The ability of a plant to produce grain, fruit, or forage depends ultimately on photosynthesis. There have been few attempts, however, to study microRNAs, which are a class of endogenous small RNAs post-transcriptionally programming gene expression, in relation to photosynthetic traits. We focused on miR408, one of the most conserved plant miRNAs, and overexpressed it in parallel in Arabidopsis, tobacco, and rice. The transgenic plants all exhibited increased copper content in the chloroplast, elevated abundance of plastocyanin, and an induction of photosynthetic genes. By means of gas exchange and optical spectroscopy analyses, we showed that higher expression of miR408 leads to enhanced photosynthesis through improving efficiency of irradiation utilization and the capacity for carbon dioxide fixation. Consequently, miR408 hyper-accumulating plants exhibited higher rate of vegetative growth. An enlargement of seed size was also observed in all three species overproducing miR408. Moreover, we conducted a 2-year-two-location field trial and observed miR408 overexpression in rice significantly increased yield, which was primarily attributed to an elevation in grain weight. Taken together, these results demonstrate that miR408 is a positive regulator of photosynthesis and that its genetic engineering is a promising route for enhancing photosynthetic performance and yield in diverse plants.

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The potential prebiotic properties of Panax ginseng polysaccharides were studied using ten strains of Lactobacillus plantarum isolated from traditional Chinese fermented foods. These probiotics showed different growth characteristics depending on the extract and strain specificity. L. plantarum C88 showed higher cell densities and growth rate when cultured on P. ginseng polysaccharides. In the in vitro antioxidant assay, P. ginseng polysaccharides combined with L. plantarum C88 were found to possess significant DPPH, ABTS and superoxide anion radicals scavenging activities, and acidic polysaccharides showed better antioxidant activity than neutral polysaccharides. Furthermore, we evaluated the antioxidant effect of acidic P. ginseng polysaccharide combined with L. plantarum C88 strain in natural ageing mice in vivo. Acidic P. ginseng polysaccharide and L. plantarum C88 together inhibited the formation of malondialdehyde (MDA) and increased the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT) and total antioxidant capacities (T-AOC) in a dose-dependent manner.

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