Produção, qualidade e conservação de tomates heterozigotos nos locos alcobaça, nonripening e ripening inhibitor

O objetivo deste trabalho foi avaliar os atributos de produtividade, qualidade e conservação pós-colheita de tomates, para comparar os efeitos promovidos pelos alelos alcobaça (norª), nonripening (nor) e ripening inhibitor (rin) em heterozigose, isoladamente ou em duplas combinações, sobre frutos de tomateiros híbridos. Foram avaliados dez tratamentos: sete híbridos experimentais quase-isogênicos, com background FloraDade x Tropic de genótipos nor+/norª, rin+/rin, nor+/nor, nor/norª, nor+/norª rin+/rin e nor+/nor rin+/rin; e três testemunhas comerciais (Floradade, Tropic e Carmen F1). Contrariamente aos genótipos rin+/rin e nor+/nor, o genótipo nor+/norª não prolongou, significativamente, a firmeza dos frutos em pós-colheita. Os genótipos duplo-mutantes norª/nor, nor+/norª rin+/rin e nor+/nor rin+/rin foram eficientes em atrasar a perda de firmeza e a evolução da coloração dos frutos; os efeitos dos locos nor+/norª e rin+/rin, juntos, sofreram desvios significativos em relação à soma dos efeitos desses locos, quando atuaram separadamente, no sentido de intensificarem esses atrasos. O uso de híbridos heterozigotos, nas duplas combinações entre os locos norª, nor e rin, mostrou-se vantajoso por propiciar frutos firmes, com maior extensão da vida pós-colheita, em comparação com o uso dos híbridos portadores desses locos isoladamente. A qualidade dos frutos duplo-mutantes não foi limitada pelo atraso na evolução da coloração vermelha.

Tissue culture parameters in sweet orange cultivars

The objective of this work was to establish tissue culture parameters for gene transfer in sweet orange cultivars. Epicotyl explants with different ages were cultured with 6-benzylaminopurine (BAP), kanamycin and hygromycin. Shoots were cultured with alpha-naphthaleneacetic acid (NAA) alone or in combination with indole-3-butyric acid (IBA). The requirement of BAP for shoot development was genotype-specific. Epicotyl explants from 35-day-old seedlings produced significantly more shoots per explant in 'Pêra'. Kanamycin inhibited shoot regeneration for the most cultivars. The percentage of shoots that produced roots in 'Pêra' was significantly higher in medium with NAA and IBA than with NAA alone.

Growth regulators, culture media and antibiotics in the in vitro shoot regeneration from mature tissue of citrus cultivars

The objective of this study was to evaluate the effects of 6-benzylaminopurine (BAP) and α-naphthaleneacetic acid (NAA) combinations, basal media and beta-lactam antibiotics on in vitro organogenesis from mature stem segments of 'Pêra', 'Valência' and 'Bahia' sweet oranges and 'Cravo' rangpur lime. For induction of shoot regeneration, the segments of the four cultivars were placed on Murashige and Skoog (MS) medium containing the following BAP/NAA concentrations: 0.0/0.0; 0.25/0.0; 0.25/0.25; 0.5/0.0; 0.5/0.5; 1.0/0.0; 2.0/0.0; 2.0/0.25; 2.0/0.5; and 2.0/1.0 mg L-1. In order to test the influence of the culture media on shoot-bud induction, (MS), Murashige and Tucker (MT), and woody plant medium (WPM) formulations were evaluated, associated with the best combination of plant growth regulators obtained in the previous experiment. The influence of four beta-lactam antibiotics (timentin, cefotaxime sodium salt, meropenem trihydrate and augmentin) on shoot regeneration was determined. Better regeneration responses were achieved when internodal segments were cultured onto MS-based medium with 500 mg L-1 cefotaxime with the following BAP/NAA concentrations: 0.5 + 0.25 mg L-1 for 'Cravo', 1.0 + 0.25 mg L-1 for 'Valência' and 'Bahia', and 1.0 + 0.5 mg L-1 for 'Pêra'. Genotype, growth regulators, basal media and beta-lactam antibiotics affect the morphogenetic response in mature tissues of citrus.