Characterization of the endophytic antagonist pY11T-3-1 against bacterial soft rot of Pinellia ternata

Biocontrol is an emerging trend aimed at reducing chemical input while increasing plant fitness, productivity and resistance to diseases in sustainable agriculture. An antagonist, pY11T-3-1, was herein characterized for potential applications against soil-borne plant diseases.

In vitro antagonistic assays, the antagonist pY11T-3-1 was demonstrated able to obviously reduce the occurrence of the soft rot disease on Pinellia ternata, potato, pepper, tomato, cucumber and eggplant tubers or fruits, with higher prevention (90%) on P. ternata. It showed a broad antagonistic spectrum against 23 tested bacterial and fungal phytopathogens, which were distributed in 14 genus and 17 species. However, it inhibited only two of the seven bacterial nonpathogens. Phenotypic characterizations showed that the antagonist pY11T-3-1 was similar to Pseudomonas aeruginosa. Its major fatty acids were 18:1 w7c (22.17%), 16:0 (20.21%), 12:0 2OH (12.45%), 16:1w7c/15 iso2OH (10.95%) and 10:0 3OH (10.79%), which is a different profile from that of Ps. aeruginosa. The 16S rRNA and gyr B gene sequences shared 100 and 99% similarity with Ps. aeruginosa, respectively. The phylogenetic trees showed that it was clustered with Ps. aeruginosa.

The antagonist pY11T-3-1 was characterized as Ps. aeruginosa with a unique fatty acid profile.

With broad antagonistic spectrum and host selectivity, the antagonist pY11T-3-1 may provide a more environmental and economical alternative to the control of soil-borne disease on P. ternata, which needs further investigation.