Publications by year


Publications by Authors

Recent Publications


Contact Us

Head of Institute: Prof. Oren Froy

Administrative manager: Ms. Yael Fruchter

Office Address:
Institute of Biochemistry, Food Science and Nutrition,
Robert H. Smith Faculty of Agriculture, Food and Environment,
The Hebrew University of Jerusalem, 
P.O.Box 12, Rehovot 7610001, ISRAEL

Tel: +972 - (0)8-9489385
Fax: +972 - (0)8-9363208
Email Address:


Basheer, L. ; Dag, A. ; Yermiyahu, U. ; Ben-Gal, A. ; Zipori, I. ; Kerem, Z. Effects of reclaimed wastewater irrigation and fertigation level on olive oil composition and quality. Journal of the Science of Food and Agriculture 2019, 99, 6342-6349. Publisher's VersionAbstract
BACKGROUND: Irrigation of olives increases fruit and oil yields. Due to scarcity of freshwater, low-quality water including recycled wastewater (RWW) is utilized in orchards. Here, effects of irrigation with RWW and of fertilization on the composition and quality of olive oil were studied. RESULTS: Long-term RWW irrigation of ‘Barnea’ and ‘Leccino’ olive had no significant negative effects on either oil composition or quality parameters, including free fatty acids (FFAs), peroxide value (PV), total phenolics content (TPC), fatty acid profiles and organoleptic characteristics. The average FFA contents for both cultivars were less than 0.8% during most of the experimental period, except the seasons 2009 and 2012–2013 for Barnea where the values were raised up to 1.4%. The measured PV levels were less than 9 and 5 mmol O2 kg-1 oil for Barnea and Leccino, respectively. In the last season of the experiment for each cultivar, higher TPC were observed in oils obtained from RWW irrigation with reduced fertilization (Re–) as compared to the treatments with the recommended fertilization [freshwater irrigation (Fr) and RWW irrigation (Re+) with standard dose of fertilizers], where the TPC increment exceeded 70% in Barnea and 25% in Leccino. The treatments had only minor effects on the fatty acid profile, reflected in slightly altered levels of C18:2 and C18:3 fatty acids. CONCLUSION: The use of RWW, combined with the consideration of nutrients arriving with such water to provide appropriate fertilization, was found suitable for olive irrigation to ensure optimal yields while preserving oil quality. © 2019 Society of Chemical Industry. © 2019 Society of Chemical Industry
Goldental-Cohen, S. ; Biton, I. ; Many, Y. ; Tavrizov, K. ; Dourou, A. M. ; Zemach, H. ; Tonutti, P. ; Kerem, Z. ; Avidan, B. ; Sperling, O. ; et al. Removal of flowers or inflorescences affects ‘Barnea’ olive fruitlet post-anthesis abscission. Journal of Horticultural Science and Biotechnology 2019, 94, 488-498. Publisher's VersionAbstract
A typical olive (Olea europaea L.) inflorescence consists of about 20 flowers. However, in many cultivars, only one fruit develops. This is due to massive abscission of flowers and fruitlets, which occurs during the first month after anthesis. In this study, we used the olive cultivar 'Barnea' to characterize the abscission mechanism and to try to increase fruit set by increasing the number of developed fruit per inflorescence. Removing the lateral flowers 3 weeks before anthesis increased fruit set by more than 50%. Removing all inflorescences but one from a branch increased the number of developed fruits from 0.93 to 2.8 during 2017 and from 0.91 to 3.34 fruits per inflorescence in 2018. Sugar quantification in the pistil revealed that starch level is high on the day of anthesis and low 25 days later in abscised as well as in developed fruit. Soluble carbohydrates are low on the day of anthesis, low in abscised flowers/fruitlets 25 days after anthesis and high in developed fruit. Screening the natural variation found in the Israeli germplasm collection revealed that in most cultivars less than one fruit per inflorescence has developed. However, there are unique cultivars with a higher fruit set. © 2018, © 2018 The Journal of Horticultural Science & Biotechnology Trust.
Yedidia, I. ; Schultz, K. ; Golan, A. ; Gottlieb, H. E. ; Kerem, Z. Structural elucidation of three novel kaempferol otri-glycosides that are involved in the defense response of hybrid ornithogalum to pectobacterium carotovorum. Molecules 2019, 24. Publisher's VersionAbstract
Ornithogalum is an ornamental flowering species that grows from a bulb and is highly susceptible to soft-rot disease caused by Pectobacterium carotovorum (Pc). Interspecific hybridization between O. thyrsoides and O. dubium yielded hybrids with enhanced resistance to that pathogen. The hybrids displayed distinct phenolic-compound profiles with several peaks that were specifically heightened following Pc infection. Three of these compounds were isolated and identified as novel kaempferol O-tri-glycosides. The structures of these compounds were elucidated using reversed phase high-performance liquid chromatography (RP-LC), RP-LC coupled to high-resolution mass spectrometry (RP-LC-MS), and nuclear magnetic resonance (NMR) (1D 1H and 13C, DEPT, HMQC, HMBC, COSY, and NOE), in order to achieve pure and defined compounds data. The new compounds were finally identified as kaempferol 3-O-[4-O-α-L-(3-O-acetic)-rhamnopyranosyl-6-O- β-D-xylopyranosyl]-β-D-glucopyranoside, kaempferol 3-O-[4-O-α-L-(2-O-acetic)-rhamnopyranosyl- 6-O-β-D-xylopyranosyl]-β-D-glucopyranoside and kaempferol 3-O-[4-O-α-L-(2,3-O-diacetic)- rhamnopyranosyl-6-O-β-D-xylopyranosyl]-β-D-glucopyranoside. © 2019 MDPI AG. All rights reserved.
de Roos, B. ; Aura, A. - M. ; Bronze, M. ; Cassidy, A. ; Conesa, M. - T. G. ; Gibney, E. R. ; Greyling, A. ; Kaput, J. ; Kerem, Z. ; Knežević, N. ; et al. Targeting the delivery of dietary plant bioactives to those who would benefit most: from science to practical applications. European Journal of Nutrition 2019, 58, 65-73. Publisher's VersionAbstract
Background: A healthy diet and optimal lifestyle choices are amongst the most important actions for the prevention of cardiometabolic diseases. Despite this, it appears difficult to convince consumers to select more nutritious foods. Furthermore, the development and production of healthier foods do not always lead to economic profits for the agro-food sector. Most dietary recommendations for the general population represent a “one-size-fits-all approach” which does not necessarily ensure that everyone has adequate exposure to health-promoting constituents of foods. Indeed, we now know that individuals show a high variability in responses when exposed to specific nutrients, foods, or diets. Purpose: This review aims to highlight our current understanding of inter-individual variability in response to dietary bioactives, based on the integration of findings of the COST Action POSITIVe. We also evaluate opportunities for translation of scientific knowledge on inter-individual variability in response to dietary bioactives, once it becomes available, into practical applications for stakeholders, such as the agro-food industry. The potential impact from such applications will form an important impetus for the food industry to develop and market new high quality and healthy foods for specific groups of consumers in the future. This may contribute to a decrease in the burden of diet-related chronic diseases. © 2019, The Author(s).
Milenkovic, D. ; Declerck, K. ; Guttman, Y. ; Kerem, Z. ; Claude, S. ; Weseler, A. R. ; Bast, A. ; Schroeter, H. ; Morand, C. ; Vandenberghe, W. (−)-Epicatechin metabolites promote vascular health through epigenetic reprogramming of endothelial-immune cell signaling and reversing systemic low-grade inflammation. Biochemical Pharmacology 2019. Publisher's VersionAbstract
Ingestion of (−)-epicatechin flavanols reverses endothelial dysfunction by increasing flow mediated dilation and by reducing vascular inflammation and oxidative stress, monocyte-endothelial cell adhesion and transendothelial monocyte migration in vitro and in vivo. This involves multiple changes in gene expression and epigenetic DNA methylation by poorly understood mechanisms. By in silico docking and molecular modeling we demonstrate favorable binding of different glucuronidated, sulfated or methylated (−)-epicatechin metabolites to different DNA methyltransferases (DNMT1/DNMT3A). In favor of this model, genome-wide DNA methylation profiling of endothelial cells treated with TNF and different (−)-epicatechin metabolites revealed specific DNA methylation changes in gene networks controlling cell adhesion-extravasation endothelial hyperpermeability as well as gamma-aminobutyric acid, renin-angiotensin and nitric oxide hypertension pathways. Remarkably, blood epigenetic profiles of an 8 weeks intervention with monomeric and oligomeric flavanols (MOF) including (−)-epicatechin in male smokers revealed individual epigenetic gene changes targeting similar pathways as the in vitro exposure experiments in endothelial cells. Furthermore, epigenetic changes following MOF diet intervention oppose atherosclerosis associated epigenetic changes. In line with biological data, the individual epigenetic response to a MOF diet is associated with different vascular health parameters (glutathione peroxidase 1 and endothelin-1 expression, acetylcholine-mediated microvascular response), in part involving systemic shifts in blood immune cell types which reduce the neutrophil–lymphocyte ratio (NLR). Altogether, our study suggests that different (−)-epicatechin metabolites promote vascular health in part via epigenetic reprogramming of endothelial-immune cell signaling and reversing systemic low-grade inflammation. © 2019 Elsevier Inc.
Guttman, Y. ; Nudel, A. ; Kerem, Z. Polymorphism in Cytochrome P450 3A4 Is Ethnicity Related. Front. Genet., 2019, 10, 224. Publisher's VersionAbstract
Can mutations in cytochrome P450 3A4 (CYP3A4), the major food- and drug-metabolizing enzyme, serve as biomarkers for personalized precise medicine? Classical genetic studies provide only limited data regarding the frequencies of CYP3A4 mutations and their role in food-drug interactions. Here, in an analysis of one large database of 141,456 individuals, we found 856 SNPs (single nucleotide polymorphism), of which 312 are missense mutations, far more than the previously reported dozens. Analyzing the data further, it is demonstrated that the frequency of mutations differs among ethnic groups. Hierarchical clustering divided the mutations into seven groups, each corresponding to a specific ethnicity. To the best of our knowledge, this is the first comprehensive analysis of CYP3A4 allele frequencies in distinct ethnic groups. We suggest ethnicity based classification of CYP3A4 SNPs as the first step towards precise diet and medicine. Understanding which and when polymorphism might have clinical significance is a tremendously complex task. Using a modeling approach, we could predict changes in the binding poses of ligands in the active site of single variants. These changes might imply clinical effects of the overlooked protein-altering CYP3A4 mutations, by modifying drug metabolism and FDI. It may be concluded that dietary habits, and hence FDI, are matters of ethnicity. Consequently, ethnic-related polymorphism in CYP3A4 and diet may be one underlying mechanism of response to medical regimes. The approaches presented here have the power to highlight mutations of clinical relevance in any gene of interest, thus to complement the arsenal of classic genetic screening tools.
Cohen-Goldental, S. ; Biton, I. ; Zemach, H. ; Many, Y. ; Tonutti, P. ; Kerem, Z. ; Ben-Ari, G. Fruitlet abscission in olive (Olea europaea L.). In Acta Horticulturae; Acta Horticulturae; International Society for Horticultural Science (ISHS), Leuven, Belgium, 2018; pp. 215 - 220. Publisher's Version
Dag, A. ; Erel, R. ; Kerem, Z. ; Ben-Gal, A. ; Stern, N. ; Bustan, A. ; Zipori, I. ; Yermiyahu, U. Effect of nitrogen availability on olive oil quality. In Acta Horticulturae; Acta Horticulturae; International Society for Horticultural Science (ISHS), Leuven, Belgium, 2018; pp. 465 - 470. Publisher's Version
van-Oss, R. P. ; Gopher, A. ; Kerem, Z. ; Peleg, Z. ; Lev-Yadun, S. ; Sherman, A. ; Zhang, H. - B. ; Vandemark, G. ; Coyne, C. J. ; Reany, O. ; et al. Independent selection for seed free tryptophan content and vernalization response in chickpea domestication. Plant Breeding 2018, 137, 290-300. Publisher's VersionAbstract
Abstract Chickpea shows a distinct domestication trajectory vis-a-vis pod dehiscence and growth cycle mediated by vernalization insensitivity compared with its companion Near Eastern legumes. Our objectives were: (i) to map the quantitative trait loci (QTLs) associated with vernalization response and seed free tryptophan in domesticated × wild chickpea progeny and (ii) estimate the genetic correlation between vernalization response and free tryptophan content. A domesticated × wild chickpea cross was used to document phenotypic segregation in both traits and to construct a skeletal genetic map for QTL detection. A number of vernalization response and seed free tryptophan content QTLs were documented in both F2 and F3 generations. No significant genetic correlation between these two traits was observed. Epistatic relationship between two free tryptophan loci was documented. It is evident that selection for high seed tryptophan is easier to accomplish relative to selection for vernalization insensitivity. This suggests that the two traits were selected independently in antiquity, thereby corroborating earlier claims for conscious selection processes associated with chickpea domestication.
Barazani, O. ; Waitz, Y. ; Tugendhaft, Y. ; Dorman, M. ; Dag, A. ; Hamidat, M. ; Hijawi, T. ; Kerem, Z. ; Westberg, E. ; Kadereit, J. W. Testing the potential significance of different scion/rootstock genotype combinations on the ecology of old cultivated olive trees in the southeast Mediterranean area. 2017, 17, 3. Publisher's VersionAbstract
A previous multi-locus lineage (MLL) analysis of SSR-microsatellite data of old olive trees in the southeast Mediterranean area had shown the predominance of the Souri cultivar (MLL1) among grafted trees. The MLL analysis had also identified an MLL (MLL7) that was more common among rootstocks than other MLLs. We here present a comparison of the MLL combinations MLL1 (scion)/MLL7 (rootstock) and MLL1/MLL1 in order to investigate the possible influence of rootstock on scion phenotype.
Elyasiyan, U. ; Nudel, A. ; Skalka, N. ; Rozenberg, K. ; Drori, E. ; Oppenheimer, R. ; Kerem, Z. ; Rosenzweig, T. Anti-diabetic activity of aerial parts of Sarcopoterium spinosum. 2017, 17, 356. Publisher's VersionAbstract
Sarcopoterium spinosum (S. spinosum) is used by Bedouin medicinal practitioners for the treatment of diabetes. While the anti-diabetic activity of S. spinosum root extract was validated in previous studies, the activity of aerial parts of the same plants has not been elucidated yet. The aim of this study was to clarify the glucose lowering properties of the aerial parts of the shrub.
Ehrlich, Y. ; Regev, L. ; Kerem, Z. ; Boaretto, E. Radiocarbon Dating of an Olive Tree Cross-Section: New Insights on Growth Patterns and Implications for Age Estimation of Olive Trees. Frontiers in Plant Science 2017, 8 1918. Publisher's VersionAbstract
The age of living massive olive trees is often assumed to be between hundreds and even thousands of years. These estimations are usually based on the girth of the trunk and an extrapolation based on a theoretical annual growth rate. It is difficult to objectively verify these claims, as a monumental tree may not be cut down for analysis of its cross-section. In addition, the inner and oldest part of the trunk in olive trees usually rots, precluding the possibility of carting out radiocarbon analysis of material from the first years of life of the tree. In this work we present a cross-section of an olive tree, previously estimated to be hundreds of years old, which was cut down post-mortem in 2013. The cross-section was radiocarbon dated at numerous points following the natural growth pattern, which was made possible to observe by viewing the entire cross-section. Annual growth rate values were calculated and compared between different radii. The cross-section also revealed a nearly independent segment of growth, which would clearly offset any estimations based solely on girth calculations. Multiple piths were identified, indicating the beginning of branching within the trunk. Different radii were found to have comparable growth rates, resulting in similar estimates dating the piths to the 19th century. The estimated age of the piths represent a terminus ante quem for the age of the tree, as these are piths of separate branches. However, the tree is likely not many years older than the dated piths, and certainly not centuries older. The oldest radiocarbon-datable material in this cross-section was less than 200 years old, which is in agreement with most other radiocarbon dates of internal wood from living olive trees, rarely older than 300 years.
Basheer, L. ; Schultz, K. ; Guttman, Y. ; Kerem, Z. In silico and in vitro inhibition of cytochrome P450 3A by synthetic stilbenoids. Food Chemistry 2017, 237, 895 - 903. Publisher's VersionAbstract
Inhibition of cytochrome P450 3A4 (CYP3A4), the major drug metabolizing enzyme, by dietary compounds has recently attracted increased attention. Evaluating the potency of the many known inhibitory compounds is a tedious and time consuming task, yet it can be achieved using computing tools. Here, CDOCKER and Glide served to design model inhibitors in order to characterize molecular features of an inhibitor. Assessing nitro-stilbenoids, both approaches suggested nitrostilbene to be a weaker inhibitor of CYP3A4 than resveratrol, and stronger than dimethoxy-nitrostilbene. Nitrostilbene and resveratrol, but not dimethoxy-nitrostilbene, engage electrostatic interactions in the enzyme cavity, and with the haem. In vitro assessment of the inhibitory capacity supported the in silico predictions, suggesting that evaluating the electrostatic interactions of a compound with the prosthetic group allows the prediction of inhibitory potency. Since both programs yielded related results, it is suggested that for CYP3A4, computing tools may allow rapid identification of potent dietary inhibitors.
Zipori, I. ; Bustan, A. ; Kerem, Z. ; Dag, A. Olive paste oil content on a dry weight basis (OPDW): An indicator for optimal harvesting time in modern olive orchards. Grasas y Aceites 2016, 67. Publisher's Version
Sebastiani, L. ; Gucci, R. ; Kerem, Z. ; Fernández, J. E. Physiological Responses to Abiotic Stresses. In The Olive Tree Genome; Rugini, E. ; Baldoni, L. ; Muleo, R. ; Sebastiani, L., Ed. The Olive Tree Genome; Springer International Publishing: Cham, 2016; pp. 99 - 122. Publisher's VersionAbstract
Olive (Olea europaea L.) trees are widespread in Mediterranean agroecosystems and are now extensively cultivated in different warm-temperate regions of the world such as North and South America, Australia, New Zealand, and South Africa, and even in the monsoon systems of China and India. In the Mediterranean area, the biological and agronomical success of this species is due to its adaptability to the Mediterranean climatic conditions: mild, wet winters with temperatures that drop below 10 °C but rarely below 0 °C and warm, dry summers. When weather conditions become more extreme (drought, high, or low temperatures) or soil conditions are not optimal for olive growth (salinity, low oxygen, nutrient deficiencies), the plant can be subjected to abiotic stresses, which may have negative effects on its physiology. The damages derived from stresses caused by environmental constrains are often not immediately recognized in olive orchards, since plants are largely grown in non-specialized planting systems that are managed with limited cultural practices. However, due to the renewed interest in extra-virgin olive oil for its beneficial health effects, olive cultivation has now been modified from traditional low-density and low-input to high-density and high-input growing systems. Information on the effect of abiotic stresses on trees under the new cultivation systems is scarce due to the wide differences in management practices, environmental conditions and the increase in the use of selected varieties. Under these new conditions, the abiotic factors and their related stresses might have a strong impact on both yield and quality. In this chapter, we focus on physiological responses of olive trees to drought, salinity, and temperature stress. The reader can refer to the existing literature for other abiotic stresses.
Rosianski, Y. ; Freiman, Z. E. ; Cochavi, S. M. ; Yablovitz, Z. ; Kerem, Z. ; Flaishman, M. A. Advanced analysis of developmental and ripening characteristics of pollinated common-type fig (Ficus carica L.). 2016, 198, 98 - 106. Publisher's VersionAbstract
Development and ripening processes differ in pollinated and parthenocarpic fruit. While the facultative parthenocarpic common-type fig fruit serves as a receptacle for flower development, it becomes fleshy by either pollination or through a parthenocarpic process. Here we studied the effect of pollination on common-type fig fruit development and ripening characteristics compared to the parthenocarpic fruit under otherwise identical conditions. The effects of pollination on fruit development were investigated on the tree and in storage. Pollinated fruit showed altered developmental processes. Ripened pollinated fruit were round, in contrast to the pear-like shape of the parthenocarpic fruit. The pollinated fruit also had a larger diameter and weight and improved firmness compared to the parthenocarpic fruit. At harvest, the pollinated fruit exhibited more commercially desirable physical and taste characteristics, with advanced fertile nutlets compared to the sterile undeveloped non-bearing nutlets of the parthenocarpic fruit. During storage, senescence and spoilage of the pollinated fruit were slower than in parthenocarpic fruit, as manifested by firmness, internal texture, weight, size, shriveling, and decay. Thus, pollination of the common-type fig cultivar Brown Turkey delayed senescence and extended the shelf life of its fruit. The external and internal morphological differences throughout post-pollination development make common-type fig an excellent research tool for studies of physiological and molecular aspects of pollination.
Tugendhaft, Y. ; Eppel, A. ; Kerem, Z. ; Barazani, O. ; Ben-Gal, A. ; Kadereit, J. W. ; Dag, A. Drought tolerance of three olive cultivars alternatively selected for rain fed or intensive cultivation. 2016, 199, 158 - 162. Publisher's VersionAbstract
Physiological drought response was evaluated for two olive cultivars commonly grown under rain fed conditions (‘Souri’ and ‘Picual’) and another selected for intensive, irrigated cultivation (‘Barnea’). ‘Souri’ is a traditional local Israeli cultivar, ‘Picual’ originated in Spain and ‘Barnea’ is a modern Israeli cultivar. Trees in pots were alternatively provided well irrigated conditions (100% FC, field capacity) or allowed to dry, first to 33% FC and then to 10% FC. Under conditions of greatest water availability, the ‘Barnea’ cultivar had the highest stomatal conductance and net photosynthesis, significantly higher than that found in ‘Souri’. Stomatal conductance and leaf water potential of ‘Souri’ and ‘Picual’ at 33% FC were not affected relative to the well irrigated treatment but decreased significantly at 10% FC. Photosynthetic parameters of ‘Souri' and ‘Picual’ were not affected by water stress. Stem growth was also not affected by drought in ‘Souri’ but was reduced at 10% FC in ‘Picual’. In contrast, the ‘Barnea’ showed higher sensitivity to low water availability with stomatal conductance and net photosynthesis reduced at 33% FC and sharp decreases in these and leaf water potential occurring at 10% FC. At 10% FC ‘Barnea’ trees showed stem shrinkage, a phenomenon not observed in the other cultivars. These results suggest a tradeoff between selection for suitability in intensively irrigated orchards and tolerance to drought.
Rosianskey, Y. ; Dahan, Y. ; Yadav, S. ; Freiman, Z. E. ; Milo-Cochavi, S. ; Kerem, Z. ; Eyal, Y. ; Flaishman, M. A. Chlorophyll metabolism in pollinated vs. parthenocarpic fig fruits throughout development and ripening. 2016, 244, 491 - 504. Publisher's VersionAbstract
Expression of 13 genes encoding chlorophyll biosynthesis and degradation was evaluated. Chlorophyll degradation was differentially regulated in pollinated and parthenocarpic fig fruits, leading to earlier chlorophyll degradation in parthenocarpic fruits.
Basheer, L. ; Schultz, K. ; Kerem, Z. Inhibition of cytochrome P450 3A by acetoxylated analogues of resveratrol in in vitro and in silico models. 2016, 6 31557. Publisher's VersionAbstract
Many dietary compounds, including resveratrol, are potent inhibitors of CYP3A4. Here we examined the potential to predict inhibition capacity of dietary polyphenolics using an in silico and in vitro approaches and synthetic model compounds. Mono, di and tri-acetoxy resveratrol were synthesized, a cell line of human intestine origin and microsomes from rat liver served to determine their in vitro inhibition of CYP3A4 and compared to that of resveratrol. Docking simulation served to predict the affinity of the synthetic model compounds to the enzyme. Modelling of the enzyme’s binding site revealed three types of interaction: hydrophobic, electrostatic and H-bonding. The simulation revealed that each of the examined acetylations of resveratrol led to the loss of important interactions of all types. Tri-acetoxy resveratrol was the weakest inhibitor in vitro despite being the more lipophilic and having the highest affinity for the binding site. The simulation demonstrated exclusion of all interactions between tri-acetoxy resveratrol and the heme due to distal binding, highlighting the complexity of the CYP3A4 binding site, which may allow simultaneous accommodation of two molecules. Finally, the use of computational modelling may serve as a quick predictive tool to identify potential harmful interactions between dietary compounds and prescribed drugs.
Rosianski, Y. ; Doron-Faigenboim, A. ; Freiman, Z. E. ; Lama, K. ; Milo-Cochavi, S. ; Dahan, Y. ; Kerem, Z. ; Flaishman, M. A. Tissue-Specific Transcriptome and Hormonal Regulation of Pollinated and Parthenocarpic Fig (Ficus carica L.) Fruit Suggest that Fruit Ripening Is Coordinated by the Reproductive Part of the Syconium. Frontiers in Plant Science 2016, 7 1696. Publisher's VersionAbstract
In the unconventional climacteric fig (Ficus carica) fruit, pollinated and parthenocarpic fruit of the same genotype exhibit different ripening characteristics. Integrative comparative analyses of tissue-specific transcript and of hormone levels during fruit repining from pollinated vs. parthenocarpic fig fruit were employed to unravel the similarities and differences in their regulatory processes during fruit repining. Assembling tissue-specific transcripts into 147,000 transcripts with 53,000 annotated genes provided new insights into the spatial distribution of many classes of regulatory and structural genes, including those related to color, taste and aroma, storage, protein degradation, seeds and embryos, chlorophyll, and hormones. Comparison of the pollinated and parthenocarpic tissues during fruit ripening showed differential gene expression, especially in the fruit inflorescence. The distinct physiological green phase II and ripening phase III differed significantly in their gene-transcript patterns in both pulp and inflorescence tissues. Gas chromatographic analysis of whole fruits enabled the first determination of ripening-related hormone levels from pollinated and non-pollinated figs. Ethylene and auxin both increased during fruit ripening, irrespective of pollination, whereas no production of active gibberellins or cytokinins was found in parthenocarpic or pollinated ripening fruit. Tissue-specific transcriptome revealed apparent different metabolic gene patterns for ethylene, auxin and ABA in pollinated vs. parthenocarpic fruit, mostly in the fruit inflorescence. Our results demonstrate that the production of abscisic acid (ABA), non-active ABA–GE conjugate and non-active indoleacetic acid (IAA)–Asp conjugate in pollinated fruits is much higher than in parthenocarpic fruits. We suggest that fruit ripening is coordinated by the reproductive part of the syconium and the differences in ABA production between pollinated and parthenocarpic fig fruit might be the key to their different ripening characteristics.