Tobacco Growth Promotion by the Entomopathogenic Fungus, <i>Isaria javanica</i> pf185

Abstract

<i>Isaria javanica</i> pf185 is an important entomopathogenic fungus with potential for use as an agricultural biocontrol agent. However, the effect of <i>I. javanica</i> pf185 on plant growth is unknown. Enhanced tobacco growth was observed when tobacco roots were exposed to spores, cultures, and fungal cell-free culture supernatants of this fungus. Tobacco seedlings were also exposed to the volatiles of <i>I. javanica</i> pf185 <i>in vitro</i> using I-plates in which the plant and fungus were growing in separate compartments connected only by air space. The length and weight of seedlings, content of leaf chlorophyll, and number of root branches were significantly increased by the fungal volatiles. Heptane, 3-hexanone, 2,4-dimethylhexane, and 2-nonanone were detected, by solid-phase micro-extraction and gas chromatography-mass spectrophotometry, as the key volatile compounds produced by <i>I. javanica</i> pf185. These findings illustrate that <i>I. javanica</i> pf185 can be used to promote plant growth, and also as a biocontrol agent of insect and plant diseases. Further studies are necessary to elucidate the mechanisms by which <i>I. javanica</i> pf185 promotes plant growth.