Response of root explants to in vitro cultivation of marketable garlic cultivars

Garlic cultivars are sexually sterile under standard growth conditions, with direct implications for commercial production costs as well as breeding programs. Garlic is propagated commercially via bulblets, which facilitates disease transmission and virus load accumulation over vegetative generations. Tissue culture produces virus-free clones that are more productive, while keeping the desired traits of the cultivar. Consequently, this technique allows studies of garlic genetics as well as guarantees genetic conservation of varieties. We aimed at analyzing the in vitroregeneration of eight marketable cultivars of garlic using root segments as explants. For each genotype, bulblet-derived explants were isolated and introduced into MS medium supplemented with 2,4-D and 2-iP. Calli were transferred to MS medium supplemented with 8.8 mM BAP and 0.1 mM NAA (regeneration medium A), or with 4.6 mM kinetin alone (regeneration medium B). The calli were then evaluated for regeneration frequency after sixty days of in vitro cultivation. The noble cultivar \u27Jonas\u27 presented the highest rates of plant regeneration among the cultivars tested. The medium A, which contained auxin and cytokinin, induced the highest regeneration rates of all cultivars. The process described herein is simple, reproducible and can potentially be used as a tool in molecular breeding strategies for other marketable cultivars and genotypes of garlic

Genetic variation between susceptible and non-susceptible snails to Schistosoma infection using random amplified polymorphic DNA analysis (RAPDs) Variação genética entre moluscos susceptíveis e não susceptíveis à infecção pelo Schistosoma através da análise do DNA polimórfico amplificado aleatóriamente (RAPDs)

Susceptibility of snails to infection by certain trematodes and their suitability as hosts for continued development has been a bewildering problem in host-parasite relationships. The present work emphasizes our interest in snail genetics to determine what genes or gene products are specifically responsible for susceptibility of snails to infection. High molecular weight DNA was extracted from both susceptible and non-susceptible snails within the same species Biomphalaria tenagophila. RAPD was undertaken to distinguish between the two types of snails. Random primers (10 mers) were used to amplify the extracted DNA by the polymerase chain reaction (PCR) followed by polyacrylamide gel electrophoresis (PAGE) and silver staining. The results suggest that RAPD represents an efficient means of genome comparison, since many molecular markers were detected as genetic variations between susceptible and non-susceptible snails.<br>A susceptibilidade de moluscos à infecção por certos trematódeos e a sua capacidade como hospedeiro para o contínuo desenvolvimento é o problema mais deslumbrante nas relações parasita hospedeiro. O presente trabalho, focaliza nosso interesse na genética dos moluscos para determinar quais genes ou produtos gênicos são especificamente responsáveis pela susceptibilidade do molusco à infecção. DNA de alto peso molecular, foi extraído de ambos moluscos susceptíveis e não susceptíveis da espécie Biomphalaria tenagophila. Iniciadores aleatórios com 10 pares de bases foram usados na amplificação aleatória (RAPD) de ambos os DNAs e análise por eletroforese em gel de poliacrilamida e coloração com prata. Os resultados mostram que a amplificação aleatória do DNA representa um eficiente caminho para a comparação dos genomas desde que marcadores moleculares foram detectados como variantes genéticos entre os moluscos susceptíveis e não susceptíveis