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Ascorbate‐glutathione cycle and H 2 O 2 detoxification in elongating leaf bases of ryegrass: effect of inhibition of glutathione reductase activity on foliar regrowth
Author(s) -
Piquery Laurent,
Huault Claude,
Billard JeanPierre
Publication year - 2002
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2002.1160317.x
Subject(s) - glutathione , glutathione reductase , pentose phosphate pathway , meristem , antioxidant , buthionine sulfoximine , chemistry , biochemistry , botany , enzyme , biology , shoot , glycolysis , glutathione peroxidase
The role of the ascorbate‐glutathione cycle and AOS detoxification was investigated during leaf growth of defoliated and undefoliated plants of ryegrass ( Lolium perenne L. cv. Bravo). Antioxidants and related enzymatic activities were located in elongating leaf bases (ELBs) of undefoliated plants, following a decreasing gradient from basal (meristem) to distal segments, inverse to H 2 O 2 levels. In the meristematic zone, the intense activity of the ascorbate‐glutathione cycle and the supply of reducing power by the oxidative pentose phosphate pathway allowed the maintenance of both antioxidant reduction and H 2 O 2 detoxification. BCNU (1–3 bis(2‐chloroethyl)‐ N ‐nitrosourea), a glutathione reductase inhibitor, induced an increase in the meristematic zone in both H 2 O 2 and antioxidant levels and a decrease in reduced/oxidized ratios of glutathione and ascorbate. These changes were associated with a reduced foliar regrowth activity. In the absence of BCNU, defoliation did not modify the ratios of reduced/oxidized antioxidants, although it triggered a temporary increase in H 2 O 2 level. The results are discussed on the basis of a possible control of leaf growth by glutathione and ascorbate.