Growth promotion and induction of antioxidant system of tomato seedlings (Solanum lycopersicum L.) by endophyte TPs-04 under low night temperature

• We tested PGPB on tomato seedlings growth under low night temperature.
• Plants were adversely affected by night chilling stress.
• PGPB enhanced plants growth and nutrient uptake.
• Antioxidant system was induced by PGPB under night chilling stress.

This study investigated the effects of inoculation with selected 1-aminocyclopropane-1-carboxylate (ACC) deaminase-producing endophytic bacterium TPs-04 on growth promoting, nutrient uptake and antioxidant system of tomato (Solanum lycopersicum L.) seedlings under low night temperature (LNT, i.e., 6, 9 and 15 °C). Growth and nutrient uptake of tomato seedlings was reduced under different LNT stress level. Inoculation with strain TPs-04 significantly increased the length and dry weight of root and shoot, and chlorophyll content of leaves. Further analysis showed that it could enhance the uptake of N, P and K. The improvement of seedling growth might due to the plant growth promoting traits such as siderophore production, phosphorous solubilization, nitrogen fixation and ACC deaminase production indicated by TPs-04. Chilling stress resulted in rapid accumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Moreover, severe LNT (6 °C) raised the antioxidant enzyme activities compared to 9 and 15 °C treatments. The selected strain TPs-04 induced a higher increase in these antioxidant enzyme activities, and substantially decreased the accumulation of H2O2 and MDA in response to night chilling stress. Strain TPs-04 might be used as a potential bioinoculant of tomato plants protection under night chilling stress.