6-Benzylaminopurine as a potential fresh-keeping agent for Curcuma alismatifolia cut flowers: Physiological and transcriptome analysis

Curcuma alismatifolia is a significant cut flower, but its postharvest preservation remains challenging. 6-benzyla-minopurine (6-BA) can effectively delay senescence in various horticultural plants. This study demonstrated that soaking and spraying 6-BA significantly extended the vase life of four C. alismatifolia varieties, particularly 'Siam Shadow', which had the longest vase life extension of 5.1 days by spraying and 3.7 days by soaking. Further analyses of physiological, biochemical, and transcriptomic indicators were conducted on the bracts of 'Siam Shadow' under 50 mg/L 6-BA spraying treatment and control at three senescence stages: S1 (4th day), S2 (8th day), and S3 (12th day) after vase placement. The results indicated that 6-BA spraying increased superoxide dismutase (SOD) and catalase (CAT) activities in S1 and S2 while increasing peroxidase (POD) and decreasing jasmonic acid (JA) contents in all stages. Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA) identified JA content as the key differential indicator of 6-BA treatment. Transcriptome analysis revealed that 6 -BA treatment upregulated 102 antioxidant-related genes and downregulated 27 JA biosynthesis-related genes and 16 JA signal transduction-related genes in all stages. Among them, the gene families of POD, LOX, and JAZ, which are involved in peroxidase activity, JA biosynthesis, and JA signal transduction, respectively, may play major roles in delaying C. alismatifolia bract senescence. Moreover, correlation network analysis showed that 198 senescence-related transcription factors (WRKYs, NACs, etc.) were significantly correlated with 77 antioxidant-related genes, 22 JA biosynthesis-related genes, and 12 JA signal transduction-related genes. These findings suggest that 6-BA is a potential preservative for C. alismatifolia cut flowers and that it may primarily affect the expression of genes related to senescence-associated transcription factors, JA biosynthesis and signal trans-duction, and antioxidant enzymes, thereby reducing JA content and enhancing antioxidant enzyme activities, consequently delaying C. alismatifolia bract senescence.

Automated summary

This study found that soaking and spraying 6-BA can significantly extend the vase life of Curcuma alismatifolia cut flowers, particularly the variety 'Siam Shadow'. Physiological, biochemical, and transcriptomic analyses revealed the involvement of antioxidant enzymes, jasmonic acid, and senescence-associated transcription factors in delaying bract senescence. The findings suggest that 6-BA can act as a potential preservative by affecting gene expression related to JA biosynthesis and signal transduction, antioxidant enzymes, and senescence-associated transcription factors.