The chloroplast plays a pivotal role in photosynthesis. In particular, oxygen production and carbon dioxide sequestration via photosynthesis are key functions that would solve the global climate crisis. In addition, chloroplasts can provide an ideal platform for biomolecule syntheses as a host, because of its simple genome as well as higher gene expression level. Hence, the chloroplast engineering has received great attention recently. According to previous reports, unfortunately, isolated chloroplasts failed to maintain the intact metabolism due to lack of metabolites provided from other organelles including a nucleus. One of promising technologies to prolong the chloroplast metabolism is enveloping. Several studies have reported that immobilized or entrapped chloroplasts showed a longer photosynthetic activity than that of simply suspended chloroplasts in an incubation medium. Nevertheless, the effect of immobilization condition on chloroplast activity was rarely studied. Therefore, in this study, we analyze the photosynthetic gene expressions of<i> Nicotiana Tabacum</i> chloroplasts encapsulated in pectin hydrogels using RT-qPCR method. The shear modulus of a chloroplast-laden hydrogel was modulated in the range of 1000–5000 pa. In particular, the lowest modulus was well matched to the plant cytosol modulus. Under light exposure, the green color of the chloroplast-laden hydrogel was bleached out gradually and the higher stiffness of hydrogel did not rescue the decreased chlorophyll concentration. In photosynthetic gene expression analysis, the relative mRNA gene expression levels of specific genes that are related to PSI & II, cytochrome, and Calvin cycle were increased in spite of a significant decrease in chlorophyll concentration. Interestingly, the upregulated gene expression was obviously dependent on the pectin-norbornene prepolymer concentration. This means the stiffness of matrix played a key role in regulation of plastid gene expression of the encapsulated chloroplasts.

Photosynthesis-specific gene expressions of chloroplasts encapsulated in a cytosol mimetic-pectin hydrogel

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