Study : MicroRNA-guided regulation of heat stress response in wheat


MicroRNA-guided regulation of heat stress response in wheat
Sequencing of 24 small RNA libraries produced 55.2M reads while 404M reads were obtained from the corresponding 24 PARE libraries. From these, 202 miRNAs were ascertained, of which mature miRNA evidence was obtained for 104 and 36 were found to be differentially expressed after heat stress. The PARE analysis identified 589 transcripts targeted by 84 of the ascertained miRNAs. PARE sequencing validated the targets of the conserved members of miRNA156, miR166 and miR393 families as squamosa promoter-binding-like, homeobox leucine-zipper and transport inhibitor responsive proteins, respectively. Heat stress responsive miRNA targeted superoxide dismutases and an array of homeobox leucine-zipper proteins, F-box proteins and protein kinases. Query of miRNA targets to interactome databases revealed a predominant association of stress responses such as signalling, antioxidant activity and ubiquitination to superoxide dismutases, F-box proteins, pentatricopeptide repeat-containing proteins and mitochondrial transcription termination factor-like proteins. Overall design: A total of 144 Triticum aestivum cv Chinese Spring wheat plants were grown in a PG-40 growth cabinet under long-day conditions of 16 hours of light (300 μmol m−2 s−1) at 18°C and 8 hours of darkness at 16°C. At the boot stage, a set of 72 plants were exposed to a 37°C heat stress for 5 days while the other 72 plants remained under the control conditions mentioned above. The heat stressed plants were amply watered twice per day during the 5-day stress period to avoid a confounding effect with drought stress. Leaf tissue was collected from all heat-stressed and control individual plants immediately at the end of the stress period, i.e., time point zero day after treatment (0 DAT), and at one and four days after treatment (1 and 4 DAT). Equimolar amounts of RNA from the 18 samples representing a replicate, treatment and time point were pooled to create the 24 total RNA samples representing the four biological replicates, two treatments and three time points. These 24 total RNA samples were used to construct sRNA libraries.


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