Identification of stress tolerance in cotton during the germination stage and analysis of its correlation with seed composition

Abstract Drought, salt and low-temperature stress significantly reduce the germination rate of cotton seeds. Additionally, the seed composition of seeds, including protein, oil and gossypol, are also closely linked to germination performance. This study assessed the seed composition of 120 cotton genotypes and their ability to germinate under drought, salt, and low-temperature stress, and compared with under standard conditions (control). Stress resistance during the germination stage was comprehensively evaluated using principal component analysis (PCA), which categorized the genotypes into three groups: 35 high-stress tolerance, 74 medium-stress tolerance and 11 medium sensitivity. Subordinate function analysis revealed that the comprehensive resistance D values of the 120 genotypes ranged from 0.20 to 1.12. Correlation analysis showed a significant negative correlation between seed oil content and germination under drought and salt stress ( R = −0.27** and R = −0.24**). Additionally, germination under drought and salt stress were positively correlated ( R = 0.58***). SNP_A07_90682411-based Kompetitive Allele-Specific PCR (KASP) markers identified that AA-type genotypes had significantly higher D values for comprehensive stress tolerance, drought resistance and salt resistance at the germination stage compared to GG-type genotypes ( P = 0.0003, P = 0.010, and P = 0.0004, respectively). This study identified highly resistant and sensitive genotypes to various abiotic stresses, during germination and demonstrated that the ability of the newly developed KASP molecular markers effectively differentiate comprehensive germination performance under stress. These findings provide valuable references for understanding stress tolerance mechanisms during germination and breeding stress-tolerant cotton varieties.