Bio-suppression of turmeric rhizome rot disease and understanding the molecular basis of tripartite interaction among Curcuma longa, Pythium aphanidermatum and Pseudomonas fluorescens

Abstract

Turmeric rhizome rot is a devastating disease posting the major threat to turmeric cultivation. Plant growth-promoting rhizobacteria (PGPR) Pseudomonas fluorescens strain FP7 was found to exhibit disease reduction and plant growth promotional activity in various crop plants in our previous studies. In this study, efforts were made to evaluate the efficacy of P. fluorescens (FP7) bioformulations against rhizome rot disease in turmeric plants. Among the FP7 bioformulations tested, a combination of rhizome dip and soil drench of FP7 liquid formulation recorded the minimum disease incidence under glasshouse (19.00%) and field conditions (10.18% and 13.29% in the trial I and trial II respectively). Furthermore, the 2D-PAGE analysis was performed to elucidate the molecular responses of tripartite interaction between host-pathogen-bioagent through protein profiling. A total of 12 differentially expressed proteins were identified and mass spectrometry (MS) analysis revealed that proteins such as tryptophan synthase beta subunit-like, phosphoglycerate kinase, cellulose synthase 6 isoform, ATP synthase subunit beta, cysteine-rich peptide, ribosomal protein S3, clathrin assembly protein and disease resistance protein RPP13-like were found to be differentially regulated. The differentially expressed proteins during tripartite interaction might be directly or indirectly involved in disease resistance in turmeric plants. This study provides an initial insight into the molecular mechanism of tripartite interaction between host-pathogen-bioagent in turmeric plants.