Effect of endophytic bacteria application on disease caused by Xanthomonas euvesicatoria and plant physiology in pepper

Pepper (Capsicum annuum), an important economic crop in the world and in our country, suffers significant losses due to bacterial spot disease caused by Xanthomonas euvesicatoria (Xe). The aim of this study is to determine the effect and mechanisms of the biocontrol agent the Endophyte Bacteria Pseudomonas sp. G101Y4 (EB) isolate used against bacterial spot disease caused by Xe. For this purpose, the effects of the EB on the disease severity, plant biomass (root-shoot fresh dry weight), leaf number, chlorophyll content and the number of leaves formed and leaf fallen were investigated with climate chamber studies. In addition, the effects of plant age on disease development and plant hormones; Ethylene (ET), Gibberellic Acid (GA), Indole Acetic Acid (IAA), Zeatin (ZT) and Abscisic Acid (ABA) were investigated. EB application reduced disease development by 17%. It was determined that age is an important factor in disease formation and that older seedlings are more affected. EB limited disease development in both age groups, albeit at different levels. However, EB application to diseased plants at an early age made a more positive contribution than to plants at a later age. While EB application had no effect on leaf formation, it reduced the number of leaves fallen due to Xe. While Xe application increased the amount of external ET, EB application reduced it. While no significant change was observed in ZT during the disease development process, significant changes were observed in GA, IAA and ABA. However, tise effect of EB varied according to hormones