Papers by eliezer goldschmidt
The Open Plant Science Journal, 2013
Grafting is an important, widely used plant propagation technique but its physiological effects a... more Grafting is an important, widely used plant propagation technique but its physiological effects are as yet insufficiently understood. Recent studies indicate that movement of proteins and small RNAs through the graft union might be involved. MicroRNAs are known to play a significant role in regulation of higher plants’ developmental and metabolic traits. Extending this logic, we hypothesize that changes in activity of specific microRNAs are one of the mechanisms involved in physiological effects of grafting. The objective of the present study was to test this hypothesis. We determined the expression of a broad range of microRNAs in Citrus leaf petioles, as affected by grafting. Four stock/scion combinations (‘Merav’ mandarin and ‘Star Ruby‘ grapefruit scions X ‘Troyer’ citrange and ‘Volkamer’ lemon rootstocks), rootstock auto-grafts and plants of the variety used as rootstock (= non-grafted) were examined. Grafting caused a dramatic reduction in the expression of the major microRNAs...
The Open Plant Science Journal, 2013
Grafting is an important, widely used plant propagation technique but its physiological effects a... more Grafting is an important, widely used plant propagation technique but its physiological effects are as yet insufficiently understood. Recent studies indicate that movement of proteins and small RNAs through the graft union might be involved. MicroRNAs are known to play a significant role in regulation of higher plants’ developmental and metabolic traits. Extending this logic, we hypothesize that changes in activity of specific microRNAs are one of the mechanisms involved in physiological effects of grafting. The objective of the present study was to test this hypothesis. We determined the expression of a broad range of microRNAs in Citrus leaf petioles, as affected by grafting. Four stock/scion combinations (‘Merav’ mandarin and ‘Star Ruby‘ grapefruit scions X ‘Troyer’ citrange and ‘Volkamer’ lemon rootstocks), rootstock auto-grafts and plants of the variety used as rootstock (= non-grafted) were examined. Grafting caused a dramatic reduction in the expression of the major microRNAs...
Plant, Cell and Environment, 1979
Page 1. Plant, Cell and Environment (1979) 2,155-158. Bulbing of onions {Allium eepa L.): The rol... more Page 1. Plant, Cell and Environment (1979) 2,155-158. Bulbing of onions {Allium eepa L.): The role of endogenous ethylene DAVID LEVY, ELIEZER E. GOLDSCHMIDT & NAHUM KEDAR Department of Vegetable Crops, Volcani ...
Journal of the American Society for Horticultural Science
The chlorotic appearance of mineral-deficient citrus leaves presumably reflects degradative chang... more The chlorotic appearance of mineral-deficient citrus leaves presumably reflects degradative changes in chloroplast components, most of which have nitrogen as a principal constituent. To examine this assumption the size of some major nitrogen pools, the SDS-PAGE pattern of soluble and chloroplast membranal proteins, and the activities of nitrate reductase and ribulose bisphosphate carboxylase (RuBPcase) were determined in leaves of rough-lemon (Citrus volkameriana Ten. & Pasq) plants grown hydroponically for 3 to 10 months under K, Mg, and Ca deficiencies. Plants grown under minerally deficient conditions produced less biomass. Leaves developing under K, Mg, and Ca-deficient conditions had significantly reduced concentrations of the respective elements. Chlorophyll levels of the chlorotic Mg and Ca-deficient leaves were lower than those of control leaves but chlorophyll a/b ratios were not markedly different. Calcium deficiency caused significant decreases in total nitrogen, nitrates...
Plant and Cell Physiology
抄録 The fate of gibberellins (GAs) was studied in the flavedo (the external colored peel layer) of... more 抄録 The fate of gibberellins (GAs) was studied in the flavedo (the external colored peel layer) of green-harvested orange fruits, during natural and ethylene-induced senescence. GA-like substances were determined by the sugar-release barley endosperm bioassay. ...
Hortscience, 1989
Acidification of treatment solutions from pH 7 to 4, with either citratephosphate(CP) buffer or w... more Acidification of treatment solutions from pH 7 to 4, with either citratephosphate(CP) buffer or with dimethylglutaric acid-NaOH(DMG) buffer, increased [ 14 C] GA 3 uptake by «Marsh» grapefruit(Citrus paradisi Macf.) peel. Acidification was effective also when wax was removed with organic solvents and under low and high relative humidity. Acidification with either buffer permitted the use of lower GA 3 concentrations than those required to obtain the same physiological effect with neutral solutions
Plant molecular biology, 1997
Maturing citrus fruit undergo pigment changes which can be enhanced by exogenous ethylene. In ord... more Maturing citrus fruit undergo pigment changes which can be enhanced by exogenous ethylene. In order to identify genes induced by ethylene in citrus fruit peel, we cloned the gene c-thi1. mRNA corresponding to c-thi1 increased gradually in the peel during natural fruit maturation and in response to ethylene. GA3 pretreatment reduced the inductive effect of ethylene. Levels of c-thi1 increased also in juice sacs but the effect of ethylene was much less prominent. c-thi1 is homologous to yeast and plant genes encoding for an enzyme belonging to the pathway of thiamine biosynthesis. The data suggest that thiamine is involved in citrus fruit maturation.
The Biology of Citrus, 1996
The Biology of Citrus, 1996
Plant Science Letters, 1981
... SOME CHARACTERISTICS OF THE Mg-ATPase OF ISOLATED RED BEET VACUOLES ARIE ADMONa, BENJAMIN JAC... more ... SOME CHARACTERISTICS OF THE Mg-ATPase OF ISOLATED RED BEET VACUOLES ARIE ADMONa, BENJAMIN JACOBYa and ELIEZER E ... 19 TK Hodges, ATPase associated with membranes of plant cells, in: U. Liittge and MG Pitman (Eds.), Encyclopedia of Plant ...
Postharvest Biology and Technology, 2007
During postharvest storage or after exposure to anaerobic atmospheres, mandarins develop off-flav... more During postharvest storage or after exposure to anaerobic atmospheres, mandarins develop off-flavors much more rapidly than other citrus varieties, and the occurrence of these off-flavors is associated with increases in juice ethanol and acetaldehyde (AA) levels. However, the reasons why mandarins accumulate more off-flavor volatiles than other varieties are not yet understood. We studied the roles of various molecular, biochemical and anatomical factors in governing ethanolic fermentation in 'Murcott' mandarins and 'Star Ruby' grapefruit under aerobic and anaerobic conditions, and found that exposure to N 2 atmospheres for 24 h increased accumulation of ethanol and AA in the juice and peel of mandarins much more than in grapefruit. However, exposure to anaerobic atmospheres increased pyruvate kinase (PK), pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) transcript levels in both cultivars by similar amounts, suggesting that post-transcriptional and perhaps other regulatory mechanisms must be involved in governing ethanol fermentation rates. Exposure to anaerobic atmospheres increased PDC enzyme activity in both mandarins and grapefruit but had only minor effects on ADH activity. Nevertheless, mandarins had much higher (3.8-fold) levels of ADH enzyme activity in their juice vesicles than grapefruit. Anatomical observations revealed that although the total thickness of the peel (comprising the albedo, the white inner layer and the flavedo, the colored outer layer) was greater in grapefruit, the dense flavedo layer was considerably thicker in mandarins. In mandarins, the flavedo also contained more oil glands than that of grapefruit, and the albedo was thinner but more condensed. Accordingly, gas diffusion tests indicated that the peel of mandarins was less permeable to gases, and especially to ethanol vapors, than that of grapefruit. Overall, we conclude that mandarins accumulate larger amounts of AA and ethanol after harvest than grapefruit do because of higher ADH enzyme activity levels in the juice, and because their peel is less permeable to gases. The latter characteristic prevents the release of the produced off-flavor volatiles from mandarins, which results in buildup of ethanol and AA in the internal atmosphere of the fruit and the consequent perception of off-flavors.
PLANT PHYSIOLOGY, 1976
Reducing the level of endogenous ethylene in detached Shamouti oranges (Citrus sinensis L. Osbeck... more Reducing the level of endogenous ethylene in detached Shamouti oranges (Citrus sinensis L. Osbeck) by means of subatmospheric pressure did not alter the rate of chlorophyll destruction and color changes during the first 8 days after harvest in the presence or absence of exogenous ethylene. Reducing the activity of ethylene by means of CO2known to be a competitive inhibitor for ethyleneinhibited chlorophyll destruction and color change in Shamouti oranges ventilated with ethylene, but had no effect on these processes in the absence of applied ethylene. The evidence presented indicates that endogenous ethylene may not be the primary inducer for the natural color change in detached Shamouti oranges.
PLANT PHYSIOLOGY, 1989
EGTA, a specific Ca2+ chelator, inhibited the flowering response of Pharbitis nil when applied to... more EGTA, a specific Ca2+ chelator, inhibited the flowering response of Pharbitis nil when applied to the cotyledons immediately before the inductive dark period. Calcium sprayed 30 minutes after the EGTA blocked the effect of EGTA. The length of the critical dark period was increased both by EGTA and by LaCI3. The calmodulin antagonists W-7 and chlorpromazine also reduced the flowering response. On the other hand, A23187, a calcium ionophore, increased the flowering response. Both EGTA and A23187 were effective at certain times of the photoperiod but had almost no effect when applied at other times. The results indicate that the level of endogenous Ca2+ may be limiting for floral induction in Ph. nil. Ca2+ seems to play a role during the early stages of the inductive dark period.
Plant Growth Regulation, 2013
The present report describes the effect of 3-cyclopropyl-1-enyl-propanoic acid sodium salt (CPAS-... more The present report describes the effect of 3-cyclopropyl-1-enyl-propanoic acid sodium salt (CPAS-WO 2010/0822930), a novel water soluble ethylene antagonist, on senescence and grain yield of several cultivars of common wheat (Triticum aestivum L.) and durum wheat (T. durum Desf.). CPAS abolished ethyleneinduced leaf and ear organ senescence, as evidenced by the inhibition of chlorophyll degradation. CPAS application to wheat plants grown under controlled (120 mg L-1) or field conditions (110 mg L-1) significantly increased grain yield in the range of 9-13 % and 3-45 %, respectively, depending on treatment and variety. The CPAS-induced increase in grain yield was usually more significant under extreme weather conditions. In some cases spraying once at the medium milk stage was sufficient to obtain the maximum increase in grain yield, while in other cases spraying twice at the medium and late milk stages yielded the highest increase. The above data support the common view, that there is a positive causal relationship between the delay of leaf and ear organ senescence and grain yield. The results of the present study demonstrate that CPAS can effectively be used to increase wheat grain yield, and possibly the yield of other field crops, under field conditions. Keywords Chlorophyll Á Ethylene antagonist Á Grain weight Á Senescence Á Wheat Abbreviations CPAS 3-cyclopropyl-1-enyl-propanoic acid sodium salt 1-MCP 1-methylcyclopropene This paper is dedicated to Prof. Edward C. Sisler from North Carolina State University USA, for introducing me thirty years ago to the subject of ethylene antagonist research. Prof. R.Goren.
Plant Cell Reports, 1983
Chromoplast fractions from mature, chlorophyll-less 'Valencia' orange (Citrus sin... more Chromoplast fractions from mature, chlorophyll-less 'Valencia' orange (Citrus sinensis L. Osbeck) flavedo (= the outer coloured layer of citrus peel) showed considerable chlorophyllase activity. Acetone powders prepared from chromoplast fractions had 2.5× higher specific activity than those prepared from whole flavedo. Exposure of mature, chlorophyll-less fruit to ethylene caused a 2.5 to 4.0 fold increase in chlorophyllase activity. Juice chromoplasts showed negligible chlorophyllase activity. The results suggest that chlorophyllase activity as well as its induction by ethylene are not dependent upon the presence of chlorophyll in the tissue.
Journal of Experimental Botany, 2003
This study investigated the effects of radiation heatload reduction by shading on the growth and ... more This study investigated the effects of radiation heatload reduction by shading on the growth and development of citrus trees in a warm subtropical region. The experiment was conducted from mid-June until late October when daily maximal air temperature averaged 29.3°C. Two-year-old de-fruited Murcott tangor (Citrus reticulata BlancoQCitrus sinensis (L.) Osb.) trees were grown under 30% or 60% shade tunnels, or 60%¯at shade (providing midday shade only), using highly re¯ective aluminized nets. Nonshaded trees were used as the control. Shading reduced direct more than diffuse radiation. Daily radiation was reduced by 35% for the 30% Tunnel and 60% Flat treatments, and by 55% for the 60% Tunnel. Two days of intensive measurement showed that shading increased average sunlit leaf conductance by 44% and photosynthesis by 29%. Shading did not signi®cantly in¯uence root and stem dry weight growth, but it increased the increment in leaf dry weight during the three month period by an average of 28% relative to the control, while ®nal tree height in the 30% Tunnel treatment exceeded the control by 35%. Shoot to root and shoot mass ratios increased and root mass ratio decreased due to shading because of the increase in leaf dry weight. Shading increased starch concentration in leaves while the shadiest treatment, 60% Tunnel, decreased starch concentration in the roots. Carbon isotope ratio (d 13 C) of exposed leaves that developed under shading was signi®cantly reduced by 1.9½ in the 60% Tunnel, indicating that shading increased CO 2 concentrations at the chloroplasts (C c), as would be expected from increased conductance. Substomatal CO 2 concentrations, C i , computed from leaf net CO 2 assimilation rate and conductance values, also indicate that shading increases internal CO 2 concentrations. Based on tree dry mass, tree height, and total carbohydrates fractions, the 30% Tunnel and the 60% Flat were the optimal shade treatments.
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Papers by eliezer goldschmidt