Fig. 2: QTL mapping of high-temperature stress resilience in Brachypodium distachyon.

a B. distachyon accessions Bd21 and Bd21-3 grown under normal (NC) or high-temperature (HC) conditions with non-chelated iron [Fe₂(SO₄)₃]. Two-leaf-stage seedlings grown in artificial phenolic resin block containing 2.5 mg Fe L⁻¹ of non-chelated iron for 3 weeks. Scale bars, 5 cm. Relative plant height (b) and fresh weight (c) of seedlings in (a). HC values are normalized to those of NC (HC/NC). n = 6, biological replicates. d Simple ratio pigment index (SRPI) and photochemical reflectance index (PRI) from the first fully expanded leaves grown under NC or HC for 4 weeks. n = 5, biological replicates. e Relative expression of the iron deficiency–marker gene BdIRO2.1 in the first fully expanded leaves grown under NC or HC for 4 weeks. n = 3, biological replicates. f Leaf Fe content of seedlings grown under NC or HC for 4 weeks. n = 4, biological replicates. g Genotypes of recombinant inbred lines (RILs) between SNPs Bd4accM253 and Bd4accM302 in Bd21 genome. Single nucleotide polymorphism (SNP) positions are shown at the top with recombinant numbers. Orange: Bd21 fragment; blue: Bd21-3 fragment. h Aboveground fresh weights of RILs from a Bd21-3 × Bd21 cross after 25 days of prolonged high-temperature treatment. n = 4, biological replicates. i The 32.1-kb candidate region between SNP markers (Bd4accM281 and Bd4accM291). j Secretion and root levels of 2′-deoxymugineic acid (DMA) in B. distachyon Bd21 and Bd21-3 seedlings grown hydroponically with non-chelated iron under HC for 2 weeks n = 3, technical replicates. Data are means ± SEM. *P < 0.05 and **P < 0.001 (two-tailed Student’s t tests: between Bd21 and Bd21-3 in (b–d, g, j); between NC and HC in (e); between Bd21 and RILs in (h). Exact P values for significant differences are given in the graphs. Source data are provided as a Source Data file.