Genotype-dependent responses to selenium foliar application in Chilean chickpea (Cicer arietinum L.) landraces show modifications in phenolic compound composition in seeds.

Chickpea (Cicer arietinum L.) is an important dietary source of proteins and bioactive secondary metabolites. Selenium (Se) acts as a beneficial element at low concentrations, modulating redox metabolism and secondary metabolite pathways. However, the molecular basis of genotype-dependent responses to Se in Chilean chickpea landraces remains poorly understood. We evaluated physiological performance, seed biochemical composition, and transcriptomic responses of five Chilean chickpea landraces (G1-G5) following foliar application of sodium selenate (30 mg L-1) at full flowering. The landraces differed significantly in baseline relative Se levels, estimated by μ-XRF fluorescence intensity (cps), even in the absence of Se treatment. Foliar Se application did not significantly increase seed relative Se levels, although G5 showed a numerical increase (∼10%). Nevertheless, Se treatment was associated with genotype-dependent changes in plant physiology and secondary metabolism, with Se-treated G5 showing a 91% increase in seed production per plant. Pronounced genotype-dependent differences were observed between contrasting Se-absorbing landraces, including variations in antioxidant capacity and phenolic composition. Comparative transcriptomic analysis revealed distinct responses to Se between genotypes, including differential expression of genes involved in detoxification, hormone signaling, and phenylpropanoid biosynthesis. Glutathione S-transferases and MYB transcription factors exhibited contrasting expression patterns associated with the observed biochemical changes. Overall, foliar Se application was associated with genotype-dependent transcriptional and metabolic adjustments in chickpea, highlighting the importance of genetic background in Se responses. These findings provide insights into the molecular and metabolic basis of Se responses in Chilean chickpea landraces and support future Se biofortification and breeding strategies.