Investigating the impact of silencing an RNA-binding protein gene SlRBP1 on tomato photosynthesis through RNA-sequencing analysis / 生物工程学报

Photosynthesis in plants directly affects the synthesis and accumulation of organic matter, which directly influences crop yield. RNA-binding proteins (RBPs) are involved in the regulation of a variety of physiological functions in plants, while the functions of RBPs in photosynthesis have not been clearly elucidated. To investigate the effect of a glycine-rich RNA-binding protein (SlRBP1) in tomato on plant photosynthesis, a stably inherited SlRBP1 silenced plant in Alisa Craig was obtained by plant tissue culture using artificial small RNA interference. It turns out that the size of the tomato fruit was reduced and leaves significantly turned yellow. Chlorophyll(Chl) content measurement, Chl fluorescence imaging and chloroplast transmission electron microscopy revealed that the chloroplast morphology and structure of the leaves of tomato amiR-SlRBP1 silenced plants were disrupted, and the chlorophyll content was significantly reduced. Measurement of photosynthesis rate of wild-type and amiR-SlRBP1 silenced plants in the same period demonstrated that the photosynthetic rate of these plants was significantly reduced, and analysis of RNA-seq data indicated that silencing of SlRBP1 significantly reduced the expression of photosynthesis-related genes, such as PsaE, PsaL, and PsbY, and affected the yield of tomato fruits through photosynthesis.

Characterization the response of Chlamydomonas reinhardtii serine/threonine protein kinase mutant to blue light / 生物工程学报

In order to investigate the molecular mechanism of silk/threonine protein kinase (STK)-mediated blue light response in the algal Chlamydomonas reinhardtii, phenotype identification and transcriptome analysis were conducted for C. reinhardtii STK mutant strain crstk11 (with an AphvIII box reverse insertion in stk11 gene coding region) under blue light stress. Phenotypic examination showed that under normal light (white light), there was a slight difference in growth and pigment contents between the wild-type strain CC5325 and the mutant strain crstk11. Blue light inhibited the growth and chlorophyll synthesis in crstk11 cells, but significantly promoted the accumulation of carotenoids in crstk11. Transcriptome analysis showed that 860 differential expression genes (DEG) (559 up-regulated and 301 down-regulated) were detected in mutant (STK4) vs. wild type (WT4) upon treatment under high intensity blue light for 4 days. After being treated under high intensity blue light for 8 days, a total of 1 088 DEGs (468 upregulated and 620 downregulated) were obtained in STK8 vs. WT8. KEGG enrichment analysis revealed that compared to CC5325, the crstk11 blue light responsive genes were mainly involved in catalytic activity of intracellular photosynthesis, carbon metabolism, and pigment synthesis. Among them, upregulated genes included psaA, psaB, and psaC, psbA, psbB, psbC, psbD, psbH, and L, petA, petB, and petD, as well as genes encoding ATP synthase α, β and c subunits. Downregulated genes included petF and petJ. The present study uncovered that the protein kinase CrSTK11 of C. reinhardtii may participate in the blue light response of algal cells by mediating photosynthesis as well as pigment and carbon metabolism, providing new knowledge for in-depth analysis of the mechanism of light stress resistance in the algae.

Advances in using adaptive laboratory evolution technology for engineering of photosynthetic cyanobacteria / 生物工程学报

Cyanobacteria are the only prokaryotes capable of oxygenic photosynthesis, which have potential to serve as "autotrophic cell factories". However, the synthesis of biofuels and chemicals using cyanobacteria as chassis are suffered from poor stress tolerance and low yield, resulting in low economic feasibility for industrial production. Thus, it's urgent to construct new cyanobacterial chassis by means of synthetic biology. In recent years, adaptive laboratory evolution (ALE) has made great achievements in chassis engineering, including optimizing growth rate, increasing tolerance, enhancing substrate utilization and increasing product yield. ALE has also made some progress in improving the tolerance of cyanobacteria to high light intensity, heavy metal ions, high concentrations of salt and organic solvents. However, the engineering efficiency of ALE strategy in cyanobacteria is generally low, and the molecular mechanisms underpinning the tolerance to various stresses have not been fully elucidated. To this end, this review summarizes the ALE-associated technical strategies and their applications in cyanobacteria chassis engineering, following by discussing how to construct larger ALE mutation library, increase mutation frequency of strains and shorten evolution time. Moreover, exploration of the construction principles and strategies for constructing multi-stress tolerant cyanobacteria, and efficient analysis the mutant libraries of evolved strains as well as construction of strains with high yield and strong robustness are discussed, with the aim to facilitate the engineering of cyanobacteria chassis and the application of engineered cyanobacteria in the future.

Physiological and transcriptional responses to heat stress in a typical phenotype of Pinellia ternata / 中国天然药物

Pinellia ternata is an important medicinal plant, and its growth and development are easily threatened by high temperature. In this study, comprehensive research on physiological, cytological and transcriptional responses to different levels of heat stress were conducted on a typical phenotype of P. ternata. First, P. ternata exhibited tolerance to the increased temperature, which was supported by normal growing leaves, as well as decreased and sustained photosynthetic parameters. Severe stress aggravated the damages, and P. ternata displayed an obvious leaf senescence phenotype, with significantly increased SOD and POD activities (46% and 213%). In addition, mesophyll cells were seriously damaged, chloroplast thylakoid was fuzzy, grana lamellae and stroma lamellae were obviously broken, and grana thylakoids were stacked, resulting in a dramatically declined photosynthetic rate (74.6%). Moreover, a total of 16 808 genes were significantly differential expressed during this process, most of which were involved in photosynthesis, transmembrane transporter activity and plastid metabolism. The number of differentially expressed transcription factors in MYB and bHLH families was the largest, indicating that these genes might participate in heat stress response in P. ternata. These findings provide insight into the response to high temperature and facilitate the standardized cultivation of P. ternata.

Incorporation of Na+/H+ antiporter gene from Aeluropus littoralis confers salt tolerance in soybean (Glycine max L.).

To develop a salt-tolerant soybean (Glycine max L.) cultivar, a minimal linear Na+/H+ antiporter gene cassette (35S CaMV promoter, open-reading-frame of AlNHX1 from Aeluropus littoralis and NOS terminator) was successfully expressed in soybean cultivar TF-29. Southern and Northern blot analysis showed that AlNHX1 was successfully incorporated into the genome and expressed in the transgenic plants. The AlNHX1 transgenic plant lines exhibited improved growth in severe saline condition (150 mM NaCl). The transgenic lines accumulated a lower level of Na+ and a higher level of K+ in the leaves than wild-type plants under saline condition (150 mM NaCl). Observations on the chlorophyll content, photosynthetic rates, malondialdehyde and relative electrical conductivity indicated that transgenic plants exhibited tolerance to salt stress, growing normally at salt concentrations up to 150 mM. These results demonstrated that AlNHX1 was successfully transferred into soybean and the salt-tolerance was improved by the overexpression of AlNHX1.

Analysis of the activity of promoters from two photosynthesis-related genes psaF and petH of spinach in a monocot plant, rice.

The subunit III of photosystem I and ferredoxin-NADP(+)-oxidoreductase are encoded by nuclear genes, namely psaF and petH. The activity of their promoters from spinach has been evaluated in transgenic tobacco earlier. Evaluation of the activity of these Dicotyledoneae-specific promoters has been carried out in a monocot system (i.e. rice) by transient gene expression system, based on electroporation-mediated gene delivery into protoplasts from leaves and roots. It has been found that various promoter deletions show higher activity in leaf protoplasts and elements for quantitative response are widely distributed. Transgenic rice has also been produced with a petH promoter and gus reporter gene construct. Although petH promoter is a weak promoter in comparison to the 35S promoter, it expresses well in green tissues and could be useful for plant genetic engineering.