Herculano Penna Medina Filho

Caracterização isoenzimática e morfológica de clones e introduções de alho

Em virtude do grande numero de denominacoes locais para clones de alho, nem sempre correspondentes a materiais distintos, conduziu-se o presente estudo objetivando a caracterizacao e classificacao de 72 clones e introducoes de alho (Allium sativum L.), e um clone de alho-rei (A. ampeloprasum L.). Isso foi feito analisando as isoenzimas alcooldesidrogenase (ADH), esterase (EST), peroxidase (PRX) e fosfoglucoisomerase (PGI) atraves da tecnica de eletroforese horizontal em gel de amido hidrolisado de batata. Verificou-se que os clones nacionais e introduzidos se enquadram nos grupos aqui denominados DIKA ou CJLB, respectivamente para os padroes de ADH, EST, PRX e PGI. Entretanto, os padroes CILB, CJKB e CIKB foram observados em alguns clones estrangeiros, sugerindo sua maior variabilidade em relacao aos nacionais. O alho-rei apresentou padroes diferentes dos encontrados na especie A. sativum L. A associacao dos resultados da tecnica de eletroforese de isoenzinas com a caracterizacao morfologica da parte aerea, bulbos, bulbilhos, coloracao externa dos bulbos e bulbilhos e ciclo cultural, permitiu a classificacao dos clones nacionais de alho em 19 grupos distintos.

Isoenzimas na identificação precoce de híbridos e clones nucelares no melhoramento de citros

Um dos problemas relacionados ao melhoramento de citros e a poliembrionia e a consequente dificuldade, apos cruzamentos controlados, de distinguir clones nucelares dos hibridos. Estudou-se um metodo para eletroforese de isoenzimas em gel de amido para doze sistemas isoenzimicos, desenvolvendo-se procedimento apropriado para a resolucao simultânea dos sistemas fosfatase acida, peroxidase anodica e catodica, glutamato oxaloacetico transaminase, fosfoglucoisomerase, fosfoglucomutase e enzima malica. Caracterizaram-se por esses sistemas 31 clones de citros com possivel interesse para o programa de melhoramento do IAC. Estao envolvidos 7 locos e 25 alelos, permitindo uma identificacao precoce de hibridos antes do plantio no campo para avaliacoes agronomicas. Implicacoes desses estudos basicos no melhoramento e na determinacao da taxa de seedlings nucelares de porta-enxertos comerciais sao discutidas.

AVALIAÇÃO DAS CULTIVARES MUNDO NOVO, BOURBON AMARELO E BOURBON VERMELHO DE COFFEA ARABICA L. EM CAMPINAS, SP (1)

Coffea arabica L. cv. Mundo Novo is the most outstanding coffee cultivars studied at the Instituto Agronomico, Campinas, State of Sao Paulo. Besides its rusticity, this cultivar has showed high yield capacity in all Brazilian coffee growing areas. In order to further diversify the Mundo Novo genetic background, new selection of mother trees was undertaken, in 1952, in six sites where former selections were made in Urupes, SP. Four groups of coffee progenies were planted to be compared at the Central Experimental Station, in Campinas, SP: 92 new selections (S1), 12 progenies of selected Mundo Novo (S2), 6 selected progenies of Bourbon Amarelo and 7 progenies of Bourbon Vermelho cultivars of C. arabica. The 117 progenies were planted in a randomized block design, with one-plant plots and 21 replications. Yield data were collected from individual plants during 33 consecutive annual harvests, from 1955 to 1987. Prior to the 1985 harvest, observations were made on the shape of plants, vegetative vigor (IAV index, 1 to 10 points varying from the worst to the best, respectively), fruit ripening (1 point for early, 3 for medium and 5 for late ripening, respectively), seed characteristics, such as flat beans, peaberry and elephant beans, and seed size. Significative differences were found in the yield inside and between progenies groups - Mundo Novo S1, Mundo Novo S2, Bourbon Amarelo and Bourbon Vermelho. The average yield of Mundo Novo S1 was 6% superior to the of Mundo Novo S2, and both groups of Mundo Novo S1 and S2 were more productive than Bourbon Amarelo (39 and 30%) and the progenies of Bourbon Vermelho (112 and 99%), respectively. Among the 30 highest Mundo Novo yield progenies, 4 belong to S2 and 26 to S1, Mundo Novo progenies, indicating the efficiency of the selection of S1 progenies. The highest yield Mundo Novo progenies have medium maturation. However individual plants in the progenies were classified as early, medium or late maturing plants. The Mundo Novo progeny CP447 gave larger number of plants with early fruit ripening and CP502 gave the highest number of late plants. All the best Mundo Novo progenies presented normal flat, peaberry and elephant beans seed percentages and seed size. The progeny CP474 gave several plants with larger seeds. The highest yield S2 Mundo Novo progenies such as P388-17, MP376-4 and the S1 CP502, CP515, CP474, CP447, CP501, CP543, CP475, CP464 and CP441 have already been multiplied in seed plots and are being extensively planted in all coffee regions of Brazil.

Sources of resistance to leaf miner, Perileucoptera coffeella, in Coffea spp.

Procurou-se determinar, em nivel de laboratorio, por meio de infestacoes artificiais uniformes, fontes de resistencia ao bicho-mineiro Perileucoptera coffeella (Guerin-Meneville, 1842), entre as especies Coffea stenophyila, C. salvatrix, C. racemosa, C. liberica, C. eugenioides, C. kapakata, C. dewevrei, C. brevipes, C. congensis e C, canephora e os cultivares Catuai Vermelho e Mundo Novo de C. arabica. Utilizaram-se testes de livre escolha e de confinamento, sendo avaliados os seguintes parâmetros: oviposicao, numero de discos lesionados por parcela, nota visual, area foliar danificada por parcela e area foliar danificada por lagarta. De acordo com os parâmetros analisados, pode-se, com relacao ao numero de pontos atribuidos na avaliacao visual e quanto a porcentagem de discos lesionados, agrupar as especies C. stenophyila, C. brevipes, C. liberica e C. salvatrix, como altamente resistentes; C. racemosa, C. kapakata, C. dewevrei e C. eugenioides, como moderadamente resistentes, e C. congensis, C. canephora e C. arabica, como suscetiveis. Considerando os parâmetros area foliar danificada por parcela e area foliar danificada por lagarta, C. arabica pode ser classificada como altamente suscetivel, mantendo-se C. congensis e C. canephora como suscetiveis.

Genética de Coffea: XXVI. Hereditariedade do porte reduzido do cultivar Caturra

A mutacao de Coffea arabica, conhecida sob a denominacao de Caturra, caracteriza-se pela reducao do comprimento medio dos internodios dos ramos ortotropicos e plagiotropicos, o que diminui a altura das plantas, conferindo-lhes um aspecto compacto. Surgiu provavelmente no Bourbon Vermelho, e sua producao se assemelha a deste cultivar. Devido a suas caracteristicas, a densidade de plantio podera ser aumentada, refletindo favoravelmente na producac por area, e facilitando tanto a colheita como os tratos culturais e fitossanitarios. A analise genetica, realizada a partir dos tipos paternais Caturra e Normal, que abrangeu a classificacao de plantas S1, S2, S3 , S4, S5, F1, F2 e BC e cruzamentos-testes e seus descendentes, num total de 55.516 plantas, indicou que o porte reduzido do Caturra e controlado por um fator genetico simples, ao qual foi proposto o simbolo Ct. A dominância e completa, sendo indistinguiveis os cafeeiros de genotipos CtCt e Ctct. Dado o interesse que apresentam as plantas de porte reduzido, o fator Caturra vem sendo transferido a outros cultivares de C. arabica de maior interesse economico.

A tristeza dos citros e suas implicações no melhoramento genético de porta-enxertos

Brazil is the world leading citrus producer and historically, tristeza is the most serious disease in economic importance. Tristeza is caused by a single strand RNA closterovirus, Citrus Tristeza Virus (CTV), is disseminated in almost all citrus regions of the world. It is transmitted by grafting and by several species of aphids mainly Toxoptera citricida. There are several virus strains, causing variable symptoms in the majority of species and related genera of Citrus. Cross-protection by mild virus strains is an efficient technique for protecting very sensitive scions in Brazil and elsewhere. Methods for detecting and characterizing virus strains are classically based on the reaction symptoms of specific varieties and clones. However, development of serological and molecular methods have allowed progress in the characterization and in monitoring the spread of the disease. Plants may be infected with more than one strain that can undergo genetic recombination, show differential transmissibility by the vector aphids, have composition of the strain complex altered by drastic pruning, temperature, and also segregate among budwoods, or by sub-culture in different clones. Smaller defective RNAs are often associated with normal CTV particles, some correlated with symptoms of seedling yellows. Efficient control is achieved by favorable combinations of scions and rootstocks. They react in predictable interactions dependent on both, the capability to multiply the viruses and to tolerate their presence in phloem tissues. These peculiarities have important implications on practical cultivation and on the genetic improvement of scions and rootstocks. This review discuss also the reaction of grafted and non-grafted plants, and highlights problems, basic concepts and relevant implications for citrus rootstock improvement.

Melhoramento do cafeeiro: XLIII. seleção de cafeeiros resistentes ao bicho-mineiro

Several agronomic characteristics were studied in progenies from open pollinations and hybridizations of coffee trees C1195-5-6-1 and C1195-5-6-2. Both, resistant to the leaf miner (Perileucoptera coffeella), bloom profusely and are early ripening, characteristics of Coffea racemosa from which they originated via backcross to C. arabica. Hybrids of these two individuals with Icatu, Catimor, Hibrido de Timor and Catuai cultivars were evaluated. The first three cultvars, C. canephora x C. arabica backcross derivatives, are resistant to the leaf rust (Hemileia vastatrix) and the last a leading C. arabica cultivar has short stature and high yield capacity. The study of the progenies, undertaken in four experiments revealed that all these attributes, of such a diverse germoplasm, are genetically inheritable and are present in the progenies in different associations. The yield data and the fact that there are no antagonistic correlations among those attributes suggest that is possible to develop high yielding leaf miner resistant cultivars with other additional favorable traits, mainly resistance to leaf rust.

Segregações gaméticas de locos isoenzímicos em porta-enxertos de citros e suas contribuições alélicas na formação de híbridos

The rootstock clones Rangpur lime(Citrus limonia), Sunki mandarin (C. sunki), Sour orange (C. aurantium) and Trifoliate orange(Poncirus trifoliata) were studied by discontinuous horizontal starch gel electrophoresis as to genotypes and segregations of the isozyme loci Pgi-1, Pgm-1, Got-1, Got-2, Prxa-1, Aps-1 and Me-1 as well as their relative allelic contributions to more than 400 hybrids between them. The loci Aps-1 and Me-1, although useful for identifying hybrids are homozygous in the genitors and consequently were disregarded in the studies of segregation and allelic contribution. In Trifoliate orange, the duplicate Got-2 locus previously described as having the genotype MT.SS is actually SS.MT being S an allele of F in Sunki (FF.MM) and of F and M in Sour orange (FM.MM). M and T of the duplication are alleles of M of the homozygous locus of Sour orange and Sunki as determined by the banding pattern observed in the hybrids and by the formation of the correspondent intralocus heterodimers. Among 27 segregations for the five loci investigated, statistically significant distorted segregations, occurred in six (22%) of them. Considering the absence of selection provided by ideal conditions of germination, handling of young hybrid embryos in Petri dishes and determination of genotypes at the first or second leaf pair, the results probably reflect distortion in the relative proportion of alleles in the gametes of the genitors, differential transmission of the alleles or distinct viability of their bearers in the hybrid zygotes. Due to the codominance of the alleles it was possible, from the genotypes of the hybrids, to deduce the relative contribution of each allele of the heterozygous loci of the genitors. Genotypic distortions did not come from the Trifoliate orange, occurred in one locus of Sour orange and Sunki mandarin and was traced back to Rangpur lime in the three tested loci. Such marked distortions are congruent with a possible interspecific hybrid origin of Rangpur lime and also illustrate the difficulty of genetic studies in citrus involving genotype proportions in zygotic progenies.

Influências ambientais no rendimento intrínseco do café

It was studied the influence of several environmental factors on the intrinsic outturn (RI) of coffee, ratio between the weight of two flat beans and the respective fruit containing them. The RI decreased up to 18% in fruits from unripe (green) to overripe (raising) stage. In seven localities evaluated fruit RIs varied up to 12%. In two different sites of the same locality variation on RI up to 6% was observed. It was observed a difference of 2% among four experimental plots in the same site. Plants of the same cultivar grown in a single experimental plot displayed RI with differences up to 3,7%. In the same locality variations up to 330 meters in altitude were positively correlated with variations up to 4,4% in the RI. Regarding to the influence of the fruit position within the plant it was observed that RI decreased, up to 4,4% if the fruits are located farther from the orthotropic branch, 1,5% in the East side and 0,5% at the middle and upper parts of the plants. The results pointed out that there are considerable environmental influences on the intrinsic outturn of coffee. For breeding purposes, selection for higher RIs must be based on standard sampling as to ripening stage, position in the plant, and be representative of at least 10 plants of uniform progenies evaluated in the same experimental plot.

Evidência isoenzímica sobre a origem interespecífica do café Piatã

Years ago it was found in a field of Coffea arabica (2n = 44) a coffee tree different from any other known so far. Initially it was thought to be an autotetraploid either of C. liberica (2n = 22) or of C. dewevrei (2n = 22). Morphological and cytological studies of this tree and its progeny, designated by the prefix C387 of the Department of Genetics, IAC and named Piata, indicated that it was probably a natural hybrid originated from the fusion of a normal gamete (n = 22) of C. arabica and an unreduced gamete (2n = 22) of C. dewevrei. In the present study the isoenzyme banding patterns for the enzymes PGI, PGM and ADH of the seeds endosperm of Piata confirmed its interspecific origin. The alleles of combination of C. dewevrei and C. arabica for the aforementioned isoenzymes is peculiar and distinct for these species, and such alleles segregate in the seeds of the Piata. Isoenzymatic studies on seeds showed also that Piata coffee is self-compatible, and not self-incompatible as it was believed. Indeed, autogamy is quite frequent in the Piata coffee. Similar analyses may be useful for the identification of other natural hybrids among Coffea species. This could be of great value for genetic and evolution studies, and breeding of coffee, where the knowledge of the origin, genotype constitution and reproductive biology of the plants is important.