Volatile compounds mediated effects of Stenotrophomonas maltophilia strain UN1512 in plant growth promotion and its potential for the biocontrol of Colletotrichum nymphaeae

Abstract

A novel endophytic bacterium, designated strain UN1512, was isolated from strawberry leaves, and its antifungal activity against Colletotrichum nymphaeae was estimated under in vitro, in vivo, and greenhouse conditions. The bacterial isolate was identified as Stenotrophomonas maltophilia via morphological, biochemical, and molecular traits. The strain UN1512 decreased the mycelial growth of C. nymphaeae (54.92%) in dual culture. The volatile and non-volatile compounds produced by strain UN1512 reduced mycelial growth of fungal pathogen by 17.85% and 30.06%, respectively. Also, the strain was able to secrete of protease, chitinase, pectinase, siderophore, IAA, and gibberellin. In addition, disease severity of strawberry anthracnose was inhibited via inoculating the bacterial suspension in phylloplane, rhizosphere, and healthy fruits. Also, the effect of volatile compounds (VOCs) produced by strain UN1512 on growth promotion of tomato plants was investigated under in vitro and growth chamber experiments. The results showed that, these compounds significantly enhance the fresh weight and length of roots and shoots. The VOCs produced by strain UN1512 were analyzed by GC-MS and 31 identified VOCs, that Benzothiazole (18.271%), 1,3,5,7-Cyclooctatetraene-1-carboxaldehyde (9.308%), Carbonic acid, octadecyl phenyl ester (5.203%), Benzaldehyde, 2,5-bis[(trimethylsilyl)oxy]- (4.086%), Estragole (3.557%), Benzaldehyde (3.506%) were the major components. Our studies report that strain UN1512 was capable to inhibit the causal agent strawberry anthracnose, and the VOCs produced by this strain increased the tomato seedlings growth.