Mixed oligosaccharides-induced changes in bacterial assembly during cucumber (Cucumis sativus L.) growth

Abstract

The application of oligosaccharides can promote plant growth by increasing photosynthesis or inducing plant innate immunity. However, the mechanisms by which oligosaccharides affect bacterial community diversity and abundance remain unclear. In this study, a mixed oligosaccharide was applied to the growth of cucumbers. The findings of the present study suggest that the application of MixOS has significant effects on the bacterial communities in the phyllosphere, rhizosphere, and bulk soil of cucumber plants. The treatment with MixOS resulted in delayed senescence of leaves, well-developed roots, and higher fruit production. The bacterial diversity and composition varied among the different ecological niches, and MixOS application caused significant shifts in the bacterial microbiome composition, particularly in the phyllosphere. Moreover, mixed oligosaccharides increased the abundance of potential growth-promoting bacteria such as Methylorubrum spp. and Lechevalieria spp., and more zOTUs were shared between the WM and MixOS treatments. Furthermore, the bacterial co-occurrence network analysis suggested that the modularity of the phyllosphere networks was the highest among all samples. The bacterial co-occurrence networks were altered because of the application of MixOS, indicating a greater complexity of the bacterial interactions in the rhizosphere and bulk soil. These findings suggest that mixed oligosaccharides has the potential to improve plant growth and yield by modulating the bacterial communities within and outside the plants and could provide a theoretical basis for future agricultural production.

Different Oligosaccharides Induce Coordination and Promotion of Root Growth and Leaf Senescence during Strawberry and Cucumber Growth

“…Choudhary et al [32] proposed that the growth-promoting effects of copper-chitosan nanoparticles could boost maize resistance to Curvularia leaf spot by increasing leaf chlorophyll content and maintaining normal physiological processes, and even facing abiotic stress. Similarly, CSOS and MixOS treatments significantly increased the leaf SPAD of both crops (Figure 2), where the increases in strawberry leaves were consistent with Metwaly et al [7], and the increases in cucumber leaves were consistent with Tan et al [11] and Wang et al [8], when exposed to oligosaccharides. Additionally, the SPAD values were positively correlated with the total yield of strawberry and individual fruit weight of cucumber (Table 3), indicating that spraying the two tested oligosaccharides had a promotional effect on yield through increasing chlorophyll content.…”

“…Chitosan promoted individual fruit weight and total fruit weight per plant, and ultimately elevated total yield by 42% when sprayed on strawberry [6]. Wang et al [8] observed an increase in the total yield of cucumber in the MixOS group. As demonstrated in our study (Table 2), MixOS spraying significantly increased the individual fruit weight and total fruit number per plant of the strawberry and elevate the single fruit weight and total fruit weight per plant of the cucumber, ultimately promoting the total yield of both crops.…”

“…Winkler et al [18] and He et al [9] also found that the evidently different growth regulation of polysaccharides was due to the various chemical structures. Above all, the MixOS consisting of abundant single oligosaccharides had synthetic functions [8,9], and the addition of KH 2 PO 4 provided the necessary mineral elements, such as phosphorus and potassium [39], all of which improved the functionality and stability of plant growth and development.…”

“…In recent years, exogenous green ecological preparations have frequently been applied in facility production to alleviate the adverse damage caused by negative conditions through the regulation of plant growth, the increase in disease resistance and immunity, and finally, the enhancement of quality and growth in yield [6][7][8]. This approach is regarded as a primary technical solution to the aforementioned production challenges with relatively minimal investment and rapid outcomes.…”

“…At present, oligosaccharides are mainly used in the production of cash crops or high value-added agricultural products [7]. The use of chitosan of high content and low molecular weight is a current focus of research, along with the application of new composite functional oligosaccharides [8], which might effectively improve or eliminate the adverse properties of natural functional ingredients, enhancing their functional effects and expanding the application scope.…”