Beneficial effects of endophytic Pantoea ananatis with ability to promote rice growth under saline stress

Soil salinization severely inhibits plant growth, leading to a low crop yield. The aim of the current study was to isolate endophytic bacteria with the ability to promote rice growth under saline conditions.We isolated eight salt-tolerant endophytic bacteria from rice roots. An isolated strain D1 was selected due to its ability to stimulate rice seed germination in the presence of NaCl, which was identified as Pantoea ananatis D1. It exhibited multiple plant growth-promoting traits including phosphate solubilization, production of indole-3-acetic acid, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and siderophore. Inoculation of P. ananatis D1 obviously enhanced the rice root and shoot growth under normal and saline conditions. It also significantly increased the contents of chlorophyll, total soluble protein, and proline in salt-stressed rice seedlings. Moreover P. ananatis D1 could ameliorate the oxidative stress in rice induced by NaCl and Na2 CO3 treatment. The malondialdehyde content and various antioxidant enzyme activities were decreased by P. ananatis D1 inoculation in salt-affected rice. In addition, P. ananatis D1 showed a positive potential for limiting the Na+ accumulation and enhancing the K+ uptake, leading to an increase of 1·2-1·7 fold in K+ /Na+ ratio under saline environment.Pantoea ananatis D1 has the ability to improve the salt tolerance of rice seedlings.The application of plant growth-promoting bacteria (PGPB) is an eco-friendly strategy to improve plant tolerance towards abiotic stresses. We demonstrated that P. ananatis D1 could be used as an effective halotolerant PGPB to enhance rice growth in different salt-affected soils.