Arabidopsis Floral Regulators FVE and AGL24 are phloem-mobile RNAs

阿拉伯芥開花調控基因FVE與AGL24為篩管中之移動性RNA

楊鴻偉(Horng-Woei Yang) ； 余天心(Tien-Shin Yu)

《Botanical Studies》 51卷1期 (2010/01) Pp. 17-26

摘要

植物運用維管束系統來面對環境中多樣的刺激，以調節自身的生長發育。近來的研究證實，植物在葉部整合光週期的變化並利用維管束系統長距離輸送FLOWERING LOCUS T (FT)至頂芽，促進植物的開花。因此，FT被認為是追尋已久的開花素(Florigen)。然而，影響植物開花的因素除了光週期外，證據顯示尚有其他基因在植物開花的路徑中扮演系統性的調控因子。我們分析青花菜收取之篩管液，企圖找出潛在的系統性開花調控因子。利用基因微陣列(Microarray)及反轉錄聚合酶連鎖反應(RT-PCR)的分析方法，從青花菜篩管液中鑑定出FVE與AGAMOUS-LIKE 24 (AGL24)兩個與開花調控有關的RNA。酵素學上的分析證明FVE與AGL24的RNA帶有5'-cap結構及polyadenylation tail，為典型之訊息RNA(mRNA)。文獻資料顯示，大量表現FVE與AGL24可促進植物提早開花。我們以野生型阿拉伯芥為接穗嫁接至FVE或AGL24轉殖株系之砧木上。利用RT-PCR的方式，可由野生型接穗偵測出FVE或AGL24轉殖基因之RNA。顯示FVE與AGL24RNA可經由維管束系統進行長距離運送。我們的實驗結果顯示，除了FT，尚有多個基因對於植物開花具有系統性的調控。

關鍵字

阿拉伯芥 ； 青花菜 ； 開花 ； 嫁接 ； 篩管液 ； RNA長距離移動

並列摘要

Plants take advantage of the vascular system to operate environmental stimulates for finetuning their developmental programs. Recent evidence shows that the FLOWERING LOCUS T (FT) protein is the long-sought-after florigen that integrates the photoperiod variation perceived in the leaves. However, evidence also supports that other yet-to-be identified systemic regulators participate in floral induction. To this end, we investigated phloem exudates from excised broccoli (Brassica oleracea) inflorescences. Microarray and RT-PCR analyses revealed that at least two RNAs of floral regulators, FVE and AGAMOUS-LIKE 24 (AGL24), are present in the phloem sap. Enzymatic analysis demonstrated that the phloem-sap RNAs contain a 5' cap and a polyadenlylation tail, which suggests that phloem sap contains typical mRNAs. Arabidopsis grafting experiments were used to test whether these RNAs move long distance along the phloem translocation stream. Consistent with previous reports, Arabidopsis transformants expressing FVE and AGL24 displayed an early flowering phenotype. When wild-type scions were grafted onto P35S-FVE or P35S-AGL24 transformant stocks, the RNAs of transgenic FVE and AGL24 were detected from the wild-type scions. Thus, both FVE and AGL24 RNAs can move long distance across the graft union. Our data support the notion that multiple systemic floral regulators may participate in floral regulation.

並列關鍵字

Arabidopsis ； Brassica oleracea ； Flowering ； Grafting ； Phloem sap ； RNA long-distance movement