Abstract
When mulberry leaves were irradiated with UV for various durations, the prolonged UV exposure significantly increased the level of proline as compared to the control plants. Also, the lipid peroxidation increased in the UV stressed plants. Moreover, the level of proline in treated leaf tissues increased within 5 h of incubation and reached a maximum level in 25 h. Conversely, mulberry moracins began accumulating after 20 h of UV stress. The transition in the lipid peroxidation began to decrease when moracins began to accumulate, suggesting that moracins have a protective role in UV stressed plants. The results obtained in this study imply that both proline and mulberry moracins are free radical quenchers. However, moracins were ∼1000 times more effective than proline in scavenging activity, suggesting that proline may be a primary protectant, and moracins, which accumulate at a later stage under UV-stress, act as a secondary protectant.
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