| 摘要: | 川七（Anredera cordifolia），通常被稱為馬德拉藤（Madeira-vine, MV），是一種屬於巴塞蘭科（Basellaceae）的多肉藤蔓植物，原產於南美洲，常綠且生長迅速，分布於世界各地。川七植株莖每3.5至4小時會逆時針旋轉一次。每日測量顯示，當川七接觸到支撐物後，其生長速度可快達30倍。對活體川七進行的體內X射線繞射顯示，在其莖內出現了結晶的IAA（吲哚乙酸，C10H9NO3）、4-Cl-IAA（4-氯吲哚乙酸，C10H8ClNO2）和6-Cl-IAA（6-氯吲哚乙酸，C10H8ClNO2）。從川七莖中提取的IAA進行小角度中子散射光譜分析，顯示從頂端向下輸送的結晶IAA逐漸增大。對提取的IAA進行的高解析度X射線繞射分析發現，攀爬中的川七內含有顯著更多的4-Cl-IAA和6-Cl-IAA，而非尚在擺動中的川七。氣相層析-質譜儀（GC-MS）光譜顯示，攀爬中的川七頂端生產的IAA比擺動中的組別多出9%，而4-Cl-IAA和6-Cl-IAA則多出90%。更多的4-Cl-IAA和6-Cl-IAA被輸送至川七的無接觸面，而非接觸面。對自然攀爬川七進行的體內中子斷層掃描顯示，無接觸面部位的H+濃度顯著高於接觸面部位。同時，吸收光譜顯示無接觸面部位的擴張蛋白（expansin）含量也高於接觸部位。這些研究結果從分子層面揭示了川七因接觸支撐物而觸發更快且差異化生長的機制。雖然植物無法像動物那樣迅速移動，但它們能對環境非常敏感，並表現出多種運動形式。其中，擺動隨後攀爬或纏繞支撐物是藤本植物生長的典型特徵。藤本植物的生長頂端會以大範圍的圓周運動擺動，這一過程被稱為迴旋運動（circumnutation），找到一個可以纏繞的支撐物後並繼續生長。纏繞支撐物後，藤本植物將減少對自我支撐組織的能量投入，而將更多能量用於加速生長。這種對機械接觸作出的反應行為被稱為向觸性（thigmotropism）。向觸性最早由查爾斯·達爾文於其1880年出版的著作《植物運動的力量》（The Power of Movement in Plants）中描述。向觸性反應會觸發兩種行動：更快速的生長和差異化生長。此外，本研究結果也證實了川七的無性繁殖構造—零餘子，其粉末具有顯著的抑菌效果。;Anredera cordifolia, also known as Madeira-vine (MV) is an evergreen fast climber that grows all over the world. MV rotates counterclockwise every 3.5 to 4 hours. It is a South American species of succulent vine of the family Basellaceae. Daily measurements indicate that the growth rate of Madeira vine (MV) can grow up to 30 times faster when encountering a support. Small-angle neutron scattering spectra of IAA extracted from MV stems demonstrate a progressive increase in the size of crystallized IAA as it is transported downward from the shoot apex. High-resolution X-ray diffraction analysis of the extracted IAA shows significantly higher concentrations of 4-Cl-IAA and 6-Cl-IAA in climbing MVs compared to swaying MVs. Also, in vivo X-ray diffraction on live MV stems reveals the presence of crystallized indole-3-acetic acid (IAA, C10H9NO3), 4-chloroindole-3-acetic acid (4-Cl-IAA, C10H8ClNO2), and 6-chloroindole-3-acetic acid (6-Cl-IAA, C10H8ClNO2) in the stems. Gas chromatography-mass spectrometry (GC-MS) data indicate that climbing MVs produce 9% more IAA and 90% more combined 4-Cl-IAA and 6-Cl-IAA at their apexes than swaying MVs. Moreover, more 4-Cl-IAA and 6-Cl-IAA are transported to the non-contact side of the vine than to the contact side. In vivo neutron tomography of naturally climbing MVs reveals a substantially higher concentration of H+ ions in the non-contact regions compared to the contact regions. Absorption spectra further show much greater presence of expansin in the non-contact areas than in the contact areas. These findings provide molecular insights into the mechanisms that drive the accelerated and differential growth of MVs in response to contact with a support. Although plants cannot move as swiftly as animals, they are highly attuned to their environment and capable of various movements. Among these movements, the swaying followed by climbing or twining around a support is characteristic of vine plants. The tip of a growing vine stem swings in wide areas, a phenomenon known as circumnutation, until it encounters a support to wrap around as it continues to grow. Once the vine has twined around a support, it allocates less energy to developing its own supportive tissue and instead invests more in accelerating its growth. This behavior, which occurs in response to mechanical contact, is referred to as thigmotropism. Thigmotropism was first described by Charles Darwin in his 1880 publication, “The Power of Movement in Plants”. The thigmotropic response initiates two key actions: enhanced growth and differential growth. Furthermore, this research findings have confirmed that the asexual reproductive structures of Madeira vine (MV), specifically aerial tubers, exhibit significant antibacterial effects in their powdered form. |
