RESUMO
An efficient procedure for in vitro propagation of Herreria salsaparrilha Martius was established from single-node explants (fourth and fifth nodes from apex to the base) derived from donor plants maintained under shading-house conditions. After surface sterilization, explants are inoculated in test tubes containing 15 mL of Murashige and Skoog (MS) medium without growth regulators. Cultures are maintained under 35 µmol m-2 s-1 irradiance, a 16/8-h light/dark light regime, at 26 ± 2 °C. The subcultures are carried out under the same conditions, adding 6-benzyladenine 1.0 mg/L and Phytagel® 2.8 g/L. Shoots are elongated and rooted by transferring individual shoots to half-strength MS medium without growth regulators. After 25-30 days, elongated rooted shoots are transferred to plastic pots containing 25-30 mL of sterile distilled water, covered with a transparent plastic bag, and kept under the same growth room conditions for 2 days. Plants are transferred to cups containing autoclaved and washed sand and kept in a shading house (50% light interception) for acclimatization. True-to-type adult plants were successfully recovered under ex vitro conditions.
Assuntos
Aclimatação , Brotos de Planta , Brotos de Planta/crescimento & desenvolvimento , Plantas Medicinais/química , Meios de Cultura/química , Raízes de Plantas/crescimento & desenvolvimentoRESUMO
Bacterial wilt of the common bean caused by Curtobacterium flaccumfacienspv. flaccumfaciensresults in economic losses. The aim of this study was to analyze the colonization of C. flaccumfaciens pv. flaccumfaciens in resistant, moderately resistant, and susceptible genotypes of common bean plants. The genotypes OuroBranco and IPA 9 (resistant), Diacol Calima (moderately resistant), and CNFRS 11997 and CNFP 10429 (susceptible) were inoculated in the epicotyl, with 100 µL of bacterial suspension of the BRM 14933(Cff25). Disease severity was evaluated 21 days after inoculation (DAI), on a scale from 1 to 9. Plant samples were prepared for scanning electron microscopy analyses. Ouro Branco and IPA 9 (resistant) plants exhibited low colonization, the formation of filaments surrounding bacterial cells and vestures more developed in the pit the xylem vessels. Diacol Calima (moderately resistant) plants presented lower levels of colonization and filament formation than that of resistant cultivars. CNFC 10429 and CNFRS 11997 (susceptible) showed high levels of colonization in the xylem and vessel obstruction, preventing water and nutrient flow, which explains the symptoms of wilt and plant death. Thus, resistance to C. flaccumfacienspv. flaccumfacienscan be explained by plant's capacity to limit pathogen propagation as a post-formed defense mechanismin this pathosystem.(AU)
Curtobacterium flaccumfaciens pv. flaccumfaciensé causadora da murcha-de-curtobacterium, responsável por perdas econômicas.O objetivo deste estudo foi analisara colonização de C. flaccumfaciens pv. flaccumfaciensem genótipos de feijoeiro comumresistente, moderamente resistente e suscetível. Ouro Branco e IPA 9 (resistente), Diacol Calima (moderadamente resistente), CNFRS 11997 e CNFP 10429 (suscetíveis) foram inoculados,no epicótilo,com 100 µL de suspensão bacteriana do isolado BRM 14933(Cff25). A severidade da doença foi avaliada 21 dias após a inoculação, utilizando a escala de 1 a 9. As amostras para MEV foram desidratadas em série alcoólica, secas em ponto crítico com dióxido de carbono (CO2), banhadas em ouro e analisadas em microscópio eletrônico de varredura. As plantas de Ouro Branco e IPA 9 (resistentes) exibiram baixa colonização, formação de filamentos envolvendo células bacterianas e guarnições mais desenvolvidas nas pontoaçõesdos vasos do xilema. Diacol Calima (moderadamente resistente) apresentou menor colonização e formação de filamentos do que as cultivares resistentes. Os genótipos CNFC 10429 e CNFRS 11997 (suscetíveis) mostraram grande colonização no xilema, com vasos obstruídos, impedindo o fluxo de água e nutrientes, explicando os sintomas de murcha e morte da planta. Portanto, a resistência à C. flaccumfacienspv. flaccumfacienspode ser explicada pela capacidade da planta em limitar a multiplicação do patógeno como um mecanismo de defesa celular, sugerindo que este é um dos fatores de resistência estrutural pós-formado que ocorre nesse patossistema.(AU)