Induced systemic salt tolerance in rice by indigenous bacteria isolated from Java coastal plants under gnotobiotic system

Abstract

Bacteria associated with plants grown in saline natural habitat provide an advantage to the host they colonize and their utilization would give a great benefit for alleviating the salt stress to the plants growing in such environment. With the objective to find the most promising bacterial strains to be used for induction of salt tolerance in agricultural crops, we evaluated 12 bacterial isolates that previously isolated from plants grown in the Java coastal area. Gnotobiotic system was performed to test the ability of isolates in enhancing salt tolerance in three different varieties of rice (Ciherang, IF8, Situbagendit) under different levels of NaCl. The result suggested that promising isolates for enhanced salt tolerance in rice seedling are E194-3, D150 and R146-6 for root endophyte, leaf endophyte and rhizoplane respectively. Isolate E194-3 (root endophyte) gave the best result at highest concentration NaCl of 200 mM by increasing the root length, shoot length, fresh weight and dry weight 21%, 39%, 62% and 49% respectively (means from three rice varieties) in comparison to uninoculated control. This study suggested that gnotobiotic assay for evaluating rice seedling growth promotion by bacterial endophyte and rhizoplane under salt condition could be used for the selection of potential bacterial strains subjected to further testing of bacterial isolates to be used in inducing salt tolerance in rice under field conditions.