FUNCTION OF PLANT GROWTH PROMOTING FUNGI AND THEIR CONTROL OF SOIL-BORNE DISEASES

植物促生真菌（PGPF）具有促进植物生长和抑制病害的能力。还发现一些PGPF菌株能够诱导黄瓜对炭疽病病原菌Colletotrichum orbiculare的系统保护。黄瓜植株甚至用PGPF的培养滤液（CF）处理也诱导了对这种疾病的系统抗性。经CFs处理的根在病原菌的侵入点处诱导木质化，表明CFs中存在激发子物质。以黄瓜果片为材料，采用化学发光法检测CFs的诱导活性。用ARGUS-50测定了CFs处理的黄瓜果片的化学发光。PGPF的CFs引起明显的超氧化物生成。青霉GP 17 -2的CF具有极高的化学发光活性，其强度几乎是其它菌株的100倍。用蛋白酶处理或高压灭菌或除去脂质后，活性没有丧失。含有分子量大于2，000，000的物质的透析CF级分是高度有效的。该组分能诱导黄瓜下胚轴表皮组织明显木质化。木质化和超氧化物的产生被认为与诱导抗性的表达密切相关。

Plant growth promoting fungi (PGPF) exhibited the ability of plant growth promotion as well as disease suppression. Some PGPF isolates were also found capable of inducing systemic protection in cucumber against Colletotrichum orbiculare, the anthracnose pathogen. Cucumber plants even treated with culture filatrates (CFs) of PGPF induced a systemic resistance against this disease. Roots treated with CFs induced lignification at the points of attemped penetration by the pathogen indicating that elicitor substance(s) existed in the CFs. The elicitor activity of CFs was evaluated by the chemiluminescence assay using cucumber fruit disks. The emission of chemiluminescence from cucumber fruit disks treated with CFs was determined using ARGUS-50. The CFs of PGPF elicited conspicuous superoxide generation. The chemiluminescence activity of the CF of Penicillium GP17-2 was extremely high, and its intensity was almost 100 X that of other isolates. The activity was not lost after treatment with protease or autoclaving or after removal of lipid. The dialyzed CF fraction containing substances of MW.more than 2,000,000 was highly effective. This fraction could induce conspicuous lignification in the epidermal tissues of cucumber hypocotyl. Both lignification and superoxide generation are thought to be intimately related with the expression of induced resistance.