Preservation of Phakopsora pachyrhizi Uredospores

Abstract

This study compared different temperatures and dormancy-reversion procedures for preservation of Phakopsora pachyrhizi uredospores. The storage temperatures tested were room temperature, 5°C, )20°C and )80°C. Dehydrated and non-dehydrated uredospores were used, and evaluations for germination (%) and infectivity (no. of lesions⁄cm 2 ) were made with fresh harvested spores and after 15, 29, 76, 154 and 231 days of storage. The dormancy-reversion procedures evaluated were thermal shock (40°C⁄5 min) followed or not by hydration (moist chamber⁄24 h). Uredospores stored at room temperature were viable only up to a month of storage, regardless of their hydration condition. Survival of uredospores increased with storage at lower temperatures. Dehydration of uredospores prior to storage increased their viability, mainly for uredospores stored at 5°C, )20°C and )80°C. At 5°C and )20°C, dehydrated uredospores showed increases in viability of at least 47 and 127 days, respectively, compared to non-dehydrated spores. Uredospore germination and infectivity after storage for 231 days (7.7 months), could only be observed at )80°C, for both hydration conditions. At this storage temperature, dehydrated and non-dehydrated uredospores exhibited 56 and 28% of germination at the end of the experiment, respectively. Storage at )80°C also maintained uredospore infectivity, based upon levels of infection frequency, for both hydration conditions. Among the dormancyreversion treatments applied to spores stored at )80°C, those involving hydration allowed recoveries of 85 to 92% of the initial germination.

Influência do estádio fenológico e da idade dos trifólios de soja na infecção de Phakopsora pachyrhizi

“…O isolado utilizado foi obtido em plantas de soja infectadas naturalmente, provenientes do campo experimental do Setor de Fitopatologia da ESALQ/USP, Piracicaba, SP, e multiplicado na cultivar BRS 154, sendo os esporos armazenados periodicamente em nitrogênio líquido, conforme metodologia proposta por Furtado et al (2008).…”

GERMINATION AND INFECTION OF Phakopsora pachyrhizi UNDER SIMULATED ENVIRONMENT OF THE CENTRAL AREA OF SANTA FE, ARGENTINA

“…Evaluations were performed in vitro, under laboratory conditions and in vivo, to analyze the infective capacity of spores and disease progress during the pathogenicity assay performed in under greenhouse conditions (Furtado et al, 2008).…”

“…The GU % was estimated as: (germinated urediniospore number / total number of urediniospores counted on 16 visual fields with 4 replications) x 100. Number of GU between evaluation times were recognized by staining of the active (alive) germinative hyphas with cotton blue (Furtado et al, 2008;Park et al, 2008).…”

“…Leaflets were previously soaked with sterilized water and then air-dried. Then, urediospores were distributed on the adaxial surface of leaves using the spatula-slide technique (Dhingra and Sinclair, 1985;Furtado et al, 2008). Inoculated plants were observed daily and weekly after symptom detection using a non-destructive method.…”

Identification and mapping of resistance genes to Phakopsora pachyrhizi in soybean (Glycine max L.) accession PI 594767-A

“…For inoculation, PPUFV02 spores were obtained from plants of the 'Conquista' cultivar and stored at -80°C. The uredospores were subjected to heat shock for 10 min at 40°C in a water bath, and rehydrated for 24 h to break their dormancy (Furtado et al, 2008). The concentration of uredospores was then determined by counting them in a Neubauer chamber using an optical microscope (Olympus CX40, Olympus Latin America, USA).…”