An endophytic fungus interacts with the defensin-like protein OsCAL1 to regulate cadmium allocation in rice.

Defensin-like proteins are conserved in multicellular organisms and contribute to innate immune responses against fungal pathogens. In rice, defensins play a novel role in regulating cadmium (Cd) efflux from the cytosol. However, whether the antifungal activity of defensins correlates with Cd-efflux function remains unknown. In this study, we isolated an endophytic Fusarium, designed Fo10, by a comparative microbiome analysis of rice plants grown in a paddy contaminated with Cd. Fo10 is tolerant to high levels of Cd, but is sensitive to the defensin-like protein OsCAL1, which mediates Cd efflux to the apoplast. We found that Fo10 symbiosis in rice is regulated by OsCAL1 dynamics, and Fo10 coordinates multiple plant processes, including Cd uptake, vacuolar sequestration, efflux to the environment, and formation of Fe plaques in the rhizosphere. These processes are dependent on the salicylic acid signaling pathway to keep Cd levels low in the cytosol of rice cells and to decrease Cd levels in rice grains without any yield penalty. Fo10 also plays a role in Cd tolerance in the poaceous crop maize and wheat, but has no observed effects in the eudicot plants Arabidopsis and tomato. Taken together, these findings provide insights into the mechanistic basis underlying how a fungal endophyte and host plant interact to control Cd accumulation in host plants by adapting defense responses to promote the establishment of a symbiosis that permits adaptation to high-Cd environments.

Two ABCI family transporters, OsABCI15 and OsABCI16, are involved in grain-filling in rice.

Seed development is critical for plant reproduction and crop yield, with panicle seed-setting rate, grain-filling, and grain weight being key seed characteristics for yield improvement. However, few genes are known to regulate grain filling. Here, we identify two adenosine triphosphate (ATP)-binding cassette (ABC)I-type transporter genes, OsABCI15 and OsABCI16, involved in rice grain-filling. Both genes are highly expressed in developing seeds, and their proteins are localized to the plasma membrane and cytosol. Interestingly, knockout of OsABCI15 and OsABCI16 results in a significant reduction in seed-setting rate, caused predominantly by the severe empty pericarp phenotype, which differs from the previously reported low seed-setting phenotype resulting from failed pollination. Further analysis indicates that OsABCI15 and OsABCI16 participate in ion homeostasis and likely export ions between filial tissues and maternal tissues during grain filling. Importantly, overexpression of OsABCI15 and OsABCI16 enhances seed-setting rate and grain yield in transgenic plants and decreases ion accumulation in brown rice. Moreover, the OsABCI15/16 orthologues in maize exhibit a similar role in kernel development, as demonstrated by their disruption in transgenic maize. Therefore, our findings reveal the important roles of two ABC transporters in cereal grain filling, highlighting their value in crop yield improvement.

Spatio-temporal heterogeneity of the coupling between digital economy and green total factor productivity and its influencing factors in China.

The synergy of the digital economy and green total factor productivity (TFP) is the foundation for achieving beneficial outcomes for both the economy and environment. This synergy is also the catalyst for high-quality development and sustainable economic growth in China. The study applied a modified Ellison-Glaeser (EG) index, super-efficiency slacks-based measure (SBM) with a Malmquist-Luenberger (ML) index, coupling coordination degree, and other models to explore the spatiotemporal heterogeneity of the coupling between the digital economy and green TFP from 2011 to 2020 and also analyzed the influencing factors of the coupling. The results show that the coupling between the digital economy and green TFP showed an overall upward trend from imbalance to synergy during the study period. The distribution of the synergistic coupling expanded from point-like to band-like, and there was a significant spreading pattern from the east to the center or west China. The number of cities in a transition state decreased significantly. Spatial jumps, a coupling linkage effect, and evolution in time were prominent. Additionally, the absolute difference among cities expanded. Although coupling in the west experienced the fastest growth rate, the coupling in the east and resource-based cities showed significant benefits. Coupling did not reach an ideal coordinated state, and a neutral interaction pattern remains to be formed. Industrial collaboration, industrial upgrading, government support, economic foundation, and spatial quality all positively impacted the coupling; technological innovation had a lagged effect; and environmental regulation has not reached its full potential. Further, the positive effects of government support and spatial quality performed better in the east and in non-resource-based cities. Due to the optimization of industrial structure, the coupling of the west and resource-based cities achieved better dividends; however, spatial quality needs further improvement. Therefore, the efficient coordination of China's digital economy and green TFP requires a scientific, reasonable, localized, and distinctive approach.

Dual-function DEFENSIN 8 mediates phloem cadmium unloading and accumulation in rice grains.

Grain cadmium (Cd) is translocated from source to sink tissues exclusively via phloem, though the phloem Cd unloading transporter has not been identified yet. Here, we isolated and functionally characterized a defensin-like gene DEFENSIN 8 (DEF8) highly expressed in rice (Oryza sativa) grains and induced by Cd exposure in seedling roots. Histochemical analysis and subcellular localization detected DEF8 expression preferentially in pericycle cells and phloem of seedling roots, as well as in phloem of grain vasculatures. Further analysis demonstrated that DEF8 is secreted into extracellular spaces possibly by vesicle trafficking. DEF8 bound to Cd in vitro, and Cd efflux from protoplasts as well as loading into xylem vessels decreased in the def8 mutant seedlings compared with the wild type. At maturity, significantly less Cd accumulation was observed in the mutant grains. These results suggest that DEF8 is a dual function protein that facilitates Cd loading into xylem and unloading from phloem, thus mediating Cd translocation from roots to shoots and further allocation to grains, representing a phloem Cd unloading regulator. Moreover, essential mineral nutrient accumulation as well as important agronomic traits were not affected in the def8 mutants, suggesting DEF8 is an ideal target for breeding low grain Cd rice.

The small peptide CEP1 and the NIN-like protein NLP1 regulate NRT2.1 to mediate root nodule formation across nitrate concentrations.

Legumes acquire fixed nitrogen (N) from the soil and through endosymbiotic association with diazotrophic bacteria. However, establishing and maintaining N2-fixing nodules are expensive for the host plant, relative to taking up N from the soil. Therefore, plants suppress symbiosis when N is plentiful and enhance symbiosis when N is sparse. Here, we show that the nitrate transporter MtNRT2.1 is required for optimal nodule establishment in Medicago truncatula under low-nitrate conditions and the repression of nodulation under high-nitrate conditions. The NIN-like protein (NLP) MtNLP1 is required for MtNRT2.1 expression and regulation of nitrate uptake/transport under low- and high-nitrate conditions. Under low nitrate, the gene encoding the C-terminally encoded peptide (CEP) MtCEP1 was more highly expressed, and the exogenous application of MtCEP1 systemically promoted MtNRT2.1 expression in a compact root architecture 2 (MtCRA2)-dependent manner. The enhancement of nodulation by MtCEP1 and nitrate uptake were both impaired in the Mtnrt2.1 mutant under low nitrate. Our study demonstrates that nitrate uptake by MtNRT2.1 differentially affects nodulation at low- and high-nitrate conditions through the actions of MtCEP1 and MtNLP1.

Vacuolar nitrate efflux requires multiple functional redundant nitrate transporter in Arabidopsis thaliana.

Nitrate in plants is preferentially stored in vacuoles; however, how vacuolar nitrate is reallocated and to which biological process(es) it might contribute remain largely elusive. In this study, we functionally characterized three nitrate transporters NPF5.10, NPF5.14, and NPF8.5 that are tonoplast-localized. Ectopic expression in Xenopus laevis oocytes revealed that they mediate low-affinity nitrate transport. Histochemical analysis showed that these transporters were expressed preferentially in pericycle and xylem parenchyma cells. NPF5.10, NPF5.14, and NPF8.5 overexpression significantly decreased vacuolar nitrate contents and nitrate accumulation in Arabidopsis shoots. Further analysis showed that the sextuple mutant (npf5.10 npf5.14 npf8.5 npf5.11 npf5.12 npf5.16) had a higher 15NO3-uptake rate than the wild-type Col-0, but no significant difference was observed for nitrate accumulation between them. The septuple mutant (npf5.11 npf5.12 npf5.16 npf5.10 npf5.14 npf8.5 clca) generated by using CRISPR/Cas9 showed essentially decreased nitrate reallocation compared to wild type when exposed to nitrate starvation, though no further decrease was observed when compared to clca. Notably, NPF5.10, NPF5.14, and NPF8.5 as well as NPF5.11, NPF5.12, and NPF5.16 were consistently induced by mannitol, and more nitrate was detected in the sextuple mutant than in the wild type after mannitol treatment. These observations suggest that vacuolar nitrate efflux is regulated by several functional redundant nitrate transporters, and the reallocation might contribute to osmotic stress response other than mineral nutrition.

Analysis of the Ecological Carrying Capacity of Fish Resources in Shengjin Lake, Anhui Province, China.

The carrying capacity of fish is related to the sustainability of fisheries' activities in water bodies. The fish carrying capacity of a water body is the maximum fish yield that can be carried by the natural bait organisms in the water body under the ideal natural conditions without feeding and fertilization. The evaluation of fish productivity is an important basis for rational stocking, rational fishing, and the scientific utilization of natural bait resources in a water area. This paper adopts the background data of the Shengjin Lake fishery ecosystem and uses the bait-based estimation method. The results show that (1) the annual yield of silver carp fed on phytoplankton is 1.5 million kg; (2) the annual yield of bighead carp fed on zooplankton is 1.295 million kg; (3) the annual yield of benthos is 310,000 kg; (4) the annual yield of organic detritus is 280,000 kg; and (5) as the coverage of water grass in Shengjin Lake is less than 10%, it should be protected and restored rather than used by fish. In general, the annual maximum carrying capacity of fish in Shengjin Lake is 3.385 million kg, except for water and grass.

A combined approach to evaluate total phosphorus/inorganic phosphate levels in plants.

Inorganic phosphate (Pi) and phosphorus (P) homeostasis are essential for plant growth and yield, and reliable detection of dynamic Pi/P in different tissues is important for studying their biological functions. Here, we report a combined protocol for rapid determination of Pi/P levels. We first perform 31P NMR assay to reveal the intracellular Pi distribution and then dissect the level of Pi/P by the chromogenic reaction and ICP-MS analysis. Finally, we take µXRF element fluorescence assay to achieve the visual P distribution. For complete details on the use and execution of this protocol, please refer to Ma et al. (2021).

The nitrate transporter OsNPF7.9 mediates nitrate allocation and the divergent nitrate use efficiency between indica and japonica rice.

Nitrate allocation in Arabidopsis (Arabidopsis thaliana) represents an important mechanism for mediating plant environmental adaptation. However, whether this mechanism occurs or has any physiological/agronomic importance in the ammoniphilic plant rice (Oriza sativa L.) remains unknown. Here, we address this question through functional characterization of the Nitrate transporter 1/Peptide transporter Family (NPF) transporter gene OsNPF7.9. Ectopic expression of OsNPF7.9 in Xenopus oocytes revealed that the gene encodes a low-affinity nitrate transporter. Histochemical and in-situ hybridization assays showed that OsNPF7.9 expresses preferentially in xylem parenchyma cells of vasculature tissues. Transient expression assays indicated that OsNPF7.9 localizes to the plasma membrane. Nitrate allocation from roots to shoots was essentially decreased in osnpf7.9 mutants. Biomass, grain yield, and nitrogen use efficiency (NUE) decreased in the mutant dependent on nitrate availability. Further analysis demonstrated that nitrate allocation mediated by OsNPF7.9 is essential for balancing rice growth and stress tolerance. Moreover, our research identified an indica-japonica divergent single-nucleotide polymorphism occurring in the coding region of OsNPF7.9, which correlates with enhanced nitrate allocation to shoots of indica rice, revealing that divergent nitrate allocation might represent an important component contributing to the divergent NUE between indica and japonica subspecies and was likely selected as a favorable trait during rice breeding.

Two NPF transporters mediate iron long-distance transport and homeostasis in Arabidopsis.

Iron (Fe) transport and reallocation are essential to Fe homeostasis in plants, but it is unclear how Fe homeostasis is regulated, especially under stress. Here we report that NPF5.9 and its close homolog NPF5.8 redundantly regulate Fe transport and reallocation in Arabidopsis. NPF5.9 is highly upregulated in response to Fe deficiency. NPF5.9 expresses preferentially in vasculature tissues and localizes to the trans-Golgi network, and NPF5.8 showed a similar expression pattern. Long-distance Fe transport and allocation into aerial parts was significantly increased in NPF5.9-overexpressing lines. In the double mutant npf5.8 npf5.9, Fe loading in aerial parts and plant growth were decreased, which were partially rescued by Fe supplementation. Further analysis showed that expression of PYE, the negative regulator for Fe homeostasis, and its downstream target NAS4 were significantly altered in the double mutant. NPF5.9 and NPF5.8 were shown to also mediate nitrate uptake and transport, although nitrate and Fe application did not reciprocally affect each other. Our findings uncovered the novel function of NPF5.9 and NPF5.8 in long-distance Fe transport and homeostasis, and further indicated that they possibly mediate nitrate transport and Fe homeostasis independently in Arabidopsis.

Emissive oxidase-like nanozyme based on an organic molecular cage.

In this study, we introduced four "claw-like" units of dipicolylamine (DPA) to a tetraphenylethylene (TPE)-based organic molecular cage (DPA-TPE-Cage). Coordinated with Zn2+ ions, the obtained ZnDPA-TPE-Cage exhibited aggregation induced emission (AIE) effects and oxidase-like properties, which endowed it with the ability to selectively image and kill Gram-positive bacteria S. aureus efficiently.

Functional Silencing of HSD17B2 in Prostate Cancer Promotes Disease Progression.

PURPOSE: Steroidogenic enzymes are essential for prostate cancer development. Enzymes inactivating potent androgens were not investigated thoroughly, which leads to limited interference strategies for prostate cancer therapy. Here we characterized the clinical relevance, significance, and regulation mechanism of enzyme HSD17B2 in prostate cancer development. EXPERIMENTAL DESIGN: HSD17B2 expression was detected with patient specimens and prostate cancer cell lines. Function of HSD17B2 in steroidogenesis, androgen receptor (AR) signaling, and tumor growth was investigated with prostate cancer cell lines and a xenograft model. DNA methylation and mRNA alternative splicing were investigated to unveil the mechanisms of HSD17B2 regulation. RESULTS: HSD17B2 expression was reduced as prostate cancer progressed. 17ßHSD2 decreased potent androgen production by converting testosterone (T) or dihydrotestosterone (DHT) to each of their upstream precursors. HSD17B2 overexpression suppressed androgen-induced cell proliferation and xenograft growth. Multiple mechanisms were involved in HSD17B2 functional silencing including DNA methylation and mRNA alternative splicing. DNA methylation decreased the HSD17B2 mRNA level. Two new catalytic-deficient isoforms, generated by alternative splicing, bound to wild-type 17ßHSD2 and promoted its degradation. Splicing factors SRSF1 and SRSF5 participated in the generation of new isoforms. CONCLUSIONS: Our findings provide evidence of the clinical relevance, significance, and regulation of HSD17B2 in prostate cancer progression, which might provide new strategies for clinical management by targeting the functional silencing mechanisms of HSD17B2.See related commentary by Mostaghel, p. 1139.

The C-ETS2-TFEB Axis Promotes Neuron Survival under Oxidative Stress by Regulating Lysosome Activity.

Excessive reactive oxygen species/reactive nitrogen species (ROS/RNS) produced as a result of ageing causes damage to macromolecules and organelles or leads to interference of cell signalling pathways, which in turn results in oxidative stress. Oxidative stress occurs in many neurodegenerative diseases (e.g., Parkinson's disease) and contributes to progressive neuronal loss. In this study, we show that cell apoptosis is induced by oxidative stress and that lysosomes play an important role in cell survival under oxidative stress. As a compensatory response to this stress, lysosomal genes were upregulated via induction of transcription factor EB (TFEB). In addition, localization of TFEB to the nucleus was increased by oxidative stress. We also confirmed that TFEB protects cells from oxidative stress both in vitro and in vivo. Finally, we found that C-ETS2 senses oxidative stress, activates TFEB transcription, and mediates the upregulation of lysosomal genes. Our results demonstrate a mechanistic pathway for inducing lysosomal activity during ageing and neurodegeneration.