Tree peony seeds are rich in α-linolenic acid (ALA), and the peony seed oil is now being produced in China. Paeonia ostii is the most widely used tree peony species for oil extraction, which is commercially called Fengdan and treated as a single cultivar. Here, 50 P. ostii individuals from the same population in northern China were randomly selected for fatty acids (FAs) analysis. Thirteen FAs were isolated, and the most abundant five were palmitic acid (5.31–6.99%), stearic acid (1.22–2.76%), oleic acid (18.78–28.15%), linoleic acid (11.86–26.10%), and ALA (41.11–57.51%). There were significant individual differences of plants in FA quality and quantity and the linoleic acid content in Plant No. 48 even exceeded the scope of 1–99%. Further statistical analysis indicated that most of the individual FAs, saturated FAs, unsaturated FAs, and total FAs levels showed significant positive correlations to each other, whereas the seed yield per plant was independent and not correlated to the factors mentioned above. Ward’s hierarchical clustering results grouped the 50 plants into four clusters based on FA contents and seed yield, and the seven plants in Cluster IV were identified as good candidates for oil production. Our results confirmed that the individual differences did occur in P. ostii and Fengdan cannot be simply treated as one uniform cultivar. Also, these results may help simplify the selection of plants for oil peony breeding and accelerate the development of the oil peony industry.

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.