Aquaporins (AQPs) regulate the transport of water and other substrates, aiding plants in adapting to stressful environments. However, the knowledge of AQPs in salt‐secreting and viviparous Avicennia ...marina is limited. In this study, 46 AmAQPs were identified in A. marina genome, and their subcellular localisation and function in transporting H2O2 and boron were assessed through bioinformatics analysis and yeast transformation. Through analysing their expression patterns via RNAseq and real‐time quantitative polymerase chain reaction, we found that most AmAQPs were downregulated in response to salt and tidal flooding. AmPIP (1;1, 1;7, 2;8, 2;9) and AmTIP (1;5, 1;6) as salt‐tolerant candidate genes may contribute to salt secretion together with Na+/H+ antiporters. AmPIP2;1 and AmTIP1;5 were upregulated during tidal flooding and may be regulated by anaerobic‐responsive element and ethylene‐responsive element cis‐elements, aiding in adaptation to tidal inundation. Additionally, we found that the loss of the seed desiccation and dormancy‐related TIP3 gene, and the loss of the seed dormancy regulator DOG1 gene, or DOG1 protein lack heme‐binding capacity, may be genetic factors contributing to vivipary. Our findings shed light on the role of AQPs in A. marina adaptation to intertidal environments and their relevance to salt secretion and vivipary.
Summary statement
AmAQPs respond to salinity and tidal inundation in Avicennia marina, some of which play a role in salt gland secretion and function as water effluxes. The absence of TIP3, an aquaporin isoform, and the loss of DOG1, or its ability to bind to heme, may be one of the causes of vivipary in mangrove plants.
Brassinosteroid (BR) has been shown to modulate plant tolerance to various stresses. S‐nitrosoglutathione reductase (GSNOR) is involved in the plant response to environment stress by fine‐turning the ...level of nitric oxide (NO). However, whether GSNOR is involved in BR‐regulated Na+/K+ homeostasis to improve the salt tolerance in halophyte is unknown. Here, we firstly reported that high salinity increases the expression of BR‐biosynthesis genes and the endogenous levels of BR in mangrove Kandelia obovata. Then, salt‐induced BR triggers the activities and gene expressions of GSNOR and antioxidant enzymes, thereafter decrease the levels of malondialdehyde, hydrogen peroxide. Subsequently, BR‐mediated GSNOR negatively regulates NO contributions to the reduction of reactive oxygen species generation and induction of the gene expression related to Na+ and K+ transport, leading to the decrease of Na+/K+ ratio in the roots of K. obovata. Finally, the applications of exogenous BR, NO scavenger, BR biosynthetic inhibitor and GSNOR inhibitor further confirm the function of BR. Taken together, our result provides insight into the mechanism of BR in the response of mangrove K. obovata to high salinity via GSNOR and NO signaling pathway by reducing oxidative damage and modulating Na+/K+ homeostasis.
Summary Statement
Salinity increases brassinosteroid (BR)‐biosynthesis genes expression and endogenous BR in mangrove Kandelia obovata.
BR enhances the activity and gene expression of S‐nitrosoglutathione reductase that negatively regulates nitric oxide signaling and reactive oxygen species level, while, BR regulates antioxidant enzymes and Na+/K+ homeostasis.
•A. ilicifolius migrated to the intertidal habitats at 16.89 Mya.•Unique unigenes drives adaptation of A. ilicifolius to environment.•Positive selection of genes promotes A. ilicifolius growth in the ...intertidal habitats.
Acanthus is a unique genus covering both mangroves and terrestrial species, and thus is an ideal system to comparatively analyze the mechanisms of mangrove adaptation to intertidal habitats. We performed RNA sequencing of the mangrove plant Acanthus ilicifolius and its two terrestrial relatives, Acanthus leucostachyus and Acanthus mollis. A total of 91,125, 118,290, and 141,640 unigenes were obtained. Simple sequence repeats (SSR) analysis showed that A. ilicifolius had more SSRs, the highest frequency of distribution, and higher in polymorphism potential compared to the two terrestrial relatives. Phylogenetic analyses suggested a relatively recent split between A. ilicifolius and A. leucostachyus, i.e., about 16.76 million years ago (Mya), after their ancestor divergence with A. mollis (32.11 Mya), indicating that speciation of three Acanthus species occurred in the Early to Middle Miocene. Gene Ontology (GO) enrichment revealed that the unique unigenes in A. ilicifolius are predominantly related to rhythmic process, reproductive process and response to stimuli. The accelerated evolution and positive selection analyses indicated that the genus Acanthus migrated from terrestrial to intertidal habitats, where 311 pairs may be under positive selection. Functional enrichment analysis revealed that these genes associated with essential metabolism and biosynthetic pathways such as oxidative phosphorylation, plant hormone signal transduction, photosynthetic carbon fixation and arginine and proline metabolism, are related to the adaptation of A. ilicifolius to intertidal habitats, which are characterized by high salinity and hypoxia. Our results indicate the evolutionary processes and the mechanisms underlying the adaptability of Acanthus to various harsh environments from the arid terrestrial to intertidal habitats.
Hydrogen sulfide (H2S) is considered to mediate plant growth and development. However, whether H2S regulates the adaptation of mangrove plant to intertidal flooding habitats is not well understood. ...In this study, sodium hydrosulfide (NaHS) was used as an H2S donor to investigate the effect of H2S on the responses of mangrove plant Avicennia marina to waterlogging. The results showed that 24‐h waterlogging increased reactive oxygen species (ROS) and cell death in roots. Excessive mitochondrial ROS accumulation is highly oxidative and leads to mitochondrial structural and functional damage. However, the application of NaHS counteracted the oxidative damage caused by waterlogging. The mitochondrial ROS production was reduced by H2S through increasing the expressions of the alternative oxidase genes and increasing the proportion of alternative respiratory pathway in the total mitochondrial respiration. Secondly, H2S enhanced the capacity of the antioxidant system. Meanwhile, H2S induced Ca2+ influx and activated the expression of intracellular Ca2+‐sensing‐related genes. In addition, the alleviating effect of H2S on waterlogging can be reversed by Ca2+ chelator and Ca2+ channel blockers. In conclusion, this study provides the first evidence to explain the role of H2S in waterlogging adaptation in mangrove plants from the mitochondrial aspect.
Summary statement
H2S reduces mitochondrial ROS production by increasing the expressions of the alternative oxidase gene (AOX) and increases the proportion of alternative respiratory pathway in the total respiration, while H2S alleviates the mitochondrial structural damages including loss of bilayer membranes and blurring of mitochondrial cristae, and functional damages such as decrease of mitochondrial membrane potential (ΔΨm), membrane permeability transition pores opening, Cyt c release and the blockage of electron transfer along the mitochondrial electron transport chain caused by waterlogging‐induced oxidative stress. Secondly, H2S enhances the capacity of the antioxidant system through upregulating the expression of SOD, CAT, and APX genes to scavenge excess ROS. Last, H2S induces Ca2+ influx in the roots under waterlogging. Our results provide the better understanding of the role of H2S in adaptation of mangrove plants to the coastal intertidal environment from the mitochondrial aspect.
SUMMARY
Salicylic acid (SA) is known to enhance salt tolerance in plants. However, the mechanism of SA‐mediated response to high salinity in halophyte remains unclear. Using electrophysiological and ...molecular biological methods, we investigated the role of SA in response to high salinity in mangrove species, Kandelia obovata, a typical halophyte. Exposure of K. obovata roots to high salinity resulted in a rapid increase in endogenous SA produced by phenylalanine ammonia lyase pathway. The application of exogenous SA improved the salt tolerance of K. obovata, which depended on the NADPH oxidase‐mediated H2O2. Exogenous SA and H2O2 increased Na+ efflux and reduced K+ loss by regulating the transcription levels of Na+ and K+ transport‐related genes, thus reducing the Na+/K+ ratio in the salt‐treated K. obovata roots. In addition, exogenous SA‐enhanced antioxidant enzyme activity and its transcripts, and the expressions of four genes related to AsA‐GSH cycle as well, then alleviated oxidative damages in the salt‐treated K. obovata roots. However, the above effects of SA could be reversed by diphenyleneiodonium chloride (the NADPH oxidase inhibitor) and paclobutrazol (a SA biosynthesis inhibitor). Collectively, our results demonstrated that SA‐induced salt tolerance of K. obovata depends on NADPH oxidase‐generated H2O2 that affects Na+/K+ and redox homeostasis in response to high salinity.
Significance Statement
Our study further clarified the role of salicylic acid (SA) in the networks of salt tolerance in mangrove plants. The results are of great scientific significance in complementing the mechanism of SA in salt tolerance of halophyte.
Despite the recent surge of interest in inorganic lead halide perovskite nanocrystals, there are still significant gaps in their stability disturbance and the understanding of their destabilization, ...assembly, and growth processes. Here, we discover that polar solvent molecules can induce the lattice distortion of ligand-stabilized cubic CsPbI3, leading to the phase transition into orthorhombic phase, which is unfavorable for photovoltaic applications. Such lattice distortion triggers the dipole moment on CsPbI3 nanocubes, which subsequently initiates the hierarchical self-assembly of CsPbI3 nanocubes into single-crystalline nanowires. The systematic investigations and in situ monitoring on the kinetics of the self-assembly process disclose that the more amount or the stronger polarity of solvent can induce the more rapid self-assembly and phase transition. These results not only elucidate the destabilization mechanism of cubic CsPbI3 nanocrystals, but also open up opportunities to synthesize and store cubic CsPbI3 for their practical applications in photovoltaics and optoelectronics.
Asthma is the most common chronic disease in the respiratory system of children caused by abnormal immunity that responses to common antigens. Lonicerin exerts anti-inflammatory activity in other ...inflammatory models through targeting enhancer of zeste homolog 2 (EZH2) that is related to asthma. We sought to explore the role and mechanism of lonicerin in regulating allergic airway inflammation. Mice were intraperitoneally injected 10 µg ovalbumin (OVA) on postnatal day 5 (P5) and P10, and then inhaled 3% aerosolized OVA for 10 min every day on P18-20, to establish asthmatic mice model. Lonicerin (10 or 30 mg/kg) was given to mice by intragastric administration on P16-P20. Notably, the administration of lonicerin amended infiltration of inflammatory cells and mucus hypersecretion. OVA-specific IgE level, inflammatory cell count and inflammatory cytokines in asthmatic mice were reduced after lonicerin treatment. Moreover, it suppressed the activity of EZH2 and activation of nuclear factor-kappa B (NF-κB) as evidenced by decreasing tri-methylation of histone H3 at lysine 27 and reducing nuclear translocation of NF-κB p65. In a word, Lonicerin may attenuate asthma by inhibiting EZH2/NF-κB signaling pathway.
Cadmium (Cd) is a toxic heavy metal affecting the normal growth of plants. Nitrate (NO3−) and ammonium (NH4+) are the primary forms of inorganic nitrogen (N) absorbed by plants. However, the ...mechanism of N absorption and regulation under Cd stress remains unclear. This study found that: (1) Cd treatment affected the biomass, root length, and Cd2+ flux in Solanum nigrum seedling roots. Specifically, 50 μM Cd significantly inhibited NO3− influx while increased NH4+ influx compared with 0 and 5 μM Cd treatments measured by non-invasive micro-test technology. (2) qRT-PCR analysis showed that 50 μM Cd inhibited the expressions of nitrate transporter genes, SnNRT2;4 and SnNRT2;4-like, increased the expressions of ammonium transporter genes, SnAMT1;2 and SnAMT1;3, in the roots. (3) Under NH4+ supply, 50 μM Cd significantly induced the expressions of the aquaporin genes, SnPIP1;5, SnPIP2;7, and SnTIP2;1. Our results showed that 50 μM Cd stress promoted NH4+ absorption by up-regulating the gene expressions of NH4+ transporter and aquaporins, suggesting that high Cd stress can affect the preference of N nutrition in S. nigrum.
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•50 μM Cd increased Cd2+ influx of S. nigrum seedlings compared with 5 μM Cd.•50 μM Cd inhibited NO3− influx and NH4+ efflux in root meristem zone.•NH4+ influx was promoted by 50 μM Cd in root elongation zone compared with 5 μM Cd.•Cd treatment promoted NH4+ transporter SnAMT1;3 expression in roots.•50 μM Cd promoted aquaporin SnTIP2;1 expression in roots.
Main conclusion
Whole-genome duplication, gene family and lineage-specific genes analysis based on high-quality genome reveal the adaptation mechanisms of
Avicennia marina
to coastal intertidal ...habitats.
Mangrove plants grow in a complex habitat of coastal intertidal zones with high salinity, hypoxia, etc. Therefore, it is an interesting question how mangroves adapt to the unique intertidal environment. Here, we present a chromosome-level genome of the
Avicennia marina
, a typical true mangrove with a size of 480.43 Mb, contig N50 of 11.33 Mb and 30,956 annotated protein-coding genes. We identified 621
Avicennia
-specific genes that are mainly related to flavonoid and lignin biosynthesis, auxin homeostasis and response to abiotic stimulus. We found that
A. marina
underwent a novel specific whole-genome duplication, which is in line with a brief era of global warming that occurred during the paleocene–eocene maximum. Comparative genomic and transcriptomic analyses outline the distinct evolution and sophisticated regulations of
A. marina
adaptation to the intertidal environments, including expansion of photosynthesis and oxidative phosphorylation gene families, unique genes and pathways for antibacterial, detoxifying antioxidant and reactive oxygen species scavenging. In addition, we also analyzed salt gland secretion-related genes, and those involved in the red bark-related flavonoid biosynthesis, while significant expansions of key genes such as
NHX
,
4CL
,
CHS
and
CHI
. High-quality genomes in future investigations will facilitate the understand of evolution of mangrove and improve breeding.
Selfish genetic elements are pervasive in eukaryote genomes, but their role remains controversial. We show that
, a major quantitative genetic locus for hybrid male sterility between wild rice (
) ...and Asian cultivated rice (
), contains two tightly linked genes
(
) and
.
encodes a toxic genetic element that aborts pollen in a sporophytic manner, whereas
encodes an antidote that protects pollen in a gametophytic manner. Pollens lacking
are selectively eliminated, leading to segregation distortion in the progeny. Analysis of the genetic sequence suggests that
arose first, followed by gradual functionalization of
Furthermore, this toxin-antidote system may have promoted the differentiation and/or maintained the genome stability of wild and cultivated rice.
