營養對香蕉炭疸病菌附著器形成及潛伏感染之影響

Abstract

香蕉炭疽病菌(Colletotrichum musae)在青香蕉或是熟香蕉果皮上之分生胞子發芽率與附著器形成率並無差異；接種傷口會促進分生胞子發芽但抑制附著器之形成。在添加10,000ppm單寧的PDA平板上，分生胞子發芽後不長發芽管而直接形成附著器，此附著器在乾燥下可存活六十天並保有活力。香蕉表面分泌物濃度在催熟後第五天開始增加，至第八天時醣類濃度為未催熟青香蕉之六倍，至第十天時暴增為八十五倍，而蛋白質濃度則增為十二倍，分生胞子在此濃度相當之葡萄糖及asparagine中幾乎完全發芽並生長良好，不形成附著器，而催熟九天後之滲漏養分則只能使分生胞子發芽並形成附著器。以蒸餾水沖洗黃熟香蕉上接種部位，會延遲病斑之出現。 There are no differences between the rates of conidial germination and appressorial formation of Colietotrichum musae on the green banana peel and on the ripen banana. Wounding might enhance the conidial germination and the mycelial growth on the banana peel but inhibit the formation of appressoria. Appressoria formed from conidia directly with no germ tube on the PDA amended with 10,000 ppm tannin. Appressoria were capable of with standing high concentration of 10,000 ppm tannin and dryness for more than 60 days. The leachates from banana markedly increased 10 days after ripening, carbohydrates increased 85 times and the proteins increased 12 times Using the glucose and asparagine to replace carbohydrate and protein, respectively, in the leachate of banana peel, results showed that low concentration of nutrient leachated from the banana peel 9 days after ripening only stimulated conidial germination and appressorial formation but not mycelial growth on the millipore membrane placed on the agarose plate, but high concentration of nutrient leachated from the banana peel 10 days after ripening was capable of enhancing mycelial growth and inhibiting appressorial formation. Dripping to remove leachates from the surface of banana peel might also delay infection.