Among the rich repertoire of strategies that allow plants to adapt to high-temperature stress is heat-stress memory. The mechanisms underlying the establishment and maintenance of heat-stress memory are poorly understood, although the chromatin opening state appears to be an important structural basis for maintaining heat-stress memory. The chromatin opening state is influenced by epigenetic modifications, making DNA and histone modifications important entry points for understanding heat-shock memory. Current research suggests that traditional heat-stress signaling pathway components might be involved in chromatin opening, thereby promoting the establishment of heat-stress memory in plants. In this review, we discuss the relationship between chromatin structure-based maintenance and the establishment of heat-stress memory. We also discuss the association between traditional heat-stress signals and epigenetic modifications. Finally, we discuss potential research ideas for exploring plant adaptation to high-temperature stress in the future.

Heat stress negatively affects wheat production in many regions of the world. At present, sensitivity to heat stress remains one of the least understood aspects of wheat genetics and breeding, and measures for preventing heat stress are understudied. In this study, we used three cultivars of winter wheat (GY2018, SL02-1 and SY20) to evaluate the effect of heat stress at different days after anthesis (DAA) on yield and quality. Heat stability of the cultivars were analyzed and evaluated for the effects of two kinds of regulators on wheat under heat stress conditions. Heat treatment at 7 DAA led to the most substantial reduction in yield while GY2018 had the best heat stability with respect to yield, and demonstrated the most positive effects on several quality traits including protein content, sedimentation volume and glutenin and gliadin contents. Heat treatment at 14 DAA had the least reduction in yield, while SY20 had the best heat stability with respect to yield and heat treatment had minimal effects on quality. Heat treatment at 21 DAA had only a limited effect on yield, while SL02-1 had the best heat stability with respect to yield, but it showed the most negative effects on quality. Stable time at 14 DAA and protein content at 21 DAA can be used as indicators for detecting the stability of quality under heat stress. Among the three studied cultivars, SY20 was the most sensitive to heat stress with the stable time decreasing from 26.4 to 9.1 min, a higher sedimentation volume at 7 DAA, and a lower γ-gliadin content which increased 2.4-fold under high-temperature treatment. The addition of various regulators had different effects: potassium dihydrogen phosphate (KDP) was more protective of yield with heat stress at 7 DAA, while Duntianbao (DTB) had better effects on quality with heat stress at 21 DAA.

Leaf rust (LR), caused by Puccinia triticina, is a major constraint to global wheat production. Identifying quantitative trait loci (QTLs), conferring adult-plant resistance (APR), and developing breeder-friendly markers are essential for durable disease control. In this study, a recombinant inbred line (RIL) population derived from Liang66-S × Hengmai28 was evaluated for leaf rust severity across four environments. Maximum disease severity (MDS) showed continuous variation and moderate to high correlations among environments, indicating polygenic inheritance. Five APR QTLs were mapped on chromosomes 2BL, 3BS, 3BL, 7BL and 7DL, explaining 4.5–9.8% of the phenotypic variance (PVE) with LOD scores of 2.9–7.9. Among these, QLr.DFI-2BL, QLr.DFI-3BS, and QLr.DFI-7BL correspond to previously reported APR loci, whereas QLr.DFI-3BL and QLr.DFI-7DL represent potentially novel loci. QLr.DFI-3BL was detected across all four environments, while QLr.DFI-3BS and QLr.DFI-7BL showed the highest R² (7.7–8.5% and 8.4–9.8%). Multiple defense-related genes within the QTL intervals for LR were identified, including the putative NBS-LRR, the putative BTB/POZ-MATH, F-box, receptor-like kinase, polyphenol oxidase, calcium-dependent protein kinase, peroxidase, and ethylene-responsive transcription factors. Based on the flanking markers, five KASP markers were developed. K-LR-3BS (for QLr.DFI-3BS) and K-LR-7BL (for QLr.DFI-7BL) successfully genotyped a natural population with 120 accessions, with call rates of 100% and 94.2%, and showed significant association with reduced leaf rust severity. However, further validation in diverse genetic backgrounds and populations is required before they can be considered for routine marker-assisted selection. These results provide two KASP markers as promising markers that require further validation in diverse backgrounds and highlight QLr.DFI-3BS and QLr.DFI-7BL as promising targets for fine mapping and eventual cloning of APR genes in wheat.

Grain protein content (GPC) is extremely important for common wheat (Triticum aestivum L.) end-use quality. Identifying genetic loci for GPC is helpful in creating new varieties with good processing quality. Linmai2 and Zhong892 are two elite wheat varieties with differences in GPC. In the present study, a recombinant inbred line (RIL) population derived from Linmai2 and Zhong892 was used to identify GPC loci. Linkage mapping was conducted by combining the wheat 90K single nucleotide polymorphisms (SNPs) chip data and GPC from four environments. Five QTLs on chromosomes 1B, 2B, 4A, 4B and 6B were identified, and designated as QGPC.lfnu-1BL, QGPC.lfnu-2BS, QGPC.lfnu-4AS, QGPC.lfnu-4B and QGPC.lfnu-6BS, respectively, explaining 5.21–11.38% of the phenotypic variances. The favorable alleles of QGPC.lfnu-1BL, QGPC.lfnu-4AS, QGPC.lfnu-4B and QGPC.lfnu-6BS originated from Zhong892, while the favorable allele of QGPC.lfnu-2BS came from Linmai2. Among these, QGPC.lfnu-1BL, QGPC.lfnu-2BS, QGPC.lfnu-4AS, and QGPC.lfnu-4B are potentially novel loci, whereas QGPC.lfnu-6BS likely represents the re-detection of Gpc-B1. Additionally, competitive allele-specific PCR (KASP) markers suitable for breeding were developed, and genetic effects were validated in a natural population. Four KASP markers, KASP-GPC-1BL, KASP-GPC-2BS, KASP-GPC-4B and KASP-GPC-6BS, were significantly associated with GPC in a diverse panel of 140 wheat varieties. A total of twelve potential genes involved in nitrogen assimilation, amino acid biosynthesis and transport, and NPF transporter and protein turnover were proposed as candidate genes within the intervals of five QTLs. These findings identified stable QTLs, available KASP markers and promising candidate genes for marker assisted selection to accelerate wheat GPC improvement.