Expression analysis of pathogenesis-related (PR) genes in Brassica rapa upon Alternaria brassicicola infection

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dc.contributor.advisorBhorali, Priyadarshini
dc.contributor.authorR, Aryasree
dc.date.accessioned2024-06-25T14:39:32Z
dc.date.available2024-06-25T14:39:32Z
dc.date.issued2023
dc.description.abstractAlternaria blight caused by Alternaria brassicicola is the most widespread fungal disease of oilseed Brassicas. Conventional breeding to develop Alternaria resistant cultivars has not been successful due to non-availability of suitable resistance sources. For the development of resistant cultivars, identification of important defense or resistance-related genes is needed. Plants activate different biological pathways upon infection by pathogens and a large number of defense-related genes are modulated during such interactions locally as well as systemically. In a previous study, RNAseq of a wild relative of Brassica, Sinapis alba, was carried out in which several defense related genes were found to be highly upregulated during Alternaria infection. Based on the results of this study, the present research was undertaken to investigate and validate the gene expression patterns of selected gene candidates in the susceptible cultivar B. rapa var. Toria (TS-38) in order to check the function of these genes in conferring resistance. To initiate the study, infected tissues of a highly susceptible Toria variety TS-38, showing characteristic symptoms of Alternaria blight were collected for isolation and purification of the pathogen. On the basis of conidial morphology as observed through microscopic studies, the pathogen was identified to be Alternaria brassicicola. Molecular detection of the fungus was carried out by amplification using ITS primers followed by sequencing. Pathogenicity test was done through detached leaf assay and seedling inoculation test and confirmation was done by testing the Koch postulates. After pathogen inoculation, ROS generation and proline accumulation were detected during the biotic stress. Staining with trypan blue helped to visualise necrosis in response to A. brassicicola infection in the leaf tissues. Finally, total RNA was isolated from the B. rapa inoculated (and control) leaf tissues followed by cDNA preparation for real time qRT-PCR analysis of gene expression. Primers available from the previous study, which were designed using S. alba sequences of some important gene candidates, including PR and resistance-related genes were used for the expression analysis. The results depict that all the PR genes were upregulated at lower levels at 24 hpi. Later, although the expression increased towards 48 hpi, it gradually decreased. The resistance related genes also showed upregulation with peak expression at 48 hpi, but later downregulated. Interestingly, one disease resistance (DR) gene showed downregulation across all the time points in the susceptible cultivar and and could be an important gene responsible for resistance. Thus, all the genes are clearly implicated to have a role in active defense responses. As a future prospect, complete functional characterization of such genes could be done as they would serve as important potential candidates for developing disease resistant varieties of Brassica.
dc.identifier.urihttps://krishikosh.egranth.ac.in/handle/1/5810210867
dc.language.isoEnglish
dc.subAgricultural Biotechnology
dc.themeExpression analysis of pathogenesis-related (PR) genes in Brassica rapa upon Alternaria brassicicola infection
dc.these.typeM.Sc
dc.titleExpression analysis of pathogenesis-related (PR) genes in Brassica rapa upon Alternaria brassicicola infection
dc.typeThesis
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