- 學位論文
內生菌處理之水稻於溫度逆境下之耐受性影響
Effect of Bacterial Endophyte Inoculation On Rice Tolerance Under Temperature Stress
摘要
本研究在探討經內生細菌處理之水稻是否能促進其在溫度逆境下之生長。我們挑選了八株促進植物生長的內生菌接種於水稻種子，待二週齡後將其置於觀察溫度逆境狀況下（22°C /15°C的低溫環境或41°C/26°C的熱逆境各15天）使其生長，並以未接種的控制組進行比較。在低溫環境下，接種LS-029、088和124的植株與控制組相比，根長分別有明顯增加11%、7%、 9%；接種LS-029、077和088的植株，其地上部長度比控制組明顯增加18%、14%和25%；接種LS-004、029、077和088的植株，植株鮮重比控制組明顯增加8%、 8%、 13%和10%；接種LS-079、 088和124的植株，於植物總葉綠素含量上比控制組明顯為高。在高溫環境下，只有接種LS-029的植株其根長比控制組增加12%；接種LS-079的植株，其鮮重以及乾重比控制組高出16%和12%；而接種LS-124的植株，在地上部長度、鮮重以及乾重分別比控制組多9%、9%、 3%。另外，於連續處理5天熱逆境（43°C/43°C）後於室溫進行5天的回復實驗中，接種LS-077、079、 088和124的植株與控制組相比其葉片凋萎率有明顯的降低。有趣的是，LS-077、079、088的最適接種時期為2週齡之水稻幼苗，而LS-124則是在植株種子期進行染菌為最適。綜合以上結果可以得知，內生細菌對於水稻在初期發育階段可增加水稻於溫度逆境下的耐受性。
並列摘要
The present study aimed at identifying bacterial endophytes which could promote rice growth under temperature stress. Eight plant growth promoting endophytes (PGPEs) were selected to inoculate rice seeds (Oryza sativa L.) and the plantlets were allowed to grow under temperature stress (chilling stress at 22oC/15oC day/night or heat stress at 41oC/26oC day/night both for 15 days) and their growth parameters were compared to non-inoculated control. Under chilling stress, inoculation of strains LS-029, 088, and 124 showed significant increases in plant root length of about 11%, 7%, and 9%, respectively; while inoculation of strains LS-029, 077 and 088 increased plant shoot length of about 18%, 14%, and 25%, respectively. Plants inoculated with strains LS-004, 029, 077 and 088 showed significant increases in fresh weight of about 8%, 8%, 13%, and 10%, respectively. Increase in plant total chlorophyll contents were observed in rice seedlings inoculated with strains LS-079, 088 and 124. Under heat stress, only the inoculation of strain LS-029 showed significant increase in plant root length of about 12%. Inoculation of strain LS-079 showed significant increases in fresh and dry weight of about 16% and 12%, respectively, while inoculation of strain LS-124 showed significant increases in shoot length, fresh weight, and dry weight of about 9%, 9% and 3%, respectively. Plants inoculated with endophytes under 5 days of continuous heat stress (43oC/43oC day/night) followed by 5 days recovery at normal temperature revealed that strains LS-077, 079, 088 and 124 showed significant reduction of plant withering rate as compared to the non-inoculated control. Interestingly, the optimal inoculation timing for LS-077, 079 and LS-088 to exhibit the best seedling thermal stress-recovery was after 2 weeks of germination, whereas the optimal inoculation timing for LS-124 was during the seed stage. Overall, the results proved that bacterial endophytes could improve rice temperature stress tolerance during early stage of development.