Salinity is a major abiotic stress that threatens crop yield and food supply in saline soil areas. Wheat (Triticum aestivum L.) is the most important cereal crop in arid and semiarid land areas, which are often adversely affected by soil salinity. Hence, creating salt tolerance wheat is of great value for utilizing saline soils. In this study, two wheat cultivars QingMai 6 (QM6, salt-tolerant) and Chinese Spring (CS, salt-sensitive) were subjected to salinity stress. Morphological analysis showed that the seedlings of QM6 grew better than CS under salt stress conditions, especially in roots. Electron microscopic studies revealed that salinity stress caused significantly more root hairs and less effect on normal chloroplast structure in QM6 than these in CS. Moreover, QM6 showed a higher photosynthetic activity under salt stress conditions compared to CS. Further investigation showed the salt-tolerant phenotypes of QM6 were accompanied by decreases of reactive oxygen species (ROS) content, and lower antioxidant enzyme activities after salt treatment compared with CS. Additionally, qRT-PCR analyses revealed that the expression level of ROS-scavenging genes (TaSOD6, TaCAT1/5/6, TaPOD7, TaP5CS1) and stress-responsive genes (TaDREB3, TaWRKY19, TaERF5a, TaLTP1, TaTIP2) displayed more transcripts in QM6 than CS. These results provide insight into the mechanisms underlying salt tolerance in wheat, and could be potentially used to develop salt tolerant wheat varieties.

Root architectural traits at the seedling stage have been demonstrated to be crucial for the efficient uptake of nutrients and drought tolerance in wheat. To dissect the genetic basis of these traits from the D genome, 182 recombinant inbred lines (RILs) derived from the common wheat TAA10 crossed with resynthesized allohexaploid wheat XX329 possessed similar AABB genomes were used for QTL mapping of five root traits in hydroponic-cultured seedlings, including lateral root number (LRN), seminal root number (SRN), root hair length (RHL), root diameter (RD), and total root volume (TRV). A total of seven QTLs were identified for the five root traits, with six possible novel QTLs for LRN, RHL, RD and TRV, accounting for 4.98–12.17% of phenotypic variation. One QTL (QLrn.qau-5D.2), controlling lateral root number, was fine mapped an approximate 5.0-Mb interval harboring 80 annotated genes, including five auxin-related genes. We further validated that QLrn.qau-5D.2 in NIL^TAA10 significantly enhanced yield-related traits, such as plant height, spike length, spike compactness, tiller number per plant and grain yield per plant, as comparison with NIL^XX329. Collectively, these results provide vital insights for fine-mapping QTLs associated with LRN, SRN, RHL, RD and TRV and facilitate the root morphologic designs for enhancing yield performance.

Porcine blood polypeptide (PBP) has been reported to play roles in plant growth. However, its functions in alleviating salt stress in wheat remain unclear. The present study was conducted to investigate the physiological and biochemical mechanisms underlying the effects of PBP on wheat salt tolerance. Morphological analysis showed that PBP-primed seedlings exhibited improved growth performance, significantly greater biomass accumulation, and enhanced root system development. Physiological assessments showed that primed seedlings displayed higher values of Pn, Gs, Tr, Fv/Fm, Fv′/Fm′, Φ_PSII, and NPQ, along with increased contents of total chlorophyll, Pro, TSS, and RWC. In addition, the activities of antioxidant enzymes, including SOD, CAT, POD, and APX, were significantly elevated, whereas the levels of H₂O₂, O₂⁻, MDA, and REC were significantly reduced. PCA indicated that antioxidant enzyme activity, osmotic regulation, and ROS accumulation were the major factors associated with the PBP-mediated salt stress response. Furthermore, qRT-PCR analysis suggested that exogenous PBP might enhance wheat salt tolerance by coordinately modulating multiple molecular mechanisms. Taken together, this study broadens the potential applications of PBP by demonstrating its capacity to improve wheat salt tolerance.

Drought stress is a devastating natural stress that threatens crop productivity and quality. Mitigating the adverse effects of drought stress on wheat is a key object in agriculture. C-repeat binding transcription factor/DROUGHT RESPONSE ELEMENT BINDING FACTOR 1 (CBF/DREB1) transcription factors are well known for their role in cold acclimation. However, the involvement of CBF genes in drought stress and the mechanisms underlying their function remain poorly understood. In this study, 81 CBFs were identified in wheat, which were further clustered into four distinct lineages based on phylogenetic analysis. Chromosomal localization indicated that most CBF genes were dispersed across chromosome 5. We identified three homoeologous genes (TaCBF14A, TaCBF14B, and TaCBF14D) that were simultaneously upregulated under drought stress based on RNA-seq analysis. According to the high expression after drought stress, TaCBF14B was selected for further functional analysis. Subcellular localization and transcriptional activation activity analysis indicated that TaCBF14B likely functions as a transcription factor involved in drought stress tolerance. Overexpression of TaCBF14B in Arabidopsis enhanced the primary root growth by 13.49% (OE1), 12.56% (OE2), and 19.53% (OE3) under 200 mM mannitol treatment, and 21.65% (OE1), 16.63% (OE2), and 28.13% (OE3) under 250 mM mannitol treatment compared to WT. Meanwhile, the water loss rate of transgenic lines was 56% in WT leaves, but only 44%, 50%, and 40% in OE1, OE2, and OE3 lines, respectively. Compared to the wild type, POD activities of OE1, OE2, and OE3 were significantly increased by 42.94%, 29.41%, and 62.52%, respectively. And the Pro activities in OE1, OE2, and OE3 were significantly increased by 16.33%, 5.18%, and 29.09%, respectively, compared to the wild type. Additionally, the MDA content in OE1, OE2, and OE3 was significantly reduced by 40.53%, 15.81%, and 54.36%, respectively. Further analysis showed that the transgenic lines were hypersensitive to abscisic acid (ABA), and exhibited increased expression of AtABI3. We speculate that TaCBF14B plays an important role in enhancing drought tolerance. In summary, our findings provide new insights into the functional roles of CBF genes in drought stress tolerance.