Abstract
BACKGROUND: RING-type E3 ligases are critical regulators of diverse plant processes, yet their roles in maize remain poorly defined, particularly in drought responses. To address this knowledge gap, we conducted an integrative analysis of maize RING genes, combining evolutionary profiling, and candidate-gene association studies to identify drought-associated candidates. Key genes were further characterized via quantitative expression profiling, subcellular localization, in vitro ubiquitination assay, and functional validation in transgenic Arabidopsis. This study aimed to provide new insights into the maize RING gene family's role in drought stress adaptation. RESULTS: We employed three distinct methods and identified a total of 590 proteins. Phylogenetic analysis revealed that these proteins could be grouped into 11 separate clusters. Our findings suggested that the expansion of the RING family in maize was likely due to gene duplication events. Notably, genetic variations in ZmRING-93 were significantly associated with drought tolerance, and its expression was up-regulated under various abiotic stress conditions and hormone treatments. We further discovered that ZmRING-93 was a functional ubiquitin E3 ligase that localized to the nucleus, cytoplasm, and parts of the endoplasmic reticulum. Transgenic Arabidopsis plants overexpressing ZmRING-93 exhibited enhanced drought tolerance, with a lower water loss rate, further supporting the importance of ZmRING-93 in drought tolerance. CONCLUSIONS: These findings revealed that ZmRING-93 contributed to drought tolerance in maize and provided a basis for further investigation of the role of RING domain-containing proteins.