探討印度梨形孢真菌增強水稻耐乾旱逆境能力之生理機制

Study on the Physiological Mechanism of Piriformospora indica Improves Drought Stress Tolerance in Rice

蔡璿如(Hsuan-Ju Tsai)

指導教授 ： 王淑珍

國立臺灣大學/生物資源暨農學院/農藝學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201602572

摘要

印度梨形孢真菌(Piriformospora indica, P. indica)為可促進植物生長的根部內共生真菌，益生菌根真菌對植物生長的助益包括促進植物養分利用效率及提升植物對生物性及非生物性逆境之耐受性。隨著全球氣候變遷增加了旱災發生之機率，連帶對於糧食生產造成衝擊，在水稻栽培過程中需要大量灌溉用水，如何在水資源有限的情況下，維持水稻的正常生產，成為了一個重要的挑戰。本研究針對水稻品種臺農六十七號(Oryza sativa L. cv. Tainung 67, TNG67)，探討其與P. indica共生後對水稻生長發育的影響以及乾旱逆境耐受性之改變。根據結果顯示，與對照組相比，接種P. indica的水稻植株抽穗時間將提前約4天，平均每株穗數亦較對照組提升，進而增加每株水稻之平均榖粒重，顯示P. indica具有提升水稻產量之潛力。以Polyethylene Glycol處理模擬乾旱逆境的試驗中，P. indica可維持水稻幼苗地上部及地下部較佳之生長勢，降低葉片的傷害指數，保有較佳的光合作用效率。此外，與P. indica共生之水稻在遭遇乾旱逆境後，能較快速的關閉氣孔，推測P. indica快速誘導氣孔關閉減少水分散失可能是P. indica協助水稻提升耐旱性的機制之一。丙二醛 (malondialdehyde)含量為氧化逆境指標之一，試驗結果顯示P. indica可降低乾旱逆境下葉部及地下部的丙二醛累積，並且透過提升抗氧化酵素活性及抗氧化物質含量，清除逆境下生成的活性氧化物 (reactive oxygen species, ROS)，故推論強化植株的抗氧化能力為P. indica提升水稻乾旱逆境耐受性的調控機制之一。

關鍵字

水稻 (Oryza sativa L.) ； 印度梨形孢真菌 (Piriformospora indica) ； 乾旱逆境 ； 氣孔 ； 氧化逆境

並列摘要

Piriformospora indica (P. indica) is a mutualistic plant root endophytic fungus which is beneficial to host-plant growth; in some case, endophyte can also help to improve environmental stress tolerance of plants. Drought is one of the major environmental stresses on crop production in worldwide, and water scarcity undoubtedly is a limiting factor for rice production. In our study, we focused on the effect of P. indica on rice (Oryza sativa L. cv. Tainung 67, TNG67) growth and drought stress tolerance. The results showed that the heading date of P. indica-colonized rice plants was 4 days earlier than that of non-colonized rice. The number of pancicels and grain yield were also improved by P. indica. To evaluate the P. indica effect on the improvement of drought tolerance of rice plants, seedlings were exposed to polyethylene glycol (PEG) to mimic drought stress (-1 MPa). P. indica-colonized rice maintained higher biomass of both root and shoot tissues compared with non-colonized rice under drought stress condition. P. indica also reduced the levels of leaf damage caused by PEG treatment and maintained better photosynthesis efficiency. Furthermore, P. indica promoted the rapid stomatal closure under drought. Using malondialdehyde (MDA) as a biomarker to monitor the level of oxidative stresses, the results showed P. indica reduced MDA accumulations which induced by drought stresses in leaves and roots. Activities of several antioxidant enzymes were up-regulated and GSH/GSSG ratio was increased in P. indica-colonized rice seedlings under drought stress. It was suggested that P. indica colonization improve drought stress tolerance of rice plants was mediated reducing oxidative stress status.

並列關鍵字

rice (Oryza sativa L.) ； Piriformospora indica ； drought stress ； stomata ； oxidative stress

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