RNA-Seq Analysis of Developing Grains of Wheat to Intrigue into the Complex Molecular Mechanism of the Heat Stress Response
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Date
2022-06
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Abstract
Heat stress is one of the significant constraints affecting wheat production worldwide. To
ensure food security for ever-increasing world population, improving wheat for heat stress
tolerance is needed in the presently drifting climatic conditions. At the molecular level,
heat stress tolerance in wheat is governed by a complex interplay of various heat stress
associated genes. We used a comparative transcriptome sequencing approach to study
the effect of heat stress (5°C above ambient threshold temperature of 20°C) during grain
f
illing stages in wheat genotype K7903 (Halna). At 7 DPA (days post-anthesis), heat stress
treatment was given at four stages: 0, 24, 48, and 120 h. In total, 115,656 wheat genes
were identified, including 309 differentially expressed genes (DEGs) involved in many
critical processes, such as signal transduction, starch synthetic pathway, antioxidant
pathway, and heat stress-responsive conserved and uncharacterized putative genes that
play an essential role in maintaining the grain filling rate at the high temperature. A total
of 98,412 Simple Sequences Repeats (SSR) were identified from de novo transcriptome
assembly of wheat and validated. The miRNA target prediction from differential expressed
genes was performed by psRNATarget server against 119 mature miRNA. Further, 107,107
variants including 80,936 Single nucleotide polymorphism (SNPs) and 26,171 insertion/
deletion (Indels) were also identified in de novo transcriptome assembly of wheat and
wheat genome Ensembl version 31. The present study enriches our understanding of
known heat response mechanisms during the grain filling stage supported by discovery
of novel transcripts, microsatellite markers, putative miRNA targets, and genetic variant.
This enhances gene functions and regulators, paving the way for improved heat tolerance
in wheat varieties, making them more suitable for production in the current climate
change scenario.