Citrate, a major determinant of citrus fruit quality, accumulates early in fruit development and ... more Citrate, a major determinant of citrus fruit quality, accumulates early in fruit development and declines towards maturation. The isomerization of citrate to isocitrate, catalyzed by aconitase is a key step in acid metabolism. Inhibition of mitochondrial aconitase activity early in fruit development contributes to acid accumulation, whereas increased cytosolic activity of aconitase causes citrate decline. It was previously hypothesized that the block in mitochondrial aconitase activity, inducing acid accumulation, is caused by citramalate. Here, we investigated the effect of citramalate and of another aconitase inhibitor, oxalomalate, on aconitase activity and regulation in callus originated from juice sacs. These compounds significantly increased citrate content and reduced the enzyme's activity, while slightly inducing its protein level. Citramalate inhibited the mitochondrial, but not cytosolic form of the enzyme. Its external application to mandarin fruits resulted in inhibition of aconitase activity, with a transient increase in fruit acidity detected a few weeks later. The endogenous level of citramalate was analyzed in five citrus varieties: its pattern of accumulation challenged the notion of its action as an endogenous inhibitor of mitochondrial aconitase. Metabolite profiling of oxalomalate-treated cells showed significant increases in a few amino acids and organic acids. The activities of alanine transaminase, aspartate transaminase and aspartate kinase, as well as these of two c-aminobutyrate (GABA)-shunt enzymes, succinic semialdehyde reductase (SSAR) and succinic semialdehyde dehydrogenase (SSAD) were significantly induced in oxalomalate-treated cells. It is suggested that the increase in citrate, caused by aconitase inhibition, induces amino acid synthesis and the GABA shunt, in accordance with the suggested fate of citrate during the acid decline stage in citrus fruit.
Background Citrus is one of the most important and widely grown commodity fruit crops. In this st... more Background Citrus is one of the most important and widely grown commodity fruit crops. In this study a label-free LC-MS/MS based shot-gun proteomics approach was taken to explore three main stages of citrus fruit development. These approaches were used to identify and evaluate changes occurring in juice sac cells in various metabolic pathways affecting citrus fruit development and quality. Results Protein changes in citrus juice sac cells were identified and quantified using label-free shotgun methodologies. Two alternative methods, differential mass-spectrometry (dMS) and spectral counting (SC) were used to analyze protein changes occurring during earlier and late stages of fruit development. Both methods were compared in order to develop a proteomics workflow that could be used in a non-model plant lacking a sequenced genome. In order to resolve the bioinformatics limitations of EST databases from species that lack a full sequenced genome, we established iCitrus. iCitrus is a comp...
Fruit development and ripening are key processes in the production of the phytonutrients that are... more Fruit development and ripening are key processes in the production of the phytonutrients that are essential for a balanced diet and for disease prevention. The pathways involved in these processes are unique to plants and vary between species. Climacteric fruit ripening, especially in tomato, has been extensively studied; yet, ripening of non-climacteric fruit is poorly understood. Although the diVerent species share common pathways; developmental programs, physiological, anatomical, biochemical composition and structural diVerences must contribute to the operation of unique pathways, genes and proteins. Citrus has a non-climacteric fruit ripening behavior and has a unique anatomical fruit structure. For the last few years a citrus genome-wide ESTs project has been initiated and consists of 222,911 clones corresponding to 19,854 contigs and 37,138 singletons. Taking advantage of the citrus database we analyzed the citrus proteome. Using LC-MS/MS we analyzed soluble and enriched membrane fractions of mature citrus fruit to identify the proteome of fruit juice cells. We have identiWed ca. 1,400 proteins from these fractions by searching NCBI-nr (green plants) and citrus ESTs databases, classiWed these proteins according to their putative function and assigned function according to known biosynthetic pathways.
Globularia sarcophylla, originating from the Canary Islands, was recently introduced as a new cut... more Globularia sarcophylla, originating from the Canary Islands, was recently introduced as a new cut flower in Israel. Two major problems have prevented its commercialization: the late-summer blooming and the low quality of its flowering shoots. In the present work we studied the factors affecting G. sarcophylla flowering. We found that long-day (LD) conditions slightly promote flowering but artificial photoperiodic illumination does not enable the manipulation of flowering time. On the other hand, treatment with the gibberellin (GA)-biosynthesis inhibitor, Uniconazol, had a dramatic promotive effect on flowering time. Application of Uniconazol in autumn or winter induced flowering in winter or early spring, respectively. The inhibitor did not advance flowering during the summer or in the phytotron under high temperatures. When plants were grown in the spring/summer under heavy shading, they did not flower unless they were treated with Uniconazol. Uniconazol treatment also improved flower quality by reducing the length of inflorescence pedicles. This effect was found in all seasons. Based on our results, we raise the hypothesis that Uniconazol treatment induces flowering by diverting assimilates to the apex. Inhibition of GA biosynthesis under conditions limiting photosynthetic activity reduces vegetative growth and increases the availability of assimilates to the apex, leading to flower initiation. However, under high irradiance and/or high temperatures, when the levels of assimilates are sufficient to induce natural flowering, the inhibitor has no further effect.
Mature citrus fruits, which are classified as non-climacteric, evolve very low amounts of ethylen... more Mature citrus fruits, which are classified as non-climacteric, evolve very low amounts of ethylene during ripening but respond to exogenous ethylene by ripening-related pigment changes and accelerated respiration. In the present study we show that young citrus fruitlets attached to the tree produce high levels of ethylene, which decrease dramatically towards maturation. Upon harvest, fruitlets exhibited a climacteric-like rise in ethylene production, preceded by induction of the genes for 1-aminocyclopropane-1-carboxylate (ACC) synthase 1 (CsACS1), ACC oxidase 1 (CsACO1) and the ethylene receptor CsERS1. This induction was advanced and augmented by exogenous ethylene or propylene, indicating an autocatalytic system II-like ethylene biosynthesis. In mature, detached fruit, very low rates of ethylene production were associated with constitutive expression of the ACC synthase 2 (CsACS2) and ethylene receptor CsETR1 genes (system I). CsACS1 gene expression was undetectable at this stage, even following ethylene or propylene treatment, and CsERS1 gene expression remained constant, indicating that no autocatalytic response had occurred. The transition from system II-like behavior of young fruitlets to system I behavior appears to be under developmental control.
Mature citrus fruits, which are classified as non-climacteric, evolve very low amounts of ethylen... more Mature citrus fruits, which are classified as non-climacteric, evolve very low amounts of ethylene during ripening but respond to exogenous ethylene by ripening-related pigment changes and accelerated respiration. In the present study we show that young citrus fruitlets attached to the tree produce high levels of ethylene, which decrease dramatically towards maturation. Upon harvest, fruitlets exhibited a climacteric-like rise in
Globularia sarcophylla, originating from the Canary Islands, was recently introduced as a new cut... more Globularia sarcophylla, originating from the Canary Islands, was recently introduced as a new cut flower in Israel. Two major problems have prevented its commercialization: the late-summer blooming and the low quality of its flowering shoots. In the present work we studied the factors affecting G. sarcophylla flowering. We found that long-day (LD) conditions slightly promote flowering but artificial photoperiodic illumination does not enable the manipulation of flowering time. On the other hand, treatment with the gibberellin (GA)-biosynthesis inhibitor, Uniconazol, had a dramatic promotive effect on flowering time. Application of Uniconazol in autumn or winter induced flowering in winter or early spring, respectively. The inhibitor did not advance flowering during the summer or in the phytotron under high temperatures. When plants were grown in the spring/summer under heavy shading, they did not flower unless they were treated with Uniconazol. Uniconazol treatment also improved flower quality by reducing the length of inflorescence pedicles. This effect was found in all seasons. Based on our results, we raise the hypothesis that Uniconazol treatment induces flowering by diverting assimilates to the apex. Inhibition of GA biosynthesis under conditions limiting photosynthetic activity reduces vegetative growth and increases the availability of assimilates to the apex, leading to flower initiation. However, under high irradiance and/or high temperatures, when the levels of assimilates are sufficient to induce natural flowering, the inhibitor has no further effect.
Different organisms use gradual seasonal changes in pho-toperiod to correctly time diverse develo... more Different organisms use gradual seasonal changes in pho-toperiod to correctly time diverse developmental processes, such as transition to flowering in plants. Florigen is a sys-temic signal formed in leaves exposed to specific envi-ronmental cues, mainly photoperiodic, and ...
Although leaves and other vegetative tissues are generally considered as non-climacteric, citrus ... more Although leaves and other vegetative tissues are generally considered as non-climacteric, citrus leaves show a climacteric system II behaviour after detachment. Upon harvest, young, fully expanded 'Valencia' orange (Citrus sinensis) leaves (~60-d-old) exhibited two phases of ethylene production. The first phase, up to 6 d after detachment, was characterized by a low and constant ethylene production (system I pathway), associated with a constitutive expression of ACC synthase 2 (CsACS2), CsERS1, and CsETR1. ACC synthase 1 (CsACS1) was not expressed during this phase and autoinhibition of ethylene production was apparent following treatment with exogenous ethylene or propylene. The second phase, 7-12 d after detachment, was characterized by a climacteric rise in ethylene production, preceded by the induction of CsACS1 and ACC oxidase 1 (CsACO1) gene expression in the system II pathway. This induction was accelerated and augmented by exogenous ethylene or propylene, indicating an autocatalytic system II ethylene biosynthesis. Mature leaves (6-8-months-old) behaved similarly, except that the climacteric peak in ethylene production occurred earlier (day 5). Young and mature leaves varied in the timing of the climacteric ethylene rise and CsACS1 and CsACO1 induction. The two phases of ethylene production, system I and system II, were also detected in wounded leaf discs of both young and mature leaves. The first phase peaked 15 min after excision and the second phase peaked after 6 h.
Citrate, a major determinant of citrus fruit quality, accumulates early in fruit development and ... more Citrate, a major determinant of citrus fruit quality, accumulates early in fruit development and declines towards maturation. The isomerization of citrate to isocitrate, catalyzed by aconitase is a key step in acid metabolism. Inhibition of mitochondrial aconitase activity early in fruit development contributes to acid accumulation, whereas increased cytosolic activity of aconitase causes citrate decline. It was previously hypothesized that the block in mitochondrial aconitase activity, inducing acid accumulation, is caused by citramalate. Here, we investigated the effect of citramalate and of another aconitase inhibitor, oxalomalate, on aconitase activity and regulation in callus originated from juice sacs. These compounds significantly increased citrate content and reduced the enzyme’s activity, while slightly inducing its protein level. Citramalate inhibited the mitochondrial, but not cytosolic form of the enzyme. Its external application to mandarin fruits resulted in inhibition...
Label-free LC-MS/MS-based shotgun proteomics was used to quantify the differential protein synthe... more Label-free LC-MS/MS-based shotgun proteomics was used to quantify the differential protein synthesis and metabolite profiling in order to assess metabolic changes during the development of citrus fruits. Our results suggested the occurrence of a metabolic change during citrus fruit maturation, where the organic acid and amino acid accumulation seen during the early stages of development shifted into sugar synthesis during the later stage of citrus fruit development. The expression of invertases remained unchanged, while an invertase inhibitor was upregulated towards maturation. The increased expression of sucrose-phosphate synthase and sucrose-6-phosphate phosphatase and the rapid sugar accumulation suggest that sucrose is also being synthesized in citrus juice sac cells during the later stage of fruit development.
Citrus is one of the most important and widely grown commodity fruit crops. In this study a label... more Citrus is one of the most important and widely grown commodity fruit crops. In this study a label-free LC-MS/MS based shot-gun proteomics approach was taken to explore three main stages of citrus fruit development. These approaches were used to identify and evaluate changes occurring in juice sac cells in various metabolic pathways affecting citrus fruit development and quality. Protein changes in citrus juice sac cells were identified and quantified using label-free shotgun methodologies. Two alternative methods, differential mass-spectrometry (dMS) and spectral counting (SC) were used to analyze protein changes occurring during earlier and late stages of fruit development. Both methods were compared in order to develop a proteomics workflow that could be used in a non-model plant lacking a sequenced genome. In order to resolve the bioinformatics limitations of EST databases from species that lack a full sequenced genome, we established iCitrus. iCitrus is a comprehensive sequence database created by merging three major sources of sequences (HarvEST:citrus, NCBI/citrus/unigenes, NCBI/citrus/proteins) and improving the annotation of existing unigenes. iCitrus provided a useful bioinformatics tool for the high-throughput identification of citrus proteins. We have identified approximately 1500 citrus proteins expressed in fruit juice sac cells and quantified the changes of their expression during fruit development. Our results showed that both dMS and SC provided significant information on protein changes, with dMS providing a higher accuracy. Our data supports the notion of the complementary use of dMS and SC for label-free comparative proteomics, broadening the identification spectrum and strengthening the identification of trends in protein expression changes during the particular processes being compared.
Citrate, a major determinant of citrus fruit quality, accumulates early in fruit development and ... more Citrate, a major determinant of citrus fruit quality, accumulates early in fruit development and declines towards maturation. The isomerization of citrate to isocitrate, catalyzed by aconitase is a key step in acid metabolism. Inhibition of mitochondrial aconitase activity early in fruit development contributes to acid accumulation, whereas increased cytosolic activity of aconitase causes citrate decline. It was previously hypothesized that the block in mitochondrial aconitase activity, inducing acid accumulation, is caused by citramalate. Here, we investigated the effect of citramalate and of another aconitase inhibitor, oxalomalate, on aconitase activity and regulation in callus originated from juice sacs. These compounds significantly increased citrate content and reduced the enzyme's activity, while slightly inducing its protein level. Citramalate inhibited the mitochondrial, but not cytosolic form of the enzyme. Its external application to mandarin fruits resulted in inhibition of aconitase activity, with a transient increase in fruit acidity detected a few weeks later. The endogenous level of citramalate was analyzed in five citrus varieties: its pattern of accumulation challenged the notion of its action as an endogenous inhibitor of mitochondrial aconitase. Metabolite profiling of oxalomalate-treated cells showed significant increases in a few amino acids and organic acids. The activities of alanine transaminase, aspartate transaminase and aspartate kinase, as well as these of two c-aminobutyrate (GABA)-shunt enzymes, succinic semialdehyde reductase (SSAR) and succinic semialdehyde dehydrogenase (SSAD) were significantly induced in oxalomalate-treated cells. It is suggested that the increase in citrate, caused by aconitase inhibition, induces amino acid synthesis and the GABA shunt, in accordance with the suggested fate of citrate during the acid decline stage in citrus fruit.
Background Citrus is one of the most important and widely grown commodity fruit crops. In this st... more Background Citrus is one of the most important and widely grown commodity fruit crops. In this study a label-free LC-MS/MS based shot-gun proteomics approach was taken to explore three main stages of citrus fruit development. These approaches were used to identify and evaluate changes occurring in juice sac cells in various metabolic pathways affecting citrus fruit development and quality. Results Protein changes in citrus juice sac cells were identified and quantified using label-free shotgun methodologies. Two alternative methods, differential mass-spectrometry (dMS) and spectral counting (SC) were used to analyze protein changes occurring during earlier and late stages of fruit development. Both methods were compared in order to develop a proteomics workflow that could be used in a non-model plant lacking a sequenced genome. In order to resolve the bioinformatics limitations of EST databases from species that lack a full sequenced genome, we established iCitrus. iCitrus is a comp...
Fruit development and ripening are key processes in the production of the phytonutrients that are... more Fruit development and ripening are key processes in the production of the phytonutrients that are essential for a balanced diet and for disease prevention. The pathways involved in these processes are unique to plants and vary between species. Climacteric fruit ripening, especially in tomato, has been extensively studied; yet, ripening of non-climacteric fruit is poorly understood. Although the diVerent species share common pathways; developmental programs, physiological, anatomical, biochemical composition and structural diVerences must contribute to the operation of unique pathways, genes and proteins. Citrus has a non-climacteric fruit ripening behavior and has a unique anatomical fruit structure. For the last few years a citrus genome-wide ESTs project has been initiated and consists of 222,911 clones corresponding to 19,854 contigs and 37,138 singletons. Taking advantage of the citrus database we analyzed the citrus proteome. Using LC-MS/MS we analyzed soluble and enriched membrane fractions of mature citrus fruit to identify the proteome of fruit juice cells. We have identiWed ca. 1,400 proteins from these fractions by searching NCBI-nr (green plants) and citrus ESTs databases, classiWed these proteins according to their putative function and assigned function according to known biosynthetic pathways.
Globularia sarcophylla, originating from the Canary Islands, was recently introduced as a new cut... more Globularia sarcophylla, originating from the Canary Islands, was recently introduced as a new cut flower in Israel. Two major problems have prevented its commercialization: the late-summer blooming and the low quality of its flowering shoots. In the present work we studied the factors affecting G. sarcophylla flowering. We found that long-day (LD) conditions slightly promote flowering but artificial photoperiodic illumination does not enable the manipulation of flowering time. On the other hand, treatment with the gibberellin (GA)-biosynthesis inhibitor, Uniconazol, had a dramatic promotive effect on flowering time. Application of Uniconazol in autumn or winter induced flowering in winter or early spring, respectively. The inhibitor did not advance flowering during the summer or in the phytotron under high temperatures. When plants were grown in the spring/summer under heavy shading, they did not flower unless they were treated with Uniconazol. Uniconazol treatment also improved flower quality by reducing the length of inflorescence pedicles. This effect was found in all seasons. Based on our results, we raise the hypothesis that Uniconazol treatment induces flowering by diverting assimilates to the apex. Inhibition of GA biosynthesis under conditions limiting photosynthetic activity reduces vegetative growth and increases the availability of assimilates to the apex, leading to flower initiation. However, under high irradiance and/or high temperatures, when the levels of assimilates are sufficient to induce natural flowering, the inhibitor has no further effect.
Mature citrus fruits, which are classified as non-climacteric, evolve very low amounts of ethylen... more Mature citrus fruits, which are classified as non-climacteric, evolve very low amounts of ethylene during ripening but respond to exogenous ethylene by ripening-related pigment changes and accelerated respiration. In the present study we show that young citrus fruitlets attached to the tree produce high levels of ethylene, which decrease dramatically towards maturation. Upon harvest, fruitlets exhibited a climacteric-like rise in ethylene production, preceded by induction of the genes for 1-aminocyclopropane-1-carboxylate (ACC) synthase 1 (CsACS1), ACC oxidase 1 (CsACO1) and the ethylene receptor CsERS1. This induction was advanced and augmented by exogenous ethylene or propylene, indicating an autocatalytic system II-like ethylene biosynthesis. In mature, detached fruit, very low rates of ethylene production were associated with constitutive expression of the ACC synthase 2 (CsACS2) and ethylene receptor CsETR1 genes (system I). CsACS1 gene expression was undetectable at this stage, even following ethylene or propylene treatment, and CsERS1 gene expression remained constant, indicating that no autocatalytic response had occurred. The transition from system II-like behavior of young fruitlets to system I behavior appears to be under developmental control.
Mature citrus fruits, which are classified as non-climacteric, evolve very low amounts of ethylen... more Mature citrus fruits, which are classified as non-climacteric, evolve very low amounts of ethylene during ripening but respond to exogenous ethylene by ripening-related pigment changes and accelerated respiration. In the present study we show that young citrus fruitlets attached to the tree produce high levels of ethylene, which decrease dramatically towards maturation. Upon harvest, fruitlets exhibited a climacteric-like rise in
Globularia sarcophylla, originating from the Canary Islands, was recently introduced as a new cut... more Globularia sarcophylla, originating from the Canary Islands, was recently introduced as a new cut flower in Israel. Two major problems have prevented its commercialization: the late-summer blooming and the low quality of its flowering shoots. In the present work we studied the factors affecting G. sarcophylla flowering. We found that long-day (LD) conditions slightly promote flowering but artificial photoperiodic illumination does not enable the manipulation of flowering time. On the other hand, treatment with the gibberellin (GA)-biosynthesis inhibitor, Uniconazol, had a dramatic promotive effect on flowering time. Application of Uniconazol in autumn or winter induced flowering in winter or early spring, respectively. The inhibitor did not advance flowering during the summer or in the phytotron under high temperatures. When plants were grown in the spring/summer under heavy shading, they did not flower unless they were treated with Uniconazol. Uniconazol treatment also improved flower quality by reducing the length of inflorescence pedicles. This effect was found in all seasons. Based on our results, we raise the hypothesis that Uniconazol treatment induces flowering by diverting assimilates to the apex. Inhibition of GA biosynthesis under conditions limiting photosynthetic activity reduces vegetative growth and increases the availability of assimilates to the apex, leading to flower initiation. However, under high irradiance and/or high temperatures, when the levels of assimilates are sufficient to induce natural flowering, the inhibitor has no further effect.
Different organisms use gradual seasonal changes in pho-toperiod to correctly time diverse develo... more Different organisms use gradual seasonal changes in pho-toperiod to correctly time diverse developmental processes, such as transition to flowering in plants. Florigen is a sys-temic signal formed in leaves exposed to specific envi-ronmental cues, mainly photoperiodic, and ...
Although leaves and other vegetative tissues are generally considered as non-climacteric, citrus ... more Although leaves and other vegetative tissues are generally considered as non-climacteric, citrus leaves show a climacteric system II behaviour after detachment. Upon harvest, young, fully expanded 'Valencia' orange (Citrus sinensis) leaves (~60-d-old) exhibited two phases of ethylene production. The first phase, up to 6 d after detachment, was characterized by a low and constant ethylene production (system I pathway), associated with a constitutive expression of ACC synthase 2 (CsACS2), CsERS1, and CsETR1. ACC synthase 1 (CsACS1) was not expressed during this phase and autoinhibition of ethylene production was apparent following treatment with exogenous ethylene or propylene. The second phase, 7-12 d after detachment, was characterized by a climacteric rise in ethylene production, preceded by the induction of CsACS1 and ACC oxidase 1 (CsACO1) gene expression in the system II pathway. This induction was accelerated and augmented by exogenous ethylene or propylene, indicating an autocatalytic system II ethylene biosynthesis. Mature leaves (6-8-months-old) behaved similarly, except that the climacteric peak in ethylene production occurred earlier (day 5). Young and mature leaves varied in the timing of the climacteric ethylene rise and CsACS1 and CsACO1 induction. The two phases of ethylene production, system I and system II, were also detected in wounded leaf discs of both young and mature leaves. The first phase peaked 15 min after excision and the second phase peaked after 6 h.
Citrate, a major determinant of citrus fruit quality, accumulates early in fruit development and ... more Citrate, a major determinant of citrus fruit quality, accumulates early in fruit development and declines towards maturation. The isomerization of citrate to isocitrate, catalyzed by aconitase is a key step in acid metabolism. Inhibition of mitochondrial aconitase activity early in fruit development contributes to acid accumulation, whereas increased cytosolic activity of aconitase causes citrate decline. It was previously hypothesized that the block in mitochondrial aconitase activity, inducing acid accumulation, is caused by citramalate. Here, we investigated the effect of citramalate and of another aconitase inhibitor, oxalomalate, on aconitase activity and regulation in callus originated from juice sacs. These compounds significantly increased citrate content and reduced the enzyme’s activity, while slightly inducing its protein level. Citramalate inhibited the mitochondrial, but not cytosolic form of the enzyme. Its external application to mandarin fruits resulted in inhibition...
Label-free LC-MS/MS-based shotgun proteomics was used to quantify the differential protein synthe... more Label-free LC-MS/MS-based shotgun proteomics was used to quantify the differential protein synthesis and metabolite profiling in order to assess metabolic changes during the development of citrus fruits. Our results suggested the occurrence of a metabolic change during citrus fruit maturation, where the organic acid and amino acid accumulation seen during the early stages of development shifted into sugar synthesis during the later stage of citrus fruit development. The expression of invertases remained unchanged, while an invertase inhibitor was upregulated towards maturation. The increased expression of sucrose-phosphate synthase and sucrose-6-phosphate phosphatase and the rapid sugar accumulation suggest that sucrose is also being synthesized in citrus juice sac cells during the later stage of fruit development.
Citrus is one of the most important and widely grown commodity fruit crops. In this study a label... more Citrus is one of the most important and widely grown commodity fruit crops. In this study a label-free LC-MS/MS based shot-gun proteomics approach was taken to explore three main stages of citrus fruit development. These approaches were used to identify and evaluate changes occurring in juice sac cells in various metabolic pathways affecting citrus fruit development and quality. Protein changes in citrus juice sac cells were identified and quantified using label-free shotgun methodologies. Two alternative methods, differential mass-spectrometry (dMS) and spectral counting (SC) were used to analyze protein changes occurring during earlier and late stages of fruit development. Both methods were compared in order to develop a proteomics workflow that could be used in a non-model plant lacking a sequenced genome. In order to resolve the bioinformatics limitations of EST databases from species that lack a full sequenced genome, we established iCitrus. iCitrus is a comprehensive sequence database created by merging three major sources of sequences (HarvEST:citrus, NCBI/citrus/unigenes, NCBI/citrus/proteins) and improving the annotation of existing unigenes. iCitrus provided a useful bioinformatics tool for the high-throughput identification of citrus proteins. We have identified approximately 1500 citrus proteins expressed in fruit juice sac cells and quantified the changes of their expression during fruit development. Our results showed that both dMS and SC provided significant information on protein changes, with dMS providing a higher accuracy. Our data supports the notion of the complementary use of dMS and SC for label-free comparative proteomics, broadening the identification spectrum and strengthening the identification of trends in protein expression changes during the particular processes being compared.
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Papers by Ehud Katz