[Genome-wide identification of the ASR gene family and analysis of its expression pattern under various stress...

Abscisic acid, stress and ripening-induced (ASR) proteins play crucial roles in plant ripening induction and stress responses. Although ASR proteins have been identified in various plant species, systematic studies in sugarcane remain limited, and their structural and functional characteristics are poorly understood. To this end, this study aimed to systematically identify members of the sugarcane ASR gene family at the genome-wide level, elucidate their molecular characteristics and evolutionary relationships, and investigate their expression patterns during growth, development, and stress responses. The results showed that a total of 40 ShASR genes from the Saccharum spp. cultivar 'R570' and 15 SsASR genes from the wild species Saccharum spontaneum were identified. All the predicted ASR proteins contained the characteristic ABA/WDS domain. Phylogenetic analysis, using rice ASR proteins as a reference, classified the sugarcane ASRs into three distinct subfamilies. Physicochemical property predictions indicated that sugarcane ASR proteins were stable and hydrophilic, mainly localized to the nucleus. Further analyses of gene structures, duplication patterns, and chromosomal distribution revealed that ASR genes mainly expanded through whole-genome or segmental duplication events and exhibited subfamily-specific clustering on chromosomes. Promoter analysis showed enrichment of cis-acting elements related to stress and plant hormone responses, as well as growth and development. Transcriptomic data revealed that most ASR genes were expressed in sugarcane leaf, leaf sheath, pith, skin, and bud samples and were responsive to smut pathogen infection and drought stress. RT-qPCR results confirmed that six ShASR genes (ShASR1, ShASR6, ShASR14, ShASR20, ShASR25, and ShASR40) showed differential expression patterns in response to exogenous plant hormone treatments and smut pathogen challenge. These findings suggested that ShASR genes might play important roles in regulating stress responses, disease resistance, and development in sugarcane. This study provides a comprehensive understanding of the sugarcane ASR gene family and offers valuable genetic resources for molecular breeding of stress-tolerant sugarcane cultivars.