Functional Characterization and Evolutionary Analysis of Glycine-Betaine Biosynthesis Pathway in Red Seaweed Pyropia yezoensis

Abstract

The red seaweed Pyropia yezoensis is an ideal research model for dissecting the molecular mechanisms underlying its robust acclimation to abiotic stresses in intertidal zones. Glycine betaine (GB) was an important osmolyte in maintaining osmotic balance and stabilizing the quaternary structure of complex proteins under abiotic stresses (drought, salinity, etc.) in plants, animals, and bacteria. However, the existence and possible functions of GB in Pyropia remain elusive. In this study, we observed the rapid accumulation of GB in desiccated Pyropia blades, identifying its essential roles in protecting Pyropia cells against severe osmotic stress. Based on the available genomic and transcriptomic information of Pyropia, we computationally identified genes encoding the three key enzymes in the GB biosynthesis pathway: phosphoethanolamine N-methyltransferase (PEAMT), choline dehydrogenase (CDH), and betaine aldehyde dehydrogenase (BADH). Pyropia had an extraordinarily expanded gene copy number of CDH (up to seven) compared to other red algae. Phylogeny analysis revealed that in addition to the one conservative CDH in red algae, the other six might have originated from early gene duplication events. In dehydration stress, multiple CDH paralogs and PEAMT genes were coordinating up-regulated and shunted metabolic flux into GB biosynthesis. An elaborate molecular mechanism might be involved in the transcriptional regulation of these genes.

Comparative Quantitative Proteomics Reveals the Desiccation Stress Responses of the Intertidal Seaweed NEOPORPHYRA haitanensis

“…Each thallus was weighed, spread in a glass dish, and then exposed to air in the incubator. The sample was collected when its water loss based on weight was 30%, 50%, or 80%, as described in Mao et al (2019). The exposure times required for achieving 30%, 50%, and 80% water loss were 5-6 min, 10-15 min, and 30-40 min, respectively.…”

Ascophyllum nodosum-Based Biostimulants: Sustainable Applications in Agriculture for the Stimulation of Plant Growth, Stress Tolerance, and Disease Management

“…Sugar accumulation maintains total osmotic potential in plant cells during salt stress (Shukla et al, 2011). In addition to their role in osmotic adjustments, the availability and inter-organ transport of sugars play an important regulatory role in salt-stressed plants (Hare et al, 1998). The data reported by Elansary et al (2017) indicated that ANE treatments enhanced the total non-structural carbohydrates in turf grass exposed to prolonged salinity, by increasing photochemical efficiency.…”

Overexpression of the pitaya phosphoethanolamine N-methyltransferase gene (HpPEAMT) enhanced simulated drought stress in tobacco

“…6 MDA (a) content and SOD (b) and POD (c) activity in WT and T2 transgenic lines (L10, L11 and L16) exposed to PEG (− 4.9 MPa) at different time points. Data are the means ± SEs of three biological replicates; asterisks indicate significant differences (*p < 0.05, **p < 0.01) in comparison with the wild type significantly upregulated in pitaya under drought stress (Fan et al 2014), and the same phenomenon has also been documented in red seaweed (Mao et al 2019). Therefore, PEAMT is possibly responsive to drought stress and may be useful in genetic engineering to improve the drought tolerance ability of plants.…”