Mapping QTLs with additive and epistatic effects for awn length and their effects on kernel-related traits in common wheat.

Introduction: Wheat awns are crucial determinants of wheat yield due to their capacity to photosynthesize and exchange gas. Understanding the genetic basis of awn length (AL) is essential for improving wheat yield in molecular breeding programs. Methods: In this study, quantitative trait loci (QTLs) of AL were analyzed using recombinant inbred line (RIL) mapping population referred to as YY-RILs, which was derived from a cross between Yannong 15 (YN15) and Yannong 1212 (YN1212). Results and discussion: Seven putative additive QTLs and 30 pairwise epistatic QTLs for AL were identified. Among them, five novel additive QTLs (except qAl-2A and qAl-5A.2) and 30 novel pairwise epistatic QTLs were identified. qAl-5A.1 was repeatedly identified in all five environment datasets, which was considered to be one novel stable QTL for AL with minor additive effects. eqAl-2B.2-2 significantly interacted with eight loci and could be of great importance in regulating awn development. The genes associated with the major stable QTL of qAl-5A.2 and the minor stable QTL of qAl-2A were B1 and WFZP-A, respectively. Awn lengths exhibited significant genetic correlations with kernel weight and kernels per spike, which could affect grain protein content to a lesser extent. This study enhances our understanding of the genetic basis of awn development and identifies novel genes as well as markers for future genetic improvement of wheat yield.

Allelic variations of HMW-GS and LMW-GS and quality analysis in Yannong series wheat cultivars/derivative lines.

Introduction: Gluten quality is one of the most important traits of the common wheat (Triticum aestivum L.). In Chinese wheat production, Yannong series cultivars/derivative lines possess unique characteristics and play an important role in both yield and quality contribution. Methods: To dissect their genetic basis of the gluten quality, in this study, allelic variations of high-molecular-weight glutenin subunit (HMW-GS) and low-molecular-weight glutenin subunit (LMW-GS) in 30 Yannong series wheat cultivars/derivative lines and three check cultivars were evaluated using the allele-specific molecular markers, and six crucial quality indexes were also further measured and analyzed. Results: The results demonstrated that the frequencies of HMW-GSs By8, Dx5+Dy10 and Dx5+Dy10+Dy12 in these 30 genotypes and three check cultivars accounted for 87.9%, 24.2% and 9.1%, respectively. For the allelic variations of LMW-GSs, Glu-A3a, Glu-A3b, Glu-A3c, Glu-A3f, and Glu-A3g were identified in 18, 9, 13, 11, and 2 genotypes, respectively; Glu-B3d, Glu-B3g and Glu-B3f were identified in 13, 23 and 4 genotypes, respectively. Notably, Yannong 999, containing By8 + Dx5 + Dy10, and Jinan 17 containing By8 + Dy12 both meet the national standard for high-quality wheat and belong to the category of first-class high-quality strong gluten wheat. Discussion: These findings can provide reference for wheat quality improvement and popularization in the production.

Genetic basis of an elite wheat cultivar Guinong 29 with harmonious improvement between multiple diseases resistance and other comprehensive traits.

Fungal diseases, such as powdery mildew and rusts, significantly affect the quality and yield of wheat. Pyramiding diverse types of resistance genes into cultivars represents the preferred strategy to combat these diseases. Moreover, achieving collaborative improvement between diseases resistance, abiotic stress, quality, and agronomic and yield traits is difficult in genetic breeding. In this study, the wheat cultivar, Guinong 29 (GN29), showed high resistance to powdery mildew and stripe rust at both seedling and adult plant stages, and was susceptible to leaf rust at the seedling stage but slow resistance at the adult-plant stage. Meanwhile, it has elite agronomic and yield traits, indicating promising coordination ability among multiple diseases resistance and other key breeding traits. To determine the genetic basis of these elite traits, GN29 was tested with 113 molecular markers for 98 genes associated with diseases resistance, stress tolerance, quality, and adaptability. The results indicated that two powdery mildew resistance (Pm) genes, Pm2 and Pm21, confirmed the outstanding resistance to powdery mildew through genetic analysis, marker detection, genomic in situ hybridization (GISH), non-denaturing fluorescence in situ hybridization (ND-FISH), and homology-based cloning; the stripe rust resistance (Yr) gene Yr26 and leaf rust resistance (Lr) genes Lr1 and Lr46 conferred the stripe rust and slow leaf rust resistance in GN29, respectively. Meanwhile, GN29 carries dwarfing genes Rht-B1b and Rht-D1a, vernalization genes vrn-A1, vrn-B1, vrn-D1, and vrn-B3, which were consistent with the phenotypic traits in dwarf characteristic and semi-winter property; carries genes Dreb1 and Ta-CRT for stress tolerance to drought, salinity, low temperature, and abscisic acid (ABA), suggesting that GN29 may also have elite stress-tolerance ability; and carries two low-molecular-weight glutenin subunit genes Glu-B3b and Glu-B3bef which contributed to high baking quality. This study not only elucidated the genetic basis of the elite traits in GN29 but also verified the capability for harmonious improvement in both multiple diseases resistance and other comprehensive traits, offering valuable information for breeding breakthrough-resistant cultivars.

Genome-Wide Analysis and Identification of UDP Glycosyltransferases Responsive to Chinese Wheat Mosaic Virus Resistance in Nicotiana benthamiana.

Glycosylation, a dynamic modification prevalent in viruses and higher eukaryotes, is principally regulated by uridine diphosphate (UDP)-glycosyltransferases (UGTs) in plants. Although UGTs are involved in plant defense responses, their responses to most pathogens, especially plant viruses, remain unclear. Here, we aimed to identify UGTs in the whole genome of Nicotiana benthamiana (N. benthamiana) and to analyze their function in Chinese wheat mosaic virus (CWMV) infection. A total of 147 NbUGTs were identified in N. benthamiana. To conduct a phylogenetic analysis, the UGT protein sequences of N. benthamiana and Arabidopsis thaliana were aligned. The gene structure and conserved motifs of the UGTs were also analyzed. Additionally, the physicochemical properties and predictable subcellular localization were examined in detail. Analysis of cis-acting elements in the putative promoter revealed that NbUGTs were involved in temperature, defense, and hormone responses. The expression levels of 20 NbUGTs containing defense-related cis-acting elements were assessed in CWMV-infected N. benthamiana, revealing a significant upregulation of 8 NbUGTs. Subcellular localization analysis of three NbUGTs (NbUGT12, NbUGT16 and NbUGT17) revealed their predominant localization in the cytoplasm of N. benthamiana leaves, and NbUGT12 was also distributed in the chloroplasts. CWMV infection did not alter the subcellular localization of NbUGT12, NbUGT16, and NbUGT17. Transient overexpression of NbUGT12, NbUGT16, and NbUGT17 enhanced CWMV infection, whereas the knockdown of NbUGT12, NbUGT16 and NbUGT17 inhibited CWMV infection in N. benthamiana. These NbUGTs could serve as potential susceptibility genes to facilitate CWMV infection. Overall, the findings throw light on the evolution and function of NbUGTs.