新穎材料農業：農業新穎材料在植物保健開發、應用與機理【植物病理學系/張碧芳教授】
| 論文篇名 | 英文：Degenerated virulence and irregular development of Fusarium oxysporum f. sp. niveum induced by successive subculture 中文：重覆繼代培養誘發西瓜蔓割病菌 Fusarium oxysporum f. sp. niveum 之型態變化與毒力退化 |
| 期刊名稱 | Journal of Fungi |
| 發表年份,卷數,起迄頁數 | 2020, 6, 382 |
| 作者 | Chang, Tao-Ho(張道禾); Lin, Ying-Hong; Wan, Yu-Ling; Chen, Kan-Shu; Huang, Jenn-Wen(黃振文); Chang, Pi-Fang Linda(張碧芳)* |
| DOI | 10.3390/jof6040382 |
| 中文摘要 | 真菌於人工培養基中多次繼代培養常發生生長變異和病原毒力退化，西瓜蔓割病菌 (Fusarium oxysporum f. sp. niveum, Fon) 也曾發現具有相同的特性，在本研究中發現繼代培養會增加變異的發生率，為了進一步了解發生變異後病菌之差異，因此以 Fon 野生型 (sporodochial type, ST) 與兩類變異型態 (菌絲型： Mycelial type, MT 和黏膜型：Pionnotal type, PT) 分析其生長發育和病原性，不同變異型態 (PT2, PT3, PT11 與 MT6) 在菌絲生長、分生孢子產量和厚膜孢子生成的能力與野生型有相當顯著的差異，同時利用病土接種方法發現變異菌株在西瓜上造成的病程發展較野生型態緩慢且毒力較低，因此後續分析變異菌株細胞壁分解酵素 (纖維素酶、果膠酶與木膠多糖酶) 之活性和9組毒力相關基因 (fmk1、 fgb1、 pacC、 xlnR、 pl1、 rho1、 gas1、 wc1 與 fow1) 之表現差異，結果發現變異菌株之細胞壁分解酵素活性皆較野型態低，且 fmk1、 xlnR 與 fow1 在變異菌株上的表現量明顯較野生型低。在本研究中發現菌株繼代培養和菌株老化相關，且會造成細胞壁分解酵素的活性降低和毒力相關基因表現的下降，最終造成毒力的下降，未來如能繼續探討變異成因的機制或許可應用於未來的病害管理策略中。 |
| 英文摘要 | Successive cultivation of fungi on artificial media has been reported to cause the sectorization, which leads to degeneration of developmental phenotype, and virulence. Fusarium oxysporum f. sp. niveum (Fon), the causal agent of watermelon Fusarium wilt, forms degenerated sectors after successive cultivation. In the present research, we demonstrated that subculture with aged mycelia increased the incidence of degenerations. To further investigate the differences between the Fon wild type (sporodochial type, ST) and variants (MT: mycelial type and PT: pionnotal type), developmental phenotypes and pathogenicity to watermelon were examined. Results in variants (PT2, PT3, PT11, and MT6) were different from ST with mycelia growth, conidia production and chlamydospore formation. Virulence of degenerated variants on susceptible watermelon Grand Baby (GB) cultivar was determined after inoculation with Fon variants and Fon ST. In root dipping methods, Fon variants showed no significant differences in disease progress compared with ST. Fon variants showed a significant decrease in disease progression compared with ST through infested soil inoculation. The contrasting results of two inoculation methods suggest that the degenerative changes due to repeated successive cultivation may lead to the loss of pathogen virulence-related factors of the early stage of Fon infection process. Therefore, cell wall-degrading enzymes (CWDEs; cellulase, pectinase, and xylanase) activities of different variants were analyzed. All Fon degenerated variants demonstrated significant decreases of CWDEs activities compared with ST. Additionally, transcript levels of 9 virulence-related genes (fmk1, fgb1, pacC, xlnR, pl1, rho1, gas1, wc1, and fow1) were assessed in normal state. The degenerated variants demonstrated a significantly low level of tested virulence-related gene transcripts except for fmk1, xlnR, and fow1. In summary, the degeneration of Fon is triggered with successive subculture through aged mycelia. The degeneration showed significant impacts on virulence to watermelon, which was correlated with the reduction of CWDEs activities and declining expression of a set of virulence-related genes. |
| 發表成果與本中心研究主題相關性 | 黃振文與張碧芳教授團隊發現田間分離之西瓜蔓割病菌，在多次純培養繼代後會造成病原菌培養型態變異與毒力退化，也發現該退化現象與病原菌之細胞壁分解酵素活性及多種毒力因子基因表現有關，此研究探討之毒力退化之因素未來或可應用於病害管理或篩選可用之農業應用新資材，為本中心子計畫五之衍伸研究內容。 |
