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PubMed2004

Cloning and sequence analysis of a low temperature-induced gene from trifoliate orange with unusual pre-mRNA processing.

Exposure of cold-hardy Rubidoux trifoliate orange [Poncirus trifoliata (L) Raf.] plants to temperatures from 28 degrees C to -5 degrees C enabled us to isolate and characterize a novel citrus low-temperature gene (CLT) with two transcripts, called CLTa and CLTb, from leaves and stems. CLTa was produced when plants were subjected to low temperatures (starting at 10 degrees C), while CLTb was constitutively expressed. Both CLTa and CLTb have the same open reading frame (ORF) of 165 nucleotides and encode a small (54 deduced amino acid) protein. However, CLTa has an additional 98 nucleotides in the 3'-untranslated region (UTR) that are absent in CLTb. Expression analysis using relative quantitative RT-PCR demonstrated that CLTa is expressed exclusively at low temperatures, while CLTb is expressed constitutively (expression verified from 33 degrees C to -5 degrees C). A GenBank database search identified 61 nucleotides inside of the ORF that are highly similar to low-temperature-responsive genes from Arabidopsis thaliana and Solanum tuberosum. The deduced amino acid sequence revealed similarity with low-temperature-responsive proteins from A. thaliana, Oryza sativa, and S. tuberosum of 77%, 81%, and 73.9%, respectively. A genomic clone was isolated, and the genome organization revealed the presence of three exons and two introns, the second of which is in the 3' UTR and participates in alternative 3' splice site selection. One of the 3' splice sites of the second intron was located immediately before the additional 98-bp non-coding fragment of CLTa, and the second at the very end of the 98-bp fragment. Additionally, the presence of the tetranucleotides TCTT and TTCT, which are involved in the regulation of transcript processing in animals and possibly also active in peach, was found in this intron. Competition for splicing sites on the pre-mRNA in the spliceosome, which is induced by low temperature, may be involved in the production of the two transcripts of the CLT gene.

Acclimatization↗
PubMed2003

Regulation of gibberellin 20-oxidase gene expression and gibberellin content in citrus by temperature and citrus exocortis viroid.

A cDNA clone coding for a gibberellin (GA) 20-oxidase ( CcGA20ox1), an enzyme of GA biosynthesis, which when expressed in vitro catalyzed the conversion of GA(12) to GA(9) and of GA(53) to GA(20), was isolated from the citrus hybrid Carrizo citrange (C itrus sinensis x Poncirus trifoliata). Transcripts of CcGA20ox1 were abundant in the apex and leaves and much less abundant in internodes, nodes and roots. Seedlings of Carrizo citrange cultured under a 32 degrees C/27 degrees C (day/night) regime elongated more than seedlings growing under 17 degrees C/12 degrees C conditions. The effect of higher temperature was associated with more CcGA20ox1 transcripts and with higher content of GA(1), the main active GA in citrus, in the shoot. The infection of Etrog citron ( Citrus medica) plants with citrus exocortis viroid (CEVd), which produces a stunted phenotype, reduced the levels of transcripts in the apical shoot hybridizing to the gene CcGA20ox1 of Carrizo citrange and the content of GA(1). Thus GA(1) content correlated with CcGA20ox1 transcript levels. In contrast, results for gibberellic acid (GA(3)) and paclobutrazol applications to Carrizo citrange showed that CcGA20ox1 expression was subject to feed-back regulation. These observations indicate that the feed-back regulation of GA20ox operates mostly when the levels of active GAs have been dramatically altered. The results also show that the growth reduction induced by environmental (temperature) and biotic (CEVd) factors may be partially due to the modulation of the expression of GA20ox genes.

Citrus↗
PubMed2005

Identification of cold acclimated genes in leaves of Citrus unshiu by mRNA differential display.

Citrus unshiu is freeze tolerant to -10 degrees C when fully acclimated after exposure to cold, nonfreezing temperatures. To gain an understanding of its cold tolerance mechanism, mRNA differential display reverse transcriptase polymerase chain reaction (DDRT-PCR) and quantitative relative RT-PCR were used to study gene expression under a gradual cold-acclimation temperature regime. Six up-regulated and two down regulated genes were identified based on their amino acid sequences. The identified proteins encoded by the up-regulated genes were: 14-3-3 protein, 40S ribosomal protein S23, putative 60S ribosomal protein L15, nucleoside diphosphate kinase III protein, regulator of chromosome condensation-like protein, and amino acid permease 6. The proteins encoded by the two down-regulated genes were: miraculin-like protein and beta-galactosidase. Their individual function has been briefly reviewed based on published information. In addition to the findings in this study, we compared the function of cold responsive genes of Poncirus trifoliata, a very cold hardy relative of Citrus species that is freeze tolerant to -30 degrees C when fully acclimated, to the function of genes in the current study.

14-3-3 Proteins↗
PubMed2006

Analysis of microsatellites in citrus unigenes.

Simple sequence repeats (SSRs) were investigated in the unigene sequences from expressed sequence tags (EST) of sweet orange (Citrus sinensis osbeck), trifoliate orange (Poncirus trifoliata Raf.) and other citrus species and cultivars. A total of 37 802 citrus unigene sequences corresponding to 23.29 Mb were searched, resulting in the identification of 8,218 SSRs. Among them there were 4,913 (59.8%) mono-, 1,419 (17.3%) di-, 1,709 (20.8%) tri-, 114 (1.39%) tetra-, 23 (0.28%) penta- and 40 (0.49%) hexa-nucleotide SSRs. The estimated frequency of SSRs was approximately 1/2.8 kb, which could be extrapolated to 1 SSR-containing unigene in 4.6 unigenes. The maximum length of the SSR ranged from 40 to 105 bp depending on the repeating numbers of the motif in the SSR. The overall average length of SSRs was 20.9 bp. The frequencies of different SSR types (di-, tri-, tetra-, and penta-nucleotide repeats) were very similar between sweet orange and trifoliate orange. The mononucelotide repeats appeared to be the most abundant SSRs within sweet orange and trifoliate orange, followed by trimeric repeats. The adenine rich repeats such as A/T, AG, AT, AAG AAAT, AAAG, AAAT, AAAAG, AAAAT etc. were predominant in each type of SSRs (mono-, di-, tri-, tetra-, and penta-), whereas the C/G, CG, CCG repeats were less abundant. Twenty-five primer pairs flanking EST-SSR loci were designed to detect the possible polymorphism of six citrus cultivars including sweet orange and trifoliate orange. The PCR result with all these 25 primer pairs revealed the existence of polymorphism within six citrus cultivars confirming that citrus EST database could be efficiently exploited for the development of gene-derived SSR markers.

Base Sequence↗
PubMed2003

Effects of baicalein, berberine, curcumin and hesperidin on mucin release from airway goblet cells.

Baicalein, berberine, curcumin and hesperidin are the major components derived from Scutellaria baicalensis, Coptis japonica, Curcuma longa and Poncirus trifoliata, respectively. These plants have been used for the treatment of diverse chronic inflammatory diseases including respiratory disease in oriental medicine and their respective major components were reported to have various biological effects including anti-inflammatory activity. In the present study, we investigated whether these four natural products affect mucin release from airway goblet cells and compared the possible activities of these agents with the inhibitory action on mucin release by PLL and the stimulatory action by ATP. Confluent primary hamster tracheal surface epithelial (HTSE) cells were metabolically radiolabeled using 3H-glucosamine for 24 h and chased for 30 min in the presence of varying concentrations of each agent to assess the effects on 3H-mucin release. The results were as follows: (i) baicalein did not affect mucin release significantly; (ii) berberine, curcumin and hesperidin increased mucin release at the highest concentration (10 - 4 M); (iii) PLL inhibited and ATP increased mucin release. We conclude that berberine, curcumin and hesperidin can increase mucin release by directly acting on airway mucin-secreting cells and suggest that these agents be further studied for possible use as mild expectorants during the treatment of chronic airway diseases. Abbreviations. PLL:poly- L-lysine ATP:adenosine triphosphate HTSE:hamster tracheal surface epithelial DMSO:dimethylsulfoxide IL-12:interleukin-12 PBS:phosphate-buffered saline

Animals↗
PubMed2004

Effects of betaine, coumarin and flavonoids on mucin release from cultured hamster tracheal surface epithelial cells.

Betaine, coumarin, hesperidin and kaempferol are the components derived from Lycium chinense, Angelicae decursiva, Poncirus trifoliata and Polygonatum odoratum, respectively. These plants have been used for the treatment of respiratory diseases in oriental medicine and their respective components were reported to have various biological effects. In this study, we investigated whether these natural products affect mucin release from cultured hamster tracheal surface epithelial cells and compared the possible activities of these agents with the inhibitory action on mucin release by poly-L-lysine and the stimulatory action by adenosine triphosphate. Confluent primary hamster tracheal surface epithelial cells were metabolically radiolabeled using (3)H-glucosamine for 24 h and treated for 30 min in the presence of varying concentrations of each agent to assess the effects on (3)H-mucin release. The results were as follows: (i) Coumarin and kaempferol did not affect mucin release significantly; (ii) Betaine and hesperidin increased mucin release at the highest concentration; (iii) Poly-L-lysine inhibited and adenosine triphosphate increased mucin release. We conclude that betaine and hesperidin can increase mucin release by direct acting on airway mucin-secreting cells and suggest these agents be further studied for the possible use as mild expectorants during the treatment of chronic airway diseases.

Animals↗
PubMed1995

An unusual group 2 LEA gene family in citrus responsive to low temperature.

Six cDNAs representing unique cold-induced sequences have been cloned from the hardy citrus relative Poncirus trifoliata. Among these, pBCORc115 and pBCORc119 were found to belong to the same gene family. Sequencing data indicated that pBCORc115 and pBCORc119 each contained an open reading frame, coding for a 19.8 kDa protein (COR19) and a smaller 11.4 kDa protein (COR11) respectively. Inspection of the deduced amino acid sequences revealed three large repeats in COR19, but only one was present in the COR11. Two elements: a Q-clustered tract and a K-rich motif were identified in each repeat. The K-rich motifs were similar to those of cotton D-11 and Group 2 LEA proteins. A Serine-cluster, a common feature in many Group 2 LEA-like proteins, was also found in these proteins, but it was in an unusual position at the carboxy-terminus. A bipartite motif of basic residues, similar to known nuclear targeting sequences, was also present in COR19 and COR11, suggesting that members of this protein family may have a nuclear targeting function. The expression of COR19 mRNA in response to cold acclimation, drought, flooding, and salinization was examined. COR19 expression in leaf tissue was induced in response to cold acclimation, but repressed during drought and flooding stress.

Adaptation, Physiological↗
PubMed2006

Assessing genetic diversity and population structure in a citrus germplasm collection utilizing simple sequence repeat markers (SSRs).

Twenty-four simple sequence repeat (SSR) markers were used to detect molecular polymorphisms among 370 mostly sexually derived Citrus accessions from the collection of citrus germplasm maintained at the University of California, Riverside. A total of 275 alleles were detected with an average of 11.5 alleles per locus and an average polymorphism information content of 0.625. Genetic diversity statistics were calculated for each individual SSR marker, the entire population, and for specified Citrus groups. Phylogenetic relationships among all citrus accessions and putative non-hybrid Citrus accessions were determined by constructing neighbor-joining trees. There was strong support for monophyly at the species level when hybrid taxa were removed from the data set. Both of these trees indicate that Fortunella clusters within the genus Citrus but Poncirus is a sister genus to Citrus. Additionally, Citrus accessions were probabilistically assigned to populations or multiple populations if their genotype indicated an admixture by a model-based clustering approach. This approach identified five populations in this data set. These separate analyses (distance and model based) both support the hypothesis that there are only a few naturally occurring species of Citrus and most other types of Citrus arose through various hybridization events between these naturally occurring forms.

Alleles↗
PubMed2006

Efficient production of transgenic citrus plants using isopentenyl transferase positive selection and removal of the marker gene by site-specific recombination.

The presence of marker genes conferring antibiotic resistance in transgenic plants represents a serious obstacle for their public acceptance and future commercialization. In citrus, selection using the selectable marker gene nptII, that confers resistance to the antibiotic kanamycin, is in general very effective. An attractive alternative is offered by the MAT system (Multi-Auto-Transformation), which combines the ipt gene for positive selection with the recombinase system R/RS for removal of marker genes from transgenic cells after transformation. Transformation with a MAT vector has been attempted in two citrus genotypes, Pineapple sweet orange (Citrus sinensis L. Osb.) and Carrizo citrange (C. sinensis L. Osb. x Poncirus trifoliata L. Raf.). Results indicated that the IPT phenotype was clearly distinguishable in sweet orange but not in citrange, and that excision was not always efficient and precise. Nevertheless, the easy visual detection of the IPT phenotype combined with the higher transformation efficiency achieved in sweet orange using this system open interesting perspectives for the generation of marker-free transgenic citrus plants.

Alkyl and Aryl Transferases↗
PubMed2001

Characterization and regulation of ammonium transport systems in Citrus plants.

We have investigated both the kinetics and regulation of 15NH4+ influx in roots of 3-month-old hydroponically grown Citrus (Citrus sinensis L. Osbeck x Poncirus trifoliata Blanco) seedlings. The 15NH4+ influx is saturable below an external ammonium concentration of 1 mM, indicating the action of a high-affinity transport system (HATS). The HATS is under feedback repression by the N status of the plant, being down-regulated in plants adequately supplied with N during growth, and up-regulated by N-starvation. When assayed between 1 and 50 mM [15NH4+]0, the 15NH4+ influx showed a linear response typical of a low-affinity transport system (LATS). The activity of the LATS increased in plants supplied with NH4+ as compared with plants grown on an N-free medium. Transfer of the plants to N-free solution resulted in a marked decrease in the LATS-mediated 15NH4+ influx. Accordingly, resupply of NH4+ after N-starvation triggered a dramatic stimulation of the activity of the LATS. These data provide evidence that in Citrus plants, the LATS or at least one of its components is inducible by NH4+. Even when up-regulated, both the HATS and the LATS displayed a limited capacity, as compared with that usually found in herbaceous species. The use of various metabolic uncouplers or inhibitors indicated that 15NH4+ influx mediated by the HATS is strongly dependent on energy metabolism and H+ transmembrane electrochemical gradient. By contrast, the LATS is not affected by protonophores or inhibitors of the H(+)-ATPase, suggesting that its activity is mostly driven by the NH4+/NH3 transmembrane gradient. In agreement with these hypotheses, the HATS-mediated 15NH4+ influx was strongly inhibited when the solution pH was raised from 4 to 7, whereas influx mediated by the LATS was slightly stimulated.

Biological Transport↗
PubMed1992

Antiplatelet actions of some coumarin compounds isolated from plant sources.

Xanthyletin, xanthoxyletin, suberosin (all from Citrus grandis), aurapten (from Severinia huxifolia) and poncitrin (from Poncirus trifoliata) were isolated and their chemical structures were characterized to be coumarin compounds. All these coumarin compounds except xanthyletin inhibited the aggregation and ATP release of rabbit platelets induced by arachidonic acid, collagen, ADP, platelet-activating factor (PAF) or U46619 (a thromboxane A2 analog). Thrombin-induced ATP release, but not the aggregation, was also inhibited by these compounds. Xanthyletin inhibited only platelet aggregation induced by arachidonic acid and collagen, while poncitrin inhibited that caused by PAF more markedly than other coumarin compounds. The thromboxane B2 formation in washed platelets caused by arachidonic acid and collagen was suppressed by these coumarin compounds. The phosphoinositide breakdown caused by collagen and PAF was also inhibited by these compounds. They did not affect fibrinogen-induced aggregation of elastase-treated platelets. These antiplatelet actions were immediate, reversible by washout and independent on the incubation time (except suberosin). Antiaggregating effect was also studied by an electrical impedance method and the inhibitory effect of coumarin compounds on the whole blood and platelet-rich plasma was much less than that of platelet suspension in the aggregation induced by collagen, PAF and ADP. It is concluded that the antiplatelet actions of these coumarin compounds are due to the inhibition on thromboxane A2 formation and phosphoinositides breakdown.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2004

Inhibitory effect of Daesungki-Tang on the invasiveness potential of hepatocellular carcinoma through inhibition of matrix metalloproteinase-2 and -9 activities.

Daesungki-Tang (DST), a drug preparation consisting of four herbs, that is, Rhei radix et rhizoma (RR; the roots of Rheum coreanum Nakai, Daehwang in Korean), Aurantiii frutus immaturus (AFI; immature fruits of Poncirus trifolita Rafin., Jisil in Korean), Magnoliae cortex (MC; the stem bark of Magnolia officinalis Rehd. Et Wils., Hubak in Korean), and Mirabilite (MS; Matrii sulfas, Mangcho in Korean), is a traditional Korean herbal medicine that is widely used in the treatment of cancer metastasis, gastrointestinal complaints, vascular disorders, and atherosclerosis-related disorders. In this study, water extracts of DST and each of the four ingredient herbs were prepared. The extracts were tested for cytotoxic activity on human hepatocellular carcinoma cells, Hep3B cells using the XTT assay method. The inhibitory effect of the extracts on the invasion of Hep3B cells was also tested using matrigel precoated transwell chambers. DST effectively inhibited the invasion of Hep3B cells, compared with the control groups in a dose-dependent manner. In addition, a gelatin zymography assay showed that DST decreased the gelatinolytic activity of matrix metalloproteinases-2 (MMP-2; IC50 = 87 microg/ml) and -9 (MMP-9; IC50 = 75 microg/ml) that are secreted from Hep3B cells, respectively. Among the four herbal ingredients of DST, only MC has been shown to significantly inhibit the invasion of Hep3B cells and MMP-2 and -9 activities. From these results, it can be concluded that DST has some potential for use as an antitumor agent.

Antineoplastic Agents, Phytogenic↗
PubMed2001

3',5'-Di-C-beta-glucopyranosylphloretin, a flavonoid characteristic of the genus Fortunella.

Dihydrochalcone derivative, 3',5'-di-C-beta-glucopyranosylphloretin (1), is present in the genus Fortunella, (F. crassifolia, F. japonica, F. margarita, F. polyandra and F. hindsii). These species accumulate a large quantity of 1 in their fruits (peel, 6.5-15.2 mg/g in dry wt; juice sac, 1.5-10.5 mg/g) and in their leaves (21.3-60.2 mg/g). Twenty-seven Tanaka's Citrus species examined lack 1, but C. madurensis and C. halimii contain 1 in large quantities in their peels (25.1 and 33.6 mg/g) and juice sacs (4.1 and 4.2 mg/g). Poncirus species do not contain 1. Fortunella-citrus hybrids, the Orangequat [C. unshiuxF. crassifolia], the Thomasville citrangequat [Fortunella sp.x(C. sinensisxPoncirus trifoliata)], and seven hybrid progenies [F. margaritaxC. junos], contain large amounts of 1 in their peels (17.0-7.9 mg/g) and juice sacs (2.0-9.9 mg/g). These facts suggest that accumulation of 1 is a generic trait of the genus Fortunella and that the inheritance of the trait among the intergeneric hybrids is controlled by a dominant allele. Thus C. madurensis and C. halimii are thought to originate from natural hybrids between the genera Citrus and Fortunella. Phloridzin, which has the same aglycon as 1, was not detected in the citrus plants examined.

Flavonoids↗
PubMed2003

An in vitro system combined with an in-house quantitation assay for screening hepatitis C virus inhibitors.

Hepatitis C virus (HCV) infection is a serious global health problem. Interferon-alpha (IFN-alpha) and ribavirin have demonstrated efficacy in the treatment of HCV infection; however, these therapies display many side effects. To screen the anti-HCV compounds from plants, we established an in vitro model for inoculation of HCV by centrifugation-facilitated method. The HCV RNA molecules were then quantitated by nested competitive reverse transcription-polymerase chain reaction (cRT-PCR) using fluorescein-labeled primers, and analyzed by ABI Prism 310. The positive and negative strands of HCV RNA were detectable in Vero cells on Day 7 post-infection, suggesting that the HCV RNA was present in the cell model system. The cell culture system was further used to screen the anti-HCV activities of 4 Chinese herbal formulas and 15 formula components. IFN-alpha showed an antiviral effect. The formulas exhibited no anti-HCV activities, while Arnebia euchroma, Thlaspi arvense, and Poncirus trifoliata displayed anti-HCV activities. Therefore, these results pointed out the possibility by using the cell culture system established in this study to screen the herb extracts for their anti-HCV activities.

Animals↗
PubMed1998

Relationship between volatile components of citrus fruit essential oils and antimicrobial action on Penicillium digitatum and penicillium italicum.

This study examined the effect of volatile components of citrus fruit essential oils on P. digitatum and P. italicum growth. The hydrodistilled essential oils of orange (Citrus sinensis cvv. "Washington navel", "Sanguinello", "Tarocco", "Moro", "Valencia late", and "Ovale"), bitter (sour) orange (C. aurantium), mandarin (C. deliciosa cv. "Avana"), grapefruit (C. paradisi cvv. "Marsh seedless" and "Red Blush"), citrange (C. sinensis x Poncirus trifoliata cvv. "Carrizo" and "Troyer"), and lemon (C. limon cv. "Femminello", collected in three periods), were characterized by a combination of GC and GC/MS analyses. The antifungal efficacy of the oils was then examined at progressively reduced rates. Findings showed a positive correlation between monoterpenes other than limonene and sesquiterpene content of the oils and the pathogen fungi inhibition. The best results were shown by the citrange oils, whose chemical composition is reported for the first time, and lemon. Furthermore P. digitatum was found to be more sensitive to the inhibitory action of the oils.

Citrus↗
PubMed2000

Characterization of the low affinity transport system for NO(3)(-) uptake by Citrus roots.

Three-month old citrange Troyer (hybrid of Citrus sinensis x Poncirus trifoliata) seedlings were grown hydroponically and, after a period of NO(3)(-) starvation, plants were transferred to solutions enriched with K(15)NO(3) (96% atoms 15N excess) to measure 15NO(3)(-) uptake rates as a function of external 15NO(3)(-) concentrations. Two different NO(3)(-) uptake systems were found. Between 1 and 50 mM 15NO(3)(-) in the uptake solution medium, the uptake rate increased linearly due to the low affinity transport system (LATS). Nitrate reductase activity showed the same response to external [NO(3)(-)], and also appears to be regulated by the rate of nitrate uptake. Nitrate pre-treatments had a represive effect on NO(3)(-) uptake rate measured at 5 or 30 mM external [15NO(3)(-)]. The extent of the inhibition depended on the [NO(3)(-)] during the pre-treatment and in the uptake solution. These results suggest that the LATS of Citrus seedlings is under feedback control by the N status of the plant. Accordingly, addition of amino acids (Glu, Asp, Asn, Gln) to the uptake solution resulted in a decrease in 15NO(3)(-) uptake rate. However, the inactivation of nitrate reductase activity after treatment of the seedlings with either 100 or 500 µM WO(4)(2-) did not affect the activity of the LATS. Metabolic uncouplers, 2,4-DNP and KCN, reduced the uptake rate by 43.3% and 41.4% respectively at 5mM external [15NO(3)(-)]. However, these compounds had little effect when 15NO(3)(-) uptake was assayed at 30 mM external concentration. The ATPase inhibitors DCCD and DES reduced 15NO(3)(-) uptake by 68.8%-35.6%, at both external [15NO(3)(-)]. Nitrate uptake by the LATS declined with the increase of the solution pH beyond pH 4. The data presented are discussed in the context of the kinetics, energy dependence and regulation of NO(3)(-) uptake.

Journal Article↗
PubMed1999

Inhibitory effect of Epstein-Barr virus activation by Citrus fruits, a cancer chemopreventor.

To search useful compounds in Citrus fruit for cancer chemoprevention, we carried out a primary screening of extracts of fruit peels and seeds from 78 species of the genus Citrus and those from two Fortunella and one Poncirus species, which were closely related to the genus Citrus. These Citrus extracts inhibited the Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA) as a useful screening method for anti-tumor promoters. Our results indicated that Citrus containing substances may be inhibit susceptibility factors involved in the events leading to the development of cancer.

Animals↗
PubMed2003

Leaf volatile compounds of seven citrus somatic tetraploid hybrids sharing willow leaf mandarin (Citrus deliciosa Ten.) as their common parent.

Volatile compounds were extracted by a pentane/ether (1:1) mixture from the leaves of seven citrus somatic tetraploid hybrids sharing mandarin as their common parent and having lime, Eurêka lemon, lac lemon, sweet orange, grapefruit, kumquat, or poncirus as the other parent. Extracts were examined by GC-MS and compared with those of their respective parents. All hybrids were like their mandarin parent, and unlike their nonmandarin parents, in being unable to synthesize monoterpene aldehydes and alcohols. The hybrids did retain the ability, although strongly reduced, of their nonmandarin parents to synthesize sesquiterpene hydrocarbons, alcohols, and aldehydes. These results suggest that complex forms of dominance in the mandarin genome determine the biosynthesis pathways of volatile compounds in tetraploid hybrids. A down-regulation of the biosynthesis of methyl N-methylanthranilate, a mandarin-specific compound, originates from the genomes of the nonmandarin parents. Statistical analyses showed that all of the hybrids were similar to their common mandarin parent in the relative composition of their volatile compounds.

Alcohols↗