Partial purification and characterization of 2, 4-diacetylphloroglucinol producing Pseudomonas fluorescens VSMKU3054 against bacterial wilt disease of tomato

We find out the antimicrobial potential of partially purified 2,4-diacetylphloroglucinol (DAPG) against Ralstonia solanacearum and fungal plant pathogens isolated from tomato rhizobacterium Pseudomonas fluorescens VSMKU3054. The present study is mainly focused on the control of wilt disease of tomato by our isolate VSMKU3054 and DAPG. The cell free culture filtrate of P. fluorescens VSMKU3054 was significantly arrested the growth of R. solanacearum and fungal pathogens such as Rhizoctonia solani, Sclerotium rolfsii, Macrophomina phaseolina and Fusarium oxysporum compared to control. The existence of DAPG from the crude metabolites of P. fluorescens VSMKU3054 was confirmed on TLC with Rf value 0.34, which is coincide with that of authentic phloroglucinol. The partially purified DAPG exhibited much higher activity against R. solanacearum at 30 µg/ml than the fungal plant pathogens compared to control. The antimicrobial partially purified compound was identified as DAPG by UV, FT-IR and GC–MS analysis. The percentage of live cells of R. solanacearum when supplemented with DAPG at 30 µg/ml, significantly controlled the living nature of R. solanacearum up to 68% compared to tetracycline and universal control observed under high content screening analysis. The selected isolate P. fluorescens VSMKU3054 and DAPG significantly controlled wilt disease of tomato up to 59.5% and 42.12% on 3rd and 7th days compared to positive and negative control by detached leaf assay. Further, in silico analysis revealed that high interaction of DAPG encoding protease with lectin which is associated with R. solanacearum. Based on our findings, we confirmed that P. fluorescens VSMKU3054 and DAPG could be used a potential bio inoculants for the management of bacterial wilt disease of tomato.     

Marker-aided selection and validation of various $${ }$$ gene combinations for rice blast resistance in elite rice variety ADT 43

Rice blast caused by fungal pathogen Pyricularia oryzae has a major impact on reducing yield potential of rice. In this study, homozygous plants were selected using microsatellite markers from the \(\hbox {BC}_{3}\hbox {F}_{2}\) population pyramided with four major genes in elite rice variety ADT 43. Background and selected lines with various blast resistance gene combinations were screened under natural conditions to study the effects of various gene combinations. Upon inspection of lines with different gene combinations, the three-gene pyramided line Pi54+Pi33+Pi1 was found to be highly resistant with the score of 3.3 followed by other three-gene pyramided lines Pi54+Pi2+Pi1 and Pi33+Pi2+Pi1, with the scores of 3.9 and 3.8, respectively. Two-gene pyramided lines Pi54+Pi1, Pi33+Pi1 and Pi2+Pi1 were found to be moderately resistant with a mean score of 4.0 each. In the case of monogenic lines, positive plants for Pi54 performed almost equal to three-gene pyramided lines with a mean score of 3.6. Lines with Pi2 and Pi1 were found to be moderately resistant and moderately susceptible with the mean scores of 4.1 and 4.5, respectively.