Transcripts of wheat at a target locus on chromosome 6B associated with increased yield, leaf mass and chlorophyll index under combined drought and heat stress

• Published in: PloS one Vol. 15; no. 11; p. e0241966
• Main Authors: Schmidt, Jessica, Garcia, Melissa, Brien, Chris, Kalambettu, Priyanka, Garnett, Trevor, Fleury, Delphine, Tricker, Penny J
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 09.11.2020; Public Library of Science (PLoS)
• Subjects: Agricultural production; Amino acids; Biology and Life Sciences; Carbohydrates; Chlorophyll; Chlorophyll - metabolism; Chromosomes; Chromosomes, Plant - genetics; Climate change; Crop yield; Crop yields; Drought; Drought index; Droughts; Ecology and Environmental Sciences; Engineering and Technology; Environmental stress; Food; Gene expression; Gene Expression Profiling - methods; Gene Expression Regulation, Plant; Gene mapping; Gene regulation; Gene sequencing; Genes; Genetic aspects; Genetic research; Genomes; Genotyping; Grain; Gravimetry; Heat; Heat stress; Heat tolerance; Heat-Shock Response; Metabolism; Photosynthesis; Physical Sciences; Physiological aspects; Physiology; Plant hardiness; Plant Leaves - genetics; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant Proteins - genetics; Quantitative Trait Loci; R&D; Rain; Research & development; Ribonucleic acid; RNA; Seeds; Sequence Analysis, RNA; Transcription (Genetics); Triticum - genetics; Triticum - growth & development; Triticum - metabolism; Triticum aestivum; Water use; Wheat; Australia; Europe; South Australia Australia
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0241966

Drought and heat stress constrain wheat (Triticum aestivum L.) yields globally. To identify putative mechanisms and candidate genes associated with combined drought and heat stress tolerance, we developed bread wheat near-isogenic lines (NILs) targeting a quantitative trait locus (QTL) on chromosome 6B which was previously associated with combined drought and heat stress tolerance in a diverse panel of wheats. Genotyping-by-sequencing was used to identify additional regions that segregated in allelic pairs between the recurrent and the introduced exotic parent, genome-wide. NILs were phenotyped in a gravimetric platform with precision irrigation and exposed to either drought or to combined drought and heat stress from three days after anthesis. An increase in grain weight in NILs carrying the exotic allele at 6B locus was associated with thicker, greener leaves, higher photosynthetic capacity and increased water use index after re-watering. RNA sequencing of developing grains at early and later stages of treatment revealed 75 genes that were differentially expressed between NILs across both treatments and timepoints. Differentially expressed genes coincided with the targeted QTL on chromosome 6B and regions of genetic segregation on chromosomes 1B and 7A. Pathway enrichment analysis showed the involvement of these genes in cell and gene regulation, metabolism of amino acids and transport of carbohydrates. The majority of these genes have not been characterized previously under drought or heat stress and they might serve as candidate genes for improved abiotic stress tolerance.