Plant and Cell Physiology, 1967, Vol. 8, No. 3 423-432
© 1967
Article |
RESPIRATORY METABOLISM IN THE PHLOEM, XYLEM AND CAMBIUM OF CARROT ROOT
Department of Botany, Faculty of Science, University of Tokyo Hongo, Tokyo
Comparisons of respiratory metabolism among the phloem, cambium and xylem of mature carrot root were carried out and the following results were obtained.
1) The activity of O2 uptake on a dry weight basis in the cambium was higher than that in the xylem. The phloem showed the lowest activity. 2) RQ was close to unity in all the three tissues. 3) The inhibition rate of O2 uptake by malonate was considerably high in the three tissues. The highest inhibition was observed in the cambium. 4) In the phloem and xylem the malonic inhibition rate of 14CO2 release from G-U-14C was not so high as compared with that of O2 uptake. In the cambium, however, those of O2 uptake and 14CO2 output were comparable. 5) Malonate treatment did not cause any significant change in RQ. 6) The C6/C1 ratio was highest in the cambium and lowest in the phloem.
From these it is concluded that the participation of the TCA cycle in respiration is great in all the three tissues of carrot root, and among the three the cambium has the highest activity of the cycle. As for the PP pathway, the xylem and phloem have a higher activity than the cambium.
(Received April 11, 1967; )
![]()
CiteULike
Connotea
Del.icio.us What's this?