Knockdown of glycine decarboxylase complex alters photorespiratory carbon isotope fractionation in Oryza sativa leaves. (6th March 2019)

• Record Type: Journal Article
• Authors: Giuliani, Rita; Karki, Shanta; Covshoff, Sarah; Lin, Hsiang-Chun; Coe, Robert A; Koteyeva, Nuria K; Quick, W Paul; Von Caemmerer, Susanne; Furbank, Robert T; Hibberd, Julian M; Edwards, Gerald E; Cousins, Asaph B
• Is Part Of: Journal of experimental botany. Volume 70:Number 10(2019)
• Page Start: 2773
• Page End: 2786
• Publication Date: 2019-03-06
• Subjects: 13C discrimination -- C4 photosynthesis -- CO2 exchange -- GDC knockdown -- leaf dark respiration -- photorespiration -- rice; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/erz083
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract : The disruption of photorespiration in GDC knockdown rice plants alters leaf photorespiratory 13 CO2 fractionation and carbon isotope exchange. Abstract: The influence of reduced glycine decarboxylase complex (GDC) activity on leaf atmosphere CO2 and 13 CO2 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 p O2 ), 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 13 CO2 (Δo ) than the wild-type. This difference in Δo was in part due to lower 13 C photorespiratory fractionation ( f ) ascribed to alternative decarboxylation of photorespiratory intermediates. Furthermore, the leaf dark respiration rate ( R d ) was enhanced and the 13 CO2 composition of respired CO2 (δ 13 CRd ) showed a tendency to be more depleted in the gdch knockdown plants. These changes in R d and δ 13 CRd 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 13 CO2 exchange, particularly the 13 C decarboxylation fractionation associated with photorespiration.