Temporal transcriptome profiling reveals expression partitioning of homeologous genes contributing to heat and drought acclimation in wheat (Triticum aestivum L.)

Abstract

BackgroundHexaploid wheat (Triticum aestivum) is a globally important crop. Heat, drought and their combination dramatically reduce wheat yield and quality, but the molecular mechanisms underlying wheat tolerance to extreme environments, especially stress combination, are largely unknown. As an allohexaploid, wheat consists of three closely related subgenomes (A, B, and D), and was reported to show improved tolerance to stress conditions compared to tetraploid. But so far very little is known about how wheat coordinates the expression of homeologous genes to cope with various environmental constraints on the whole-genome level.ResultsTo explore the transcriptional response of wheat to the individual and combined stress, we performed high-throughput transcriptome sequencing of seedlings under normal condition and subjected to drought stress (DS), heat stress (HS) and their combination (HD) for 1 h and 6 h, and presented global gene expression reprograms in response to these three stresses. Gene Ontology (GO) enrichment analysis of DS, HS and HD responsive genes revealed an overlap and complexity of functional pathways between each other. Moreover, 4,375 wheat transcription factors were identified on a whole-genome scale based on the released scaffold information by IWGSC, and 1,328 were responsive to stress treatments. Then, the regulatory network analysis of HSFs and DREBs implicated they were both involved in the regulation of DS, HS and HD response and indicated a cross-talk between heat and drought stress. Finally, approximately 68.4 % of homeologous genes were found to exhibit expression partitioning in response to DS, HS or HD, which was further confirmed by using quantitative RT-PCR and Nullisomic-Tetrasomic lines.ConclusionsA large proportion of wheat homeologs exhibited expression partitioning under normal and abiotic stresses, which possibly contributes to the wide adaptability and distribution of hexaploid wheat in response to various environmental constraints.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0511-8) contains supplementary material, which is available to authorized users.

Genomic Imprinting Was Evolutionarily Conserved during Wheat Polyploidization

“…It is thought that homoeologs make unequal contributions to total gene expression levels in polyploid wheat and that gene expression is regulated in a complex manner during grain development, possibly due to crosstalk between genomes during polyploidization (Akhunova et al, 2010;Chagué et al, 2010;Leach et al, 2014;Liu et al, 2015;Han et al, 2016). In this study, a major proportion of homoeologous gene pairs (65.8%) indeed exhibited divergent expression patterns in terms of genomic imprinting in polyploid wheat.…”

Wheat Oxygen Evolving Enhancer Protein: Identification and Characterization of Mn-Binding Metalloprotein of Photosynthetic Pathway Involved in Regulating Photosytem II Integrity and Network of Antioxidant Enzymes under Heat Stress

“…HD2329 showed 1.93-fold increase in the expression under HS of 30ºC for 1h.HD2985 during grain-filling showed expression of 2-fold in response to HS of 38ºC for 1 h. Similarly, HD2329 showed 1.75-fold increase in the expression in response to HS of 38ºC for 1 h. Pawlowicz et al, (2012) observed that increase in the accumulation of PsbO gene in Tall fescue (Festuca arundinacea) in response to drought stress. A significant, positive, and linear correlation has been reported by Liu et al, (2015) in which they have showed the increase in digital fold expression of PsbO gene under heat and drought stress in wheat. Choulet et al, (2014) also reported the increased digital expression of PsbO gene in different tissues of wheat.…”

Hormone signaling pathways under stress combinations

“…In addition, expression of transcript homologous to Arabidopsis Rap2.6L was significantly up-regulated in wheat in response to drought or heat stress applied individually, but not to the drought and heat stress combination. 31 Overexpression of Rap2.6L in Arabidopsis was shown to enhance tolerance to abiotic stresses via activating hormone signaling pathways involving ABA, JA, SA and ethylene. 32,33 These results suggest that, to some extent, regulatory mechanisms of hormone signaling pathways underlying tailored responses of plants to drought, heat and their combination might be different depending on plant species.…”