Chlorophyll (Chl) degradation was found to be related to the endogenous gibberellin (GA) content in shoots during senescence in the perennial plant Paris polyphylla var. yunnanensis (Franch.). Treatment with gibberellic acid (GA 3 ) significantly increased the content of endogenous GAs (GA 4 + GA 7 ), retarded the senescence of shoots, and the degradation of proteins and Chl. Chlorophyllase, Mg-dechelation and peroxidase activities increased more in control plants than in those treated with GA 3 . GA 3 treatment also protected lipoxygenase activity, which decreased significantly in control plants.

Nitrogen remobilization during senescence has been studied in perennial herb Paris polyphylla. We analyzed changes in N content, amino acids, N-remobilization enzymes and effects of gibberellic acid (GA) during natural senescence. There was a gradual decrease in the content of N, chlorophyll and soluble proteins and activities of glutamine synthetase (GS; EC 6.3.1.2) and glutamate dehydrogenase (GLDH; EC 1.4.1.2). Activity staining and Western blots showed that GS2 activity decreased, whereas GS1 activity was relatively stable over time. In contrast, the C/N ratio and total amino acid content increased. Among individual amino acids, the proportions of glutamine (Gln) and asparagine (Asn) increased, and proportions of arginine, aspartate and glycine decreased. Treatment with GA slowed the senescence and retarded decreases in the activities of GS and GLDH and the content of N, chlorophyll and soluble proteins. Conversely, this treatment slowed increases in the C/N ratio, total free amino acid content, and proportions of Gln and Asn. We conclude that low N resorption efficiency during senescence of P. polyphylla results from a sharp decrease in N remobilization enzyme activity.Additional key words: C/N ratio, glutamate dehydrogenase, glutamine synthetase, nitrogen resorption efficiency.