Objective Dark septate endophytes (DSEs) were screened for growth promotion and disease resistance to gray mold of tomato plants.

Methods An experimentation using 8 species of DSEs cultured on PDA plates along with the gray mold, Botrytis cinerea Pers. Fr, was conducted to examine the inhibitory effects of the DSEs on the pathogen. On a MS medium, growth indicators of tomato seedlings germinated from seeds with the DSEs were monitored. Infection rates of the tomato seedlings in the co-culture were observed.

Results Of the 8 DSEs, Xylaria berteroi (BND 6-R1-13) significantly enhanced the seedling growth, increased the leaf pigments content, boosted the root development (as shown on the increased lateral root number and root/shoot ratio), and heightened the root activity. It significantly inhibited the B. cinerea colony proliferation, achieving a control efficacy of 44.8%. Another DSE, Cordyceps javanica (BND 5-R1-3) significantly increased the lateral root count, root activity, and anthocyanin content of the tomato seedlings. And a third one, Pantospora guazumae (BND 5-L2-3) significantly inhibited the growth of B. cinerea showing a control efficacy of 73.5%.

Conclusion For the first time, the significant inhibitory effects of X. berteroi (BND 6-R1-13) and P. guazumae (BND 5-L2-3) on B. cinerea were reported by this study. In co-culturing with X. berteroi (BND 6-R1-13) for 15 d, the growth of the tomato seedlings was significantly enhanced. In addition, with the significant inhibitory effect on B. cinerea, the DSE would warrant further investigation for tomato farming application.