Knockdown of glycine decarboxylase complex alters photorespiratory carbon isotope fractionation in Oryza sativa leaves
Journal
Journal of Experimental Botany
Journal Volume
70
Journal Issue
10
Start Page
2773
End Page
2786
ISSN
1460-2431
1754-6621
0022-0957
Date Issued
2019-03-06
Author(s)
Giuliani,Rita
Karki,Shanta
Covshoff,Sarah
Coe,Robert A
Koteyeva,Nuria K
Quick,W Paul
Caemmerer,Susanne Von
Furbank,Robert T
Hibberd,Julian M
Edwards,Gerald E
Cousins,Asaph B
Abstract
The influence of reduced glycine decarboxylase complex (GDC) activity on leaf atmosphere CO2 and 13CO2 exchange was tested in transgenic Oryza sativa with the GDC H-subunit knocked down in leaf mesophyll cells. Leaf measurements on transgenic gdch knockdown and wild-type plants were carried out in the light under photorespiratory and low photorespiratory conditions (i.e. 18.4 kPa and 1.84 kPa atmospheric O2 partial pressure, respectively), and in the dark. Under approximately current ambient O2 partial pressure (18.4 kPa pO2), the gdch knockdown plants showed an expected photorespiratory-deficient phenotype, with lower leaf net CO2 assimilation rates (A) than the wild-type. Additionally, under these conditions, the gdch knockdown plants had greater leaf net discrimination against 13CO2 (Δo) than the wild-type. This difference in Δo was in part due to lower 13C photorespiratory fractionation (f) ascribed to alternative decarboxylation of photorespiratory intermediates. Furthermore, the leaf dark respiration rate (Rd) was enhanced and the 13CO2 composition of respired CO2 (δ13CRd) showed a tendency to be more depleted in the gdch knockdown plants. These changes in Rd and δ13CRd were due to the amount and carbon isotopic composition of substrates available for dark respiration. These results demonstrate that impairment of the photorespiratory pathway affects leaf 13CO2 exchange, particularly the 13C decarboxylation fractionation associated with photorespiration.
Subjects
13C discrimination
C4 photosynthesis
CO2 exchange
GDC knockdown
leaf dark respiration
photorespiration
rice
SDGs
Publisher
Oxford University Press
Type
journal article