文心蘭切花栽培技術與開花調控機制之研究

Abstract

文心蘭為臺灣重要的出口切花，有其重要的經濟地位。本研究的目的是調查在兩種光強度分別為光合光子通量密度(PPFD) 40% (LI-40)和30% (LI-30)下，三種肥料處理對兩種文心蘭切花栽培種品種‘檸檬綠’(Oncidesa Gower Ramsey “Honey Angel, HA)及‘黃金之星’(“Golden Star”, GS) 對假球莖生長量和開花品質的影響。以農民慣行肥料處理作為對照，由 N:K = 1:1.12 的液體肥料與57.3%有機質肥料(7.8% N、0.8% P2O5、0.3% K2O)混合，每週兩次葉面施用。肥料分期處理為氮鉀肥不同比例於不同生長期分期施用(假球莖出鞘期施用N:P:K=1:1:5，抽梗開花期施用N:P:K=1:1:1)。肥料輪施處理由氮鉀肥不同比例輪施(N:P:K=1:1:5和N:P:K=1:1:1 )，每週葉面施用各一次，調查植株生長量與開花品質。與‘檸檬綠’相比，‘黃金之星’在農民慣行肥料和肥料輪施處理後假球莖球長顯著增加，‘黃金之星’在PPFD 30%以農民慣行肥料處理的假球莖球長81.65 mm為最長。在肥料輪施處理下假球莖球寬隨著光強度的增加而增加，‘黃金之星’在PPFD 40%下以肥料輪施處理的假球莖球寬有最大值，與農民慣行肥料處理下的PPFD 30%相比，PPFD40%的假球莖球厚最大且顯著增加。‘黃金之星’在農民慣行肥料處理下的花梗長度的顯著優於‘檸檬綠’，並且‘黃金之星’在PPFD 30%中最長的花梗長度表現。‘檸檬綠’的分支數和小花數在PPFD40%下顯著高於PPFD 30%，並且以農民慣行肥料和肥料分期處理處理時有最佳表現。不同光強度環境的肥培管理可以促進文心蘭假球莖生長量和開花品質有最佳表現。 目前已知文心蘭的開花機制與維生素C(ascorbate)和穀胱甘?(glutathione, GSH)的氧化還原狀態有關，然而所造成的開花分子機制仍尚未明瞭。我們利用次世代定序技術來調查分別受到穀胱甘?氧化態(GSSG, glutathione disulfide)、還原態(GSH)或還原態生合成抑制劑(buthionine sulfoximine, BSO)處理後的文心蘭假球莖部位之全轉錄體表現，結果得到219,814個差異性基因。其中GSSG處理之正向與負向差異性基因數分別為36,341及20,815個，而GSH處理之正向與負向差異性基因數為22,780及29,952個；BSO處理之正向與負向差異性基因數為32,963及21,881個。再依基因體本體整合性分類系統(GO ontology)歸納這些差異性基因與生物程序與分子功能層次有關。基因體本體整合性分類系統分析顯示參與生殖生長及開花反應有關，且有被註解的正向、負向差異性基因數分別為92及43個。KEGG pathway分析顯示有22(GSSG)、32(GSH)、74(BSO)個差異性基因參與澱粉與醣類代謝途徑。本研究的結論說明文心蘭的開花機制可能是藉由GSSG刺激醣類代謝相關基因表達，進而調控開花基因表現。

Oncidiums are a vital export cut flower and has a significant economic position in Taiwan. This study aimed to investigate the pseudobulb growth and flowering characteristics of the two Oncidesa Gower Ramsey cultivars ‘Honey Angel (HA)’ and ‘Golden Star (GS)’cultivated under three kinds of fertilizer treatments in response to 40% light intensity (LI-40) and 30% light intensity (LI-30, as control) photosynthetic photon flux density over a five-month period. The conventional-fertilizer (CF) treatment, as a control, consisted of a liquid manure solution of N: K = 1: 1.12 mixed with 7.8% N, 0.8% P2O5, 0.3% K2O, and 57.3% of organic matter that was foliage-applied to plants twice a week. The stage-fertilizer (SF) treatment consisted of N: P: K = 1:1:5 foliage-applied to plants in an unsheathing pseudobulb stage until reaching inflorescence, followed by N: P: K=1:1:1 application until the end of the experiment. The fortnight-fertilizer (FF) treatment consisted of N: P: K=1:1:5 and N: P: K=1:1:1 with interval-rotate foliage-application to plants weekly until the end of the experiment. Plant pseudobulb growth and flowering qualities were recorded and calculated. The GS cultivar significantly increased PL when treated with CF and FF compared to HA, and GS treated with CF under LI-30 exhibited the longest PL at 81.65 mm. PW increased as LI increased under FF treatment, and the largest PW was observed in GS treated with FF under LI-40. A maximal and significant increase in PT occurred in LI-40 compared to LI-30 under the CF treatment. GS had a significantly higher FL compared to HA treated with CF, and the longest FL was detected in GS under LI-30. HA had a significantly higher FB and FN under LI-40 than under LI-30, and the highest number of FB and FN in HA occurred when it was treated with CF and SF, respectively. Precision management of fertilization treatments in response to LI can maximize pseudobulb growth, development, and flowering quality in oncidiums. Flowering regulation is also the central issue of oncidiums for agricultural management. Previous studies have revealed that flowering mechanisms and related to ascorbate (AsA) and glutathione (GSH) redox status. However, the molecular mechanisms of the flowering in oncidiums remain unclear. In this work, RNA-seq was used to investigate the global transcriptomic expression of pseudobulb in Oncidesa ‘Gower Ramsey’ that has been treated each with GSSG (glutathione disulfide), GSH (glutathione), and BSO (buthionine sulfoximine), and compared with mock. Four transcriptome databases were integrated and assembled into 219,814 unigenes. These unigenes have shown that, comparing with mock, differentially expressed genes (DEGs) including 36,341 up-regulated and 20,815 down-regulated genes in GSSG, 22,780 up-regulated and 29,952 down-regulated genes in GSH; 32,963 up-regulated and 21,881 down-regulated genes in BSO. Besides, the Gene Ontology analysis indicated 92 up-regulated and 43 down-regulated genes. Furthermore, the DEGs were functionally annotated to associate reproductive growth and flowering regulation. KEGG pathway analysis revealed 22(GSSG),32(GSH) and 74(BSO) DEGs that were involved in starch and sucrose metabolisms. These data implied that the treatment of GSSG can effectively activate starch metabolism and relate to the genetic network of flowering regulation.