Proteomic analysis of sugarcane - Colletotrichum falcatum interaction

Abstract

Detailed studies were conducted to understand the changes in the proteome profile of resistant and susceptible sugarcane cultivars in response to pathogen challenge. The samples were collected 24 h after pathogen inoculation from the stalk tissues of two sugarcane cultivars viz., Co 93009 (resistant to red rot) and CoC 671 (susceptible to red rot). The protein samples were subjected to standardized 2-DE protocol. The analysis of the proteome profile revealed the upregulation/ induction of about 106 proteins and down-regulation of about 30 proteins, in response to pathogen inoculation. The differentially regulated protein spots were then characterized by peptide mass finger printing using eLD-IT-TOF-MS/MS analysis. The MS analysis revealed the differential regulation of important proteins involved in PAMPs triggered innate immunity, signal transduction and few resistance gene analogues. Based on the putatively assigned functions, the identified spots were categorized into 8 groups and represented in the pie chart. The major portion of the up-regulated proteins belongs to the signal transduction (21%) and transcription/transcription factors. The proteins related to metabolism (13%) and defense/stress was also found to be the other major categories induced by pathogen challenge. Among the down regulated proteins, major portions belonged to metabolism (17%) and cell growth & development (13%) categories. The present study on the proteome-level changes that occur during C. falcatum- sugarcane interaction using 2-DE is the first attempt to standardize proteome analysis and to identify specific proteins involved in red rot resistance in sugarcane. Among the differentially regulated proteins, quantitative difference in expression was noticed between resistant and susceptible cultivars. In conclusion, tight regulation typical of resistance response against biotropic pathogens was observed in the resistant variety. Whereas, in the susceptible variety the response was more general and placid, a favorable situation for necrotropic phase of the pathogen. This is the first such study, concerning host-pathogen interaction in sugarcane involving 2- DE. The results clearly demonstrated the suitability of proteomics based analysis in deciphering components involved in host pathogen interaction.