Disease resistance in transgenic plants has been improved, for the first time, by the insertion of a gene from a biocontrol fungus. The gene encoding a strongly antifungal endochitinase from the mycoparasitic fungus Trichoderma harzianum was transferred to tobacco and potato. High expression levels of the fungal gene were obtained in different plant tissues, which had no visible effect on plant growth and development. Substantial differences in endochitinase activity were detected among transformants. Selected transgenic lines were highly tolerant or completely resistant to the foliar pathogens Alternaria alternata , A. solani , Botrytis cinerea , and the soilborne pathogen Rhizoctonia solani . The high level and the broad spectrum of resistance obtained with a single chitinase gene from Trichoderma overcome the limited efficacy of transgenic expression in plants of chitinase genes from plants and bacteria. These results demonstrate a rich source of genes from biocontrol fungi that can be used to control diseases in plants.

Aims: In a search for an antifungal peptide with a high activity against Aspergillus¯avus, Bacillus subtilis AU195 was selected from a collection of isolates with antagonistic activity against A.¯avus. Methods and Results: To identify the antifungal peptides, a protein puri®cation scheme was developed based on the detection of the antifungal activity in puri®ed fractions against A.¯avus. Two lipopeptides were puri®ed with anion exchange and gel ®ltration chromatography. Their masses were determined to be 1045 and 1059 1 m/z with mass spectrometry, and their peptide moiety was identical to bacillomycin D. Conclusions: AU195 synthesized a mixture of two antifungal bacillomycin D analogues with masses of 1045 and 1059, the 14 mass unit difference representing the difference between a C15 and a C16 lipid chain. Signi®cance and Impact of the Study: Both bacillomycin D analogues were active at the same concentration against A.¯avus, but the different lipid chain length apparently affected the activity of the lipopeptide against other fungi.

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The stimulation exerted by the endophytic bacterium Bacillus pumilus strain SE34 in plant defense reactions was investigated at the ultrastructural leve1 using an in vitro system in which rootinducing T-DNA pea (Pisum sativum 1.) roots were infected with the pea root-rotting fungus Fusarium oxysporum f. sp. pisi. In nonbacterized roots, the pathogen multiplied abundantly through much of the tissue including the vascular stele, whereas in prebacterized roots, pathogen growth was restricted to the epidermis and the outer cortex. In these prebacterized roots, typical host reactions included strengthening the epidermal and cortical cell walls and deposition of newly formed barriers beyond the infection sites. Wall appositions were found to contain large amounts of callose in addition to being infiltrated with phenolic compounds. The labeling pattern obtained with the gold-complexed laccase showed that phenolics were widely distributed in Fusarium-challenged, bacterized roots. Such compounds accumulated in the host cell walls and the intercellular spaces as well as at the surface or even inside of the invading hyphae of the pathogen. The wall-bound chitin component in Fusarium hyphae colonizing bacterized roots was preserved even when hyphae had undergone substantial degradation. These observations confirm that endophytic bacteria may function as potential inducers of plant disease resistance.