Strategy of endophytic bacterial communities in alfalfa roots for enhancing plant resilience to saline–alkali stress and its application

Soil salinization is an abiotic stress factor that can harm plant growth. Root endophytic bacteria may be associated with the resilience of plants to saline–alkaline stress. This study investigated the diversity, composition, and function of endophytic bacterial communities in alfalfa roots under saline–alkali stress, and screened a key bacterial strain associated with saline–alkali resistance. 16 S rRNA amplicon sequencing showed that high levels of saline alkalinity significantly reduced the diversity of endophytic bacterial communities and the relative abundance of beneficial bacterial taxa, such as Rhizobiales and Pseudomonas. Long durations of saline–alkali significantly decreased the abundance of predicted functional genes related to nitrogen metabolism in the alfalfa root endophytic bacterial community. Additionally, we isolated a key strain Pseudomonas with saline-alkali tolerance which could colonise roots and considerably improve physiological characteristics and plant growth. We found that colonization with Pseudomonas can considerably enhance plant resistance to saline-alkali stress and that the composition and function of the endophytic bacterial communities in roots likely contribute to plant tolerance to saline-alkali stress.