The effect of light and temperature on in vitro germination and germ tube growth of urediniospores of Tranzschelia discolor

Abstract

The effect of light on in vitro germination of urediniospores of Tranzschelia discolor was studied over time at different intensitities (up to 400 8E m-2 s-l) within the temperature range 5�C to 20�C. A model was also developed from the data to predict germination at different combinations of light, temperature and times of leaf wetness. Light retarded the germination process, and its effect increased in direct proportion to intensity. At 20�C, for example, the time taken to exceed 80% germination increased from 2 h in the dark to 9 h at 200 8E m-2 s-l. The model showed that there was an interaction between light and temperature, with the effect of light becoming more pronounced as the temperature declined below 20�C. Germination percentages of the order of 90% were, however, recorded within 24 h at all combinations of light intensity and temperature studied. Light also influenced germ tube growth, causing a reduction in the rate of growth. As in germination, its effect increased with increasing light intensity. At 20�C, the average germ tube length at 9 h was 541 8m in the dark, compared with 227 8m at 200 8E m-2 s-1 and 148 8m at 400 8E m-2 s-l. A similar effect was observed at 5�C, where the average germ tube length at 24 h was 274 8m in the dark compared with 157 8m at 200 8E m-2 s-l. The effects of light on the germination and germ tube growth of urediniospores under field conditions are discussed.

Effect of light exposure on in vitro germination and germ tube growth of eight species of rust fungi

“…vaccinni, P. hemerocallidis and Ph. pachyrhizi and to a lesser extent P. menthae in the present study is consistent with work on several rust fungi (Ellison et al 1992;Givan and Bromfield 1964a, b;Hocking 1968;Joseph and Hering 1997;Knight and Lucas 1980;Singh and Heather 1982;Sood and Sackston 1972). While urediniospore germination can indicate the relative sensitivity of rust fungi to light it was interesting to observe that germ tube elongation of all species in the current study were negatively affected by light.…”

“…This difference might be caused by several factors, including light intensity, light spectra and an interaction between light exposure and temperature. Light-induced reduction of urediniospore germination with some rust fungi is temperature sensitive (Ellison et al 1992, Joseph and Hering 1997, Singh and Heather 1982, Tollenaar and Houston 1966. In the present study temperature in the Petri dish in sunlight trials (25-35 C) was higher than in fluorescent light trials (22-24 C), although no differences were observed between treatment and dark-control dishes within experiments.…”

“…Two different light levels were obtained by placing the Petri dishes on white cardboard at two distances (approximately 30 and 90 cm) from the light bulbs. Readings were taken through a Petri dish lid (Ellison et al 1992), and PAR values were approximately 400 and 600 mmol s 21 m 22 . Corresponding visible radiation was respectively 29.6 and 44.4 Klux.…”

Components of rust resistance in lentil

“…After the Petri dishes were removed from the dew chamber, urediniospores were immediately killed and stained using lactophenol cotton blue (Ellison et al, 1992). Sixteen 1 cm 2 agar discs cut from the agar plate were scored for spore germination.…”

Variabilidade em dez populações de Hemileia vastatrix em relação à germinação e ao comprimento do tubo germinativo em quatro temperaturas

“…Em relação ao comprimento do tubo germinativo, Saccas & Charpentier (1971) encontraram o maior comprimento a 24ºC, na presença de um filme de água, enquanto Montoya & Chaves (1974) Também para outras ferrugens foram realizados estudos sobre as influências da temperatura na germinação e no crescimento do tubo germinativo, como a ferrugem da lentilha (Uromyces viciae-fabae (Pers.)) (ELLISON et al, 1990(ELLISON et al, , 1992NEGUSSIE et al, 2005). Segundo Negussie et al (2005), os urediniósporos da ferrugem da lentilha germinaram em mais de 80% a 10ºC , 15ºC, 20ºC e 25ºC e o comprimento do tubo germinativo foi de 66mm e 196mm, a 10ºC e 20ºC, respectivamente.…”