Role of Petiole in Protein Metabolism of Senescing Betel (Piper betle L.) Leaves.

Effects of depetiolation on protein metabolism during senescence of detached betel (Piper betle L.) leaves have been studied. In normal petiolated leaves, the level of chlorophyll and proteins and extent of protein synthesis declined, while the protease activity registered manifold increase with the advancement of senescence. All of these changes were delayed by depetiolation/de-midribbing treatments, though without affecting the general pattern of senescence. Thus, the presence of petiole seems to expedite protein degradation, probably due to earlier attainment of optimal concentration of proposed senescence factor(s) (Mishra and Gaur 1970 Science 167: 387).