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Lotus is an aquatic plant that is sensitive to water loss, but its seeds are longevous after seed embryo dehydration and maturation. The great difference between the responses of vegetative organs and seeds to dehydration is related to the special protective mechanism in embryos. In this study, tandem mass tags (TMT)-labeled proteomics and parallel reaction monitoring (PRM) technologies were used to obtain novel insights into the physiological regulatory networks during lotus seed dehydration process. Totally, 60,266 secondary spectra and 32,093 unique peptides were detected. A total of 5,477 proteins and 815 differentially expressed proteins (DEPs) were identified based on TMT data. Of these, 582 DEPs were continuously downregulated and 228 proteins were significantly up-regulated during the whole dehydration process. Bioinformatics and protein-protein interaction network analyses indicated that carbohydrate metabolism (including glycolysis/gluconeogenesis, galactose, starch and sucrose metabolism, pentose phosphate pathway, and cell wall organization), protein processing in ER, DNA repair, and antioxidative events had positive responses to lotus embryo dehydration. On the contrary, energy metabolism (metabolic pathway, photosynthesis, pyruvate metabolism, fatty acid biosynthesis) and secondary metabolism (terpenoid backbone, steroid, flavonoid biosynthesis) gradually become static status during lotus embryo water loss and maturation. Furthermore, non-enzymatic antioxidants and pentose phosphate pathway play major roles in antioxidant protection during dehydration process in lotus embryo. Abscisic acid (ABA) signaling and the accumulation of oligosaccharides, late embryogenesis abundant proteins, and heat shock proteins may be the key factors to ensure the continuous dehydration and storage tolerance of lotus seed embryo. Stress physiology detection showed that H2O2 was the main reactive oxygen species (ROS) component inducing oxidative stress damage, and glutathione and vitamin E acted as the major antioxidant to maintain the REDOX balance of lotus embryo during the dehydration process. These results provide new insights to reveal the physiological regulatory networks of the protective mechanism of embryo dehydration in lotus.

Carbon nanomaterials (CNMs) have remarkable chemical, physical, electrical, and structural properties and favorable biocompatibility. This study used carnation (Dianthus caryophyllus L.) cut flowers as a model to evaluate the protective effects of 3 kinds of CNMs (single-walled carbon nanotubes [SWCNT], graphene quantum dots [GQD], and fullerenes [C60]) on the antioxidant activity and senescence of plant cells. We found that 1 mg•L -1 C 60 and 25 mg•L -1 GQD extended the vase life (VL) of carnation by approximately 10%. SWCNT cannot be absorbed and transported by plant vascular tissue, and higher concentrations of SWCNT can block vascular tissue, leading to decreased VL. Physiological tests have shown that theThe malondialdehyde (MDA) and hydroxyl radical (OH•) levels significantly decreased after the GQD and C60 treatments, and the main factors that cause cell damage changed from H2O2 to OH•. The in vitro Fenton reaction and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay indicated that both C 60 and GQD may inhibit OH• generation by approximately 10% to 15%, and GQD had higher DPPH free radical scavenging activity. Accordingly, a suitable concentration of C60 and GQD can influence reactive oxygen species metabolism and downstream biological events, including the cell redox state, the antioxidant system, and membrane lipid peroxidation, effectively delaying senescence and abscission of plant tissue.

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