Characterization of the Sinapis alba Alternaria brassicicola interaction and identification of associated defense response genes

Abstract

Alternaria blight caused by Alternaria brassicicola is one of the most newlinedevastating and widespread fungal diseases of the oilseed mustards. It causes yield newlinelosses up to 47% and has been reported from various parts of the country including the newlinestate of Assam. The non-host Sinapis alba, wild relatives of Brassicaceae, has been newlinereported to have resistance against Alternaria blight disease. In order to understand this newlinenon-host mechanism, isolation and identification of pathogen, morphopathological, newlinescreening for resistance both in vitro and in vivo, histopathological study by using newlineScanning Electron Microscopy (SEM) and global gene expression using next generation newlinesequencing method(NGS), RNA-seq, has been done to develop resistance variety of newlinerapeseed mustard against Alternaria blight. For this, infected leaves, siliques and stems newlineof the Toria variety TS-38, showing the initial conspicuous characteristic symptoms of newlineAlternaria blight, were collected for isolation of the pathogen. The infected plant parts newlinewere surface sterilized and inoculated in petriplates containing Potato Dextrose Agar newline(PDA) medium under optimal conditions for fungal growth and sporulation. The newlinemycelial growth of the fungus was observed after 3days of inoculation and the hyphal newlinegrowth covered the petriplates within 15days of inoculation. On the basis of the conidial newlinemorphology as observed through microscopic studies, the pathogen was identified as newlineAlternaria brassicicola. Purification of the fungal pathogen was done by single spore newlineisolation method. Further, molecular detection of the fungus was successfully carried newlineout by amplification of the fungal genomic DNA using reported ITS primers newline(ITS1/ITS2 and ITS2/ITS4). Sequencing of the fungal ITS region also confirmed the newlinepathogen at the genus level. Further confirmation upto species level has been done with newlineA. brassicicola specific primers (ABS28). The primary screening test both in vitro newlinedetached leaf assay showed the development of infection by showing cholorotic region newlineafter 72hpi with no chlo...