Plants frequently suffer from environmental stresses in nature and have evolved sophisticated and efficient mechanisms to cope with the stresses. To balance between growth and stress response, plants ...are equipped with efficient means to switch off the activated stress responses when stresses diminish. We previously revealed such an off‐switch mechanism conferred by Arabidopsis PARAQUAT TOLERANCE 3 (AtPQT3) encoding an E3 ubiquitin ligase, knockout of which significantly enhances resistance to abiotic stresses. To explore whether the rice homologue OsPQT3 is functionally conserved, we generated three knockout mutants with CRISPR‐Cas9 technology. The OsPQT3 knockout mutants (ospqt3) display enhanced resistance to oxidative and salt stress with elevated expression of OsGPX1, OsAPX1 and OsSOD1. More importantly, the ospqt3 mutants show significantly enhanced agronomic performance with higher yield compared with the wild type under salt stress in greenhouse as well as in field conditions. We further showed that OsPQT3 expression rapidly decreased in response to oxidative and other abiotic stresses as AtPQT3 does. Taken together, these results show that OsPQT3 is functionally well conserved in rice as an off‐switch in stress response as AtPQT3 in Arabidopsis. Therefore, PQT3 locus provides a promising candidate for crop improvement with enhanced stress resistance by gene editing technology.
OsPQT3, a rice homologue of Arabidopsis PQT3 encoding an E3 ubiquitin ligase, is functionally conserved in rice. Like AtPQT3, OsPQT3 negatively regulates stress resistance. Knockout of OsPQT3 locus confers stress resistance, providing a promising candidate for crop improvement with enhanced stress resistance by gene editing technology.
Abstract
Nitrogen (N) is indispensable for crop growth and yield, but excessive agricultural application of nitrogenous fertilizers has generated severe environmental problems. A desirable and ...economical solution to cope with these issues is to improve crop nitrogen use efficiency (NUE). Plant NUE has been a focal point of intensive research worldwide, yet much still has to be learned about its genetic determinants and regulation. Here, we show that rice (Oryza sativa L.) NIN-LIKE PROTEIN 1 (OsNLP1) plays a fundamental role in N utilization. OsNLP1 protein localizes in the nucleus and its transcript level is rapidly induced by N starvation. Overexpression of OsNLP1 improves plant growth, grain yield, and NUE under different N conditions, while knockout of OsNLP1 impairs grain yield and NUE under N-limiting conditions. OsNLP1 regulates nitrate and ammonium utilization by cooperatively orchestrating multiple N uptake and assimilation genes. Chromatin immunoprecipitation and yeast one-hybrid assays showed that OsNLP1 can directly bind to the promoter of these genes to activate their expression. Therefore, our results demonstrate that OsNLP1 is a key regulator of N utilization and represents a potential target for improving NUE and yield in rice.
OsNLP1 rapidly responds to N availability, enhances N uptake and assimilation, providing great potential for breeding rice cultivars with high yield and NUE under N-limiting conditions
Summary
Nitrogen (N) is one of the key essential macronutrients that affects rice growth and yield. Inorganic N fertilizers are excessively used to boost yield and generate serious collateral ...environmental pollution. Therefore, improving crop N use efficiency (NUE) is highly desirable and has been a major endeavour in crop improvement. However, only a few regulators have been identified that can be used to improve NUE in rice to date. Here we show that the rice NIN‐like protein 4 (OsNLP4) significantly improves the rice NUE and yield. Field trials consistently showed that loss‐of‐OsNLP4 dramatically reduced yield and NUE compared with wild type under different N regimes. In contrast, the OsNLP4 overexpression lines remarkably increased yield by 30% and NUE by 47% under moderate N level compared with wild type. Transcriptomic analyses revealed that OsNLP4 orchestrates the expression of a majority of known N uptake, assimilation and signalling genes by directly binding to the nitrate‐responsive cis‐element in their promoters to regulate their expression. Moreover, overexpression of OsNLP4 can recover the phenotype of Arabidopsis nlp7 mutant and enhance its biomass. Our results demonstrate that OsNLP4 plays a pivotal role in rice NUE and sheds light on crop NUE improvement.
Nitrogen (N) is an essential macronutrient for crop growth and yield. Improving the N use efficiency (NUE) of crops is important to agriculture. However, the molecular mechanisms underlying NUE ...regulation remain largely elusive. Here we report that the OsNLP3 (NIN‐like protein 3) regulates NUE and grain yield in rice under N sufficient conditions. OsNLP3 transcript level is significantly induced by N starvation and its protein nucleocytosolic shuttling is specifically regulated by nitrate. Loss‐of‐function of OsNLP3 reduces plant growth, grain yield, and NUE under sufficient nitrate conditions, whereas under low nitrate or different ammonium conditions, osnlp3 mutants show no clear difference from the wild type. Importantly, under sufficient N conditions in the field, OsNLP3 overexpression lines display improved grain yield and NUE compared with the wild type. OsNLP3 orchestrates the expression of multiple N uptake and assimilation genes by directly binding to the nitrate‐responsive cis‐elements in their promoters. Overall, our study demonstrates that OsNLP3, together with OsNLP1 and OsNLP4, plays overlapping and differential roles in N acquisition and NUE, and modulates NUE and the grain yield increase promoted by N fertilizer. Therefore, OsNLP3 is a promising candidate gene for the genetic improvement of grain yield and NUE in rice.
Summary Statement
Crop nitrogen use efficiency (NUE) is an important agronomic trait. But the molecular mechanisms underlying NUE regulation are not well understood. This study reveals that rice NIN‐like protein 3 (OsNLP3) regulates NUE and grain yield especially under N sufficient conditions and is a promising candidate gene for improving grain yield and NUE in rice.
Summary
Rice panicles, a major component of yield, are regulated by phytohormones and nutrients. How mineral nutrients promote panicle architecture remains largely unknown.
Here, we report that ...NIN‐LIKE PROTEIN3 and 4 (OsNLP3/4) are crucial positive regulators of rice panicle architecture in response to nitrogen (N). Loss‐of‐function mutants of either
OsNLP3
or
OsNLP4
produced smaller panicles with reduced primary and secondary branches and fewer grains than wild‐type, whereas their overexpression plants showed the opposite phenotypes.
The OsNLP3/4‐regulated panicle architecture was positively correlated with N availability. OsNLP3/4 directly bind to the promoter of
OsRFL
and activate its expression to promote inflorescence meristem development. Furthermore, OsRFL activates
OsMOC1
expression by binding to its promoter.
Our findings reveal the novel N‐responsive OsNLP3/4‐OsRFL‐OsMOC1 module that integrates N availability to regulate panicle architecture, shedding light on how N nutrient signals regulate panicle architecture and providing candidate targets for the improvement of crop yield.
Catalpol is the main active ingredient of an extract from
Radix rehmanniae
, which in a previous study showed a protective effect against various types of tissue injury. However, a protective effect ...of catalpol on uterine inflammation has not been reported. In this study, to investigate the protective mechanism of catalpol on lipopolysaccharide (LPS)-induced bovine endometrial epithelial cells (bEECs) and mouse endometritis, in vitro and in vivo inflammation models were established. The Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) signaling pathway and its downstream inflammatory factors were detected by enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), western blot (WB), and immunofluorescence techniques. The results from ELISA and qRT-PCR showed that catalpol dose-dependently reduced the expression of pro-inflammatory cytokines such as tumor necrosis factor α (TNF-α), interleukin (IL)-1β, and IL-6, and chemokines such as C-X-C motif chemokine ligand 8 (CXCL8) and CXCL5, both in bEECs and in uterine tissue. From the experimental results of WB, qRT-PCR, and immunofluorescence, the expression of TLR4 and the phosphorylation of NF-κB p65 were markedly inhibited by catalpol compared with the LPS group. The inflammatory damage to the mouse uterus caused by LPS was greatly reduced and was accompanied by a decline in myeloperoxidase (MPO) activity. The results of this study suggest that catalpol can exert an anti-inflammatory impact on LPS-induced bEECs and mouse endometritis by inhibiting inflammation and activation of the TLR4/NF-κB signaling pathway.
Paraquat is one of the most widely used nonselective herbicides and has elicited the emergence of paraquat-resistant weeds. However, the molecular mechanisms of paraquat resistance are not completely ...understood. Here we report the Arabidopsis gain-of-function mutant pqt15-D with significantly enhanced resistance to paraquat and the corresponding gene PQT15, which encodes the Multidrug and Toxic Extrusion (MATE) transporter DTX6. A point mutation at +932 bp in DTX6 causes a G311E amino acid substitution, enhancing the paraquat resistance of pqt15-D, and overexpression of DTX6/PQT15 in the wild-type plants also results in strong paraquat resistance. Moreover, heterologous expression of DTX6 and DTX6-D in Escherichia coli significantly enhances bacterial resistance to paraquat. Importantly, overexpression of DTX6-D enables Arabidopsis plants to tolerate 4 mM paraquat, a near-commercial application level. DTX6/PQT15 is localized in the plasma membrane and endomembrane, and functions as a paraquat efflux transporter as demonstrated by paraquat efflux assays with isolated protoplasts and bacterial cells. Taken together, our results demonstrate that DTX6/PQT15 is an efflux transporter that confers paraquat resistance by exporting paraquat out of the cytosol. These findings reveal a molecular mechanism of paraquat resistance in higher plants and provide a promising candidate gene for engineering paraquat-resistant crops.
This study reports a gain-of-function point mutation in DTX6, which encodes a MATE family transporter that confers paraquat resistance by exporting paraquat out of the cytosol. Overexpression of mutated DTX6 (DTX6D) significantly enhances paraquat resistance, enabling Arabidopsis plants to tolerate near-commercial levels of paraquat application. This study reveals a molecular mechanism of paraquat resistance by sequestration and DTX6 is therefore a promising candidate gene for the creation of paraquat-resistant crops.
Paraquat (PQ) is the third most used broad-spectrum nonselective herbicide around the globe after glyphosate and glufosinate. Repeated usage and overreliance on this herbicide have resulted in the ...emergence of PQ-resistant weeds that are a potential hazard to agriculture. It is generally believed that PQ resistance in weeds is due to increased sequestration of the herbicide and its decreased translocation to the target site, as well as an enhanced ability to scavenge reactive oxygen species. However, little is known about the genetic bases and molecular mechanisms of PQ resistance in weeds, and hence no PQ-resistant crops have been developed to date. Forward genetics of the model plant Arabidopsis thaliana has advanced our understanding of the molecular mechanisms of PQ resistance. This review focuses on PQ resistance loci and resistance mechanisms revealed in Arabidopsis and examines the possibility of developing PQ-resistant crops using the elucidated mechanisms.
This article reviews our current understanding of paraquat resistance mechanisms in weeds and Arabidopsis thaliana and discusses their potential application to the development of paraquat-resistant crops.
•PU composites with ultralow percolation threshold of MWCNTs were in-situ polymerized.•Ultralow percolation threshold of 0.057 % MWCNTs was achieved.•The electrical properties were greatly ...improved.•The high piezoresistive behavior was observed.
Herein, a series of electrically conductive polyurethane composites with multi-walled carbon nanotubes (PU/MWCNTs) were in-situ polymerized according to tailoring the segmented PU molecules. The ultralow percolation threshold of MWCNTs (0.057 wt%) in the composites was achieved and the electrically conductive properties were markedly enhanced. The conductivity in PU@MWCNTs1-0.5 % and PU@MWCNTs2-0.5 % was lower than 1.0 × 10−1° S m-1. While PU@MWCNTs3-0.5 % had the conductivity of over 1.0 × 10-6 S m-1, almost 4 orders of significance, which was attributed to the increasing of hard segments on the PU molecule. Furthermore, the high piezoresistive properties of the composites were also observed. Therefore, this work had the important sense in decreasing the low percolation thresholds of conductive polymer composites.
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