Effects of endophyte bacteria isolated from plants developed in saline environment on angular leaf spot disease (pseudomonas syringae pv. lachrymans), salinity stress and plant growth of cucumber

The aim of this study is the isolation of endophytic bacteria (EB) from wild plants growing in the saline soil at Lake Van region. Also, the determination of EBs' characterization of the by in vitro test, and its effects on the cucumber plant growth under the salt stress and on angular leaf stain disease caused by Pseudomonas syringae pv lachrymans (Psl) have been targeted. In vivo studies were performed in a climatic chamber having 25 ± 2 °C temperature and 16 h light-8 h dark period. EBs were applied to the plant by seed coating and drenching methods. The Psl suspension was applied to the plant leaves by pulverization. The three salt concentrations (40 mM, 80 mM and 120 mM) were applied f to the seedlings by drenching methods. It was determined that 40 % of EBs have phosphatase activity, 96 % siderophore production ability, and none of them had ACC-deaminase activity. Some EB isolates were growth on medium amended with up to 15 % NaCl. EB isolates which were found successful in in vitro tests, increased plant growth at different levels according to the parameters examined. The G116S2 isolate inhibited disease severity by 39 %. T14K1 and T13K1 isolates decreased the salt stress by 23 % at 120 mM, and by 41 % - 9 % at 40 mM, respectively. The T26Y1 isolate increased the root weight, root length, stem diameter, leaf number according to control groups at 80 mM salt concentration. Also, T13K1, T14K1 and G116S2 isolates at 80 mM salt concentration increased the leaf relative water content. However, EB isolates have not effected on reducing membrane injury. Keywords: Cucumber, Endophyte bacteria, Plant growth, Psl, Salt stress