The Ephelis fungus, an epiphytic symbiont of C4-grasses, confers resistance against herbivorous pests and environmental stress

摘要

Black choke is a well-known disease of gramineous plants including rice causing sterile heads with black to grey stromata of mummified appearance. The disease is common especially in India and China and called 'Udbatta' and 'I-Chu-Hsiang' disease of rice, respectively. Many C4 warm season grasses have also been reported as hosts, such as Echinochloa crus-galli (barnyard grass), Setaria italica (foxtail millet), Pennisetum americanum (pearl millet), Sorghum vulgare (sorghum) and others, mainly in India, China and in the Americas. In Japan, the disease has been found on many species of C4-grasses, mainly in the southern region. In addition to the typical black choke symptom, most of the infected grasses have a sign of white streaks of hyphae on the leaves showing the epiphytic characteristics of the pathogenic fungus. The purpose of the paper is to characterize the causal fungus and study its epiphytic relationship with the infected plants in addition to the beneficial effect to the infected plants such as insect resistance and cold tolerance.