Previous studies have shown that waterlogging/ hypoxic conditions induce aerenchyma formation to facilitate gas exchange. Ethylene (ET) and reactive oxygen species (ROS), as regulatory signals, might also be involved in these adaptive responses. However, the interrelationships between these signals have seldom been reported. Herein, we showed that programmed cell death (PCD) was involved in aerenchyma formation in the stem of Helianthus annuus. Lysigenous aerenchyma formation in the stem was induced through waterlogging (WA), ethylene and ROS. Pre-treatment with the NADPH oxidase inhibitor diphenyleneiodonium (DPI) partially suppressed aerenchyma formation in the seedlings after treatment with WA, ET and 3-amino-1, 2, 4-triazole (AT, catalase inhibitor). In addition, pre-treatment with the ethylene perception inhibitor 1-methylcyclopropene (1-MCP) partially suppressed aerenchyma formation induced through WA and ET in the seedlings, but barely inhibited aerenchyma formation induced through ROS. These results revealed that ethylene-mediated ROS signaling plays a role in aerenchyma formation, and there is a causal and interdependent relationship during WA, ET and ROS in PCD, which regulates signal networks in the stem of H. annuus.

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In this study, ultraviolet‐B radiation (UV‐B) was used to effect the accumulation of vitamin C, phenolics and flavonoids in mung bean sprouts. Results indicate that the content of vitamin C and flavonoids increased during the initial period, and after a brief decline, reached peak levels of 25.29 ± 1.02 mg/100 g FW and 726.67 ± 7.35 mg/100 g DW, respectively, at 2.5 h (1.845 kJ m−2), while the peak levels of the phenolics were 10741.33 ± 68.04 mg/100 g DW. The thiobarbituric acid reactive substances (TBARS) content decreases with the increase in irradiation time. The activities of the related enzymes, including phenylalanine ammonia‐lyase (PAL), L‐galactono‐1, 4‐lactone dehydrogenase (GalLDH), peroxidase (POD), polyphenol oxidase (PPO) and chalcone isomerase (CHI) were determined, which showed strong correlations with the change in the content of vitamin C, phenolics and flavonoids. In conclusion, the accumulation of vitamin C, phenolics and flavonoids in mung bean sprouts can be promoted by a low‐dose UV‐B irradiation.

Considering the high metastatic potential of osteosarcoma, not only pro-apoptosis, but also anti-metastasis is important for anti-osteosarcoma therapy. Previously, the authors reported the pro-apoptotic and tumor-inhibitory effects of theabrownin (TB) on osteosarcoma cells; however, its effects on the metastasis-related migration and invasion of osteosarcoma cells remain unknown. The present study conducted RNA sequencing (RNA-seq) on xenograft zebrafish samples and performed in vitro experiments, including RT-qPCR, cell viability analysis, clone formation assay, cell cycle analysis, immunofluorescence, cell migration assay, cell invasion assay, wound healing assay and western blot (WB) analysis to evaluate the anti-metastatic effects and mechanism of TB against osteosarcoma cells. The RNA-seq data revealed that TB significantly downregulated the expression of genes involved in the microtubule bundle formation of U2OS cells, which was verified by RT-qPCR. The cell viability and clone formation data indicated that TB significantly inhibited U2OS cell viability and colony numbers. The results of cell cycle analysis revealed the blocked cell cycle progression of U2OS by TB. The immunofluorescent data revealed an evident cytoskeleton-inhibitory effect of TB against the microfilament and microtubule formation of U2OS cells. The results of cell migration and invasion demonstrated that TB significantly inhibited U2OS cell migration and invasion. The results of WB analysis revealed that TB significantly regulated key molecules of epithelial-mesenchymal transition [EMT; e.g., E-cadherin, vimentin, Snail-1, Slug and zinc finger E-box-binding homeobox 1 (ZEB-1)] and those of the nuclear factor (NF)-κB pathway (e.g., NF-κB, phospho-IKKα and phospho-IKKβ), indicating that NF-κB pathway-related EMT suppression may mediate the mechanisms underlying the anti-migratory and anti-invasive effects of TB against osteosarcoma. To the best of our knowledge, this is the first study on the inhibitory effects and mechanisms of TB on the cytoskeleton-dependent cell cycle, migration and invasion of human osteosarcoma cells. The findings presented herein suggest that TB may be a promising anti-metastatic candidate for anti-osteosarcoma therapy.

The nectaries of Ipomoea purpurea wilt in the late flowering period. The senescence process of nectaries is frequently associated with cell lysis. In this paper, various techniques were used to investigate whether programmed cell death (PCD) was involved in the senescence process of nectaries in I. purpurea. Ultrastructural studies showed that nectary cells began to undergo structural distortion, chromatin condensation, mitochondrial membrane degradation, and vacuolar-membrane dissolution and rupture after bloom. 4',6-Diamidino-2-phenylindole (DAPI) and terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine-5'-triphosphate (dUTP) nick end-labeling (TUNEL) assay showed that nectary cell nuclear DNA began to degrade during the budding stage, and disappeared in the fruiting stage. DNA gel electrophoresis showed that degradation of DNA was random. Together, these results suggest that PCD participate in the senescence of the nectary in I. purpurea. PCD began during the budding period, followed by significant changes in nectary morphology and structure during the flowering period. During the fruiting stage, the PCD process is complete and the nectary degrades.

Flowers are the main sexual reproductive organs in plants. The shapes, colours and scents of corolla of plant flowers are involved in attracting insect pollinators and increasing reproductive success. The process of corolla senescence was investigated in Ipomoea purpurea (Convolvulaceae) in this study. In the research methods of plant anatomy, cytology, cell chemistry and molecular biology were used. The results showed that at the flowering stage cells already began to show distortion, chromatin condensation, mitochondrial membrane degradation and tonoplast dissolution and rupture. At this stage genomic DNA underwent massive but gradual random degradation. However, judging from the shape and structure, aging characteristics did not appear until the early flower senescence stage. The senescence process was slow, and it was completed at the late stage of flower senescence with a withering corolla. We may safely arrive at the conclusion that corolla senescence of I. purpurea was mediated by programmed cell death (PCD) that occurred at the flowering stage. The corolla senescence exhibited an obvious temporal rhythm, which demonstrated a high degree of coordination with pollination and fertilization.

• Flowers, the reproductive organs of angiosperms, show a high degree of diversity in morphological structure and flowering habit to ensure pollination and fertilization of the plants. Effect of flower movement on pollination and fertilization was investigated in Ipomoea purpurea (Convolvulaceae) in this study. • Fluorescence microscopy was used to observe the germination of pollen grains at different temperatures. • From 04:00 to 06:00 h, the stigma was taller than the filaments, so that self-pollination could not occur, and cross-pollination was carried out by insects. Pollen grains germinated rapidly after falling on the stigma; the pollen tube reached the ovule to complete fertilization after 2-3 h. From 07:00 to 09:00 h, filaments of two stamens grew rapidly and reached the same height as the stigma, thus allowing self-crossing. But at this time, the ambient temperature was already high and was not conducive to the germination of pollen grains. The corolla closed, forming an inverted bell shape, where the inner microenvironment ensured completion of pollen germination and fertilization. • Preferential cross-pollination and delayed self-crossing of I. purpurea provided a doubly guaranteed mechanism for pollination and fertilization, facilitating its adaptation to a high temperature climate.

Summary The production patterns and nutritious qualities of mung bean sprouts are in line with the consumption needs of modern people. This study was conducted to explore the effects of low doses of UV‐B irradiation on the 3‐day growth period of mung bean sprouts. The results showed that, when mung bean sprouts were irradiated with UV‐B (0.738 kJ m−2) for 1 h per day, their total phenolic content increased by 22.80%, and the activity of polyphenol oxidase decreased by 45.45%. Hypocotyl epidermis stomata were closed, reducing water loss and the opportunity for microbes to invade plants, leading to the maintenance of freshness of the sprouts. In conclusion, UV‐B irradiation for 1 h per day during the growth of mung bean sprouts can effectively improve their preservation. This method is a low‐cost, environmental friendly and pollution‐free physical preservation technique, and it has good application prospects.