Because of the yield increase of 3.5–15% compared to conventional wheat, hybrid wheat is considered to be one of the main ways to greatly improve the wheat yield in the future.  In this study, we performed a principal component analysis (PCA) on two-line hybrids wheat and their parents using the grain weight (GW), the length of spike (LS), the kernel number of spike (KSN), and spike number (SPN) as variables.  The results showed that the variables could be classified into three main factors, the weight factor (factor 1), the quantity factor 1 (factor 2) and the quantity factor 2 (factor 3), which accounted for 37.1, 22.6 and 18.5%, respectively of the total variance in different agronomic variables, suggesting that the GW is an important indicator for evaluating hybrid combinations, and the grain weight of restorer line (RGW) could be used as a reference for parents selection.  The hybrid combination with a higher score in factor 1 direction and larger mid-parent heterosis (MPH) of the GW and its parents were used to carry out the analysis of grain filling, 1-aminocylopropane-1-carboxylicacid (ACC) and polyamine synthesis related genes.  The results suggested that the GW of superior grain was significantly higher than that of inferior grains in BS1453×JS1 (H) and its parents.  Both grain types showed a weight of H between BS1453 (M) and JS1(R), and a larger MPH, which may be caused by their differences in the active filling stage and the grain filling rate.  The ADP-glucose pyrophosphorylase (AGPase), granule bound starch synthase I (GBSSI), starch synthase III (SSS), and starch branching enzyme-I (SBE-I) expression levels of H were intermediated between M and R, which might be closely related to MPH formation of the GW.  Compared with R and H, the GW of M at maturity was the lowest.  The expression levels of spermidine synthase 2 (Spd2), ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) had significantly positive correlations with the grain filling rate (r=0.77*, 0.51*, 0.59*), suggesting their major roles in the grain filling and heterosis formation.  These provide a theoretical basis for improving the GW of photo-thermo-sensitive male sterile lines (PTSMSL) by changing the endogenous polyamine synthesis in commercial applications.

Leaf rust is a highly destructive foliar disease in wheat, causing major constraints in wheat production worldwide.  In this study, we conducted a comprehensive assessment of adult plant resistance to leaf rust in 590 accessions from the advanced backcross-nested association mapping plus inter-crossed (AB-NAMIC) population. We used 660K genotype data to perform a genome-wide association study (GWAS), identifying significant quantitative trait loci (QTLs) on chromosomes 1B, 2A, 2B, and 7D, with particular emphasis on the candidate gene TaRLK-1B on chromosome 1B.  A cleaved amplified polymorphic sequence (CAPS) marker was developed based on TaRLK-1B haplotypes and effectively differentiated between resistant and susceptible varieties.  This gene encodes a membrane-localized leucine-rich repeat receptor-like kinase (LRR-RLK) that is upregulated in response to the fungal infection that causes leaf rust.  Targeted knockout of TaRLK-1B in wheat led to reduced resistance to leaf rust, underscoring its essential role as a positive regulator in defense against this disease.  Additionally, we propose that TaRLK-1B interacts with the receptor-like cytoplasmic kinase TaRLCK1B, potentially facilitating immune signal transduction.  Our findings also demonstrate that pyramiding minor effect QTLs significantly increases resistance to leaf rust.  This study provides novel insights into resistance genes and valuable QTL information, which could improve marker-assisted wheat breeding efforts.

The embryo rescue technique plays an essential part in developing new varieties of seedless grapes. To enhance the efficiency of seedless grape embryo rescue breeding, this study evaluated 22 hybrid combinations, It systematically probed into the impacts of diverse parental genotypes and plant hormones on both embryo development and germination. In addition, an in-depth exploration was carried out regarding the transformation of abnormal plantlets. Results indicate that ‘Ruby Seedless’, ‘Delight’, ‘Huozhouheiyu’, ‘Zitian Seedless’, and ‘Zhengyan Seedless’ are suitable as maternal parents, while ‘Zitian Seedless’, ‘Shennongxiangfeng’, ‘Hongqitezao’, and ‘Guibao’ are optimal as paternal parents. Among these combinations, ‘Ruby Seedless × Shennongxiangfeng’ and ‘Ruby Seedless × Zitian Seedless’ demonstrated the highest embryo rescue efficiency. Their embryo development rates were 55.05% and 59.76%, yielding 1,348 and 2,235 viable plantlets, respectively. When 1.0 mg L^-1 ZT(Zeatin) was added to the MM3 + 0.2 mg L^-1 IAA (Indole - 3 - Acetic Acid) embryo development medium, the development rate of the ‘Ruby Seedless × Zitian Seedless’ embryos went up by a huge 64.73%. In the germination medium WPM, the supplementation of 0.2 mg L^-1 ZT + 0.2 mg L^-1 IAA resulted in the highest germination rate of 85.71% for the hybrid combination ‘Huozhouheiyu × Shine Muscat’. Furthermore, we successfully recovered a total of 3,365 abnormal plantlets and regenerated 1,234 normal plantlets through direct transformation and cotyledon induction. After hybridization, we successfully transplanted 4,287 plants. This study offers theoretical insights that can enhance the efficiency of embryo rescue breeding for seedless grapes, offering valuable resources for future breeding programs.