Carbon sink strength of nodules but not other organs modulates photosynthesis of faba bean (Vicia faba) grown under elevated [CO2] and different water supply. Issue 1 (14th April 2020)

• Record Type: Journal Article
• Authors: Parvin, Shahnaj; Uddin, Shihab; Tausz‐Posch, Sabine; Armstrong, Roger; Tausz, Michael
• Is Part Of: New phytologist. Volume 227:Issue 1(2020)
• Page Start: 132
• Page End: 145
• Publication Date: 2020-04-14
• Subjects: 13C allocation -- climate change -- drought -- legume -- N2 feedback mechanism -- photosynthetic acclimation -- root exudates -- sink limitation; Botany -- Periodicals; 580
• DOI: 10.1111/nph.16520
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: Photosynthetic stimulation by elevated [CO2 ] (e[CO2 ]) may be limited by the capacity of sink organs to use photosynthates. In many legumes, N2 ‐fixing symbionts in root nodules provide an additional sink, so that legumes may be better able to profit from e[CO2 ]. However, drought not only constrains photosynthesis but also the size and activity of sinks, and little is known about the interaction of e[CO2 ] and drought on carbon sink strength of nodules and other organs. To compare carbon sink strength, faba bean was grown under ambient (400 ppm) or elevated (700 ppm) atmospheric [CO2 ] and subjected to well‐watered or drought treatments, and then exposed to 13 C pulse‐labelling using custom‐built chambers to track the fate of new photosynthates. Drought decreased 13 C uptake and nodule sink strength, and this effect was even greater under e[CO2 ], and was associated with an accumulation of amino acids in nodules. This resulted in decreased N2 fixation, and increased accumulation of new photosynthates ( 13 C/sugars) in leaves, which in turn can feed back on photosynthesis. Our study suggests that nodule C sink activity is key to avoid sink limitation in legumes under e[CO2 ], and legumes may only be able to achieve greater C gain if nodule activity is maintained.