Blue mould disease in garlic ( Allium sativum ) is associated worldwide with various Penicillium species, and has been attributed to significant annual crop losses in Argentina; the world's second largest exporter of garlic. To identify the pathogenic Penicillium species responsible, affected plants were sampled in La Consulta station (33 ° 45 ′ S, 69 ° 02 ′ W) and placed in a damp chamber. Characteristic disease symptoms are stunted and chlorotic plants with withered leaves and reduced bulb size. Bulbs are often covered with blue/green conidial masses. Isolations were made from fungal colonies emerging on affected bulbs. Pure cultures (IBT 26466, 26467, 26511 and 26512; CMB collection, BioCentrum-DTU, Denmark) were initially identified by micromorphology as Penicillium allii , and identifications were confirmed by comparing reversed phase-HPLC secondary metabolite profiles with those of P. allii type strains.To confirm pathogenicity, sterilized garlic cloves were injured with a needle and inoculated with 5 µ L P. allii spore suspensions (adjusted to 5 × 10 6 conidia mL − 1 ). Inoculated cloves were planted in a field not previously cultivated with garlic, and the original disease symptoms were produced on inoculated plants while water-inoculated control plants remained healthy. The survival rate of inoculated plants was 68% and P. allii was reisolated from diseased field plants.Penicillium viridicatum was first reported as the causal agent of blue mould of garlic in Argentina (Gatica & Oriolani, 1984) before the characterization of P. allii (Vincent & Pitt, 1989). Penicillium allii is micromorphologically similar to P. viridicatum and both species produce yellow exudates in pure culture. To compare pathogenic ability, standard P. viridicatum strains IBT 16939 and 15053 were inoculated into sterilized garlic cloves and incubated for 12 days. The P. viridicatum strains were not able to sporulate on the garlic cloves.Penicillium hirsutum was recently reported as a pathogen on garlic in Argentina (Cavagnaro et al ., 2005). However, P. allii but not P. hirsutum has been reported as an aggressive pathogen of garlic in comparative pathogenicity trials conducted in damp chambers (Overy et al ., 2005). The results reported here suggest that P. allii , rather than P. hirsutum or P. viridicatum , is the pathogenic species responsible for garlic crop losses due to blue mould rot in Argentina. This is the first report confirming P. allii as a field pathogen of A. sativum.
A total of 147 samples of garlic ( Allium sativum ) bulbs affected by blue mould were obtained from a variety of agroclimatic districts between December 1999 and February 2000. Penicillium species were identified using both morphological and chemotaxonomic characteristics. Penicillium allii was the predominant species isolated (81·8%) in this survey and the only species proven to be pathogenic on garlic. Other species were isolated much less frequently: P. chrysogenum (13·7%), P. brevicompactum (2·8%), P. phoeniceum (0·9%), P. aurantiogriseum (0·6%) and P. flavigenum (0·2%). Colonies of P. allii could be classified into four morphotypes and their distribution seemed to be influenced by seed trade and agricultural practices. Penicillium allii isolates were grouped into three aggressiveness phenotypes (low, medium and high) based on their ability to cause disease during field trials on susceptible (Fuego INTA) and less susceptible (Castaño INTA) garlic cultivars. The number of surviving plants at 191 days after planting and postharvest bulb weight contributed the most towards aggressiveness modelling.
La riqueza cultural de las comunidades andinas de la Argentina está integrada por la diversidad de sus recursos genéticos, el desarrollo de un sistema agrícola sostenible y por el mantenimiento de sus semillas. La agricultura local es una actividad económica familiar, donde las variedades tradicionales de hortalizas son muy apreciadas por su sabor, color y aroma. Sin embargo, distintos factores sociales, económicos y ambientales afectan la diversidad de tales cultivos. Los objetivos de este trabajo fueron recuperar y conservar una muestra representativa de los recursos genéticos vegetales tradicionales aún presentes en el departamento de Valle Fértil, provincia de San Juan, Argentina, y documentar las experiencias y usos de ellos por parte de los productores. Se entrevistaron 50 familias de las cuales 26 donaron un total de 49 muestras pertenecientes a ocho especies. Las variedades criollas recolectadas mostraron una distribución geométrica típica en comunidades con pocasespecies, y un patrón de dominancia donde algunas especies están presentes en casi todas las huertas mientras que especies poco representadas se encuentran en ambientes específicos. La recuperación del germoplasma local puede prevenir la erosión genética, de modo que tanto los mejoradores como los productores puedan aprovechar la diversidad de esta colección.
En los valles andinos de la Argentina las familias producen hortalizas en forma tradicional principalmente para el autoconsumo. El zapallo (Cucurbita maxima) es un cultivo americano de gran importancia en las economías regionales andinas. Estas poblaciones criollas de zapallos se están perdiendo por el éxodo rural, la sustitución de semilla criolla por semilla comercial y las sequías frecuentes. Constituyen reservorios de genes de interés para el mejoramiento y para garantizar la seguridad alimentaria local, por lo que su conservación y caracterización son fundamentales para evitar la erosión genética. Durante 2005 se realizaron colectas en Valle Fértil, provincia de San Juan y en el noroeste argentino; se colectaron 61 poblaciones, de las cuales 27 se seleccionaron y evaluaron durante dos años en la EEA La Consulta INTA, Mendoza. Se midieron 49 caracteres de planta, flor, fruto y semilla, bajo un diseño experimental completamente aleatorizado y tres repeticiones por población. Los cultivares comerciales Marino FCA y Veronés INTA se emplearon como testigos. Las poblaciones se agruparon por caracteres de fruto, hábito de crecimiento y semilla, observándose gran diversidad morfológica entre y dentro de cada población. El trabajo permitió seleccionar materiales con caracteres de interés para el mejoramiento de la especie.
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