Activation of Teliospore Germination in Uromyces appendiculatus var. appendiculatus. I. Aging and Temperature

Abstract

The effects of aging and temperature on teliospore germination in Uromyces appendiculatus var. appendiculatus were studied.1. Indoor storage was good at ~ 4°C in the dark. Under these conditions spores remained dormant for ~ 9 mo, but thereafter germination gradually increased to a maximum (~ 63 %) after 36 mo. Spores stored outdoors showed a marked increase in germination after ~ 4 mo and reached maximum (~ 73 %) at 7-8 mo.2. The optimum temperature for germination was at 18°C. While freezing (-18°C) and thawing (20°C) had no beneficial effect on spore germination, heat treatments from 30-32°C for 3-4 d proved effective in activating teliospore germination. Heat treatments caused an increase in spore mortality. Basidiospore release from heat-treated teliospores was markedly reduced compared to control spores.3. In all experiments the emergence of metabasidia was preceded by an obligatory 3-5 d lag period regardless of the treatment given, the age or level of germinability of treated and control spores.