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.<br />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.<br />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.<br />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.