Pectobacterium carotovorum subsp. carotovorum (Pcc) is a gram-negative enteric bacterium; which can degrade the cell walls of plants to macerate plant tissue by producing certain enzymes, leading towards soft-rot symptoms1. A transposon mutagenesis research on Pcc reported 14 genes concerning with pathogenicity 2. Moreover; this bacterium also activate defense responses and cell death in the model plant Arabidopsis thaliana3. Plant exhibited defense mechanism against pathogen attack through small RNA silencing mechanism4.
In 2004; Sunkar and Zhu assessed the expression profiles of stress-responsive microRNAs (miRNAs) and their target genes following the inoculation of A. thaliana with Pcc. The miRNAs are a class of functional, small non-coding RNAs having 18 to 25 nucleotides that regulate gene expression either through post-transcriptional degradation or translational repression of their target mRNAs5. They are involved in the regulation of plant growth and development, maintenance of genome integrity, signal transduction, hormone signalling pathways, hormone homeostasis, immune system and reaction towards abiotic and biotic stresses4. By controlling stress-associated miRNAs and their target genes’ expression levels in plants is upcoming efficient technique to improve the defense mechanism of plants.
Accordingly; A.T. Djami-Tchatchou and K. Ntushelo conducted an experiment to assess, the expression of few stress responsive miRNAs against Pcc infection and their target genes in A. thaliana. In this experiment; leaves of five weeks old Arabidopsis thaliana plants were infected with Pcc and the quantitative real time-PCR, was used to determine the post infection after 0, 24, 48 and 72 hours. Moreover; the expression profiling of the stress-responsive miRNAs was done including: miR156, miR159, miR169, miR393, miR396 miR398, miR399 and miR408 along with their target genes which include: Squamosa promoter-binding-like protein, myb domain protein 101, nuclear factor Y subunit A8, concanavalin A-like lectin protein kinase, growth regulating factor 4, copper superoxide dismutase, ubiquitin-protein ligase and plantacyanin respectively.
Scientists noted the overexpression of 6 miRNAs at 24, 48 and 72 hours after infection; exhibiting suppression of their target genes. Conversely, No influence was observed by the expression of 2 miRNAs. These findings are the beginning to recognize the role of the miRNA regulation regarding shielding in response to bacterium Pcc attack. According to Djami and Ntushelo, this study will definitely pave a way for further knowledge to explore global viewpoint of the expression profiles of more miRNAs with their regulated target genes triggered against Pcc infection.
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17 November, 2019