阿拉伯芥miR169於熱逆境下的功能性分析

Functional analyses of miR169 in Arabidopsis under heat stress

鄭凱鴻(Kai-Hung Cheng)

指導教授 ： 鄭石通

國立臺灣大學/生命科學院/植物科學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.10532

摘要

miRNA是小片段的non-coding RNA，這些小片段的RNA在調控植物的生長和發育上扮演著相當重要的角色。miR169在不同物種之間是一段高度保守性的序列。在阿拉伯芥當中已知miR169家族一共有14個不同的成員。前人的研究中也指出miR169會參與在不同的非生物性逆境之調控當中。除了乾旱和缺氮逆境外，miR169也會參與在逆境當中。miR169的表現會受熱誘導而上升，目標基因轉錄因子Nuclear factor Y（NF-Y）家族中的NF-YA則是會下降。但是，miR169和熱相關的調控機制之研究仍然有限。因此，本實驗的目的是想了解miR169和NF-YA在熱逆境下，如何進行調控進而使植物耐熱。利用35S啟動子大量表現miR169的前驅序列（OE Line），或大量表現一股與mature mir169互補的序列（Target mimicry line） 抑制mir169的活性，進行NF-YA的調控，藉以了解miR169與NF-YA在熱的情況下所扮演的角色。發芽率的檢測於熱處理後，OE Line有較佳的發芽情形。先天性耐熱能力的測試中，Target mimicry line有較高的存活率，相反的，在後天性的耐熱能力測試則是OE Line有較高的存活率。也因此，下胚軸長度檢測OE Line中有些微較長的情形。根長則是部分Target mimicry line有較短的情況。總結以上的結果，miR169可藉由調控NF-YA進而使植物在不同的熱逆境條件下維持其恆定性，進而使植物更耐熱。

關鍵字

miR169 ； NF-YA ； 熱逆境 ； 耐熱性 ； 先天性耐熱能力 ； 後天性的耐熱

並列摘要

MicroRNAs (miRNAs) are small non-coding RNAs, and they play important roles in plant growth and development. miR169 is a conserved miRNA in many plant species, and it contains 14 members of the miR169 family in Arabidopsis. In addition, miR169 is known to be involved in various stress responses, including drought and nitrogen deficient. Previous studies have shown that the expression of miR169 can be induced by heat treatment, but the research on miR169-regulated mechanism in heat response is still limited. Here, we generated transgenics overexpressing miR169 and transgenics expressing target mimic inhibitor, which could inhibit miR169 activity. After heat treatment, the germination rates of seeds were slightly increased in miR169 overexpression lines compared to those in wild type. Under basal thermotolerance, the mimicry lines were also greener than the wild type. But they showed opposite result under acquired thermotolerance. In addition, the hypocotyls lengths of the miR169 overexpression lines were slightly longer compared to those of the wild type plants. Although the miR169 overexpression lines did not show any difference, but the root lengths of miR169 target mimicry lines were shorter than those of the wild types. Overall, these results showed that miR169 might regulate NF-YA expression homeostasis to be involved in different thermotolerance.

並列關鍵字

miR169 ； NF-YA, ； Heat ； Thermotolerance ； Basal thermotolerance ； Acquired thermotolerance.

參考文獻

Akman, Z. (2009). Comparison of high temperature tolerance in maize, rice and sorghum seeds by plant growth regulators. Journal of Animal and Veterinary Advances 8, 358-361.

Arshad, M., and Frankenberger Jr, W.T. (2002). Ethylene: agricultural sources and applications. (Springer).

Banowetz, G., Ammar, K., and Chen, D. (1999). Temperature effects on cytokinin accumulation and kernel mass in a dwarf wheat. Annals of Botany 83, 303-307.

Corbineau, F., Rudnicki, R., and Come, D. (1989). ACC conversion to ethylene by sunflower seeds in relation to maturation, germination and thermodormancy. Plant growth regulation 8, 105-115.

Doring, P., Treuter, E., Kistner, C., Lyck, R., Chen, A., and Nover, L. (2000). The role of AHA motifs in the activator function of tomato heat stress transcription factors HsfA1 and HsfA2. The Plant Cell Online 12, 265-278.