| Summary: | 碩士 === 國立虎尾科技大學 === 生物科技系碩士班 === 107 === Trichoderma spp., a saprophytic fungus, is commonly present in the bark, deciduous, decayed wood, tillage soil and animal excrement. Some strains with biological control function can be developed as a biological agent. In recent years, the growth of Trichoderma spp. in some regions is impeded due to the greenhouse effect and soil salinization. The heat-resistant or salt-tolerant strains were screened based on the growth ratio of the mycelial diameter,45 ℃ heat shock treatment or 2% NaCl to the control group(about 4.5cm). It was considered as heat or salt tolerance strains when the growth ratio was higher than 0.6. Among 300Trichoderma isolates, ~21% and 38% of isolates exhibited heat and salt tolerant ability, respectively. Four isolates with the best performance in both of salt tolerance and heat resistance were selected, including ETS311, NTCg-Te S4-1, AW-MLR321 and AW-MLR325. The growth of Trichoderma spp.is usually delayed as the temperature higher than 30oC. Among the tested strains, NTCg-Te S4-1 can grow continuously at 36℃. The growth of ETS311 mycelia was the least affected by heat shock at 52 ℃.AW-MLR321 continuously grew at 36℃ as well. The growth ratio of mycelial diameter of selected isolates,0.5M NaCl to the control, was higher than 50%.These strains have differently antagonism ability against Sclerotium rolfsii, Rhizoctonia solani, Alternaria brassicae and Colletotrichum higginsianum. The growth of anthraxwas inhibited the most efficiently by AW-MLR321. In addition, AW-MLR321 and AW-MLR325 have the best growth rate and sporulation capability. AW-MLR321 and AW-MLR325 and NTCg-Te S4-1 was identified as T. asperellum based on the sequence analyses of ITS region in genbank, as well as theirphenotypes.ETS311 wasidentified as T.afroharzianum .In the plant test, AW-MLR321 and NTCg-Te S4-1 had impact on Chinese cabbagein the saline. AW-MLR325 could help tomato seeds germination under saline condition. The results suggested that the selected strains couldbe applied to benefit plant growth under bio- or abio-stresspotentially.
|
|---|
