Keywords: 
• Oidium heveae B.A.Steinmann /
• germination /
• appressorium /
• hydrophobic substratum

Abstract: HO-73 strain of Oidium heveae B. A. Steinmann was cultured on parafilm surface at different hours post inoculation（ hpi） under different temperatures to observe its infection process and the infection structure formation of its conidia. O. heveae was cultured at the temperatures ranging from 15 ℃ to 34 ℃ and the suitable temperatures for conidium germination and appressorium formation ranged from 22 ℃ to 28 ℃ with the optimal temperature being 22 ℃. The infection process of the conidia of the strain from 0-24 hpi was divided into 4 stages: no germination at 0 hpi,germination at 4 hpi,appressorium formation at 6,8 hpi and secondary appressorium formation at16,24 hpi. Total RNA of the strain was isolated from the cultures at different infection stages from 0 hpi to 24 hpi.The 18 Sr RNA was detected by RT-PCR at all the infection stages and analyzed by using the phylogenetic relationship. Total RNAs of the conidia at the four infection stages were isolated by using the modified Trizol method. The18 S rRNA of O. heveae was detected in all the conidia by RT-PCR,and clustered to the same branch as Erysiphaceae by using phylogenetic analysis. The result indicated that the infection structures of O. heveae were successfully developed on parafilm surface at a temperatures ranging from 22 ℃ to 28 ℃,and that the total RNA extracted from the cultures at 0,4,6,8,16 and 24 hpi can be used for 18 S amplification.