Augusto Tulmann Neto

Genetic diversity of Musa diploid and triploid accessions from the Brazilian banana breeding program estimated by microsatellite markers

Banana (Musa spp.) is one of the most consumed fruits worldwide. Production is based mainly on triploid cultivars, and most genetic improvement programs aim to generate tetraploid hybrids obtained from the crossing of established triploid cultivars with a diploid parent genotype, improved or wild, exhibiting the trait of interest, normally resistance to biotic factors. Microsatellites were used to investigate the genetic variability and relationships between 58 Musa genotypes, including 49 diploids and nine triploid cultivars maintained at the Musa germplasm collection of the Brazilian dessert banana breeding program. Thirty-three primer pairs developed for banana were tested, and nine amplified reproducible and discrete fragments, producing a total of 115 alleles. The average number of alleles amplified per primer was 12.8, ranging from 10 to 15. The diploid genotypes presented the largest genetic variability, demonstrated by the large number of alleles detected, and the low similarity between the clones. The phenetic analysis clustered the triploid cultivars in a separated group, with the exception of the ‘Nanica’ and ‘Gros Michel’ cultivars, which showed high similarity with the diploid cultivar ‘Mambee Thu’. It was not possible to separate the wild diploid genotypes from the cultivated ones, indicating a common origin of these genotypes. A high proportion of duplicated alleles and/or loci was observed for diploid and triploid genotypes. The information gathered about the similarity between diploid and triploid accessions will help to define potential crosses to maximize the recovery of the typical fruit qualities required in Brazil (AAB, Pome and Silk dessert banana).

In vitro mutation of chrysanthemum (Dendranthema grandiflora Tzvelev) with ethylmethanesulphonate (EMS) in immature floral pedicels

Many new cultivars of chrysanthemum were derived from induced mutation. However, chemical mutagenic agents are not widely used due to their low penetration into plant tissues. The objective of the present study was to induce mutation in chrysanthemum using ethylmethanesulphonate (EMS) in immature floral pedicels, followed by the induction and production of adventitious buds in vitro. Preliminary studies on the sensitivity of pedicels to EMS revealed that the LD50 was close to 0.82% (v/v). Immature pedicels of chrysanthemum cv. Ingrid (dark pink color) were treated with 0.77% (0.075 M) EMS solution for 1 h and 45 min, which was followed by rinsing in water for 15 min and surface disinfection. Afterwards, they were cultivated in Murashige and Skoog medium (salts and vitamins) amended with 1 g l−1 of hydrolyzed casein, 1 mg l−1 6-benzylaminopurine (BAP) and 2 mg l−1 indole-3-acetic acid (IAA). A total of 910 plants were obtained from the pedicels treated with EMS and were evaluated at the flowering stage. Forty-eight mutants (5.2%) were obtained, deviating in petal color (pink-salmon, light-pink, bronze, white, yellow and salmon color). Most of them (89.6% of the total) were phenotypically uniform. The results showed the efficiency of EMS to induce in vitro mutation of chrysanthemum.Many new cultivars of chrysanthemum were derived from induced mutation. However, chemical mutagenic agents are not widely used due to their low penetration into plant tissues. The objective of the present study was to induce mutation in chrysanthemum using ethylmethanesulphonate (EMS) in immature floral pedicels, followed by the induction and production of adventitious buds in vitro. Preliminary studies on the sensitivity of pedicels to EMS revealed that the LD50 was close to 0.82% (v/v). Immature pedicels of chrysanthemum cv. Ingrid (dark pink color) were treated with 0.77% (0.075 M) EMS solution for 1 h and 45 min, which was followed by rinsing in water for 15 min and surface disinfection. Afterwards, they were cultivated in Murashige and Skoog medium (salts and vitamins) amended with 1 g l−1 of hydrolyzed casein, 1 mg l−1 6-benzylaminopurine (BAP) and 2 mg l−1 indole-3-acetic acid (IAA). A total of 910 plants were obtained from the pedicels treated with EMS and were evaluated at the flowering stage. Forty-eight mutants (5.2%) were obtained, deviating in petal color (pink-salmon, light-pink, bronze, white, yellow and salmon color). Most of them (89.6% of the total) were phenotypically uniform. The results showed the efficiency of EMS to induce in vitro mutation of chrysanthemum.

Somatic embryogenesis and the effect of particle bombardment on banana Maçã regeneration

A plant regeneration method with cell suspension cultures of banana, and the effect of biobalistic on regeneration potential are described in this report. Somatic embryos of banana were obtained from indirect embryogenesis of male inflorescence of banana cultivar Maca (AAB group). Part of the calluses formed (40%) showed embryogenic characteristics (nonfriable, compact and yellow color). The cell suspension, originated from embryogenic calluses, contained clusters of small tightly packed cells with dense cytoplasms, relatively large nuclei and very dense nucleoli. After four months of culture, somatic embryos started to regenerate. The maximum number of regenerated plants was observed between 45 and 60 days after embryo formation. In the first experiment, 401 plants were regenerated from approximately 10 mL of packed cells. In the second experiment, 399 plants were regenerated from a cell suspension six months older than that of the first experiment. Cell transformation using particle bombardment with three different plasmid constructions, containing the uid-A gene, resulted in a strong GUS expression five days after bombardment; however, plant regeneration from bombarded cells was much lower than nonbombarded ones.

Micropropagação de baixo custo em bananeira cv. Maçã em meios com diferentes fontes de carbono e avaliação da performance em campo das mudas produzidas

Este trabalho teve como objetivo reduzir o custo da micropropagacao de bananeira cv. Maca (Musa spp AAB), bem como avaliar o desenvolvimento em campo das mudas produzidas. Para tanto, cultivaram-se, no Centro de Energia Nuclear na Agricultura - USP, explantes de bananeira em meio de multiplicacao MS com diferentes fontes de carbono (acucar). As fontes de carbono testadas foram: sacarose P.A., acucar cristal e acucar mascavo. Apos a etapa de micropropagacao, as plantas foram avaliadas quanto as suas caracteristicas em campo, na cidade de Presidente Prudente-SP, em 2002. O desenvolvimento e vigor in vitro dos explantes nos tres tratamentos testados foram semelhantes. A media do numero de brotos produzidos em meio contendo acucar cristal foi semelhante ao da sacarose P.A. e superior ao do acucar mascavo. Em campo, as plantas produzidas em meios com diferentes fontes de carbono nao apresentaram diferencas estatisticas entre as caracteristicas avaliadas, e nao houve ocorrencia de variacao somaclonal. Com esta alternativa de producao in vitro de bananeira cv. Maca, pode-se ter uma reducao de cerca de 50% do custo para a producao de 1 litro de meio de cultura utilizando acucar cristal como substituto da sacarose P.A., mantendo-se a qualidade das mudas e reduzindo-se o custo de sua producao.

Plant regeneration from protoplasts isolated from primary calli using mature embryos of two Brazilian rice cultivars

A plant regeneration system from rice protoplasts using calli derived from mature embryos was established for the two Brazilian modern rice cultivars IAC-201 and IAC-165. After 30 to 40 days of in vitro culture it was possible to obtain on average 6 million protoplasts per gram of callus. Microscopic selection of embryogenic calli was a key step for protoplast isolation. The production of embryogenic calli increased when L-proline and casein hydrolysate were used in the callus induction medium. The Oc or IR52 nurse cell lines were essential for protoplast division. Different regeneration media were studied and 139 plants were regenerated which set seed. Some of the regenerated plants showed morphological variation such as the presence of awns in spite of the short time of the in vitro culture.

Irradiação gama para mutagênese in vitro em bananeira 'Terra Maranhão'

The objective of this work was to evaluate the survival of plants and shoots as well as the reduction in the height of banana cultivar Terra Maranhao in gamma rays doses. In vitro plants were irradiated with different gamma rays doses - 0, 20, 30, 40 e 60 kGy - and afterwards their multiplication rate was evaluated. The doses of 20 and 30 kGy were the most indicated for use in the Terra Maranhao cultivar, since these irradiation intensities enabled greater values for the number of buds and survival index.

New wheat genotypes tolerant to aluminum toxicity obtained by mutation induction

Seed from the sensitive wheat (Triticum aestivumL.) cultivar Anahuac was treated to gamma-ray irradiation and eleven Al3+ tolerant mutants selected. The objective was to compare these mutants to the original Anahuac and to the tolerant wheat cultivars IAC-24 and IAC-60 from 1994 to 1996 in acid (Capao Bonito) and limed (Monte Alegre do Sul) soil field trials, in the State of Sao Paulo, Brazil. Grain yield and agronomic characteristics were analyzed. All the mutant lines yielded higher than the sensitive Anahuac cultivar in the acid soils of Capao Bonito. Under limed soil conditions, 10 mutants had a similar yield to the original sensitive cultivar and one a lower yield. The majority of the mutants were similar in yield to the tolerant cultivars IAC-24 and IAC-60 under both conditions. Some of the mutants showed altered agronomic characteristics, but these alterations did not generally influence the grain yield. The results indicated that tolerant lines with good characteristics may be obtained from a susceptible cultivar by mutation induction, thus allowing cropping under conditions where Al3 + is a limiting factor.

Seleção de clones de figueira cv. roxo de Valinhos formados por gemas irradiadas

ABSTRACT - The fig tree ( Ficus cari ca L.) is a fruit tree of great world importance and, therefore, the genetic improvement becomes an important field of research for the crop improvement, being necessary to gather information on this species, mainly regarding its genetic variability so that appropriate propagation projects and management are made. However, the fig, in Brazil, is all produced from only one cultivar, Roxo de Valinhos, which produces seedless fruit, making impossible the conventional breeding. So, the fig breeding through induced mutagenic becomes a very important research line, greatly contributing to the fig culture development. The objective of this study was to select fig plants formed by cuttings treated with gamma ray. The plants used were obtained from buds of the cv. Roxo de Valinhos. The cuttings were irradiated with gamma rays in an irradiator Gamma Cell at 10 cm from the tip of the cutting, at doses of 30 Gy with dose rate of 238 Gy/h. The experiment consisted of 450 treatments, where each formed plant was a treatment. The treatments were numbered sequentially from 1 to 450 and spaced 2.5 x 1.5 m. It was evalu -ated the vegetative and the fruits characteristics, and the incidence of major crop pests and diseases. The analysis data showed that there is genetic variability among treatments and that the plants under numbers 1, 5, 20, 79, 164, 189, 194, 201, 221, 214, 258, 301, 322, 392, 433 and 440 are probably genetic mutants that should be tested as commercial orchards.

Viabilidade de pólen em clones de laranja pêra e outras variedades assemelhadas

Sterility limits sexual hybridization, but on the other hand, it is of economic importance by inducing fewer seeds per fruit in some citrus varieties. Pera sweet orange is the main cultivar in Brazil, around 50% of all sweet oranges produced in the country. This variety has good processing quality as well as for the fresh market. The importance of this cultivar for the brazilian citriculture and the necessity to search for new cultivars, which combine the good characteristics from Pera with others desirable agronomic characters, has induced new basic studies aiming at a better knowledge of genetics and reproduction of this elite variety. In this way, in this work, was studied the pollen viability for eleven clones of Pera and five others sweet orange varieties, morphologically similar to Pera, budded in Rangpur lime (Citrus limonia Osbeck). The percentile of pollen viability was evaluated using acetic carmine stain and optic microscopy. It was observed that Corsa Tardia, Pera Olimpia and Ovale San Lio varieties, presented larger quantity of viable pollen, with 65.5, 57.3 and 53.6%, respectively, most of studied genotypes showed this values varying from 30 to 50%, and those that presented fewer values were Pera Bianchi and Pera Pirangi, with approximately 28% of viable pollen as well as Ovale de Siracusa variety, which did not present pollen.

Caracterização agronômica de mutantes de bananeira obtidos por meio da radiação gama

Banana is one of the most economically important fruit, explored almost exclusively by small producers as a continuous source of food and income. Although Brazil is one of the main banana producers, the national banana production is undergo- ing serious problems especially in the phases of production and post-harvest limiting its participation in the international market. One of the main factors leading to great production losses is the toppling over due to the tall height of plants of main commercial cultivars. A strategy to solve this problem is reducing height by inducing mutation. The objective of the present work was to characterize irradiated Prata type banana mutants (cvs. Pacovan and Preciosa) during two production cycles in order to select short plants in height with good agronomic characteristics. In vitro plants of both cultivars were irradiated with gamma rays in the doses of 20 Gy (´Pacovan´, 200 plants) and 30 Gy (´Preciosa´, 200 plants) subcultivated four times and afterwards evaluated in the field during two production cycles. Four possible mutants were selected from each cultivar with height smaller than the average height of the controls after two evaluation cycles. It was observed that some of these mutants presented greater precocity and bunch weight compared to the controls. From the results obtained it is possible to select mutant plants with superior agronomic characteristics forPacovanas well asPreciosasubmitted to gamma radiation.