Systematic identification and functional insights into IGT family members involved in leaf angle regulation and...

Sugarcane, a major crop for sugar production, where growth and yield are strongly influenced by plant architecture, particularly leaf angle (LA), and stress adaptation. Optimizing LA improves light capture, photosynthesis, and lodging resistance, regulated by IGT genes, though their role in sugarcane remains unclear. This study identified 50 IGT genes across three Saccharum species: 05 SsIGT in S. spontaneum (AP85-441), 10 SoIGT in S. officinarum (LA-purple), and 35 ScIGT in S. hybrid (XTT22). Phylogenetic analysis classified them into DRO, LAZY, and TAC subfamilies. Promoter analysis revealed cis-regulatory elements linked to stress, hormone responses, and growth regulation, while miRNA prediction indicated post-transcriptional regulation. Protein network analysis highlighted conserved interactions between sugarcane IGT proteins and maize homologs. BR regulates LA and cellular dynamics, shaping sugarcane growth and architecture. Cytological analysis reveals that, moderate brassinosteroids (BRs) (3-5 μM) promoted cell enlargement and increased LA, whereas higher levels (≥10 μM) reduced cell size, restored density, and decreased LA. Subcellular localization shows that ShLAZY1 is predominantly found in the cytoplasm and nucleus, supporting its role as a transcription factor. qRT-PCR revealed that BR treatment significantly upregulated ShDRO2, ShDRO18, ShLAZY1, ShTAC1, and GRAS33, implicating them in leaf joint development and architecture regulation. Under NaCl stress (250 mM), five genes including, ShDRO2, ShDRO18, ShKnox1, ShGn1, and ShGRAS33 functioned as positive regulators, while ShLg1 and ShTAC1 acted as negative regulators, potentially influencing plant architecture via source-sink modulation. These findings highlight the integrated role of IGT genes in LA modulation and stress adaptation, offering strategies for improving sugarcane productivity and resilience.