salt-induced alternations in the content of secondary metabolites and antioxidant responses of guava seedlings

Guava (psidium guajava l.) is adapted to an extensive range of soils. however, its development is strongly affected by salinity. environmental stresses are of the major and influential factors in the amount of plant secondary metabolites, especially phenolic compounds. the purpose of this investigation was to study the leaf antioxidant and flavonoid contents (catechin, quercetin and rutin) of guava seedlings grown under 0 and 100 mm of nacl treatment. leaf samples collected 12 weeks after salinity stress treatment and total phenol, antioxidant capacity, malondialdehyde, catalase, peroxidase and protease activities and high performance liquid chromatography were examined. the research was conducted in a completely randomized block design and duncan test was used for mean comparison. according to the results, salinity enhanced total phenol content amount 2.09 times. the mda value improved in guava leaves from 0.42 mg g-1 fw under non-stress conditions to 0.76 mg g1 fw under salinity. the most catalase (182.11 μmol min-1 g-1 fw), protease (9.70 μmol min-1 g-1 fw) and peroxidase (19.99 μmol min-1 g-1 fw) activities were observed in salt exposed plants. the antioxidant capacity of the leaf extract was 62.90% in the control plants, which enhanced to 77.46% after salt treatment. the most abundant flavonoid composition of the leaf extract was rutin (770 μg mg-1 dw) in the control treatment and catechin (1110 μg mg-1 dw) in salt exposed plants. we concluded that salinity stress, in addition to a noticeable increase in the activities of catalase, peroxidase and protease enzymes, enhanced phenol, catechin and quercetin contents.

salt-induced alternations in the content of secondary metabolites and antioxidant responses of guava seedlings

guava (psidium guajava l.) is adapted to an extensive range of soils. however, its development is strongly affected by salinity. environmental stresses are of the major and influential factors in the amount of plant secondary metabolites, especially phenolic compounds. the purpose of this investigation was to study the leaf antioxidant and flavonoid contents (catechin, quercetin and rutin) of guava seedlings grown under 0 and 100 mm of nacl treatment. leaf samples collected 12 weeks after salinity stress treatment and total phenol, antioxidant capacity, malondialdehyde, catalase, peroxidase and protease activities and high performance liquid chromatography were examined. the research was conducted in a completely randomized block design and duncan test was used for mean comparison. according to the results, salinity enhanced total phenol content amount 2.09 times. the mda value improved in guava leaves from 0.42 mg g-1 fw under non-stress conditions to 0.76 mg g1 fw under salinity. the most catalase (182.11 μmol min-1 g-1 fw), protease (9.70 μmol min-1 g-1 fw) and peroxidase (19.99 μmol min-1 g-1 fw) activities were observed in salt exposed plants. the antioxidant capacity of the leaf extract was 62.90% in the control plants, which enhanced to 77.46% after salt treatment. the most abundant flavonoid composition of the leaf extract was rutin (770 μg mg-1 dw) in the control treatment and catechin (1110 μg mg-1 dw) in salt exposed plants. we concluded that salinity stress, in addition to a noticeable increase in the activities of catalase, peroxidase and protease enzymes, enhanced phenol, catechin and quercetin contents.