Reversible Burst of Transcriptional Changes during Induction of Crassulacean Acid Metabolism in Talinum triangulare

Abstract

Drought tolerance is a key factor for agriculture in the 21st century as it is a major determinant of plant survival in natural ecosystems as well as crop productivity. Plants have evolved a range of mechanisms to cope with drought, including a specialized type of photosynthesis termed Crassulacean acid metabolism (CAM). CAM is associated with stomatal closure during the day as atmospheric CO 2 is assimilated primarily during the night, thus reducing transpirational water loss. The tropical herbaceous perennial species Talinum triangulare is capable of transitioning, in a facultative, reversible manner, from C 3 photosynthesis to weakly expressed CAM in response to drought stress. The transcriptional regulation of this transition has been studied. Combining mRNA-Seq with targeted metabolite measurements, we found highly elevated levels of CAM-cycle enzyme transcripts and their metabolic products in T. triangulare leaves upon water deprivation. The carbohydrate metabolism is rewired to reduce the use of reserves for growth to support the CAM-cycle and the synthesis of compatible solutes. This large-scale expression dataset of drought-induced CAM demonstrates transcriptional regulation of the C 3 -CAM transition. We identified candidate transcription factors to mediate this photosynthetic plasticity, which may contribute in the future to the design of more drought-tolerant crops via engineered CAM.

Effect of Topical Iloprost and Nitroglycerin on Gastric Microcirculation and Barrier Function during Hemorrhagic Shock in Dogs

“…Blood samples were collected under baseline conditions and during hemorrhagic shock. The collected samples were prepared as previously described [27]. Briefly, blood samples were stored in small tubes (Vacutainer K2E EDTA 18.0 mg, Plymouth, UK) and plasma was separated via centrifugation at 0°C and 3,000 g for 15 min (Rotina 420R, Hettich Zentrifugen, Mülheim a. d. R., Germany).…”

“…The liquid supernatant was collected, degassed with a gentle stream of nitrogen (compressed nitrogen, Linde AG, Pullach, Germany) and stored at -80°C for later analysis. The extracts were dried using a speed vacuum concentrator, measured by gas chromatography-mass spectrometry (GC-MS) and analyzed using the MassHunter software (Agilent Technologies) [27]. Results are normalized to the internal standard and presented as relative amounts per microliter of blood plasma.…”

On the Evolutionary Origin of CAM Photosynthesis

“…CAM photosynthesis may be facultative, that is, induced environmentally and reversibly (i.e. Talinum triangulare [Brilhaus et al, 2016], Mesembryanthemum [Winter and Holtum, 2014]), or obligatory (Silvera et al, 2010). CAM plants also display great variation in their CO 2 fixation efficiency with some species only cycling, i.e.…”

Photorespiration Is Crucial for Dynamic Response of Photosynthetic Metabolism and Stomatal Movement to Altered CO 2 Availability

“…The emergency strategy indicated in the response (i.e., shutdown of growth, assimilation and major transcriptional investment pathways, breakdown of components), which serves plants well during temporary drought stress (Brilhaus et al, 2016), is not successful in the short term but can be in the long run. Although the block in PR leads to chlorosis and stunted to aborted growth in source leaves of the strong mutants ( Figure 6) a few days after the shift from HC to LC conditions (Boldt et al, 2005;Voll et al, 2006;Schwarte and Bauwe, 2007;Timm et al, 2012), the strong mutants, except pglp1 , survive after a long-term acclimation phase as long as light conditions are not prohibitive.…”