Systems-level dissection of salinity stress tolerance in sugarcane interspecific hybrids.

UNLABELLED: Salinity is a major abiotic factor limiting sugarcane productivity. In the present study, eight sugarcane interspecific hybrids were evaluated under control (3 dS m⁻¹) and salinity stress conditions (9 dS m⁻¹) using an integrated approach encompassing morpho-physiological, anatomical, root system architecture, ionic, and molecular studies. Under salinity stress, certain interspecific hybrids exhibited enhanced tillering (40.9%), internode production (15.8%), maintenance of SPAD values, increased Fv/Fm (5.6%), and a moderate reduction in stalk diameter (2.19%) and Leaf Area Index (5.8%). Although relative water content (RWC) declined in all genotypes, TSGS 22-385 showed the smallest reduction (7.3%) while maintaining a high Brix value (20%). Leaf anatomical changes, including epidermal thickening, bulliform cell enlargement, and maintenance of vascular bundle integrity, further contributed to stress adaptation. Root architectural analysis showed a marked increase in the tolerant genotype TSGS 22-385, with total root length increasing from 12.39 to 23.58 m, total root surface area from 394.31 to 631.10 cm², and root volume from 10.0 to 13.8 cm³, whereas the sensitive genotype TSGS 21-33 exhibited 29% and 30% reductions in root fresh and dry weights, respectively. Ionic analysis showed that TSGS 22-385 maintained higher K⁺ accumulation (2319 ppm) while restricting Na⁺ accumulation (192 ppm), indicating improved ionic homeostasis under salinity. Moreover, the genotype maintained better sucrose and purity percentages under control (21.36, 93.09) and salinity (21.2, 92.95). Pooled Analysis of Variance revealed significant effects of genotype, treatment, and genotype × treatment interaction for most morpho-physiological and biochemical traits (P ≤ 0.05). Principal component analysis revealed that PC1 (20.4%) and PC2 (18.6%) together accounted for 40.2% of the overall variation. Brix, Purity, Cane diameter, sucrose %, purity %, Root dry weight, K+ accumulation and all stress-responsive genes were positively associated with TSGS 22-385. At the molecular level, TSGS 22-385 showed strong upregulation in the Na⁺/H⁺ exchanger (5.69-fold), suggesting a potential role of NHX-mediated Na⁺ sequestration in vacuolar compartments in limiting cytosolic ion toxicity. Overall, TSGS 22-385 stands out as a promising tolerant genotype for superior growth, physiological, ionic, root architecture and molecular responses under saline conditions.

SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at https://doi.org/10.1007/s13205-026-05085-3.