Browsing by Author "Balyan, Sonia C."

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Insights into the small RNA-mediated networks in response to abiotic stress in plants
(Springer, 2015) Balyan, Sonia C.; Mutum, Roseeta D.; Kansal, Shivani; Kumar, Santosh; Mathur, Saloni; Raghuvanshi, Saurabh
Under natural conditions, plants are constantly exposed to various environmental stresses such as drought, extreme temperature, salt, UV, mechanical, or nutrient starvation. To cope with these adverse conditions, plants have evolved cascade of molecular networks to perceive and transduce the stress signals, resulting into the reprogramming of gene expression. The stress-regulated reprogramming of gene expression at post-transcriptional regulation has been emphasized with the discovery of small regulatory RNAs. Plant small RNAs represent non-coding RNAs in the size range of 20–24 nucleotides and categorized into hairpin RNAs (hpRNAs) and siRNAs. The first category includes miRNAs, lmiRNAs, and nat-miRNAs while the siRNA group includes hc-siRNA, secondary siRNAs and nat-siRNAs. Studies have shown that small RNAs, especially miRNAs, are dynamically regulated by a variety of abiotic stress conditions. Such sRNAs target a variety of downstream targets including regulatory proteins as well as metabolic enzymes and thus play pivotal role in the regulation of plant abiotic stress response. Stress appears to regulate miRNA biogenesis as well as its activity. Several miRNA gene:target pairs respond to multiple stress conditions and are conserved in various plant species indicating that miRNAs may define pivotal regulatory nodes involved in the regulation of the plant stress response. On the other hand, miRNAs also show variety-/cultivar-specific stress response indicating that they themselves are under a very dynamic regulation. The world of small RNAs is gradually unfolding and much remains to be explored, nevertheless, it has been conclusively demonstrated that small RNAs define a new dimension in the molecular regulatory network regulating the plant stress response.
Unique miRNome during anthesis in drought-tolerant indica rice var. Nagina 22
(Springer, 2015) Kansal, Shivani; Devi, Roseeta M.; Balyan, Sonia C.; Arora, Mukesh K.; Singh, Anil K.; Mathur, Saloni; Raghuvanshi, Saurabh
MAIN CONCLUSION: Drought-tolerant rice variety, Nagina 22 (N22), has a unique spikelet miRNome during anthesis stage drought as well as transition from heading to anthesis. Molecular characterization of genetic diversity of rice is essential to understand the evolution and molecular basis of various agronomically important traits such as drought tolerance. miRNAs play an important role in regulating plant development as well as stress response such as drought. In this study, we characterized the yet unexplored dynamics of the spikelet miRNA population during developmental transition from 'heading' to 'anthesis' as well as anthesis stage drought stress in a drought-tolerant indica rice variety, N22. A significant proportion of miRNA population (~20 %) in N22 spikelets is modulated during transition from heading to anthesis indicating a unique miRNome at anthesis, a developmental stage highly sensitive to stress (drought/heat). Based on the analysis of degradome data, majority of differentially regulated miRNAs appear to regulate transcription factors, some of which are implicated in regulation of development and fertilization. Similarly, drought during anthesis leads to a global change in miRNA expression pattern including those which regulate ROS homeostasis. It was possible to identify several miRNAs that were not reported to be drought responsive in earlier studies. Interestingly, a significant proportion of the drought-regulated miRNAs co-localize within QTLs related to drought tolerance and associated traits. Comparison of the expression profiles between N22 and Pusa Basmati 1 (drought sensitive) identified miRNAs with variety-specific expression patterns during phase transition (miR164, miR396, miR812, and miR1881) as well as drought stress (miR1881) indicating an evolution of a distinct and variety-specific regulatory mechanism. The promoters of these miRNAs contain LREs (light-responsive elements) and are induced by dark treatment. It was also possible to identify 4 novel miRNAs including an intronic miRNA that was conserved in both rice varieties.