Taxonomy And Identification Of Trichoderma Spp. Growing At Low-temperature And Their Inhibition Against Phytophthora Capsici

Trichoderma spp. are cosmopolitan soil fungi and their teleomorphs belongs to Hypocrea. Some of them are important biocontrol agents and have used widely to control the soil borne diseases. Pepper blight is one of typical soil borne diseases and its pathogen is Phytophthora capsici, which grow at lower temperature. The disease occurres range from16℃to32℃. The zoospores of P. capsici germinate and release range from16℃to26℃. According to the biological characteristics of pathogen, biocontrol agent growing at low temperature appropriately will get good biocontrol effect against Phytophthora capsici. In this paper, therefore, diversity of Trichoderma spp. was investigated from the mountaintops with the lower temperature area all the year. These isolates also were used to screen biocontrol agents, which are used to inhibit P. capsici.The diversity of Trichoderma spp. isolated from the mountaintop of Hunan Zhangjiajie, Shandong Mount Tai and Shanxi Taibai Mountain in China were investigated under different conditions of temperature, elevation and vegetation. A total of248isolates were collected from36soil samples. Fungal identification were used a combination of morphological and phylogenetic methods. Morphological characters were observed from different cultures. CMD cultures were used for observing conidial characters, conidiophore and phialides. Characteristics of colonies were observed on PDA and CMD under a12h alternating cycle of light and dark at a temperature of25℃. Molecular analysis were conducted based on ITS and Tefl-a sequencce. The results showed that91isolates collected from Zhangjiajie were divided into9species (T. atroviride, T. koningii, T. longipile, T. asperellum, T. koningiopsis, T. hamatum, T. harzianum, T. cerinum, T. viride),75isolates from Taibai Mountain into3species (T. viridescens, T. oblongisporum, T. polysporum) and78isolates from Mount Tai into6species (T. konigii, T. koningiopsis, T. atroviride, T. hamatum, T. cerinum, T. viride). Four isolates taxonomic position were unresoved.Antagonistic action of Trichodeerma spp and their metabolite inhibition against pepper blight were investigated. A tatol of23strains were screened, which had good antagonistic action (antagonism grade1), including9strains from Zhangjiajie [T. atroviride (TZ0108, TZ0305, TZ0602, TZ0603, TZ0210), T. asperellum (TZ0103), T. harzianum (TZ0402, TZ0403), T. viridescens (TZ0604)],7strains from Mount Tai [T. viridescens (TT0501, TT0506, TT0803, TT0805), T. konigiopsis (TT0302, TT0402, TT1001)] and7strains from Taibai Mountain[T. viridescens (TS0606, TS0904, TS1105, TS0606, TS0904), T. oblongisporum (TS1201, TS1203)]. The metabolite inhibition of Trichoderma spp against P. capsici showed that13strains from Zhangjiajie [T. atroviride (TZ0209, TZ0702, TZ0704, TZ0710, TZ1102, TZ1106, TZ1107, TZ1202, TZ1205, TZ0210), T. viridescens (TZ1003, TZ1005, TZ1204)],7strains from Mount Tai[T. viridescens (TT0501,TT0508, TT0604, TT0606, TT0906), T. hamatum (TT0108, TT0401)] and13strains from Taibai Mountain [T. viridescens (TS0102, TS0207, TS0404, TS0405, TS0504, TS0602, TS0603, TS0910, TS0911, TS1103, TS0606, TS0904), T. polysporum (TS1106)] could inhibit hyphal growth of P. capsici completely. Otherwise,4strains pose two antagonisms against pathogen, such as T. atroviride (TZ0201, from Zhangjiajie) and T. viridescens (TS0606and TS0904from Taibai Mountain, TT0501from Mount Tai).