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Nacobbus aberrans attacks weeds and cultivated plants, causing drastic crop yield losses. The tomatoes 'Superman' and 'Mykonos' are marketed as nematode resistant, but with no specifications of the nematode species. Moreover, no studies have recorded the response of these cultivars to infection by N. aberrans. We analyzed the influence of two Argentine isolates of N. aberrans (Lules and Río Cuarto) on the growth of these cultivars and Platense, a known susceptible used as a positive control. Plant growth variables, number of galls and egg masses, and gall size were measured. Mykonos infected with the Lules isolate exhibited a decrease in stem diameter. In Superman, all infected plants showed reduced shoot dry weight. Platense did not show differences (P>0.05) in growth variables between treated and control plants, however, this cultivar showed the largest galls. The Lules isolate was more aggressive than the Rio Cuarto isolate and produced a greater number of galls and egg masses on Mykonos and Platense than on Superman. These findings indicate that Superman and Mykonos were efficient hosts of N. aberrans and cannot be considered resistant to either of the two nematode isolates. [ABSTRACT FROM AUTHOR]

We characterized the infective and sporulation capacities of microbial consortia of arbuscular mycorrhizal fungi (AMF) native of Buenos Aires province (Argentina) and determined if some soil characteristics and mycorrhizal parameters could allow to select potentially beneficial inocula. Soil samples were selected from seven locations in Buenos Aires province all under agricultural (A) and pristine (P) conditions. The AMF were multiplied and mycorrhizal root colonization of trap plants was observed at 10 weeks of growth. Spore number in field was low; however, after multiplication spore density accounted for 80-1175 spores per 100g of soil. The principal component analysis showed that the P and Fe soil contents are the main modulators of infectivity and sporulation capacity. The mycorrhizal potential was determined in three locations, being high in Pristine Lobería and Agricultural Trenque Lauquen and low in Junín. Agricultural Lobería (AL) and Pristine Lobería (PL) inocula were selected and their efficiency was evaluated under controlled conditions. Even though shoot dry matter increases after inoculation was not significant (p>0.05) mycorrhizal response was greater than 40% for tomato and 25% for corn, particularly after inoculation with inocula from the agricultural management. These results could be associated to the incipient development of mycorrhizae in both species. Additional research should be conducted to further develop our findings in order to determine the factors involved in the selection of efficient inocula., (Copyright © 2014 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.)

Background: Many Alternaria species have been studied for their ability to produce bioactive secondary metabolites, such as tentoxin (TEN), some of which have toxic properties. The main food contaminant toxins are tenuazonic acid, alternariol (AOH), alternariol monomethyl ether (AME), altenuene, and altertoxins i, ii and iii., Aims: To determine the profiles of secondary metabolites characteristic of Alternaria strains isolated from tomato for their chemotaxonomic classification., Methods: The profiles of secondary metabolites were determined by HPLC MS., Results: The Alternaria isolates obtained from spoiled tomatoes belong, according to their morphological characteristics, to the species groups Alternaria alternata, Alternaria tenuissima and Alternaria arborescens, with A. tenuissima being the most frequent. The most frequent profiles of secondary metabolites belonging to the species groups A. alternata (AOH, AME, TEN), A. tenuissima (AOH, AME, TEN, tenuazonic acid) and A. arborescens (AOH, AME, TEN, tenuazonic acid) were determined, with some isolates of the latter being able to synthesize AAL toxins., Conclusions: Secondary metabolite profiles are a useful tool for the differentiation of small spored Alternaria isolates not easily identifiable by their morphological characteristics., (Copyright © 2013 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.)