圖1. 這些圖像顯示，相較之下，Ct大大增加擬南芥(阿拉伯芥)根部成長。有害之Ct3顯著抑制成長的驚人效果。
These images show the startling effect of harmful Ct3 significantly limiting root growth, compared with beneficial Ct greatly increasing root growth of thale cress.
Researchers have found that the fungus Colletotrichum tofieldiae can both support and inhibit plant growth, depending on the activation of a specific gene cluster. This discovery challenges traditional distinctions between harmful pathogens and beneficial microbes. Understanding and harnessing these traits could enhance global food security and reduce wastage.
研究人員們已經發現，Colletotrichum tofieldiae真菌，取決於特定基因簇的活化，能激勵及抑制植物生長。此發現挑戰了，在有害病原體與有益微生物之間的傳統差異處。瞭解並利用此些特質，可能提升全球糧食安全及減少浪費。
Mold and diseases caused by fungi can greatly impact the shelf life of fruits and vegetables. However, some fungi benefit their hosts by aiding plant survival.
由真菌引起的黴及疾病，會大大影響水果及蔬菜的貨架期。不過，有些真菌經由幫助植物生存，而有益於其宿主。
Colletotrichum tofieldiae (Ct) is a root mold that typically supports continued plant development even when the plant is starved of phosphorus, an important nutrient for photosynthesis and growth. Researchers studied a unique pathogenic strain of the fungi, called Ct3, which conversely inhibits plant growth.
Colletotrichum tofieldiae (Ct)是一種，通常即使在植物缺乏磷(光合作用及生長的一種重要營養物)時，也激勵植物持續成長的根部黴菌。研究人員們研究了一種，反相抑制植物成長，被稱為Ct3之真菌的獨特致病菌株。
By comparing the beneficial and harmful strains Ct strains, they found that activation of a single fungal secondary metabolism gene cluster determined the negative impact of the fungus on the host plant.
藉由比較Ct菌株，有益及有害之的菌株。他們發現了，單一真菌之次級代謝基因簇的活化，決定了真菌對寄主植物的負面影響。
When the cluster was disrupted, either genetically or by a change in environment, the fungi’s behavior changed from inhibiting growth to promoting it. Understanding mechanisms like this could help us reduce food waste by harnessing the beneficial role fungi can have on food.
當此基因簇，遺傳上或因環境中的改變，而遭擾亂時，真菌的作用從抑制變成促進成長。瞭解像上述的機制，可能有幫助於我們利用真菌，對食物能具有的有益角色，來減少食物浪費。
When your fresh strawberries go fuzzy with mold, or grapes turn gray and shrivel at the bottom of the fruit bowl, it’s always a bit disappointing and unpleasant. The culprit is typically a disease-causing fungus called Botrytis, which devastates food crops globally and is easily spread by wind and soil.
當新鮮草莓因黴菌變得模糊，或葡萄於果盤底部變灰色並枯萎時。這總是會有點令人失望及不愉快。罪魁禍首通常是一種，摧毀全球糧食作物，且很容易經由風及土壤傳播，被稱為灰色葡萄孢菌的致病真菌。
However, there are many fungi that have a less destructive relationship with their host plants, even forming partnerships that can help the plant to thrive. Promoting the beneficial traits of fungi and suppressing undesirable outcomes (like moldy fruit) would greatly aid global food security and help reduce a huge amount of food waste.
不過，有諸多與其寄主植物具較小破壞性，甚至形成能有助於植物茁壯成長的夥伴關係。促進真菌的有益特性及抑制不良後果(如發霉的水果)，將大大促進全球糧食安全，且有助於減少大量的食物浪費。
“Plant-associated fungi show varied infection lifestyles ranging from mutualistic (beneficial) to pathogenic (harmful) depending on the host enviroment. However, the mechanisms by which these microbes transit along these different lifestyles remain poorly understood,” said Associate Professor Kei Hiruma from the Graduate School of Arts and Sciences at the University of Tokyo.
來自日本東京大學文理研究院的助理教授，Kei Hiruma宣稱：「相關的植物真菌展現出，取決於宿主環境，從互惠(有益)到致病(有害)的不同感染生存方式。不過，此些微生物藉以，順著此些不同生存方式轉變的機制，仍然未被充分瞭解。」
We analyzed genetic information from varied strains of a root fungus called Colletotrichum tofieldiae using comparative transcriptomic analysis, which enabled us to study differences in gene expression between each strain. Surprisingly, we found that a single fungal secondary metabolism gene cluster, called ABA-BOT, solely determines whether the fungus exhibits pathogenic or mutualistic traits toward the host plant.”
我們使用了，令我們能研究每種菌株之間，基因表現差異的比較轉錄體分析法，來分析源自被稱為Colletotrichum tofieldiae之不同根部真菌菌株的遺傳訊息。令人驚訝的是，我們發現一種，被稱為脫落酸(ABA：abscisic acid)-灰色葡萄孢菌毒素(BOT：Botrydial )之單一真菌的次級代謝基因簇，單獨決定這種真菌是否對宿主植物，展現致病或互利共生的特質。」
Colletotrichum tofieldae is a fungus that typically benefits plants when they suffer a phosphorus deficiency, helping them thrive despite the lack of this vital nutrient. It has even been shown to increase the growth and yield of economically important crops such as maize and tomatoes.
Colletotrichum tofieldae是一種，通常在植物缺乏磷時，儘管缺乏這種重要營養物，仍有助於它們茁壯成長之有益於植物的真菌。它甚至已經被證實，提升諸如玉米及蕃茄等，經濟上重要作物的成長及產量。
In this study, the multi-institutional team used thale cress as the host plant and sourced six strains of Ct from different geographical locations to infect it with. Five strains significantly promoted plant growth, as expected, but a sixth —called Ct3 —was found to suppress nutrient uptake, inhibiting plant growth and leading to symptoms of disease. So, what caused this drastic change?
在該項研究中，此多機構的團隊使用了，擬南芥作為寄主植物，且獲得源自不同地理位置的六種Ct 菌株，來感染它。如預期那樣，五株菌株顯著促進了植物成長。不過，被稱為Ct3的第六種，被發現會抑制養分吸收，抑制植物成長且導致諸多疾病症狀。那麼，是什麼導致了此極端改變？
“We identified two key points: First, on the fungal side, that Ct3 activates the ABA-BOT biosynthesis gene cluster; and second, on the plant side, that Ct3 induces the host plant’s ABA signaling pathways, through which the fungus inhibits plant growth,” explained Hiruma.
Hiruma解釋：「我們確認了兩個關鍵點：第一點，在真菌方面，Ct3活化ABA-BOT的生物合成基因簇；第二點，在植物方面，Ct3誘導宿主植物的 諸多ABA發信號途徑，真菌透過此些途徑抑制植物成長。」
The researchers found that both pathogenic and mutualistic strains of Colletotrichum tofieldae contain the ABA-BOT gene cluster, but mutualistic strains did not express it, i.e., the genes were not activated. The discovery came as a surprise, as conventionally pathogens and mutualists were thought to have distinct characteristics, but these findings suggest that they are more intricately related.
此些研究人員發現，Colletotrichum tofieldae的致病菌株及互利共生菌株，皆具有ABA-BOT基因簇。不過，互利共生菌株並未使其作出表現。即，此些基因沒被活化。此發現令人驚訝，因為傳統上認為病原體與互利共生體具有不同的特性。不過，此些發現暗示，它們關係更為錯綜複雜。
When the gene cluster was disrupted, either at a genetic level or by changing the plant’s environment, the Ct3 was rendered nonpathogenic and even became beneficial to the host, promoting root growth. Although further study is needed, it appears that the ABA-BOT gene cluster may contribute to pathogenesis in diverse fungi beyond the Ct species.
當此基因簇遭擾亂時，不是在基因層面上，就是由於改變植物的環境。Ct3變得非致病性，甚至變得對宿主有益，而促進根部生長。雖然需要進一步研究，不過顯然ABA-BOT基因簇可能是，該Ct 物種以外，於不同真菌中，疾病發生的部分原因。
For example, it may be involved in the pathogenesis of the Botrytis which afflicts our household fruit and vegetables.
譬如，這可能與影響我們一般水果及蔬菜之灰色葡萄孢菌的發病機理直接有關。
“If we gain a comprehensive understanding of the regulatory mechanisms governing the fungal secondary metabolism gene cluster, we can devise a method to selectively suppress potential pathogenesis in otherwise beneficial fungi, optimizing their utilization in agriculture and harnessing the full potential of the microbial diversity naturally present in soil ecosystems,” said Hiruma.
Hiruma宣稱：「倘若我們獲得，有關此些左右這種真菌次級代謝基因簇之調控機制的全面瞭解，則我們能設計一種方法來選擇性抑制，於其他有益真菌中，潛在的發病機理，使最佳化其在農業上的利用，並利用於土壤生態體系統中，自然存在之微生物多樣性的全部潛力。
I have come to realize that even pathogens can exhibit nonharmful characteristics during a significant portion of their life cycles. In fact, I am beginning to contemplate the possibility that what we traditionally refer to as pathogens may actually function as beneficial microbes under other conditions.”
我已經開始瞭解，即使病原體在其生命週期的大部分時間裡，也能展現無害的特質。事實上，我正開始沉思，傳統上我們所提及，在其他條件下，病原體實際上可能與有益之微生物一樣起作用的可能性。」
網址：https://scitechdaily.com/genetic-cluster-in-root-fungus-found-to-be-the-on-off-switch-for-disease-causing-behavior/
翻譯：許東榮
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