Effects of Combined Application of Salicylic Acid and Proline on the Defense Response of Potato Tubers to Newly Emerging Soft Rot Bacteria (Lelliottia amnigena) Infection

Potato soft rot, caused by the pathogenic bacterium Lelliottia amnigena (Enterobacter amnigenus), is a serious and widespread disease affecting global potato production. Both salicylic acid (SA) proline (Pro) play important roles in enhancing tuber resistance to rot. However, combined effects of SA Pro on defense responses tubers L. infection remain unknown. Hence, controlling newly emerging rot bacteria were investigated. Sterilized healthy pretreated with 1.5 mM 2.0 24 h before an inoculation 0.3 mL suspension (3.69 × 107 CFU mL?1). Rotting was noticed surfaces hole where inoculated. Application lowered activity pectinase, protease, pectin lyase, cellulase 64.3, 77.8, 66.4 84.1%, decreased malondialdehyde hydrogen peroxide contents 77.2% 83.8%, respectively, compared control. The activities NADPH oxidase, superoxide dismutase, peroxide, catalase, polyphenol phenylalanine ammonia-lyase, cinnamyl alcohol dehydrogenase, 4-coumaryl-CoA ligase cinnamate-4-hydroxylase increased treatments 91.4, 92.4, 91.8, 93.5, 94.9, 91.3, 96.2, 94.7 97.7%, untreated stressed tubers. Six defense-related genes, pathogenesis-related protein, tyrosine-protein kinase, Chitinase-like homeodomain serine protease inhibitor, induced + treatment when individual application or Pro. This study indicates that had synergistic effect bacterium.