Orange Cultivars Research Articles

Citrus and Prunuscopia-like retrotransposons

Many of the world's most important citrus cultivars ("Washington Navel", satsumas, clementines) have arisen through somatic mutation. This phenomenon occurs fairly often in the various species and varieties of the genus.The presence of copia-like retrotransposons has been investigated in fruit trees, especially citrus, by using a PCR assay designed to detect copia-like reverse transcriptase (RT) sequences. Amplification products from a genotype of each the following species Citrus sinensis, Citrus grandis, Citrus clementina, Prunus armeniaca and Prunus amygdalus, were cloned and some of them sequenced. Southern-blot hybridization using RT clones as probes showed that multiple copies are integrated throughout the citrus genome, while only 1-3 copies are detected in the P. armeniaca genome, which is in accordance with the Citrus and Prunus genome sizes. Sequence analysis of RT clones allowed a search for homologous sequences within three gene banks. The most similar ones correspond to RT domains of copia-like retrotransposons from unrelated plant species. Cluster analysis of these sequences has shown a great heterogeneity among RT domains cloned from the same genotype. This finding supports the hypothesis that horizontal transmission of retrotransposons has occurred in the past. The species presenting a RT sequence most similar to citrus RT clones is Gnetum montanum, a gymnosperm whose distribution area coincides with two of the main centers of origin of Citrus spp. A new C-methylated restriction DNA fragment containing a RT sequence is present in navel sweet oranges, but not in Valencia oranges from which the former originated suggesting, that retrotransposon activity might be, at least in part, involved in the genetic variability among sweet orange cultivars. Given that retrotransposons are quite abundant throughout the citrus genome, their activity should be investigated thoroughly before commercializing any transgenic citrus plant where the transgene(s) is part of a viral genome in order to avoid its possible recombination with an active retroelement. Focusing on other strategies to control virus diseases is recommended in citrus.

Porta-enxertos para laranjeiras-doces (Citrus sinensis (L.) Osb.), em Rio Branco, Acre

O objetivo deste trabalho foi de avaliar o comportamento de sete cultivares de laranjeiras- doces: 'Baia 101', 'Baianinha IAC 79', 'Monte Parnaso', 'Pêra D6', 'Natal 112', 'Valência 27' e 'Aquiri', sobre diferentes porta-enxertos: limão 'Cravo', tangerinas 'Cleópatra' e 'Sunki' e citrange 'Carrizo', nas condições edafoclimáticas de Rio Branco, Acre. O delineamento experimental foi em parcelas subdivididas, com as cultivares nas parcelas, os porta-enxertos nas subparcelas e os quatro anos de avaliação como repetições. As laranjeiras 'Pêra D6', 'Natal 112' e 'Valência 27' apresentaram tendências de maior produção quando enxertadas sobre o limão 'Cravo', e a laranja 'Aquiri' quando enxertada sobre citrange 'Carrizo'. Em relação aos demais porta-enxertos, o limão 'Cravo' mostrou tendências de induzir maior produção/volume de copa e peso médio do fruto, e menor teor de sólidos solúveis totais e acidez total. As laranjas do grupo Baia ('Baia 101', 'Baianinha IAC 79' e 'Monte Parnaso') produziram frutos com baixa percentagem de suco; não são recomendadas para plantio em Rio Branco, AC. Com base nos resultados obtidos, recomendam-se os porta-enxertos citrange 'Carrizo', tangerina 'Cleópatra' e limão 'Cravo' para a laranja 'Aquiri', e o porta-enxerto limão 'Cravo' para as laranjas 'Pêra D6', 'Natal 112' e 'Valência 27'.

440 A Comparative Study on Flavor and Nutritional Attributes of `BetaSweet' Maroon Carrot (Daucus carota L.)

A new designer carrot, `BetaSweet', with high levels of anthocyanin, betacarotene, and crispy texture was developed by the Vegetable Improvement Center at Texas A&M Univ. The new carrot contained low levels of low-volatile terpenoids, responsible for the harsh flavor in carrots and high levels of reducing sugars. Carotenoid content increased with carrot maturity and stabilize at 120 days after sowing for orange and maroon genotypes; however, the maroon genotype was 35% higher than the orange cultivar. Anthocyanin, a cancer preventive compound and not detected in ordinary orange carrots, is present in `BetaSweet' maroon carrot with 89.8 mg·100 g-1 of fresh weight. High percentage of soluble solids and succulence in the maroon cultivar seemed to contribute to the favored sweetness perception by consumers. A consumer taste panel showed a significant difference between orange and maroon genotype for sweetness, texture, and overall carrot flavor.

ESTAQUIA SEMI-LENHOSA: UM MÉTODO RÁPIDO E ALTERNATIVO PARA A PRODUÇÃO DE MUDAS DE LIMA ÁCIDA 'TAHITI'

Avaliou-se o efeito de várias concentrações e tempos de exposição de dois reguladores de crescimento no enraizamento de estacas de lima ácida `Tahiti' (Citrus latifolia Tanaka). Experimentos complementares também avaliaram a eficiência do enraizamento de estacas de laranjas `Pêra' e `Valencia' (Citrus sinensis L. Osbeck) comparando-a com a da lima ácida `Tahiti'. Os trabalhos experimentais foram conduzidos, em Piracicaba, SP, em câmara de nebulização intermitente, com estacas ponteiro, semi-lenhosas, coletadas 5 meses após a brotação, com 10 cm de comprimento, sem as 3 folhas basais. O delineamento experimental adotado foi o de blocos casualizados com 4 repetições para todos os ensaios realizados. A avaliação dos tratamentos foi realizada 90 dias após a instalação de cada ensaio através da coleta dos seguintes dados biométricos (número médio de raízes/estaca enraizada-NMR, porcentagem de enraizamento-PE, porcentagem de formação de calos-PC, comprimento médio da maior raiz-CMMR e número médio de folhas/estaca enraizada-NMF). Os resultados dos ensaios permitiram as conclusões: a) O enraizamento de estacas de lima ácida `Tahiti' ocorreu com relativa facilidade (PE acima de 50%, podendo chegar a 96%), independentemente da aplicação de reguladores de crescimento; b) Estacas de laranja doce revelaram baixa PE (0,5%), independentemente da utilização de reguladores de crescimento; c) Para cada espécie estudada, não houve diferenças significativas para os parâmetros PC, NMR, CMMR e NMF. Observou-se que a obtenção de mudas de lima ácida `Tahiti' por enraizamento de estacas é um método eficiente e rápido de propagação para essa espécie.

VIABILIDADE DO PÓLEN EM VARIEDADES DE LARANJA DOCE

Uma vez que a polinização é um dos pontos decisivos para o crescimento e desenvolvimento do fruto, contribuindo com os gametas masculinos para a fecundação e determinando, na maioria das vezes, a fixação dos frutos em citros, torna-se necessário conhecer o grau de esterilidade masculina nas diferentes variedades de laranja doce para sua possível utilização em programas de melhoramento. A esterilidade é limitante para programas que envolvam a hibridação sexual, por outro lado possui sua importância econômica em citros induzindo menor número de sementes por fruto em certas variedades. Com a finalidade de caracterizar 44 variedades de laranja doce (Citrus sinensis [L.] osbeck) quanto à viabilidade do pólen, foram coletadas anteras das variedades enxertadas sobre tangerineira Cleópatra. As variedades estudadas pertencem aos principais grupos de laranja doce: com acidez (como a laranja 'Pêra'), de baixa acidez (como a laranja 'Lima'), com umbigo (como a laranja 'Bahia') e sangüíneas (como a laranja 'Rubi Blood'). O percentual de pólen viável foi avaliado por meio da coloração com carmim acético a 25% e contagem sob microscópio ótico. Foram observados valores que variaram desde 12,0% para a 'Pêra Sem Sementes' até 88,8% para a variedade 'Hamlin Reserva'. Os clones de laranja 'Hamlin' mostraram maior percentual de pólen viável. Não foi observada presença de pólen para as variedades produtoras de laranjas de umbigo, originadas da variedade Bahia. As variedades 'Pêra', 'Valência' e 'Natal', as quais são as principais cultivares da citricultura paulista e nacional, apresentaram baixos percentuais de pólen viável.

Characterization of Citrus aurantium and C. taiwanica rootstocks by isoenzyme and essential oil analysis

SummaryFour cultivars of sour orange {Citrus aurantium L.) and one of C. taiwanica Tan & Shim, originating from Greece and California, were studied biochemically. Analysis included electrophoretic separations of the leaf isoenzymes such as glutamate oxaloacetate transaminase, superoxide dismutase and malate dehydrogenase. Enzyme differences were found to be adequate for distinction at the specific level. Also, essential oils were analyzed and quantitative and qualitative differences were detected among the cultivars. C. taiwanica has a very different genotype combination from the main group of sour orange. The essential oil analysis is a useful tool for intraspecific characterization of C. aurantium cultivars. ‘Bittersweet’ is more discrete from the other sour orange cultivars.

Purification of limonoid glucosyltransferase from navel orange albedo tissues

UDP- d-glucose: limonoid glucosyltransferase was purified from albedo tissues of navel orange ( Citrus sinensis) cultivars, Frost and Newhall, by a combination of (NH 4) 2SO 4 fractionation, UDP-glucuronic acid affinity chromatography and DEAE ion exchange HPLC. This procedure resulted in a 452-fold increase in enzyme purification. This enzyme catalysed the glucosylation of both nomilin and limonin. SDS-PAGE showed a M r , of 56–58 k for the enzyme. The enzyme displayed a peak of activity between pH 6.5 and 9.0 with an optimum at 8.0. Mn 2+ stimulated enzyme activity by 66% over basal activity observed with EDTA. Activity was lost when the purified enzyme was frozen and stored in Tris-HCl buffer at pH 8.0. Published by Elsevier Science Ltd

Susceptibility and Resistance of Citrus Genotypes to Alternaria alternata pv. citri

AbstractA survey of citrus cultivars in Israel in orchards where Alternaria brown spot was common on Minneola tangelos (mandarin × grapefruit), revealed the occurrence of the disease as typical foliar and fruit lesions on Dancy and Ellendale (mandarins), on Murcott tangor (mandarin × sweet orange), on Nova and Idith (mandarin hybrids), on Calamondin, and on Sunrise and Redblush (grapefruit). Isolates of Alternaria alternata from each of these hosts were proven to be pathogenic to Minneola tangelo.The host range of A. alternata pv. citri from Israel was assayed by inoculating leaves of diverse citrus genotypes. Several mandarins and their hybrids (Dancy, Kara, King, Wilking, Satsuma, Minneola, Orlando, Mikhal, Idith, Nova, Page, Murcott), grapefruit (Marsh seedless), grapefruit × pummelo (Oroblanco), sweet orange (Shamouti, Valencia, Washington navel) Calamondin, and Volkamer citrus were susceptible. Several mandarins and their hybrids (Clementine, Avana, Yafit, Ortanique), Cleopatra, one sweet orange cultivar (Newhall), pummelo (Chandler), lemon (Eureka), Rough lemon, Rangpur lime, sweet lime, citron, limequat, sour orange, Troyer citrange and Alemow were resistant.

Identification of closely related citrus cultivars with inter-simple sequence repeat markers

Inter-simple sequence repeat (ISSR) markers generated by 22 primers were tested for their ability to distinguish among samples from 94 trees of 68 citrus cultivars. Within each of the six cultivar groups studied, most of these cultivars are so closely related that they are difficult to distinguish by other molecular-marker techniques. ISSR markers involve PCR amplification of DNA using a single primer composed of a microsatellite sequence anchored at the 3′ or 5′ end by 2–4 arbitrary, often degenerate, nucleotides. The amplification products were separated on non-denaturing polyacrylamide gels and detected by silver staining. ISSR banding profiles were very repeatable on duplicate samples. Different citrus species had very different fingerprint patterns. Within Citrus sinensis (L.) Osbeck and C. paradisi Macf., in which all cultivars have originated by the selection of mutants, ISSR markers distinguished 14 of 33 sweet orange and 1 of 7 grapefruit cultivars. Five of six lemon cultivars were discriminated by ISSR markers. Many differences were found among mandarin cultivars; however, all five satsuma cultivars analyzed had identical ISSR fingerprints. Four of five citrange cultivars were distinguishable, but ‘Troyer’ and ‘Carrizo’ had identical ISSR fingerprints. ‘Kuharske Carrizo’ citrange, which has better citrus nematode resistance than other ‘Carrizo’ citrange accessions, had unique ISSR fingerprints. Three ISSR markers that differentiated certain sweet orange cultivars were hybridized to Southern blots of sweet orange DNA digested with different restriction endonucleases. The sweet orange cultivars tested could be distinguished by these ISSR-derived RFLP markers. Moreover, one ISSR marker unique to ‘Ruby’ blood orange was observed in its progeny trees.

Total and Thermostable Pectinesterases in Citrus Juices

ABSTRACTGrapefruits, tangerines and several orange cultivars were evaluated for total and thermostable pectinesterase (TS‐PE) activity. Juices were extracted with a Fresh'n SqueezeTM Multi Fruit Juicer. Variation in total pectinesterase (PE) and TS‐PE was not significantly different between cultivars. No significant contribution by traditional quality control parameters (%pulp, °Brix, % acid, pH), to total PE or TS‐PE was observed. Positive correlations were observed between TS‐PE and total PE, when expressed on a pulp (0.669) or soluble solids (0.624) basis.

Effect of stubborn disease on growth, yield and fruit quality of Frost Washington Navel and Frost Valencia oranges in Cyprus

SummaryThe effect of stubborn disease on growth, yield and fruit quality of orange cultivars Frost Washington Navel and Frost Valencia was studied over the period 1984-1994 in Akhelia, Cyprus. Cumulative two-year yield of ‘Navel’ and nine-year yield of ‘Valencia’ orange were reduced by 19% and 34%, respectively. Growth of ‘Navel’ trees was not affected by the disease, whereas growth of ‘Valencia’ was reduced by 11%. In both healthy and infected ‘Valencia’, tree growth (trunk circumference) was linearly related to annual fruit yield. Stubborn disease affected significantly the size, weight and quality of fruits in both cultivars. Compared with fruit from healthy trees, mean fruit weight of infected ‘Navel’ and ‘Valencia’ oranges decreased by 28% and 30%, respectively, and mean fruit diameter by 12% in both varieties. Total acidity was higher and the ratio of total soluble solids to total acids was lower in both ‘Navel’ and ‘Valencia’ fruits from infected trees.

Environmental variation in physical and chemical cues used by the parasitic wasp, Aphytis melinus, for host recognition

AbstractO‐caffeoyltyrosine is a host recognition kairomone for Aphytis melinus DeBach (Aphelinidae) found in the covers of its host, California red scale, Aonidiella aurantii (Maskell) (Diaspidae). This study tests the hypothesis that the concentration of O‐caffeoyltyrosine and scale cover size are reliable indicators of scale body size, an important component of host quality for A. melinus, over a range of scale rearing conditions. Both scale cover area and O‐caffeoyltyrosine concentrations were only qualitatively related to scale body size during the third instar, the scale life stage most suitable for A. melinus. Scale cover area and O‐caffeoyltyrosine concentrations were reduced, relative to scale body size, when scale were reared on bark and leaves compared to fruits. Scale cover area and O‐caffeoyltyrosine concentration were also relatively reduced when scales were reared in mid‐summer compared to spring and fall, and when reared on orange cultivars compared to lemon cultivars in the field. Finally, scale cover area and O‐caffeoyltyrosine concentration were reduced when scale were reared at 52% compared to 100% humidity in the laboratory. Scales appear to be chemically conspicuous to A. melinus for a short period of the time in which they are physiologically susceptible. Scales that minimize their cover size and maximize the incorporation rate of O‐caffeoyltyrosine into covers may minimize their conspicuousness to A. melinus. Minimizing scale cover size, but not necessarily incorporation rates, may make scales more vulnerable to predators, however.

518 PB 456 INHERITANCE OF PROCUMBENT GROWTH CHARACTERISTICS AMONG HYBRIDS OF `CIPO' SWEET ORANGE

Citrus tree size and growth form are important traits that can be influenced by the genotype of both scion and rootstock cultivars. However, there have been very few reports of size or growth habit traits within Citrus or sexually compatible genera that might be transmitted genetically in breeding programs. A procumbent growth habit has been described for `Cipo' (Citrus sinensis [L.] Osbeck), a unique sweet orange cultivar maintained in the USDA germplasm repository. Sexual hybrids were produced between this selection and four related species, and these progenies were evaluated for two distinct traits associated with the unusual growth habit of `Cipo'. Inheritance of both drooping petiole and horizontal shoot growth were observed among the `Cipo' hybrids. Investigations are continuing on these four populations to verify segregation patterns and identify individuals possessing favorable combinations of growth habit with other desirable tree characteristics.

Fruit splitting in ‘Nova’ hybrid mandarin in relation to the anatomy of the fruit and fruit set treatments

Fruit splitting in the mandarin orange cultivar ‘Nova’ is related to the presence of an open stylar end in the fruit. This opening arises from a cavity present at the base of the style, and is formed in a variable proportion of fruits. The cells at the bottom of this style cavity form a rind-like tissue which develop into a navel structure. The size of this navel is larger in open-stylar end bearing fruits and, accordingly, in split fruit. The number of split fruit per tree is unrelated to the number of fruit set. The application of gibberellic acid (GA 3) has a variable effect on set and splitting depending on its timing. This hormone increases fruit splitting when applied at flowering, but reduces it when applied shortly after the end of the June drop. It has only a minor effect on fruit set.

Ceratitid fruitflies infesting fruit crops in Kenya

Between 1984 and 1988, a survey of fruit-infesting ceratititl fruitflies was conducted in 11 agricultural districts in Kenya. Samples of up to 18 different fruit crops were examined for infestation. The four species of fruitfly found were Ceratitis capitata, C. rosa (Pterandrus rosa), C. nigra (Trirhithrum coffeae) and C. cosyra (Pardalaspis cosyra). The first three were sympatric infestants of coffee, while the latter was exclusively found in mangoes. In addition, C. rosa also infested loquat, guava and custard apple. C. capitata infested commercial orange cultivars. This species was predominant in the main arabica coffee growing areas in the central highlands. C. rosa and C. nigra were more widespread, occurring in high proportions in most parts of the country. Generally, the proportions of the three species per coffee sample, and the mean number of each species per kg of coffee, tended to vary considerably over time and space.

Detection of Citrus Tatter Leaf Virus in Australia.

Citrus tatter leaf virus (CiTLV) was detected in trees of Meyer lemon and three Washington navel orange cultivars by graft transmission to indicator plants of Troyer and Rusk citranges, by mechanical transmission to Physalis floridana and Chenopodium quinoa, and by CiTLV antiserum decoration of flexuous virus particles with a mean length of 616 nm.

Use of multivariate analysis in the taxonomy of Citrus aurantium L. and relatives

Leaf proteins from 21 sour orange ( Citrus aurantium L.) cultivars and relatives were studied for chemotaxonomical purposes. Soluble proteins were separated by polyacrylamide gel electrophoresis. Using the patterns obtained it was possible to distinguish the different species and cultivars. Multivariate analysis was carried out, based on the densitometric readings of the proteinograms. The results of the principal components analysis showed five cultivars ‘Bergamot’ from Alcanar, ‘Bergamot Melarosa’, ‘Bouquet de Fleurs’, ‘Amargo Clementino’ and ‘Nansho daidai’ that segregated from the main cluster in the three dimensional plot. In the dendrogram obtained, these five cultivars branched at dissimilarity levels over 2.0. The possible origin of the cultivars is discussed.

PILOT COMMERCIAL PRODUCTION OF CONCENTRATED JUICES FROM CITRUS FRUITS GROWN IN NIGERIA.

The development of a natural base for beverage products covers key steps including raw materials identification and sourcing, process development, product testing an market introduction. Agege 1 - a widespread sweet orange cultivar was compared with Parson Brown sweet orange type in the production of concentrated juice (approximate 30° Brix). Yield for Agege 1 was 14-16% while Parson Brown had 9-11% based on the processing modules adopted. Analysis of samples showed 40-110 millgram percent and 125-350 microgram percent for vitamins C and A respectively. Sensory testing revealed that concentrated juice for Agege 1 had superior appearance characteristics particularly in terms of color.

The Chemical Composition of Some Cold-pressed Citrus Oils Produced in Algeria

ABSTRACT The cold-pressed oils of five orange cultivars, a Tangor hybrid and the Clementine Tangerine, which were obtained from fruit grown in Algeria, were examined by GC/MS. The orange oils were found to contain the following number of constituents: Washington-Navel (43), Portuguese (61), Valencia (43), Hamlin (24) and Sanguine (23). The Tangor hybrid oil was found to contain 34 components, while 25 components were found in the Clementine oil. The use of preparative GC as a method to remove the monoterpene hydrocarbons prior to GC/MS analysis was demonstrated.

The impact of domestication on the genetic variability in the orange carrot, cultivated Daucus carota ssp. sativus and the genetic homogeneity of various cultivars

Isozyme analysis of wild and domesticated accessions indicated that domestication of the cultivated carrot Daucus carota ssp. sativus resulted in an insignificant reduction of all genetic variability and genetic distance estimates. Although they are less variable genetically, cultivated forms maintain a high proportion of observed heterozygosity. Relative to the overall genetic variability of the species, samples from four common cultivars 'Red Cored Chantenay', 'Scarlet Nantes', 'Danvers Half Long' and 'A Plus' demonstrated a high degree of genetic similarity. This is attributed to the recent development of orange cultivars and the limited gene pool utilized in their development.