Ana Lúcia Cunha Dornelles

Caracterização do germoplasma de tangerineiras do Sul do Brasil mediante análises morfológicas e moleculares

Abstract – The objective of this work was to characterize mandarin (Citrus spp.) germplasm fromSouthern Brazil by morphological and molecular analyses. Thirty seven cultivars from 34 distinctmandarin varieties were evaluated by morphological and agronomic traits of leaves, flowers and fruits,and by microsatellite markers. The morphological and agronomic characteristics suggested that almostall varieties can be produced for commercial use, and some, as the Satsuma variety, are recommended forbreeding programs. Pooled DNA samples from 1-5 plants belonging to each cultivar were tested. Eightof the nine primers detected polymorphisms. Specific markers were found for some accessions. Thedendrogram constructed with the morphological results divided the 37 cultivars into four groups, whilethat obtained with the microsatellites clustered 35 of the 37 cultivars into three groups only. Generally,intervarietal differences are not high, and this lack of agreement in the two multifactorial analysesindicates that diverse evolutionary factors are acting at these two levels of investigation.Index terms: citrus, genetic variation, microsatellites, breeding methods.Caracterizacao do germoplasma de tangerineiras do Sul do Brasilmediante analises morfologicas e molecularesResumo – O objetivo deste trabalho foi caracterizar o germoplasma de tangerineiras ( Citrus spp.) pormeio de analises morfologicas e moleculares. Trinta e sete cultivares, pertencentes a 34 variedadesdistintas de tangerineiras, foram avaliadas pelas caracteristicas morfologicas e agronomicas de folhas,flores e frutos, bem como por analises de microssatelites. As caracteristicas morfologicas e agronomicassugerem que praticamente todas as variedades podem ser usadas comercialmente e algumas delas, comoa variedade Satsuma, sao recomendadas para uso em cruzamentos dirigidos. O DNA foi obtido deamostras extraidas de uma a cinco plantas de cada cultivar. Oito de nove primers detectaram polimorfismos.Foram encontrados marcadores especificos para alguns acessos. O dendrograma construido com osresultados morfologicos dividiu as 37 cultivares em quatro grupos, enquanto o obtido com osmicrossatelites agrupou 35 das 37 cultivares em tres grupos. As diferencas intervarietais nao sao gran-des, e esta falta de concordância nas duas analises multivariadas indica que fatores evolutivos diversosestao agindo nesses dois niveis de investigacao.Termos para indexacao: citros, variacao genetica, microsatelites, metodo de melhoramento.

Porta-enxertos utilizados na citricultura

Citric scion is the most important factor in orchard formation. The citric scion most important characteristics are the graft and rootstock origin, the root system quality and health. The rootstock affects several horticultural and sanitary characteristic in the citric trees and fruits, as total soluble solids, canopy and fruit size, diseases and cold resistance, roots distribution, etc. Rangpur lime (Citrus limonia Osbeck cv. Cravo) is the most used rootstock in Brazil (about 80%), however in the State of Rio Grande do Sul, Brazil, Trifoliate orange (Poncirus trifoliata [L.] Raf.) is found in more than 90% of the orchards. This makes citriculture vulnerable to rootstock diseases appearance, as it happened in the 40s in the whole country, when citrus Tristeza virus, killed almost all plants grafted on Sour Orange, and more recently, the problem is with the citrus decline. So the knowledge of the several rootstock characteristics and some of their use particularities can help the citrus growers in the decision process.

Produção de mudas cítricas no Rio Grande do Sul: diagnóstico da região produtora

Engenheiro Agronomo, Doutor, Professor Adjunto, Departamento de Horticultura e Silvicultura, Faculdade de Agronomia, UFRGS, CP776, 90001-970, Porto Alegre – RS. E-mail: alcunha@vortex.ufrgs.br. Autor para correspondencia.RESUMOCom o objetivo de caracterizar a producao demudas citricas, principalmente quanto ao uso de porta-enxertos ea origem do material propagativo utilizado, aplicou-se umquestionario aos viveiristas da principal zona de producao demudas do Estado do Rio Grande do Sul, pertencentes a duasassociacoes de produtores de mudas do Vale do Rio Cai, aAvimuda e a Avimaffo. O questionario foi aplicado a um total de35% dos viveiristas inscritos nas associacoes, sorteados aoacaso, durante os meses de maio a junho de 1998. Os principaisresultados demonstram que a atividade de viveirista, nessaregiao, baseia-se, principalmente, na producao de mudas citricase ja e desenvolvida ha muitos anos; o porta-enxerto maisutilizado e o Poncirus trifoliata, sendo que a enxertia e realizadacom borbulhas de origem nao controlada.Palavras-chave: producao de mudas, porta-enxertos, Poncirustrifoliata, Citrus, diagnostico.SUMMARYA questionnaire was applied in the principal nurserycitrus production area in Rio Grande do Sul State, Brasil, tocharacterize that area, in relation to rootstock and scionutilization. The nurseries researched belong to lhe Avimuda andAvimaffo producer associations m the Cai river valley. Thequestionnaire was applied to 35% of the nurseries registered inthe associations, from May to June 1998. The principal resultsshow that the most used rootstock is the Peneiras trifoliata, andthat the scion is obtained from material with non-controiledorigin.Key words: nursery production, rootstocks, Poncirus trifoliata,Citrus, diagnostic.A questionnaire was applied in the principal nursery citrus production area in Rio Grande do Sul State, Brasil, to characterize that area, in relation to rootstock and scion utilization. The nurseries researched belong to lhe Avimuda and Avimaffo producer associations m the Cai river valley. The questionnaire was applied to 35% of the nurseries registered in the associations, from May to June 1998. The principal results show that the most used rootstock is the Poncirus trifoliata, and that the scion is obtained from material with non-controiled origin.

Diversidade genética de porta-enxertos cítricos baseada em marcadores moleculares RAPD

This research intended to characterize the genetic diversity of citrus rootstocks from the Experimental Agronomic Station of the Rio Grande do Sul Federal University (EEA/ UFRGS) and rootstocks collected in nurseries of the Cai River Valley - Rio Grande do Sul - Brazil. The method used was the Random Amplification of Polymorphic DNA (RAPD) markers. Leaves of nine citrus rootstocks from EEA/UFRGS and ten accesses of trifoliate orange (Poncirus trifoliata) from different nurseries were collected. With the use of nine random primers it was possible to separate the rootstocks in two main groups: one formed by ‘Rangpur’ lime ( limonia) and the other by trifoliate orange and its hybrids of low genetic similarity. RAPD molecular marker was very efficient for the citrus rootstock characterization and for the trifoliate orange separation from its hybrids. The technique might be used to characterize cultivars, analysis of genetic variability among progenitors in improvement breeding programs of rootstock , and identify zygotic seedlings of trifoliate orange in commercial nurseries.

Poliembrionia e número de sementes por fruto de quatro cultivares de tangerineira

Four mandarin cultivars were characterized for seed number per fruit and polyembryony, three of them are used as parents in the Departamento de Horticultura e Silvicultura - Universidade Federal do Rio Grande do Sul citrus breeding program. Mandarin fruits were sampled from the Experimental Station citrus collection, in Eldorado do Sul, RS, and their seeds were extracted and counted. In esterile chamber, the embryos were excised from seeds and cultured in vitro on MT medium (Murashige & Tucker, 1962), at 26±3°C with a 16h photoperiod. The mandarin cultivars Cai, Montenegrina (Citrus deliciosa Tenore), Ponca (C. reticulata Blanco) and King (C. nobilis Loureiro) had an average of 16, 14, 8 and 24 viable seeds per fruit, respectively, and 5.7, 5.7, 7.7 and 3.2 embryos per seed. Monoembryonyc seed production was low, except in King cultivar, which had 20.4% of monoembryonic seeds. Albine embryos were also detected, which were part or total content of some seeds. In general, the species showed significant differences in relation to the studied traits. The similarities between the C. deliciosa cultivars are strong evidences for the hipotesis that Montenegrina is originated from Cai.

O uso de ácido giberélico em solução nutritiva na avaliação precoce de estatura de genótipos de trigo hexaplóide

Six hexaploid wheat genotypes with known height and giberellic acid sensibility, were used in a new method to test plant stature (rht genes) with giberellic acid nutritive solution. The plants were submitted to three periods of giberellic acid action: without giberellic acid, giberellic acid from 8th day after sowing (7 days) and giberellic acid just after sowing (15 days). The use of giberellic acid was efficient on selecting genotypes with different plant heights in all periods with giberellic tested.

Genetics of in vitro organogenesis and precocious germination of wheat embryos

As bases geneticas da germinacao precoce de embrioides de trigo e organogenese in vitro foram estudadas utilizando-se seis genotipos brasileiros e suas geracoes F1, F2, BC1F1 e BC2F1, atraves da analise de media de geracoes. Quatro pais e um conjunto de F1x92s tambem foram analisados em um experimento dialelico. Os resultados indicam que ambos caracteres sao determinados por uma complexa acao genica, ocorrendo efeitos aditivos, de dominância e epistaticos. Foram obtidos valores altos para as estimativas de herdabilidade no sentido amplo, o que indica uma forte determinacao genetica, embora este parâmetro nada informe sobre a magnitude da acao aditiva. Considerando a complexidade do controle genico, espera-se que maiores ganhos geneticos sejam obtidos selecionando para os caracteres em geracoes avancadas de populacoes segregantes. Os baixos valores de correlacao entre ambas caracteristicas e embriogenese somatica e regeneracao de plantas (dados apresentados em trabalho anterior) indicam a possibilidade de obtencao de genotipos recombinantes.

Avaliação de embriogênese somática em cultivares de aveia (Avena saliva L.)

Nine oat genotypes were cultivated in vitro to evaluate callus initiaton and subsequent somatic embryogenesis. The immature embryo were submited to different protocola (MURASHIGE & SKOOG (1962) medium with differents hormones dosages). The protocols tested caused differences in somatic embryogenesis, and the best of them was selected to continue the research. After a month in subculture medium the cali were evaluated concerning embryoid porcentage, and showed differences according to genotype in experiment 2, UFRGS 7 and UFRGS 8 presented superior means. The covariance analysis revealed that in some genotypes this parameter is important.

Avaliação de genótipos de trigo hexaplóide quanto a tolerância a toxicidade do alumínio

Aiming to test and improve lhe method of evaluation of hexaploid wheat (Triticum aestivum L.) to aluminum toxic levels in nutritive solution. Five genotypes with known reaction to toxic aluminum (Al+++) were tested in nutritivo soluction in three different Al+++ concentrations (4, 6 e l0ppm), in two experiments. The results allowed the equipament ajustment, the choice of best evaluation method to select tolerant wheat genotypes to toxic Al+++ concentrations.

Regeneração de plantas de trigo (Triticum aestivum L.) de linhas isogênicas do genótipo Maringá com genes de porte baixo (Rht1 e Rht2)

Different genotypes show different responses for in vitro plant regeneration. In previous work with lhe Maringa genotype a result of 100% of in vitro plant regeneration was obtained. The purpose of this study was to investigate the capacity of plant regeneration of Maringa genotype and two of its isogenic lines with one and two shorts heigth genes (Rht1 and Rht2). Imature embryos from: (a) Maringa, (b) the isogenic lines and (c) the crosses between these genotypes were placed on MS medium (modified by MILACH et al., 1991) with saccharose, agar and decreasing doses of 2,4D (2mg/l; 0.5mg/l; 0.1mg/l and 0.0mg/l) according to the stage of culture. The possibility of suppressing one of the stages of culture, (which uses 0.1mg/1 of 2.4D) was also evaluated. The statistic analisys demonstrated that the different genotypes gave different responses, therefore this indicates that the Rht genes had influence on plant regeneration rates. The suppression of the stage of culture which uses 0.1mg/l of 2,4D did not have any influence on regeneration, showing that this stage can be eliminated. Different genotypes had the same responses on the different culture medium sequences. The intercection between genotype x medium was not significam.