[The use of genetically modified microorganisms in agriculture to reduce or eliminate pesticide exposure]. / Utilizzo di microrganismi geneticamente modificati in agricoltura al fine di ridurre o eliminare l'esposizione a pesticidi.

P. graminea is the casual agent of barley leaf stripe. An early selection method of resistant types of barley leaf stripe was realized and validated in this research. This new method, based on Microrganism Genetically Modified (MOGM) GUS2 construction, obtains results comparable with those of classical method, reduces the work time, the use of chemicals (pesticides) and productive plants as greenhouses. Moreover, the use of MOGM GUS2 is restricted in laboratory ambient, therefore the risk of environmental spread is reduced. The early selection method has allowed to estimate the reaction to P. graminea agent in 12 several barley types usually farmed in Italy. The results were compared both, with the classical method data based on artificial clone Dg2 inoculum, and with natural inoculum data obtained in field. At all times we observed a ranking likeness.

First Record of Verticillium dahliae on Potato in Malta.

Potato is an important and highly valued crop throughout the Maltese Archipelago. Much of the production is exported to Holland. In January 2005, minor wilts and chlorosis of potato plants were observed in a field at Hal-Farrug, Luqa (Malta). Verticillium dahliae Kleb (1) was isolated on potato dextrose agar (PDA) from vascular tissue excised from the base of the plants. Three different isolates were obtained, all of which were typically distinguished by verticillately shaped conidiophores and the abundant production of microsclerotia on PDA. In May 2005, colonies of these three isolates were cultured in potato dextrose broth (PDB), from which conidial suspensions of each isolate were prepared with sterile distilled water to a concentration of 107 ml-1. For each isolate, 10 7-day-old potato seedlings were inoculated via root immersion in the inoculum suspension and transplanted to 20-cm diameter plastic pots containing a soil/peat mixture (1:1 [v/v]). Seedlings treated in the same way with sterile distilled water were used as a control. All plants were kept under controlled glasshouse conditions (20 ± 3°C) and watered to field capacity as required. Minor chlorosis and wilt of the pair of lower-most leaves was noted 7 days after inoculation. During subsequent weeks, wilt began to appear in the typical half-leaf form, while chlorosis was noted on all organs of the plants, including the principal stem (3). Symptoms were absent on the control plants. Measuring the weight of the new tubers produced by each plant revealed no apparent difference between inoculated and healthy plants; nevertheless, inoculated plants resulted in more tubers with a smaller diameter in respect to those of the uninoculated plants. V. dahliae was never isolated from tubers. Little to no variation in symptom severity was noted among plants inoculated with the three individual isolates. At the end of June, V. dahliae was reisolated on PDA from all inoculated plants, in particular, from vascular tissues originating from principal and lateral stems, crowns, and roots. All attempts to isolate the pathogen from control plants were unsuccessful. Molecular detection of the pathogen by using species-specific primers and real-time Scorpion PCR (2) confirmed the results obtained by the classical isolation method. The low symptom severity observed by the growers in the field, usually mistaken for normal dieback of aged plants, might explain why V. dahliae was never reported before on potatoes in the Maltese Archipelago. References: (1) D. L. Hawksworth and P. W. Talboys. No. 256. Descriptions of Pathogenic Fungi and Bacteria. Commonwealth Mycological Institute (CMI), Kew, Surrey, UK, 1970. (2) F. Nigro et al. Pages 454-461 in: Proc. Convegno Internazionale di Olivicoltura. VI Giornate Scientifiche SOI, Spoleto, 2002. (3) W. R. Stevenson et al., eds. Compendium of Potato Diseases. 2nd ed. The American Phytopathological Society, St Paul, MN, 2001.

First Report of Rhizopycnis vagum Associated with Tomato Roots in Italy.

Field surveys were made in several central and southern Italian tomato-growing areas for Pyrenochaeta lycopersici, the cause of corky root of tomato. In addition to P. lycopersici, a different fungus was frequently isolated from roots showing typical corky root symptoms, even after disinfestation of diseased roots with 0.1% (vol/wt) mercury chloride water solution for 1 min. The fungus was isolated from primary and secondary tomato roots in 8 of 21 fields visited. The isolates were grown on potato dextrose agar (PDA), with morphological features such as color and shape of mature conidia and pycnidia, type of conidiogenesis, presence of microsclerotia, and color of colony underside noted. Preliminary identification of the fungus was Rhizopycnis vagum Farr. To confirm the identification, the internal transcribed spacer (ITS) region of rDNA of one isolate (maintained at the ISPaVe collection at the authors' address and available on request as isolate ER 940) was amplified with two universal primers, ITS5 and ITS4. The ITS fragment was sequenced, and the nucleotide sequence compared with that of R. vagum deposited in GenBank (Accession No. AF022786). Both sequences were identical supporting the identification. R. vagum is a recently described species associated with the vine decline syndrome of melon in the United States, Guatemala, Honduras (2), and Spain (3). Eight isolates were tested for pathogenicity both on tomato (five cultivars) and melon (three cultivars) using two methods. In method 1, plantlets at the cotyledonary stage were grown on blotter in petri dishes and tested by placing a 6-mm plug of colonized PDA on the tap root (1). After 7 days, the plug was removed, and the roots were checked for symptoms. In method 2, 20-day-old seedlings were transferred to pots with infested soil (50,000 CFU/g of soil) and grown for 45 days before the roots were checked for each isolate-cultivar combination. Eight and four plants were used in tests 1 and 2, respectively. With the first method, rotten, pinkish lesions with different extensions from the inoculation point were observed on all the melon cultivars tested (Pamir, Cantalupo di Charentais, and Charme). On tomato, three of eight isolates caused root necrosis of limited extent, without pinkish discolorations at the inoculation site on cvs. Monalbo and Bonnie Best, the former showing the larger lesions. The tests on plants grown in infested soil confirmed pathogenicity on both host species, although the symptoms were of minor intensity (light, small brown lesions on secondary roots, no pinkish discoloration). The symptomatic plantlets ranged from 0 to 100% on both hosts in the petri dish tests and from 0 to 100% and 0 to 50%, respectively, for tomato and melon in the pot tests, varying according to the cultivar-isolate combination. The fungus was consistently reisolated from all symptomatic plants. To our knowledge, this is the first report of R. vagum associated with tomato roots. Although the isolates showed varying degrees of virulence with respect to host species (all being pathogenic at least on one host), the virulence of R. vagum on tomato was certainly low. Nevertheless, tomato may maintain or possibly increase inoculum for melon, which often follows tomato in Italian crop rotations. References: (1) M. Clerjeau and M. Conus. Annu. Rev. Phytopatol. 5:143, 1973. (2) D. F. Farr et al. Mycologia 90:290, 1998. (3) J. García-Jiménez et al. EPPO Bull. 30:169, 2000.

Soybean Disease Loss Estimates for the Top 10 Soybean Producing Countries in 1994.

Soybean disease loss estimates were compiled for the 1994 harvested crop from the 10 countries with the greatest soybean production. The objective was to document the major soybean disease problems in these countries and any recent changes in the severity of individual soybean diseases. Total yield losses caused by Heterodera glycines in these 10 countries were greater than those caused by any other disease. Next in order of importance were stem canker, brown spot, and charcoal rot. The total yield loss due to disease during 1994 in these countries was 14.99 million metric tons, valued at $3.31 billion. Methods used to estimate soybean disease losses were field surveys, plant disease diagnostic clinic samples, variety trial data, information from field workers and university extension staff, research plots, grower demonstrations, and private crop consultant reports. Yield loss estimates due to a particular disease varied by country. For example, yield losses due to rust were reported from China and Indonesia, but no losses due to this disease were reported from any of the remaining eight countries. Soybean disease control research and extension efforts are needed to provide more effective preventive and therapeutic disease management strategies and systems to producers.

Synthesis and microbiological evaluations of (N-heteroaryl) arylmethanamines and their Schiff bases.

The synthesis as well as the antimicrobial and antiviral activities of new (N-heteroaryl)arylmethanamines and their Schiff bases are reported. None of the tested compounds shown activity against Herpes simplex virus type 2 and against Gram positive and Gram negative bacteria. Weak or moderate activity on poliovirus Sabin type 1, on reverse transcriptase and against Cryptococcus neoformans was shown by some of the tested compounds. Viceversa several synthesized compounds exhibited a moderate or good activity against strains of Candida albicans, while only some of the tested compounds were found moderately active against strains of Candida sp. Instead numerous new compounds 3 or 4 were active as control against isolates of plant pathogenic fungi. The obtained results are discussed on the basis of structure-activity relationships.