Comprehensive analysis of AsCKX and AsIPT gene families in oat: characterization and differential regulation under alkaline and osmotic stresses.

Abstract

Cytokinins (CTKs) regulate both plant development and responses to abiotic stress. The biosynthesis and degradation of CTKs are primarily governed by the isopentenyl transferase (IPT) and cytokinin oxidase/dehydrogenase (CKX) gene families, respectively. However, a comprehensive analysis of both gene families in oat (Avena sativa) has not yet been performed. Here, we characterized the AsCKX and AsIPT genes and their encoded proteins. Additionally, we determined the levels of 6 types of endogenous CTKs, and the expression patterns of all AsCKX and AsIPT genes under alkaline and osmotic stresses. Our results showed that AsCKX and AsIPT genes exhibit diverse physicochemical properties and specific secondary and tertiary structures. Phylogenetic and synteny analyses revealed that these genes share high homology with homologs in the rice. Multiple segmental duplication events were identified both within the oat genome and between oat and other species, with clear evidence of positive selection for adaptation to abiotic stresses. Meanwhile, these genes contain various cis-acting elements associated with abiotic stresses. Expression pattern analysis indicated that, at 6 h under both alkaline and osmotic stresses, oats may respond to the stress by upregulating AsCKX and downregulating AsIPT genes to reduce the CTK content. With the prolongation of stress duration, differential changes were observed in AsCKX and AsIPT genes between two types of stresses. Interestingly, AsCKX12 was identified as a negative regulator during osmotic stress response. This work lays the groundwork for future comprehensive functional characterization of AsCKX and AsIPT genes in oat under alkaline and osmotic stress conditions.

Supplementary information: The online version contains supplementary material available at 10.1007/s12298-026-01793-5.