In Israel, scarcity of water, high input prices, and market competition limit the number of orcha... more In Israel, scarcity of water, high input prices, and market competition limit the number of orchard crops that can be grown profitably. Our approach to the further development of the horticultural industry in the dry regions of Israel—the Negev and Judean deserts—is thus to establish new crops that will demand high prices in the export markets (Mizrahi and Nerd 1996). To this end, about 40 species of rare or wild fruit trees were introduced by us into these dry regions in a number of locations that differed in terms of soil, water, and climate (Nerd et al. 1990; Mizrahi and Nerd 1996). Emphasis was placed on candidates of the Cactaceae because of their high water-use efficiency (5–10 times higher than that of most conventional crops), resulting in low water requirement (Nobel 1988, 1994). The high water-use efficiency of cacti is provided by their unique photosynthetic pathway—crassulacean acid metabolism (CAM). In CAM plants, the stomata open and CO 2 uptake takes place during the ...
The activity of nitrate reductase in tomato fruits (Lycopersicon esculentum Mill.) grown in vivo ... more The activity of nitrate reductase in tomato fruits (Lycopersicon esculentum Mill.) grown in vivo and in vitro was similar throughout development. Enzyme activity was directly correlated with fruit size. As has been shown in vivo, nitrate reductase activity was also inducible in fruits grown in vitro.
Unlike other eukaryotes, which synthesize polyamines (PA) only from ornithine, plants possess an ... more Unlike other eukaryotes, which synthesize polyamines (PA) only from ornithine, plants possess an additional pathway utilizing arginine as a precursor. In this study, we have identified cDNA clones coding for a Glycine max ornithine decarboxylase (ODC, EC 4.1.1.7) and an arginine decarboxylase (ADC, EC 4.1.1.19). Expression analysis using semi-quantitative RT-PCR approach revealed that both genes coding for enzymes involved in putrescine biosynthesis (ODC and ADC) were found in most plant organs examined. Significant expression levels of both genes were detected in root tips and hypocotyls. The spatial distribution of GmODC and GmADC transcripts in primary and lateral roots and hypocotyls revealed that these genes are co-expressed in expanding cells of cortex parenchyma, expanding cells of central cylinder in main roots and in developing tissues and expanding cells of soybean hypocotyls. The data point out a correlation of the expression patterns of GmODC and GmADC gene to certain physiological roles such as organ development and cell expansion.
The apparent association of ornithine decarboxylase (ODC) with rapid cell proliferation in develo... more The apparent association of ornithine decarboxylase (ODC) with rapid cell proliferation in developing tomato (Lycopersicon esculentum Mil. cv. Pearson ms-35) fruits has been previously described. Further evidence is provided by the use of two ODC inhibitors, a-difluoromethylornithine (a-DFMO) and a-methylornithine (a-MO). Fruit development was inhibited by these inhibitors if applied during the period of intensive cell division. When applied in vitro, the two inhibitors were shown to inhibit the activity of ODC but not that of arginine decarboxylase (ADC). When applied in vivo, a-DFMO, a catalytic irreversible inhibitor, caused 97.1% reduction of ODC activity in the dialyzed extract from the treated ovaries, while it had no effect on ADC. On the other hand, a-MO, a reversible inhibitor, did not reduce the activity of these two enzymes in the dialyzed extracts when applied in vivo. The dialysis procedure probably removed a-MO from the enzyme fraction. Putrescine, the product of both ODC and ADC, aleviated the inhibition of fruit development but did not restore ODC activity to the control level. These results suggest that in the young developing tomato fruit, ODC is the enzyme responsible for the synthesis of putrescine, which is essential for the early stages of fruit development. The reduced activity of ODC elicited by putrescine suggests a mechanism of feedback regulation by enzyme repression or release of an ODC anti-enzyme.
The flowering and pollination requirements of Cereus peruvianus (L) Mill. (Cactaceae) were invest... more The flowering and pollination requirements of Cereus peruvianus (L) Mill. (Cactaceae) were investigated in Beer Sheva, Israel, in a three-year-old plantation which had been established from seedlings, in order to domesticate this plant as a fruit crop. Plants flowered during the hot season (May-October), and flowers opened for one night only. Variations were observed in the flowers' opening time, with the early-opening plants beginning to open two hours before sunset, and the late-opening plants opening close to sunset. Flowers were visited only by day-active insects: the honey bee (Apis mellifera) and the carpenter bee (Xylocopa pubescens). The visitors' behavior indicated that they were involved in pollination. Early-opening flowers were visited both in the evening and in the morning, whereas late-openers were visited only in the morning. C. peruvianus was found to be self-incompatible, and fruit set did not occur when flowers were hand self-pollinated. Hand cross-pollinat...
Key Werd Ibscisic acid; 3-methyl&at@-&Cpentadienoic acids; biological activity; germination of le... more Key Werd Ibscisic acid; 3-methyl&at@-&Cpentadienoic acids; biological activity; germination of lettuce seed; acceleration of Tropaeolum tion of transpiration. leaf' discs senescence; inhibition of wheat coleoptile elongation; inhibi-Abstract-Thirty six different 3-methylS -aryi-2Jpentadienoic acids and esters were synthesizedusing the Reformatsky and Wittig reactions. The different geometrical isomers were conveniently separated by the dry column technique. Assignment of configuration of the pentadienoic side chain was baaed on NMR and UV properties. The biological activities of the aromatic analogs of ABA were determined in four bioassays. Most of the analogs were less active than the natural hormone. Only 3-methylS -~orophenyl A2-irans,A'-bans-pentadienoic acid exhibited high ABA-like activity in all four bioassays.
S ummary Kinetin maintains the protein content of detached leaves, but the reason is not clear. T... more S ummary Kinetin maintains the protein content of detached leaves, but the reason is not clear. This work attempted to find out whether the effect arises from maintenance of protein synthesis or retardation of protein breakdown. Protein synthesis and degradation in ...
... reported that salination of tobacco plants markedly reduced cytokinin translocation from the ... more ... reported that salination of tobacco plants markedly reduced cytokinin translocation from the root and Mizrahi, Blumenfeld and Richmond (1970) showed ... Booth et al.(1962) reported that auxin affected movement of nutrients within plants and Davies and Wareing (1965) showed ...
The question is raised whether the hormonal modifications in a plant exposed to osmotic root stre... more The question is raised whether the hormonal modifications in a plant exposed to osmotic root stress result directly from the decrease in water potential of the root environment or from disturbances of the plant's water balance. Tobacco plants were held for 24 hours under either high or low relative humidities, with or without salt. The amount of abscisic acid in the leaves of salinized plants rose markedly in low, but not in high, relative humidity. No change in the amount of extractable cytokinins was detected in any treatment. It is tentatively suggested that variations in the water
Betacyanins in peel and flesh of fruits of different Hylocereus species were identified by means ... more Betacyanins in peel and flesh of fruits of different Hylocereus species were identified by means of GC/MS, electrospray MS/MS, HPLC as well as 1 H and 13 C NMR techniques. As hitherto unknown pigments: betanidin 5-O-(2 0-O-b-D-apiofuranosyl)-b-D-glucopyranoside, betanidin 5-O-(4 0-O-malonyl)-b-D-glucopyranoside and betanidin 5-O-[(5 00-O-E-sinapoyl)-2 0-O-b-D-apiofuranosyl]-b-D-glucopyranoside were elucidated. The sinapoyl moiety attachment position in the structure of betacyanins was established for the first time. The peel contained a more complex pattern of betacyanins with apiofuranosyl moiety. Other recently identified pigments were also present in the samples and their 1 H or 13 C NMR spectra were recorded. In the case of phyllocactin and its 4 0-isomer the migration of the malonyl group was noticed.
Climatic changes have created the imminent need for the development of new crops for arid regions... more Climatic changes have created the imminent need for the development of new crops for arid regions. We started to domesticate and introduce wild and exotic fruit trees to our deserts in 1984. We tested different species in five eco zones in Israel, differing from each other in terms of maximum and minimum temperatures, type and degrees of salinities, water evaporation rates, rainfall, etc. We succeeded in cultivating pitaya species using hybrids from the Hylocereus and Selenicereus genera, and with a different species from the Cactaeae Cereus peruvianus, which we named Koubo. These two species are from the Cactaceae family, known for high water use efficiencies (WUE). We already have investors who started the semi-commercial production of Marula, Sclerocarya birrea sbsp. Caffra, and Argan—Argania spinosa. In spite of the fact that we developed good clones and knowledge of how to grow and ship White Sapote, Casimiroa edulis, and Indian jujube, Ziziphus mauritiana, we failed due to a l...
Numerous species of cacti were introduced in an attempt to diversify the types of fruit trees cul... more Numerous species of cacti were introduced in an attempt to diversify the types of fruit trees cultivable under the conditions of the Israeli Negev Desert. The new species were tested in five introduction orchards varying in type of soil, climate and irrigation water. Fruits of the Hylocereus genus, which must be grown on a trellis system under netting, were found to be of an attractive shape, color, appearance and taste. Cereus peruvianus, which grows outdoors, produced beautiful tasty fruits which varied in color from yellow to deep red. Fruits of these species are of the nonclimacteric type and are capable of withstanding long-distance transportation. Some have to be cross-pollinated while others can be self-pollinated. They flower twice or three times a year, bearing fruits from June to November. These types are characterized by a CAM photosynthetic pathway, pointing to high water use efficiency.
Field experiments were conducted to examine the effect of fertilization and short periods of drou... more Field experiments were conducted to examine the effect of fertilization and short periods of drought on the out-of-season winter crop in prickly pear [Opuntia ficus-indica (L.) Mill.]. In addition, the winter and summer crops were compared regarding floral bud production and fruit characteristics. Under both continuous fertigation (N, P, K applied with the irrigation water) and continuous irrigation, the number of floral buds per plant was much lower in the winter than in the summer crop. Fertilization increased production of floral buds in both crops, but to a greater extent in the winter crop. The increase in floral bud production in fertilized plants was associated with an increase in NO3-N content in the cladodes. Suspension of fertigation for 4 or 8 weeks immediately after the summer harvest decreased cladode water content and delayed and reduced floral bud emergence as compared with continuous fertigation (control) or late drought (4 or 8 weeks) applied 4 weeks after the summe...
The reproductive biology of the climbing cacti Hylocereus polyrhizus (Weber) Britt. & Rose, H. un... more The reproductive biology of the climbing cacti Hylocereus polyrhizus (Weber) Britt. & Rose, H. undatus (Haworth) Britt. & Rose, H. costaricensis (Weber) Britt. & Rose, and Selenicereus megalanthus (Schum. ex Vaupel) Moran (syn. Mediocactus megalanthus) was studied with the aim of cultivating the cacti in Israel as fruit crops. Flowering in Hylocereus spp. occurred in two to three waves during the summer, whereas in S. megalanthus, flowering was concentrated at the end of autumn. Flowers of all species opened 1 to 1.5 hours before sunset and closed ≈6 hours after sunrise. In the Hylocereus spp., H. polyrhizus and H. costaricensis were self-unfruitful, and cross-pollination with other species led to high fruit set (100%). Hylocereus undatus was self-fruitful, setting fruit with self-pollen. Cross-pollination between the clones of S. megalanthus led to a high fruit set and each clone was self-fruitful. In contrast to H. undatus, S. megalanthus clones could set fruit without pollen vect...
Fruit growth and ripening and the effect of various storage temperatureson fruit quality were stu... more Fruit growth and ripening and the effect of various storage temperatureson fruit quality were studied in Hylocereus undatus and H. polyrhizus growing in Beer-Sheva (Israeli Negev desert) under greenhouse conditions. Dimensional growth of the fruit had a sigmoid pattern with a negligible growth after the onset of peel color change. The first change in peel color was recorded 24-25 d after anthesis in H. undatus and 26-27 d after anthesis in H. polyrhizus. In both species, peel color turned fully red 4-5 days after first color change (mean temperature for the study period was 26.6 ± 2.1 °C). Parallel to color changes the content of pulp, SSC and soluble sugars increased while firmness and the content of starch and mucilage decreased. The surge in acidity before color change indicated the beginning of ripening processes. In H. polyrhizus fruit, which have a red-violet pulp, the pigment increased in parallel to the development of peel color. The fruit were proved nonclimacteric, and whe...
In Israel, scarcity of water, high input prices, and market competition limit the number of orcha... more In Israel, scarcity of water, high input prices, and market competition limit the number of orchard crops that can be grown profitably. Our approach to the further development of the horticultural industry in the dry regions of Israel—the Negev and Judean deserts—is thus to establish new crops that will demand high prices in the export markets (Mizrahi and Nerd 1996). To this end, about 40 species of rare or wild fruit trees were introduced by us into these dry regions in a number of locations that differed in terms of soil, water, and climate (Nerd et al. 1990; Mizrahi and Nerd 1996). Emphasis was placed on candidates of the Cactaceae because of their high water-use efficiency (5–10 times higher than that of most conventional crops), resulting in low water requirement (Nobel 1988, 1994). The high water-use efficiency of cacti is provided by their unique photosynthetic pathway—crassulacean acid metabolism (CAM). In CAM plants, the stomata open and CO 2 uptake takes place during the ...
The activity of nitrate reductase in tomato fruits (Lycopersicon esculentum Mill.) grown in vivo ... more The activity of nitrate reductase in tomato fruits (Lycopersicon esculentum Mill.) grown in vivo and in vitro was similar throughout development. Enzyme activity was directly correlated with fruit size. As has been shown in vivo, nitrate reductase activity was also inducible in fruits grown in vitro.
Unlike other eukaryotes, which synthesize polyamines (PA) only from ornithine, plants possess an ... more Unlike other eukaryotes, which synthesize polyamines (PA) only from ornithine, plants possess an additional pathway utilizing arginine as a precursor. In this study, we have identified cDNA clones coding for a Glycine max ornithine decarboxylase (ODC, EC 4.1.1.7) and an arginine decarboxylase (ADC, EC 4.1.1.19). Expression analysis using semi-quantitative RT-PCR approach revealed that both genes coding for enzymes involved in putrescine biosynthesis (ODC and ADC) were found in most plant organs examined. Significant expression levels of both genes were detected in root tips and hypocotyls. The spatial distribution of GmODC and GmADC transcripts in primary and lateral roots and hypocotyls revealed that these genes are co-expressed in expanding cells of cortex parenchyma, expanding cells of central cylinder in main roots and in developing tissues and expanding cells of soybean hypocotyls. The data point out a correlation of the expression patterns of GmODC and GmADC gene to certain physiological roles such as organ development and cell expansion.
The apparent association of ornithine decarboxylase (ODC) with rapid cell proliferation in develo... more The apparent association of ornithine decarboxylase (ODC) with rapid cell proliferation in developing tomato (Lycopersicon esculentum Mil. cv. Pearson ms-35) fruits has been previously described. Further evidence is provided by the use of two ODC inhibitors, a-difluoromethylornithine (a-DFMO) and a-methylornithine (a-MO). Fruit development was inhibited by these inhibitors if applied during the period of intensive cell division. When applied in vitro, the two inhibitors were shown to inhibit the activity of ODC but not that of arginine decarboxylase (ADC). When applied in vivo, a-DFMO, a catalytic irreversible inhibitor, caused 97.1% reduction of ODC activity in the dialyzed extract from the treated ovaries, while it had no effect on ADC. On the other hand, a-MO, a reversible inhibitor, did not reduce the activity of these two enzymes in the dialyzed extracts when applied in vivo. The dialysis procedure probably removed a-MO from the enzyme fraction. Putrescine, the product of both ODC and ADC, aleviated the inhibition of fruit development but did not restore ODC activity to the control level. These results suggest that in the young developing tomato fruit, ODC is the enzyme responsible for the synthesis of putrescine, which is essential for the early stages of fruit development. The reduced activity of ODC elicited by putrescine suggests a mechanism of feedback regulation by enzyme repression or release of an ODC anti-enzyme.
The flowering and pollination requirements of Cereus peruvianus (L) Mill. (Cactaceae) were invest... more The flowering and pollination requirements of Cereus peruvianus (L) Mill. (Cactaceae) were investigated in Beer Sheva, Israel, in a three-year-old plantation which had been established from seedlings, in order to domesticate this plant as a fruit crop. Plants flowered during the hot season (May-October), and flowers opened for one night only. Variations were observed in the flowers' opening time, with the early-opening plants beginning to open two hours before sunset, and the late-opening plants opening close to sunset. Flowers were visited only by day-active insects: the honey bee (Apis mellifera) and the carpenter bee (Xylocopa pubescens). The visitors' behavior indicated that they were involved in pollination. Early-opening flowers were visited both in the evening and in the morning, whereas late-openers were visited only in the morning. C. peruvianus was found to be self-incompatible, and fruit set did not occur when flowers were hand self-pollinated. Hand cross-pollinat...
Key Werd Ibscisic acid; 3-methyl&at@-&Cpentadienoic acids; biological activity; germination of le... more Key Werd Ibscisic acid; 3-methyl&at@-&Cpentadienoic acids; biological activity; germination of lettuce seed; acceleration of Tropaeolum tion of transpiration. leaf' discs senescence; inhibition of wheat coleoptile elongation; inhibi-Abstract-Thirty six different 3-methylS -aryi-2Jpentadienoic acids and esters were synthesizedusing the Reformatsky and Wittig reactions. The different geometrical isomers were conveniently separated by the dry column technique. Assignment of configuration of the pentadienoic side chain was baaed on NMR and UV properties. The biological activities of the aromatic analogs of ABA were determined in four bioassays. Most of the analogs were less active than the natural hormone. Only 3-methylS -~orophenyl A2-irans,A'-bans-pentadienoic acid exhibited high ABA-like activity in all four bioassays.
S ummary Kinetin maintains the protein content of detached leaves, but the reason is not clear. T... more S ummary Kinetin maintains the protein content of detached leaves, but the reason is not clear. This work attempted to find out whether the effect arises from maintenance of protein synthesis or retardation of protein breakdown. Protein synthesis and degradation in ...
... reported that salination of tobacco plants markedly reduced cytokinin translocation from the ... more ... reported that salination of tobacco plants markedly reduced cytokinin translocation from the root and Mizrahi, Blumenfeld and Richmond (1970) showed ... Booth et al.(1962) reported that auxin affected movement of nutrients within plants and Davies and Wareing (1965) showed ...
The question is raised whether the hormonal modifications in a plant exposed to osmotic root stre... more The question is raised whether the hormonal modifications in a plant exposed to osmotic root stress result directly from the decrease in water potential of the root environment or from disturbances of the plant's water balance. Tobacco plants were held for 24 hours under either high or low relative humidities, with or without salt. The amount of abscisic acid in the leaves of salinized plants rose markedly in low, but not in high, relative humidity. No change in the amount of extractable cytokinins was detected in any treatment. It is tentatively suggested that variations in the water
Betacyanins in peel and flesh of fruits of different Hylocereus species were identified by means ... more Betacyanins in peel and flesh of fruits of different Hylocereus species were identified by means of GC/MS, electrospray MS/MS, HPLC as well as 1 H and 13 C NMR techniques. As hitherto unknown pigments: betanidin 5-O-(2 0-O-b-D-apiofuranosyl)-b-D-glucopyranoside, betanidin 5-O-(4 0-O-malonyl)-b-D-glucopyranoside and betanidin 5-O-[(5 00-O-E-sinapoyl)-2 0-O-b-D-apiofuranosyl]-b-D-glucopyranoside were elucidated. The sinapoyl moiety attachment position in the structure of betacyanins was established for the first time. The peel contained a more complex pattern of betacyanins with apiofuranosyl moiety. Other recently identified pigments were also present in the samples and their 1 H or 13 C NMR spectra were recorded. In the case of phyllocactin and its 4 0-isomer the migration of the malonyl group was noticed.
Climatic changes have created the imminent need for the development of new crops for arid regions... more Climatic changes have created the imminent need for the development of new crops for arid regions. We started to domesticate and introduce wild and exotic fruit trees to our deserts in 1984. We tested different species in five eco zones in Israel, differing from each other in terms of maximum and minimum temperatures, type and degrees of salinities, water evaporation rates, rainfall, etc. We succeeded in cultivating pitaya species using hybrids from the Hylocereus and Selenicereus genera, and with a different species from the Cactaeae Cereus peruvianus, which we named Koubo. These two species are from the Cactaceae family, known for high water use efficiencies (WUE). We already have investors who started the semi-commercial production of Marula, Sclerocarya birrea sbsp. Caffra, and Argan—Argania spinosa. In spite of the fact that we developed good clones and knowledge of how to grow and ship White Sapote, Casimiroa edulis, and Indian jujube, Ziziphus mauritiana, we failed due to a l...
Numerous species of cacti were introduced in an attempt to diversify the types of fruit trees cul... more Numerous species of cacti were introduced in an attempt to diversify the types of fruit trees cultivable under the conditions of the Israeli Negev Desert. The new species were tested in five introduction orchards varying in type of soil, climate and irrigation water. Fruits of the Hylocereus genus, which must be grown on a trellis system under netting, were found to be of an attractive shape, color, appearance and taste. Cereus peruvianus, which grows outdoors, produced beautiful tasty fruits which varied in color from yellow to deep red. Fruits of these species are of the nonclimacteric type and are capable of withstanding long-distance transportation. Some have to be cross-pollinated while others can be self-pollinated. They flower twice or three times a year, bearing fruits from June to November. These types are characterized by a CAM photosynthetic pathway, pointing to high water use efficiency.
Field experiments were conducted to examine the effect of fertilization and short periods of drou... more Field experiments were conducted to examine the effect of fertilization and short periods of drought on the out-of-season winter crop in prickly pear [Opuntia ficus-indica (L.) Mill.]. In addition, the winter and summer crops were compared regarding floral bud production and fruit characteristics. Under both continuous fertigation (N, P, K applied with the irrigation water) and continuous irrigation, the number of floral buds per plant was much lower in the winter than in the summer crop. Fertilization increased production of floral buds in both crops, but to a greater extent in the winter crop. The increase in floral bud production in fertilized plants was associated with an increase in NO3-N content in the cladodes. Suspension of fertigation for 4 or 8 weeks immediately after the summer harvest decreased cladode water content and delayed and reduced floral bud emergence as compared with continuous fertigation (control) or late drought (4 or 8 weeks) applied 4 weeks after the summe...
The reproductive biology of the climbing cacti Hylocereus polyrhizus (Weber) Britt. & Rose, H. un... more The reproductive biology of the climbing cacti Hylocereus polyrhizus (Weber) Britt. & Rose, H. undatus (Haworth) Britt. & Rose, H. costaricensis (Weber) Britt. & Rose, and Selenicereus megalanthus (Schum. ex Vaupel) Moran (syn. Mediocactus megalanthus) was studied with the aim of cultivating the cacti in Israel as fruit crops. Flowering in Hylocereus spp. occurred in two to three waves during the summer, whereas in S. megalanthus, flowering was concentrated at the end of autumn. Flowers of all species opened 1 to 1.5 hours before sunset and closed ≈6 hours after sunrise. In the Hylocereus spp., H. polyrhizus and H. costaricensis were self-unfruitful, and cross-pollination with other species led to high fruit set (100%). Hylocereus undatus was self-fruitful, setting fruit with self-pollen. Cross-pollination between the clones of S. megalanthus led to a high fruit set and each clone was self-fruitful. In contrast to H. undatus, S. megalanthus clones could set fruit without pollen vect...
Fruit growth and ripening and the effect of various storage temperatureson fruit quality were stu... more Fruit growth and ripening and the effect of various storage temperatureson fruit quality were studied in Hylocereus undatus and H. polyrhizus growing in Beer-Sheva (Israeli Negev desert) under greenhouse conditions. Dimensional growth of the fruit had a sigmoid pattern with a negligible growth after the onset of peel color change. The first change in peel color was recorded 24-25 d after anthesis in H. undatus and 26-27 d after anthesis in H. polyrhizus. In both species, peel color turned fully red 4-5 days after first color change (mean temperature for the study period was 26.6 ± 2.1 °C). Parallel to color changes the content of pulp, SSC and soluble sugars increased while firmness and the content of starch and mucilage decreased. The surge in acidity before color change indicated the beginning of ripening processes. In H. polyrhizus fruit, which have a red-violet pulp, the pigment increased in parallel to the development of peel color. The fruit were proved nonclimacteric, and whe...
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