Phytosulfokine (PSK) is a tyrosine-sulfated pentapeptide found throughout the plant kingdom, playing key roles in plant growth, development, and responses to biotic and abiotic stresses. However, there is still a lack of a comprehensive analysis of the BnPSK gene family in Brassica napus. In this study, we conducted a genome-wide identification and characterized 19 BnPSK genes in oil seed plants, which are unevenly distributed across both sub-genomes (A and C). BnPSK proteins ranged from 77 to 99 amino acids (BnPSK3c and BnPSK3d) in length, all belonging to the PSK-α type and containing conserved PSK domains. Synteny analysis revealed that the expansion of the BnPSK gene family is primarily attributed to whole genome duplication, with homology to Arabidopsis thaliana PSK genes. A promoter region analysis identified cis-acting elements related to hormone and stress responses. An expression profile analysis showed that BnPSK genes are highly expressed in roots, leaves, petals, and pollens and are induced by both abiotic stresses and phytohormone application. Furthermore, RT-qPCR assay demonstrated that the expression levels of BnPSK4c, BnPSK5a, and BnPSK5b were significantly enhanced under drought stress (3~5-fold) both in plant roots and leaves following ABA application. Lastly, the application of ABA induced antioxidant activity including SOD, POD, CAT and APX (2~5-fold) and their corresponding genes (3~5-fold), and altered the ROS-signaling in rapeseed plants; also, strong evidence of mitigating drought stress was present. These findings establish a basis for further research into the role of the BnPSK gene family in oilseed plant tolerance against drought stress and underlying molecular mechanisms, offering valuable perspectives for developing novel peptides.

Brassica napus L. is a major oilseed crop whose productivity is significantly affected by abiotic stresses such as drought. PYR/PYL/RCAR (PYL) proteins act as key abscisic acid (ABA) receptors and play central roles in stress responses. However, a comprehensive genome-wide analysis of the PYL gene family in B. napus is still lacking, limiting our understanding of their functions in plant and stress adaptation. This study reports the first comprehensive genome-wide analysis of the PYL gene family in B. napus (rapeseed), cultivar ZS11, identifying 25 BnPYL genes grouped into four subfamilies, I (four genes), I-II (five genes), II (five genes), III (11 genes), and their encoded proteins were predicted to be mainly localized in the chloroplast. Structural analysis revealed diverse exon–intron organization and 10 conserved motifs. All identified BnPYLs contained Polyketide_cyc2 domains (PF10604), supporting their annotation as members of the PYL family. Promoter analysis identified cis-regulatory elements related to light response, stress regulation, and hormonal signaling. Computational analysis of post-translational modifications suggested that phosphorylation sites are mainly localized at serine and threonine residues. Tertiary structure modelling revealed conserved three-dimensional architectures among BnPYL proteins, suggesting potential functional conservation. Expression profiling and RT-qPCR analyses revealed that several BnPYL genes respond to ABA-mediated drought stress, with BnPYL15 and BnPYL22 exhibiting the highest induction (4–5-fold) and BnPYL2, BnPYL5, BnPYL6, BnPYL17, BnPYL18, and BnPYL25 showing significant upregulation (2.0–4.5-fold), suggesting potential roles in enhancing drought tolerance in B. napus.

Excess or deficiency of nitrogen affects wheat yield significantly. Several destructive and non-destructive methods are used for nitrogen diagnosis to support precision fertilizer management in wheat. Recently, UAV-based remote sensing combined with machine learning has emerged as a promising approach for wheat nitrogen assessment. A systematic review was conducted to identify strengths and gaps in the methodologically diverse literature. The PRISMA approach was used to identify relevant literature from Scopus and Web of Science databases. The extracted data were used for comparative quantitative analysis to evaluate whether studies targeted direct nitrogen variables or proxy traits, how validation rigor influenced reported performance, and which growth stages were most commonly associated with nitrogen diagnosis. Across studies with comparable reported performance, direct nitrogen studies showed a median selected R² of 0.855, while close-proxy and indirect-proxy studies showed median selected R² values of 0.868 and 0.841, respectively. Validation design also differed markedly across the literature. Most studies relied on internal-only validation, and these studies showed a higher median selected R² (0.860) than studies using independent-like validation (0.825), suggesting that reported performance may often be optimistic under less rigorous validation frameworks. Growth-stage analysis showed that nitrogen diagnosis was most commonly investigated from jointing to grain filling with most studies focusing on multiple growth stages rather than on a single stage. This indicates the use of a broader diagnostic window rather than identifying single stages of practical importance. In conclusion, the reviewed literature represents a mixture of direct nitrogen and proxy or indirect studies with stronger within-study predictive capacity than in providing robust and transferable performance for practical nitrogen management. Future research should focus on direct nitrogen diagnosis and adopt independent validation designs to link diagnosis outputs to actionable precision nutrient management.