Grain Transcriptome Dynamics Induced by Heat in Commercial and Traditional Bread Wheat Genotypes

Abstract

High temperature (HT) events have negative impact on wheat grains yield and quality. Transcriptome profiles of wheat developing grains of commercial genotypes (Antequera and Bancal) and landraces (Ardito and Magueija) submitted to heatwave-like treatments during grain filling were evaluated. Landraces showed significantly more differentially expressed genes (DEGs) and presented more similar responses than commercial genotypes. DEGs were more associated with transcription and RNA and protein synthesis in Antequera and with metabolism alterations in Bancal and landraces. Landraces upregulated genes encoding proteins already described as HT responsive, like heat shock proteins and cupins. Apart from the genes encoding HSP, two other genes were upregulated in all genotypes, one encoding for Adenylate kinase, essential for the cellular homeostasis, and the other for ferritin, recently related with increased tolerance to several abiotic stress in Arabidopsis. Moreover, a NAC transcription factor involved in plant development, known to be a negative regulator of starch synthesis and grain yield, was found to be upregulated in both commercial varieties and downregulated in Magueija landrace. The detected diversity of molecular processes involved in heat response of commercial and traditional genotypes contribute to understand the importance of genetic diversity and relevant pathways to cope with these extreme events.

Keywords: RNA sequencing; bread wheat; commercial varieties; grain transcriptome; heatwave; landraces.

FIGURE 1

Reads assignments by gene type and relationship between samples. (A) Read assignments and relative abundance of reads per type of gene. (B) Hierarchical clustering of sample-to-sample correlations based on Pearson correlations (right). (C) Multi-dimensional scaling (MDS) plot showing similarity between all samples. The comparisons were made between control (C) and high temperature (HT) reads sets of commercial varieties Antequera and Bancal and landraces Ardito and Magueija.

FIGURE 2

Differentially expressed genes (DEGs). (A) Number of DEGs between control and high temperature treated samples of commercial varieties Antequera and Bancal and landraces Ardito and Magueija. Red and blue indicate down and upregulated genes, respectively. (B–E) Venn diagrams of differentially expressed genes in commercial varieties Antequera and Bancal and landraces Ardito and Magueija: (B) upregulated in all genotypes; (C) downregulated in all genotypes; (D) downregulated in commercial varieties and upregulated in landraces; (E) upregulated in commercial varieties and downregulated in landraces. Non-overlapping regions represent the number of genes exclusive to one genotype. Overlapping regions indicate the number of genes common to two, three or four genotypes.

FIGURE 3

Gene ontology percentage of up and downregulated genes in commercial varieties Antequera and Bancal and landraces Ardito and Magueija assigned to second and third levels of biological processes, molecular functions and cellular component gene ontologies. Red and blue indicate down and upregulated genes, respectively.

FIGURE 4

KEGG pathways enrichment percentage of up and downregulated genes in commercial varieties Antequera and Bancal and landraces Ardito and Magueija associated with metabolic, environmental and genetic information processing pathways. Red and blue indicate down and upregulated genes, respectively.

FIGURE 5

Differentially expressed genes involved in nutrient reservoir activity ontology in commercial varieties Antequera and Bancal and landraces Ardito and Magueija. Red and blue indicate down and upregulated genes, respectively, and color intensity are related with the degree of gene expression alteration; gray represents unaltered genes.

FIGURE 6

Integrative analysis of grain yield, composition and transcriptomic analysis of the commercial varieties and the old landrace responses to heatwave at the grain-filling stage.