Krishnaraj, P.U.Gadag, Anusha Suresh2022-06-302022-06-302017-04https://krishikosh.egranth.ac.in/handle/1/5810184976Fusarium oxysporum f.sp. lycopersici (FOL) is a soil borne plant pathogen causing Fusarium wilt an important and destructive fungal plant diseases worldwide. The pathogenic strain of FOL was isolated from the infested plant samples and the identification of the isolate were done by cultural characteristics, pathogenicity test and PCR amplification by using specific primers and sequencing of ITS region in the 18S rDNA gene. Initially, 80 isolates of the actinobacteria were screened against FOL. Out of these, six isolates showed significant inhibition. Further, three of these were selected for the in vivo evaluation under greenhouse conditions. Arbuscular mycorrhiza (AM) culture was collected from the Department of Agricultural Microbiology, UAS, Dharwad. Under challenge inoculation with FOL, the actinobacterial isolate AUDT 626 alone and in combination with AM culture showed significant control of the wilt disease compared to others. Growth parameters such as shoot length, root length and total dry weight were observed to be far superior in this treatment. Finally, the transcriptional analysis of the tomato plants was carried out using suppression subtractive hybridization (SSH). SSH products were sequenced on Ion torrent NGS platform and data was processed and function was annotated to identify differentially expressed transcripts. The dominant transcripts which were expressed were pathogenesis related genes expressed during the interaction in the leaves in responce to inoculation of AUDT 626 alone and in with AM fungi in the presence of the pathogen. Results revealed 61 and 240 well-annotated genes expressed due to inoculation of AUDT 626 alone and with AM treated respectively. Upregulated transcripts correspond to the general stress, pathogen and abiotic stress and other function. Few expressed transcripts were of unknown function. Actinobacterial strain, AUDT 626 and AM fungus controlled the wilt disease in tomato probably by mediating induced systematic resistance and contributed to plant growth and development.EnglishThesis