Abstract:
Objective This study aimed to analyze the physiological responses and variation patterns of flavonoids in Xanthoceras sorbifolium Bunge leaves under salt spray stress, so as to provide a theoretical basis for exploring the salt resistance mechanism of Xanthoceras sorbifolium Bunge.
Methods Based on two-year-old Xanthoceras sorbifolium Bunge seedlings, saturated NaCl solution was sprayed at 0 d, 2 d, and 4 d. The growth status of seedlings and leaf stomata were observed; physiological indicators related to salt stress (including SOD activity, MDA content, soluble sugar content, and proline content) and the content changes of flavonoid components (quercetin, kaempferol, luteolin, gallocatechin, epicatechin gallate, and epigallocatechin) in leaves were determined.
Results Salt spray stress reduced the stomatal conductance of Xanthoceras sorbifolium Bunge leaves. Compared with the control, SOD activity, MDA content, soluble sugar content, and proline content increased significantly, and showed an overall upward trend with prolonged stress duration. However, the increase rate of these physiological indices during the mild stress stage (0~2 d) was significantly higher than that during the severe stress stage (2~4 d). The contents of individual flavonoid components and total flavonoids in leaves initially decreased and then increased with increasing stress duration. Furthermore, total flavonoid content was positively correlated with kaempferol, epicatechin gallate, and epigallocatechin.
Conclusion Xanthoceras sorbifolium Bunge leaves adapt to salt spray stress through physiological responses such as increasing SOD activity, MDA content, soluble sugar content, and proline content, and reduced stomatal conductance. The synergistic changes between physiological indicators and flavonoid contents are involved in the stress response process. These findings provide a scientific basis for exploring the salt resistance mechanism of Xanthoceras sorbifolium Bunge and breeding germplasm with high flavonoid content.
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