5.00 µmol L−1) or Mo (0.031–0.500 µmol L−1) was the main plot, and cultivar was the sub-plot. Petal quilling was observed with leaf-B of 11.3–19.4 mg kg−1 dry mass (DM), whereas Mo deficiency was not observed with leaf-Mo of 1.0–3.7 mg kg−1 DM. Optimized supplies resulted in leaf tissue levels of 48.8–72.5 mg B kg−1 DM and 1.9–4.8 mg Mo kg−1 DM. Boron uptake efficiency was more important than B utilization efficiency in sustaining plant/inflorescence growth with decreasing B supply, whereas Mo uptake and utilization efficiencies appeared to hav...
Moderate levels of zinc (3.50, 1.75 or 0.875 μmol·L−1 Zn) or copper (0.75, 0.38 or 0.19 μmol·L−1 ... more Moderate levels of zinc (3.50, 1.75 or 0.875 μmol·L−1 Zn) or copper (0.75, 0.38 or 0.19 μmol·L−1 Cu), in combination with a complete suite of other essential nutrients, were supplied up to flower bud break only, to two cultivars of subirrigated, potted, pinched chrysanthemums. Market-quality plants were produced with sufficient leaf-zinc or leaf-copper even though the delivery of the respective nutrient could be reduced by 75% compared with an industry standard. These results are interpreted as evidence for improved uptake efficiency with decreasing Zn or Cu delivery. Our modified delivery practice could contribute to low-input production of floricultural crops.
Postharvest deterioration can result in qualitative and quantitative changes in the marketability... more Postharvest deterioration can result in qualitative and quantitative changes in the marketability of horticultural commodities, as well as considerable economic loss to the industry. Low temperature and controlled atmosphere conditions (low O2 and elevated CO2) are extensively employed to prolong the postharvest life of these commodities. Nevertheless, they may suffer from chilling injury and other physiological disorders, as well as excessive water loss and bacterial/fungal decay. Research on the postharvest physiological, biochemical, and molecular responses of horticultural commodities indicates that low temperature/controlled atmosphere storage is associated with the promotion of γ-aminobutyrate (GABA) pathway activity, with or without the accumulation of GABA, delaying senescence, preserving quality and ameliorating chilling injury. Regardless of whether apple fruits are stored under low temperature/controlled atmosphere conditions or room temperature, elevated endogenous GABA ...
Polyamines (PAs) are ubiquitous aliphatic amines that play important roles in growth, development... more Polyamines (PAs) are ubiquitous aliphatic amines that play important roles in growth, development, and environmental stress responses in plants. In this study, we report that exogenous application of spermine (Spm) is effective in the induction of resistance to gray mold disease, which is caused by the necrotrophic fungal pathogen Botrytis cinerea, on tomato (Solanum lycopersicum), bean (Phaseolus vulgaris), and Arabidopsis thaliana. High throughput transcriptome analysis revealed a priming role for the Spm molecule in the genus Arabidopsis, resulting in strong upregulation of several important defense-associated genes, particularly those involved in systemic-acquired resistance. Microscopic analysis confirmed that Spm application potentiates endogenous defense responses in tomato leaves through the generation of reactive oxygen species and the hypersensitive response, which effectively contained B. cinerea growth within the inoculated area. Moreover, co-application of Spm and salic...
Academic scientists face an unpredictable path from plant biology research to real-life applicati... more Academic scientists face an unpredictable path from plant biology research to real-life application. Fundamental studies of γ-aminobutyrate and carotenoid metabolism, control of Botrytis infection, and the uptake and distribution of mineral nutrients illustrate that most academic research in plant biology could lead to innovative solutions for food, agriculture, and the environment. The time to application depends on various factors such as the fundamental nature of the scientific questions, the development of enabling technologies, the research priorities of funding agencies, the existence of competitive research, the willingness of researchers to become engaged in commercial activities, and ultimately the insight and creativity of the researchers. Applied research is likely to be adopted more rapidly by industry than basic research, so academic scientists engaged in basic research are less likely to participate in science commercialization. It is argued that the merit of Discovery...
Greenhouse floriculture operations pose significant environmental risk due to extensive inputs of... more Greenhouse floriculture operations pose significant environmental risk due to extensive inputs of fertilizer, especially nitrogen and phosphorus (P). Recent evidence shows that the use efficiency for nitrogen or sulphur is markedly improved in subirrigated potted chrysanthemums (Chrysanthemum morifolium Ramat.) by supplying a moderate level of the nutrient during vegetative growth, and removing the entire nutrient suite at the onset of reproductive growth, without adverse effects on plant quality. Here, two split-plot experiments were conducted with subirrigated, potted, disbudded chrysanthemums grown in a peat:perlite mixture under greenhouse conditions (high- or low-ambient light) with inorganic orthophosphate (Pi) treatment (2.6 mmol L−1 Pi supplied during the vegetative and reproductive stages, and 2.6, 1.95, or 1.3 mmol L−1 Pi supplied during the vegetative stage only) as the main plot and cultivar (‘Olympia’ and ‘Covington’) as the subplot. Market quality plants with sufficien...
Polyamines represent a potential source of 4-aminobutyrate (GABA) in plants exposed to abiotic st... more Polyamines represent a potential source of 4-aminobutyrate (GABA) in plants exposed to abiotic stress. Terminal catabolism of putrescine in Arabidopsis thaliana involves amine oxidase and the production of 4-aminobutanal, which is a substrate for NAD+-dependent aminoaldehyde dehydrogenase (AMADH). Here, two AMADH homologs were chosen (AtALDH10A8 and AtALDH10A9) as candidates for encoding 4-aminobutanal dehydrogenase activity for GABA synthesis. The two genes were cloned and soluble recombinant proteins were produced in Escherichia coli. The pH optima for activity and catalytic efficiency of recombinant AtALDH10A8 with 3-aminopropanal as substrate was 10.5 and 8.5, respectively, whereas the optima for AtALDH10A9 were approximately 9.5. Maximal activity and catalytic efficiency were obtained with NAD+ and 3-aminopropanal, followed by 4-aminobutanal; negligible activity was obtained with betaine aldehyde. NAD+ reduction was accompanied by the production of GABA and β-alanine, respectiv...
1-Methylcyclopropene (1-MCP) delays ethylene-meditated ripening of apple (Malus domestica Borkh.)... more 1-Methylcyclopropene (1-MCP) delays ethylene-meditated ripening of apple (Malus domestica Borkh.) fruit during controlled atmosphere (CA) storage. Here, we tested the hypothesis that 1-MCP and CA storage enhances the levels of polyamines (PAs) and 4-aminobutyrate (GABA) in apple fruit. A 46-week experiment was conducted with "Empire" apple using a split-plot design with four treatment replicates and 3°C, 2.5 kPa O2, and 0.03 or 2.5 kPa CO2 with or without 1 μL L(-1) 1-MCP. Total PA levels were not elevated by the 1-MCP treatment. Examination of the individual PAs revealed that: (i) total putrescine levels tended to be lower with 1-MCP regardless of the CO2 level, and while this was mostly at the expense of free putrescine, large transient increases in soluble conjugated putrescine were also evident; (ii) total spermidine levels tended to be lower with 1-MCP, particularly at 2.5 kPa CO2, and this was mostly at the expense of soluble conjugated spermidine; (iii) total spermi...
Background The ubiquitous, non-proteinaceous amino acid GABA (γ-aminobutyrate) accumulates in pla... more Background The ubiquitous, non-proteinaceous amino acid GABA (γ-aminobutyrate) accumulates in plants subjected to abiotic stresses such as chilling, O2 deficiency and elevated CO2. Recent evidence indicates that controlled atmosphere storage causes the accumulation of GABA in apple (Malus x domestica Borkh.) fruit, and now there is increasing interest in the biochemical mechanisms responsible for this phenomenon. Here, we investigated whether this phenomenon could be mediated via Ca2+/calmodulin (CaM) activation of glutamate decarboxylase (GAD) activity. Results GAD activity in cell-free extracts of apple fruit was stimulated by Ca2+/CaM at physiological pH, but not at the acidic pH optimum. Based on bioinformatics analysis of the apple genome, three apple GAD genes were identified and their expression determined in various apple organs, including fruit. Like recombinant Arabidopsis GAD1, the activity and spectral properties of recombinant MdGAD1 and MdGAD2 were regulated by Ca2+/Ca...
Subirrigation systems are popular for reducing nutrient usage in indoor floricultural production.... more Subirrigation systems are popular for reducing nutrient usage in indoor floricultural production. Two open subirrigation experiments were conducted in a commercial setting using multiple chrysanthemum cultivars and up to 75% less N–P–K than industry standards. The lowest N–P–K levels supplied in the nutrient solution (in mmol·L−1: 5.4 N, 0.71−0.97 P, 1.9−4.1 K) up to bud break, were associated with acceptable leaf N–P–K levels [4.5−5.4% dry matter (DM), 0.23−0.60% DM, and 3.3−5.6% DM, respectively]. These findings validate our modified delivery practice and the use of lower N–P–K inputs in the production of subirrigated pot chrysanthemums.
Industry standards for nutrient delivery to greenhouse-grown ornamentals are typically in excess ... more Industry standards for nutrient delivery to greenhouse-grown ornamentals are typically in excess of the plant’s needs and can be reduced without causing adverse effects. Previous studies have reduced the level of specific nutrients or suite of nutrients over the entire crop cycle or at the onset of reproductive growth. Here, two split-plot experiments (four blocks each) were conducted with subirrigated, potted, disbudded chrysanthemums (Chrysanthemum morifolium Ramat.) grown under greenhouse conditions with sulphate treatment (2.25 mmol L−1 S supplied continuously over the crop cycle in experiment 2 only and 2.25, 1.125, or 0.5625 mmol L−1 S interrupted at inflorescence emergence) as the main plot and cultivar (‘Olympia’ and ‘Covington’) as the sub-plot. Morphological characteristics of plants with fully-expanded inflorescences were unaffected by decreasing S delivery over the crop cycle. Dry mass (DM) yields and S budgets revealed that supply-based S use and S uptake efficiencies i...
g-Aminobutyric acid transaminase (GABA-T) catalyses the breakdown of GABA to succinic semialdehyd... more g-Aminobutyric acid transaminase (GABA-T) catalyses the breakdown of GABA to succinic semialdehyde. In this report, three GABA-T isoforms were identified in the tomato (Solanum lycopersicum L.) plant. The deduced amino acid sequences of the three isoforms are highly similar over most of their coding regions with the exception of their N-terminal regions. Transient expression of the individual full-length GABA-T isoforms
The authors describe the development of gamma aminobutyrate (GABA) as a potential control agent i... more The authors describe the development of gamma aminobutyrate (GABA) as a potential control agent in plant invertebrate pest systems. The evidence indicates that GABA accumulation in plants in response to biotic and abiotic stresses is mediated via the activation of glutamate decarboxylase. More applied research, based on the fact that GABA acts as an inhibitory neurotransmitter in invertebrate pests, indicates that ingested GABA disrupts nerve functioning and causes damage to oblique-banded leafroller larvae, and that walking or herbivory by tobacco budworm and oblique-banded leafroller larvae stimulate GABA accumulation in soybean and tobacco, respectively. In addition, elevated levels of endogenous GABA in genetically engineered tobacco deter feeding by tobacco budworm larvae and infestation by the northern root-knot nematode. It is concluded that genetically engineered crop species overexpressing glutamate decarboxylase and having high GABA-producing potential may be an alternat...
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