A novel chloroplast super-complex consisting of the ATP synthase and photosystem I reaction center

Recent developments in the engineering of Rubisco activase for enhanced crop yield

Rubisco activase (RCA) catalyzes the release of inhibitory sugar phosphates from ribulose-1,6-biphosphate carboxylase/oxygenase (Rubisco) and can play an important role in biochemical limitations of photosynthesis under dynamic light and elevated temperatures. There is interest in increasing RCA activity to improve crop productivity, but a lack of understanding about the regulation of photosynthesis complicates engineering strategies. In this review, we discuss work relevant to improving RCA with a focus on advances in understanding the structural cause of RCA instability under heat stress and the regulatory interactions between RCA and components of photosynthesis. This reveals substantial variation in RCA thermostability that can be influenced by single amino acid substitutions, and that engineered variants can perform better in vitro and in vivo under heat stress. In addition, there are indications RCA activity is controlled by transcriptional, post-transcriptional, post-translational, and spatial regulation, which may be important for balancing between carbon fixation and light capture. Finally, we provide an overview of findings from recent field experiments and consider the requirements for commercial validation as part of efforts to increase crop yields in the face of global climate change.

Metabolome and transcriptome profiles in quinoa seedlings in response to potassium supply

BACKGROUND

Quinoa (Chenopodium quinoa Willd.) is a herb within the Quinoa subfamily of Amaranthaceae, with remarkable environmental adaptability. Its edible young leaves and grains are rich in protein, amino acids, microorganisms, and minerals. Although assessing the effects of fertilization on quinoa yield and quality has become an intensive area of research focus, the associated underlying mechanisms remain unclear. As one of the three macro nutrients in plants, potassium has an important impact on plant growth and development. In this study, extensive metabolome and transcriptome analyses were conducted in quinoa seedlings 30 days after fertilizer application to characterize the growth response mechanism to potassium.  RESULTS: The differential metabolites and genes present in the seedlings of white and red quinoa cultivars were significantly enriched in the photosynthetic pathway. Moreover, the PsbQ enzyme on photosystem II and delta enzyme on ATP synthase were significantly down regulated in quinoa seedlings under potassium deficiency. Additionally, the differential metabolites and genes of red quinoa seedlings were significantly enriched in the arginine biosynthetic pathway.

CONCLUSIONS

These findings provide a more thorough understanding of the molecular changes in quinoa seedlings that occur under deficient, relative to normal, potassium levels. Furthermore, this study provides a theoretical basis regarding the importance of potassium fertilizers, as well as their efficient utilization by growing quinoa seedlings.

Insight into the regulatory networks underlying the high lipid perennial ryegrass growth under different irradiances

Under favourable conditions, perennial ryegrass (Lolium perenne) engineered to accumulated high lipid (HL) carbon sink in their leaves was previously shown to also enhance photosynthesis and growth. The greater aboveground biomass was found to be diminished in a dense canopy compared to spaced pots. Besides, the underlying genetic regulatory network linking between leaf lipid sinks and these physiological changes remains unknown. In this study, we demonstrated that the growth advantage was not displayed in HL Lolium grown in spaced pots under low lights. Under standard lights, analysis of differentiating transcripts in HL Lolium reveals that the plants had elevated transcripts involved in lipid metabolism, light capturing, photosynthesis, and sugar signalling while reduced expression of genes participating in sugar biosynthesis and transportation. The plants also had altered several transcripts involved in mitochondrial oxidative respiration and redox potential. Many of the above upregulated or downregulated transcript levels were found to be complemented by growing the plants under low light. Overall, this study emphasizes the importance of carbon and energy homeostatic regulatory mechanisms to overall productivity of the HL Lolium through photosynthesis, most of which are significantly impacted by low irradiances.

Analysis of Cyclocarya paliurus flavonoids modulation on the physiology and gene expression in Enterococcus faecalis under bile salt stress

Enterococcus faecalis (E. faecalis) is one of the probiotic groups in the intestinal tract which has varieties of functional effects in the host, such as a protective barrier, nutritional efficacy and antibacterial effects. Stress conditions such as low pH, bile salts, and hypertonicity are inevitable negative factors for the normal survival of E. faecalis in the gastrointestinal tract. Under the stress and inhibition of bile salt, E. faecalis needs specific adaptation and coping style if it wants to successfully colonize the intestine stably. The appropriate concentration of flavonoids can assist probiotics to serve a beneficial role and help them resist the stress of external irresistible environmental factors. In the present research, RNA-sequence (RNA-seq) technology was employed to investigate the influence of Cyclocarya paliurus flavonoids (CPF) on Enterococcus faecalis 131-2 (E. faecalis 131-2) exposed to bile salt stress. Analysis results revealed that under bile salt stress, many genes related to cellular process, catalytic activity, and transport activity were significantly differentially expressed (P < 0.05), and some not expected variations of which could be partly alleviated by supplementation of CPF, indicating its capacity to improve the bile salt tolerances of E. faecalis 131-2. Additionally, CPF alleviated the obvious inhibitory effects of bile salt stress on the exponential growth of E. faecalis 131-2. An overall view of the physiological and transcriptomic changes of E. faecalis 131-2 under bile salt stresses with or without CPF will further deepen our understanding of the mechanism by which CPF assists E. faecalis 131-2 to perform beneficial functions in the gastrointestinal environment.