Identificação de espécies de citros mediante polimorfismo enzimático Identification of citrus species by means of enzymatic polymorphism

Estudou-se, mediante polimorfismo enzimático em gel de poliacrilamida, a variabilidade genética das espécies de laranja-doce (Citrus sinensis); laranja-azeda (C. aurantium); tangerinas clementina (C. clementina), sunki (C. sunki), cleópatra (C. reshni) e poncã (C. rsticulata); lima-da-pérsia (C. limettioides); limão-galego (C. aurantifolia); limão-cravo (C. limonia) e trifoliata (Poncirus trifoliata). Extratos de folhas foram analisados para as isoenzimas de malato deidrogenase (MDH), enzima málica (ME), leucino amino peptidase (LAP), glutamato oxaloacetato transaminase (GOT), fosfoglucoisomerase (PGI), fosfoglucomutase (PGM) e isocitrato deidrogenase (IDH). Verificou-se grande variabilidade genética interespecífica, porém nenhuma entre os cultivares de laranja-doce. Foram encontradas algumas aloenzimas, além das referidas pela literatura em gel de amido, como aquelas de uma região próxima ao loco conhecido por Pgm-1, responsável por proteínas monoméricas. Este sistema, denominado PGM, revelou a maior diferenciação entre as espécies, tendo apresentado duas regiões distintas com 9 alelos. No sistema MDH, foram considerados dois locas codificando para proteínas diméricas com 7 alelos; no ME, um loco com 3 alelos; no LAP, possivelmente dois locos responsáveis por proteínas monoméricas com 4 alelos; no GOT, dois focos com 7 alelos; no PGI, um loco com 3 alelos e no IDH, um loco com 4 alelos.<br>The genetic diversity of citrus cultivars was studied by polyacrylamide gel electrophoresis on sweet orange (C. sinensis); tangerines (C. clementine, C. sunki, C. reshni, C. reticulata); Palestine lime (C. Iimettioides); West Indian lime (C. aurantifolia); Rangpur lime (C. limonia), Sour orange (C. aurantium) and Poncirus trifoliata. Citrus leaf extracts were analysed for isozymes of malato dehidrogenase (MDH), malic enzyme (ME), leucine aminopeptidase (LAP), glutamate oxaloacetate transaminase (GOT), phosphoglucose isomerase (PGI), phosphoglucose mutase (PGM) and isocitrate dehydrogenase (IDH). Interespecific differences were observed; but, none between intraespecific C. sinensis cultivars. Some allozymes were observed in addition to those reffered in the literature on starch gel; e.g., allozymes located next to the known Pgm-1 loci. The PGM system revealed the best differentiation between the cultivars. It showed monomeric proteins and 9 alleles. The MDH system had two loci with 7 alleles; the ME system one locus with 3 alleles; the LAP system one possible locus next to the known Lap-1 and 4 alleles; the GOT two loci for dimeric proteins with 7 alleles; the PGI one locus with 3 alleles; and, the IDH one locus with 4 alleles

Ploidia e fertilidade de pólen em progênies de citros Ploidy and pollen fertility in citrus hybrids

Este trabalho foi desenvolvido para estimar a fertilidade do pólen e determinar o nível de ploidia em progênies dos cruzamentos da tangerineira 'Montenegrina' (C. deliciosa Ten.) com a tangerineira 'King' (C. nobilis Lour.) e com a laranjeira 'Caipira' (C. sinensis (L.) Osb.). As plantas, de pés-francos e com idade entre 11 e 12 anos, são mantidas na Estação Experimental Agronômica da Universidade Federal do Rio Grande do Sul, em Eldorado do Sul. Avaliaram-se o nível de ploidia, através da contagem dos cromossomos em células em meiose, e a fertilidade do pólen, por coloração do pólen com carmim propiônico, em 2005 e 2006. Todos os híbridos avaliados são diplóides e a fertilidade de pólen variou de zero a 98%. C27 - híbrido de 'Montenegrina' x 'Caipira' - revelou-se praticamente estéril, e a fertilidade de C21, do mesmo cruzamento, é de 10%. A menor fertilidade observada no cruzamento da 'Montenegrina' x 'King' foi de 42%.<br>This work was performed to estimate pollen fertility and determinate the ploidy level of 11 to 12 years old progenies of crosses of 'Montenegrina' mandarin (Citrus deliciosa Ten.) with 'King' mandarin (C. nobilis Lour.) and with 'Caipira' sweet orange (C. sinensis (L.) Osb.) maintained at Estação Experimental Agronômica of UFRGS, in Eldorado do Sul, Brazil. The ploidy level was determined by chromosome countings in meiosis cells and pollen fertility evaluated by staining pollen grains with propionic carmine. All evaluated hybrids are diploid and pollen fertility varied from zero to 98%. C27, a hybrid 'Montenegrina' x 'Caipira', was found is sterile, and C21, from the same cross, showed 10 % fertility. The lowest observed fertility in the progeny 'Montenegrina' x 'King' was 42 %

Chemical composition of the leaf essential oil of grapefruits ( Citrus paradisi Macf.) in relation with the genetic origin

International audienceThe composition of twenty-four samples of essential oil isolated from leaves of Citrus paradisi Macf. growing in a northern area of citrus cultivation in Mediterranean climate (Corsica) was investigated by GC (RI), GC-MS and C-13 NMR. Thirty-six compounds accounting for 94.9-99.3% of the oil composition were identified. The oils contained mainly monoterpene hydrocarbons and specially sabinene (up to 60.2%),(E)-beta-ocimene (up to 15.0%) and punctually gamma-terpinene (up to 56.1%), beta-pinene (up to 30.9%) and p-cymene (up to 12.5%). The twenty-four compositions were submitted to k-means partitioning and principal component analysis, which allowed the distinction of one homogeneous group of twenty-two grapefruits (main compound sabinene, mean = 47.1%). This group included eighteen cultivars derived by mutation from the ancestral grapefruit tree (Duncan) and four cultivars known to be interspecific hybrids. Two out group cultivars were clearly differentiated from others by original chemical compositions, in agreement with their hybrid origin