Systematic characterization of the N-terminal acetyltransferase gene family reveals that OsNAA30 regulates plant height and tillering in rice

Physicochemical properties, molecular characteristics, and expression profiles of the NAT gene family members were elucidated in rice. 2. OsNAA30 exhibits dual nucleocytoplasmic localization and possesses NatC catalytic activity. 3. OsNAA30 plays a positive role in regulating plant architecture by modulating gibberellin and cell cycle genes and is associated with trait variation relevant to breeding. N-terminal acetyltransferases (NATs) fundamentally regulate plant growth and development through protein N-terminal acetylation (NTA), a crucial post-translational modification. Although their functional importance is recognized, systematic characterization of NATs remains unexplored in Oryza sativa . This study identified 14 OsNAA genes distributed non-uniformly across 12 chromosomes in japonica rice. Phylogenetic analysis combined with conserved domain studies revealed distinct evolutionary clades of OsNAT catalytic subunits with preserved structural architectures. Analysis of promoter regions identified a prevalence of stress-responsive and growth-related cis -elements, corresponding to developmental stage-specific expression patterns throughout vegetative and reproductive phases. Several OsNAA genes exhibited substantial transcriptional responses to cold, drought, NaCl, and heat stresses. Furthermore, gibberellin (GA) promotes the upregulation of specific OsNAA genes during seedling development. Collinear analysis demonstrated that segmental and singleton duplication events drive the expansion of the OsNAT family. Functional characterization revealed that OsNAA30 localizes to the nucleus and cytoplasm, displaying canonical NatC activity in vitro . Deletion of OsNAA30 led to reduced plant height and fewer tillers, accompanied by decreased cell elongation in the stem internodes. OsNAA30 appears to regulate rice growth by suppressing the expression of GA catabolism genes and cell cycle regulators of plant height and tillering. Additionally, analysis of the OsNAA30 haplotype links this gene to variations in plant height, culm length, and tiller number, indicating that the OsNAA30 locus may have influenced the local adaptation of plant architecture. This research provides essential insights into the OsNAT gene family and establishes OsNAA30 as a valuable genetic target for molecular breeding in rice.