Heading date (HD) in wheat determines geographic adaptation, seasonal performance, and ultimately affects yield and quality. However, the genetic regulation of HD remains unclear. Here, we identified an Ethyl Methane Sulfonate (EMS)-induced wheat mutant, je0072, which headed two days earlier than the wild-type (WT) cultivar Jing411 without significant changes in yield components. Bulked segregant analysis (BSA) using an F₂ population of 618 individuals identified the early-heading locus to the long arm of chromosome 5D. Genetic fine mapping further narrowed the locus to a 460-kb interval containing 10 high-confidence genes based on the Chinese Spring v2.1 reference genome. Sequence variation analysis identified a candidate gene, TaBGLU1-5D, encoding β-glycosyl hydrolase 1, which harbored a T-to-C substitution at position 31. Functional validation using independent mutants confirmed the role of TaBGLU1-5D in regulating HD. Transcriptome sequencing revealed that differentially expressed genes (DEGs) between WT and je0072 spikes at the heading stage were significantly enriched in starch and sucrose metabolism pathways. Weighted Gene Co-expression Network Analysis (WGCNA) further identified MADS-box transcription factor TaMADS26 as a regulatory hub associated with TaBGLU1-5D. We also found that TaBGLU1-5D modulates expression of key heading date-related genes, including VRN1, VRN3, and VRT2, thereby influencing HD. These results provide new insights into the genetic control of HD in wheat, and offer valuable resources for HD optimization in breeding programs.

Waterlogging is a growing threat to wheat production in high-rainfall areas. In this study, a doubled haploid (DH) population developed from a cross between Yangmai 16 (waterlogging-tolerant) and Zhongmai 895 (waterlogging-sensitive) was used to map quantitative trait loci (QTL) for waterlogging tolerance using a high-density 660K single-nucleotide polymorphism (SNP) array. Two experimental designs, waterlogging concrete tank (CT) and waterlogging plastic tank (PT), were used to simulate waterlogging during anthesis in five environments across three growing seasons. Waterlogging significantly decreased thousand-kernel weight (TKW) relative to non-waterlogged controls, although the degree varied across lines. Three QTL for waterlogging tolerance were identified on chromosomes 4AL, 5AS, and 7DL in at least two environments. All favorable alleles were contributed by the waterlogging-tolerant parent Yangmai 16. QWTC.caas-4AL exhibited pleiotropic effects on both enhancing waterlogging tolerance and decreasing plant height. Six high-confidence genes were annotated within the QTL interval. The combined effects of QWTC.caas-4AL and QWTC.caas-5AS greatly improved waterlogging tolerance, while the combined effects of all three identified QTL (QWTC.caas-4AL, QWTC.caas-5AS, and QWTC.caas-7DL) exhibited the most significant effect on waterlogging tolerance. Breeder-friendly kompetitive allele-specific PCR (KASP) markers (K_AX_111523809, K_AX_108971224, and K_AX_110553316) flanking the interval of QWTC.caas-4AL, QWTC.caas-5AS, and QWTC.caas-7DL were produced. These markers were tested in a collection of 240 wheat accessions, and three superior polymorphisms of the markers distributed over 67 elite cultivars in the test population, from the Chinese provinces of Jiangsu, Anhui, and Hubei. The three KASP markers could be used for marker-assisted selection (MAS) to improve waterlogging tolerance in wheat.

Cytokinins (CKs) function in plant development and during stress responses, but their role in drought tolerance in wheat is unknown. In the present study, 24 isopentenyltransferase (IPT) genes, encoding rate-limiting enzymes in CK biosynthesis were identified in the wheat genome. The chromosomal locations and structures of the genes, protein properties, and phylogenetic relationships were characterized. ATP/ADP TaIPT genes showed tissue-specific expression. TaIPT2, TaIPT7, and TaIPT8 expression was rapidly induced by 0.5–1 h drought treatments, which decreased to low levels after 2 h drought treatment, as did most other TaIPT genes. TaIPT8-5a/5b/5d triple mutants showed decreased levels of tZ-type CK under normal and drought conditions and reduced drought tolerance, which, however, did not manifest as phenotype alterations. By contrast, transgenic wheat plants with drought-induced TaIPT8 showed increased drought tolerance. Our study provides a foundation for further investigation of TaIPT genes and novel insights into the role of CKs in the drought response of wheat.