NBU Journal of Plant Sciences, Vol. 07, No. 01

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Author: search.filters.author.Saha, D.

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    Isolation and identification of a virulent Ralstonia solanacearum by fliC gene amplification and induction of chitinase by 2-amino butyric acid for control of bacterial wilt in tomato plants
    (University of North Bengal, 2013-03) Saha, A.; Mandal, H.; Saha, D.
    Ralstonia solanacearum is a devastating, soil borne bacterial pathogen of tomato. The pathogen is nonmotile in planta but highly motile in culture. On the basis of physiological and biochemical characteristics 26 isolates have been purified and identified as Ralstonia solanacearum. The flic gene is responsible for the movement of bacteria. Ralstonia specific fliC gene amplification is the indication of virulence of the pathogen. In the present study one R. solanacearum isolate has been identified by PCR amplification of the fliC gene using fliC gene specific primer. Following isolation and identification of the virulent isolate, fresh tomato plants were induced by application of 2- amino butyric acid (ABA). The defense enzyme, chitinase was estimated in treated plants. Treated inoculated plants did not show any visible symptoms of wilt even after 14 days of inoculation. Significantly it was observed that chitinase was increased in the 2-ABA-treated plants and also in the treated-inoculated plants. The increased chitinase activity in the treated plants showed that 2-ABA has the resistance inducing capacity in tomato plants against Ralstonia solanacearum.
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    Begomovirus causing leaf curl disease in tomato (Lycopersicon esculentum L.) in sub-Himalayan West Bengal, India
    (University of North Bengal, 2013-03) Saha, B.; Saha, D.; Saha, A.
    Tomato (Lycopersicon esculentum L.) is an extensively cultivated vegetable crop in India. In the year 2009, a survey was conducted to find leaf curls of tomato in different locations of sub-Himalayan West Bengal, India. During the survey a severe leaf curl disease was observed. The characteristic disease symptoms (puckered leaves) and presence of whitefly (Bemisia tabaci) population indicated the possibility of begomovirus infection. Total DNA was extracted from the infected samples and PCR was carried out using begomovirus specific primers. An amplicon of expected size ( ̴1280 bp) was found when PALIc1960 and PARIv722 were used as primers in agarose gel electrophoresis. The PCR Amplicons of two samples (collected from two different places of present study area) were cloned and sequenced (GenBank accession nos. HM856626 and HM856627). The sequence data analysis of partial coat protein gene (AV1), full replication enhancer protein gene (AC3) and partial transcription activator protein gene (AC2) of 831 nt revealed highest 98% similarities with several isolates of Tobacco curly shoot virus (TBCSV) at both nucleotide and amino acid levels. The phylogenetic analysis also showed close relationship of the present isolates with different variants of TbCSV. Based on highest sequence similarities and closest relationships with TbCSV the viruses (present in infected tomato plants) were considered as Begomovirus. Transmission of the virus in tomato could not be done by sap transmission procedure. In experimental insect transmission tests, test plants showed symptoms very much like the natural symptoms. Artificial transmission was confirmed by comparing the PCR Amplicons raised from the experimentally infected plants.