Premium
The alternative oxidase in roots of Poa annua after transfer from high‐light to low‐light conditions
Author(s) -
Millenaar Frank F.,
Roelofs Roeland,
GonzàlezMeler Miquel A.,
Siedow James N.,
Wagner Anneke M.,
Lambers Hans
Publication year - 2000
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2000.00832.x
Subject(s) - poa annua , chemistry , botany , biology , poaceae
Summary The activity of the alternative pathway can be affected by a number of factors, including the amount and reduction state of the alternative oxidase protein, and the reduction state of the ubiquinone pool. To investigate the importance of these factors in vivo , we manipulated the rate of root respiration by transferring the annual grass Poa annua L. from high‐light to low‐light conditions, and at the same time from long‐day to short‐day conditions for four days. As a result of the low‐light treatment, the total respiration rate of the roots decreased by 45%, in vitro cytochrome c oxidase capacity decreased by 49%, sugar concentration decreased by 90% and the ubiquinone concentration increased by 31%, relative to control values. The absolute rate of oxygen uptake via the alternative pathway, as determined using the 18 O‐isotope fractionation technique, did not change. Conversely, the cytochrome pathway activity decreased during the low‐light treatment; its activity increased upon addition of exogenous sugars to the roots. Interestingly, no change was observed in the concentration of the alternative oxidase protein or in the reduction state of the protein. Also, there was no change in the reduction state of the ubiquinone pool. In conclusion, the concentration and activity of the alternative oxidase were not changed, even under severe light deprivation.