Chitosan nanoparticles (CSNPs) conferred salinity tolerance in maize by upregulating E3 ubiquitin-protein ligase, P5CS1, HKT1, NHX1, and PMP3 genes

This study explored the transcriptional behaviors of several candidate genes in response to the application of CSNPs (50 and 100 mgl^-1) in maize seedlings grown under two salinity levels (NaCl of 0.07 and 0.14 gkg^-1soil). Employing CSNPs at both concentrations mitigated the inhibitory role of salinity on the leaf and root fresh weights. The application of CSNPs enhanced the transcription of the E3 ubiquitin-protein ligase gene by an average of threefold, contrasted with the salinity controls. The Δ1-pyrroline-5-carboxylate synthetase (P5CS1) gene was upregulated in response to both individual and mixed treatments of CSNPs and salinity. The transcription of the high-affinity K⁺ transporter (HKT1) gene displayed an upward trend in response to the CSNPs and salinity treatments. The Na⁺/H⁺ exchangers (NHX1) gene exhibited a similar trend to that of the HKT1 gene. The utilization of CSNPs was accompanied by an upregulation in the plasma membrane proteolipid 3 (PMP3) gene, contrasted with the salinity controls. The phenylalanine ammonia-lyase (PAL) activity displayed an upward trend in response to the foliar application of CSNPs. The CSNPs at the 100 mgl^-1 concentration were more capable of inducing the ascorbate peroxidase enzyme under both salinity conditions than the 50 mgl^-1 dose. The simultaneous exposure of maize seedlings to CSNPs and salinity resulted in the drastic upregulation of the catalase activities. This study provides novel insights into the major mechanisms underlying the stress-mitigating effects of CSNPs, thereby providing a suitable platform for their application in sustainable agricultural practices.