Xingwei Zheng

Plant growth-promoting rhizobacteria (PGPR) provide critical ecological value in sustainable agriculture by enhancing plant growth and stress tolerance through improved nutrient acquisition and increased environmental adaptability. As a versatile genus of PGPR, Streptomyces shows great potential for promoting plant growth. However, the molecular mechanisms by which Streptomyces regulates plant root development remain largely unclear. In this study, we explored the molecular basis associated with wheat root developmental responses to Streptomyces pactum Act12 using pot experiments combined with multi-omics approaches. The pot experiment demonstrated that Act12 treatment significantly increased wheat biomass and enhanced total root length (44.6%), root surface area (73.3%), root diameter (34.0%), and root tip number (66.6%). Integrated transcriptomic and metabolomic analyses suggested that Act12 treatment was associated with altered auxin signaling and coordinated changes in carbohydrate metabolism, the TCA cycle, and sterol biosynthesis. These multi-omics signatures provide hypotheses for how Act12 may contribute to root developmental regulation in wheat.

Objectives: Low-temperature stress has become a key factor severely restricting seedling growth in wheat, highlighting the growing importance of research on low-temperature tolerance in wheat. Most previous studies focused on the aboveground organs, and only a minority specifically targeted the roots. Methods: In this study, a recombinant inbred line population derived from a cross between DH118 and Jinmai 919 was used to dissect the genetic regulatory mechanism underlying root growth and development in wheat seedlings under low-temperature conditions. Results: A total of 9 QTLs associated with low-temperature tolerance coefficient were identified; among them, QCi.saw-2B and QCi.saw-5B were validated to be significantly associated with cold tolerance in a natural population including 289 wheat accessions. Moreover, 13 candidate genes from QTL intervals regulating root growth and development under low-temperature stress were further identified based on RNA sequencing. Conclusions: These results provide a foundation for further exploring the regulatory mechanism of root growth and development in wheat under low-temperature stress.

Introduction: Steamed bread (SB) is a daily food in many countries in the world, but the relationship between HMW-GS and the quality of SB remain unclear.Methods: This study investigated the effects of 12 subunit combinations on the characteristics of SB, including volume, physical properties, and sensory evaluation, combined with the microstructure and dough rheological properties.Results: The locus effect results showed, volume and physical properties of SB were Glu-D1>Glu-B1>Glu-A1, while sensory scores Glu-B1>Glu-D1>Glu-A1. According to individual subunit effects, subunit 1 at Glu-A1 locus, 7+8 and 7+9 subunits at Glu-B1 locus, and 2+10 and 5+12 subunits at Glu-D1 locus were significantly superior to other subunits in physical indices like volume, chewiness, glueyness, and sensory scores, and were less affected by moisture. The effect of subunits combination is mainly affected by subunits, and the combination of superior subunits tends to make SB quality better. The subunit combinations (1, 7+8, 5+12), (N, 7+9, 2+10) and (1, 7+9, 5+12) had better physical properties indexes, sensory scores, dense, uniform and delicate micro-pore structure, and smaller thickness wall.Discussion: The results showed that protein content, wet gluten content and stability time were the main factors affecting the volume and physical properties of SB. The protein content, wet gluten content and stability time of flour in 7+8, 7+9, 2+10 and 5+12 subunits were higher. Therefore, the quality of SB containing these subunits was found better.

Wheat (Triticum aestivum L.) is a crucial cereal crop, contributing around 20% of global caloric intake. However, challenges such as diminishing arable land, water shortages, and climate change threaten wheat production, making yield enhancement crucial for global food security. The heading date (HD) is a critical factor influencing wheat’s growth cycle, harvest timing, climate adaptability, and yield. Understanding the genetic determinants of HD is essential for developing high-yield and stable wheat varieties. This study used a doubled haploid (DH) population from a cross between Jinmai 47 and Jinmai 84. QTL analysis of HD was performed under three phosphorus (P) treatments (low, medium, and normal) across six environments, using Wheat15K high-density SNP technology. The study identified 39 QTLs for HD, distributed across ten chromosomes, accounting for 2.39% to 29.52% of the phenotypic variance. Notably, five stable and major QTLs (Qhd.saw-3A.7, Qhd.saw-3A.8, Qhd.saw-3A.9, Qhd.saw-4A.4, and Qhd.saw-4D.3) were consistently detected across varying P conditions. The additive effects of these major QTLs showed that favorable alleles significantly delayed HD. There was a clear trend of increasing HD delay as the number of favorable alleles increased. Among them, Qhd.saw-3A.8, Qhd.saw-3A.9, and Qhd.saw-4D.3 were identified as novel QTLs with no prior reports of HD QTLs/genes in their respective intervals. Candidate gene analysis highlighted seven highly expressed genes related to Ca²⁺ transport, hormone signaling, glycosylation, and zinc finger proteins, likely involved in HD regulation. This research elucidates the genetic basis of wheat HD under P stress, providing critical insights for breeding high-yield, stable wheat varieties suited to low-P environments.

Flag-leaf-related traits including length (FLL), width (FLW), area (FLA), thickness (FLT), and volume (FLV) of flag leaves are the most important determinants of plant architecture and yield in wheat. Understanding the genetic basis of these traits could accelerate the breeding of high yield wheat varieties. The present study used a doubled haploid (DH) population to identify quantitative trait loci (QTL) for five flag-leaf-related traits and to analyze their correlation with grain-yield-related traits. Leaf thickness at two-thirds of the leaf length from tip to collar represented the average leaf thickness as measured with freehand sections and was used to calculate the leaf volume. This approach is a new means to easily measure FLV. A total of 79 QTL controlling the five traits were detected, explaining 3.09%-14.52% of the phenotypic variation. Among them, 15 stable QTL were identified, including two major QTL for FLT, six for FLW, three for FLA, two for FLT and two for FLV. QFLL-4A, QFLW-4B, QFLA-5D.1, QFLA-7A, QFLA-7D.1, QFLT-2B, QFLT-6A, QFLV-2A and QFLV-7D are likely novel loci. In addition, flag-leaf-related traits and grain-yield-related traits were significantly correlated. Taken together, these results provide a better understanding of the genetic basis underlying flag-leaf-related traits. Also, target regions for fine mapping and marker-assisted selection were identified and these will be valuable for breeding high yielding bread wheat.

Vitamin B9, particularly folic acid, is an essential molecule for human health. Wheat flour is one of the major sources of calorie intake by humans. The selection of folate-rich genotypes in wheat breeding can enhance the natural folate value in the daily diet. This study used a precise, high-performance liquid chromatography (HPLC) assay to analyze folate content in a 262-accession Chinese wheat mini-core collection (MCC) grown under three environments. Four folate derivatives in grains including tetrahydrofolate (THF), 5-methyltetrahydrofolate (5-CH₃-THF), 5-formyltetrahydrofolate (5-CHO-THF), and 5,10-methenyltetrahydrofolate (5,10-CH⁺THF) were considered. An association analysis of water regimes, accession types, released years, geographical origin, and agronomic traits with folate content was conducted for the first time. There was a large amount of variation in folate content in the analyzed accessions, with genotype identified as the main influencing factor. Total folate content was significantly correlated with the content of the four MCC derivatives under the three environments. 5-CH₃-THF and 5-CHO-THF were the most abundant among the four folate derivatives and were positively correlated with high folate content. The 12 accessions with the highest folate content showed an average of more than 80 μg/100 g. The analysis demonstrated that this Chinese wheat had not undergone extensive selection for folate content during breeding, which is unrelated to the geographical origin, accession types, winter/spring types, and grain colors of wheat. The content of THF, 5-CH₃-THF, and 5,10-CH⁺THF was significantly negatively correlated with grain width, grain thickness, and thousand kernel weight. A relatively weak negative relationship manifested between folate contents and flowering date, whereas no significant correlation with tiller number, grain number per spike, maturity date, height, and spike length was detected. The investigation benefits wheat breeders for folate enhancement.

Key message Genetic architecture controlling grain lutein content of common wheat was investigated through an integration of genome-wide association study (GWAS) and linkage analysis. Putative candidate genes involved in carotenoid metabolism and regulation were identified, which provide a basis for gene cloning and development of nutrient-enriched wheat varieties through molecular breeding. Abstract Lutein, known as ‘the eye vitamin’, is an important component of wheat nutritional and end-use quality. However, the genetic manipulation of grain lutein content (LUC) in common wheat has not previously been well studied. Here, quantitative trait loci (QTL) associated with the LUC measured by high performance liquid chromatography (HPLC) were first identified by integrating a genome-wide association study (GWAS) and linkage mapping. A Chinese wheat mini-core collection (MCC) of 262 accessions and a doubled haploid (DH) population derived from Jinchun 7 and L1219 were genotyped using the 90K SNP array. A total of 124 significant marker-trait associations (MTAs) on all 21 wheat chromosomes except for 1A, 4D, and 5B that formed 58 QTL were detected. Among them, six stable QTL were identified on chromosomes 2AL, 2DS, 3BL, 3DL, 7AL, and 7BS. Meanwhile, three of the ten QTL identified in the DH population, QLuc.5A.1 and QLuc.5A.2 on chromosome 5AL and QLuc.6A.2 on 6AS, were stable and independently explained 5.58–10.86% of the phenotypic variation. The QLuc.6A.2 region colocalized with two MTAs identified by GWAS. Moreover, 71 carotenoid metabolism-related candidate genes were identified, and the allelic effects were analyzed in the MCC panel based on the 90K array. Results revealed that the genes CYP97A3 (Chr. 6B) and CCD1 (Chr. 5A) were significantly associated with LUC. Additionally, the gene PSY3 (QLuc.5A.1) and several candidate genes involved in the methylerythritol 4-phosphate (MEP) pathways colocalized with stable QTL regions. The present study provides potential targets for future functional gene exploration and molecular breeding in common wheat.

The synonymous codons usage shows a characteristic pattern of preference in each organism. This codon usage bias is thought to have evolved for efficient protein synthesis. Synonymous codon usage was studied in genes of the hexaploid wheat Triticum aestivum (AABBDD) and its progenitor species, Triticum urartu (AA), Aegilops tauschii (DD), and Triticum turgidum (AABB). Triticum aestivum exhibited stronger usage bias for G/C-ending codons than did the three progenitor species, and this bias was especially higher compared to T. turgidum and Ae. tauschii. High GC content is a primary factor influencing codon usage in T. aestivum. Neutrality analysis showed a significant positive correlation (pT. aestivum.