花反轉無性珠芽之可能基因調控─以俄氏草為例

Candidate genes analysis of flower reversion to bulbils in Titanotrichum oldhamii (Hemsl.) Soler.

陳彥君(Yan-Jun Chen)

指導教授 ： 王俊能

國立臺灣大學/生命科學院/生態學與演化生物學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.00326

摘要

苦苣苔科的俄氏草具有鮮豔的黃色總狀花序，但大多依靠珠芽和根莖的營養繁殖，在夏天開花後，當秋末短日照下，會從花序莖頂分生組織抽長出珠芽枝繐。在過去的研究中發現，當過度表現 KNOTTED 1-LIKE HOMEOBOX (KNOX) 基因會在菸草葉子表現產生異位的花序分生組織。因此能夠調控分生組織及無限生長的KNOX 基因和與其拮抗，控制有限生長及葉原體產生的ARP 基因，可能參與在珠芽形成過程中。我們從俄氏草中釣取了兩個KNOX 基因─ToSTM 和ToBP，及與其結抗的ToPHAN 基因。為了釐清ToSTM、ToBP 和 ToPHAN 是否有參與在珠芽形成的過程中，我們藉由RNA 原位雜交實驗來比較這些基因在營養分生組織、花序分生組織和珠芽分生組織的表現位置。結果顯示ToSTM、ToBP 和ToPHAN均有表現在珠芽分生組織，預期之外的是ToPHAN 在分生組織中心有較大的表現區域。在較晚期的珠芽分生組織，更可以看到ToPHAN 表現在分生組織的邊緣。這暗示這些基因可能參與珠芽穗的形成，而ToPHAN 可能與晚期珠芽的形成有關。相較於模式植物阿拉伯芥中，KNOX 基因與ARP 基因拮抗的關係，並沒有在俄氏草中發現，它們似乎共同調控了珠芽的形成，需要進一步的功能性分析實驗來驗證。

關鍵字

俄氏草 ； 珠芽 ； KNOX 基因 ； ARP 基因 ； STM ； PHANTASTICA

並列摘要

Titanotrichum oldhamii appears to rely largely on asexual reproduction by bulbils and rhizomes. It has inflorescences bearing either showy yellow flowers or asexual bulbils and a reversion from flowering to asexual bulbiliferous shoots. Overexpression of KNOTTED 1-LIKE HOMEOBOX (KNOX) results in epiphyllous infloresences on the surface of tobacco leaves resembling bulbiliferous shoots. In addition, KNOX gene has been proved antagonisticly interacts with a lateral organ specification gene, ARP gene, to convert shoot into determinant primordia. To test whether these genes are involved in T. oldhamii bulbiliferous shoots development, ToSTM and ToBP (KNOX homologues) and ToPHAN (ARP homologue) were isolated. Their expression patterns were compared in vegetative shoot meristem, floral meristem, and bulbiliferous shoot meristem via RNA in-situ hybridization. ToSTM was expressed in bulbiliferous shoot meristem. Unexpectedly, ToPHAN shared the same expression areas as ToSTM: both were expressed in the center of bulbil meristems but ToPHAN had even a wider expression area. However, at later stage ToPHAN appeared to be expressed in the boundary of bulbil primordia. This implied that both genes were involved in bulbiliferous shoot meristem formation while ToPHAN also specified later stages of bulbil formation. ToPHAN and ToSTM seemed to co-opt into bulbil development. Their role thus remains to be explored by promoter analysis and functional analysis in the future.

並列關鍵字

Titanotrichum oldhamii ； bulbil ； KNOX gene ； ARP gene ； STM ； PHANTASTICA

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