水稻生長素輸入運送蛋白家族的分析

Characterization of Auxin Influx Carrier Family in Rice (Oryza sativa L.)

曾郁恒(Yu-Heng Tseng)

指導教授 ： 余淑美

國立臺灣大學/生命科學院/基因體與系統生物學學位學程/碩士(2016年)

https://doi.org/10.6342/NTU201601665

摘要

生長素(auxin)為重要之植物賀爾蒙，參與細胞週期、器官發育，以及型態的生成。生長素藉由極性生長素運輸(polar auxin transport)在整個根部以及地上部建立生長素梯度來調控器官的生長。極性生長素運輸主要由生長素輸入運送蛋白(AUX/LAX)以及生長素輸出運送蛋白(PIN)達成。在阿拉伯芥裡，生長素輸入運送蛋白以及生長素輸出運送蛋白已經被大量証實對植物發育有重大的影響。在水稻中，生長素輸出運送蛋白已有許多研究，可是生長素輸入運送蛋白卻受到極少的關注。在本篇研究中，我們利用β-葡萄糖醛酸苷酶報導系統(GUS reporter system)以及突變株分析來研究水稻生長素輸入運送蛋白OsLAX1、OsLAX3、OsLAX5在植株的表現形式，以及探討其功能。結果顯示，在根部，OsLAX1表現在成熟區；OsLAX5表現在延伸與成熟區，而OsLAX3則特別表現在側根生長點的周圍。在葉片，OsLAX1、OsLAX3、OsLAX5皆表現在維管束組織。除此之外，OsLAX1以及OsLAX3也會在葉肉細胞表現。另外，OsLAX1也會專一的表現在氣孔以及毛狀體。在胚胎發育的過程中，OsLAX1會表現在糊粉層、胚乳轉移細胞以及胚胎。更進一步的突變株分析也發現，OsLAX1以及OsLAX3會調控根部發育，由於分別在OsLAX1以及OsLAX3大量表現的突變株觀察到更密集的側根，而OsLAX1剔除的突變株則有相反的形態。雖然其它突變株經由分析之後証實與OsLAX基因無關，可是他們所擁有的型態，可以讓我們了解更多未知、關於根部發育的分子機制。

關鍵字

生長素 ； 極性生長素運輸 ； 極性生長素運輸

並列摘要

Auxin is a crucial phytohormone that participates in cell-cycle regulation, organogenesis and pattern formation. Auxin regulates organ development through an auxin gradient in both roots and shoots. The auxin gradient is established by polar auxin transport, and is mediated by various auxin influx and efflux carriers. Extensive studies on auxin carriers have been conducted in Arabidopsis, and their dysfunction causes several developmental defects. In rice, researches have largely been focused on efflux carriers, while influx carriers are often neglected. In this study, expression patterns of the rice auxin influx carriers OsLAX1, OsLAX3 and OsLAX5 were analyzed using a GUS reporter system in transgenic rice plants, and mutant phenotyping was conducted to determine the functions of the auxin influx carrier family. Results show that, in roots, OsLAX1 is expressed in the maturation zone, OsLAX5 is expressed in both the elongation and maturation zones, while OsLAX3 is specifically expressed around the lateral root primordium. In leaf blade, OsLAX1 is expressed in stomata and trichomes while OsLAX3 and OsLAX5 are not. For OsLAX1, OsLAX3 and OsLAX5, they are all observed to be expressed in vascular tissue, such as phloem, xylem and vascular bundle. However, only OsLAX5 is specifically expressed in vascular tissue, since OsLAX1 and OsLAX3 also expressed in mesophyll cells. During embryogenesis, OsLAX1 expression could be observed in the aleurone layer, or the endosperm transfer cell, and in the embryo. Moreover, mutant analyses suggest that OsLAX1 and OsLAX3 regulate lateral root development as an OsLAX1 overexpression mutant has a higher lateral root density and that of an OsLAX1 knock-out mutant is lower, while an OsLAX3 overexpression mutant has shorter lateral roots. Although some other mutant phenotypes are not caused by auxin influx carrier genes, they could unveil how plant growth is fine-tuned at the molecular level.

並列關鍵字

Auxin ； Polar auxin transport ； Auxin influx carrier protein

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