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.
Seed germination is a crucial checkpoint for plant survival under unfavorable environmental conditions. Ab- scisic acid （ABA） signaling plays a vital role in integrating environmental information to ...regulate seed germination. It has been well known that MCMI/AGAMOUS/DEFICIENS/SRF （MADS）-box transcription factors are key regulators of seed and flower development in Arabidopsis. However, little is known about their functions in seed germination. Here we report that MADS-box transcription factor AGL21 is a negative regulator of seed germination and post-germination growth by controlling the expression of ABA-INSENSITIVE 5 （ABIb＇） in Arabidopsis. The AGL21-overexpressing plants were hypersensitive to ABA, salt, and osmotic stresses during seed germination and early post-germination growth, whereas ag121 mutants were less sensitive. We found that AGL21 positively regulated ABI5 expression in seeds. Consistently, genetic analyses showed that AGL21 is epistatic to ABI5 in controlling seed germination. Chromatin immunoprecipitation assays further demonstrated that AGL21 could directly bind to the ABI5 promoter in plant cells. Moreover, we found that AGL21 responded to multiple environmental stresses and plant hormones during seed germination. Taken together, our results suggest that AGL21 acts as a surveillance integrator that incorporates environmental cues and endogenous hormonal signals into ABA signaling to regulate seed germination and early post-germination growth.
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.
Nitrate is an essential nutrient and an important signaling molecule in plants. However, the molecular mechanisms by which plants perceive nitrate deficiency signaling are still not well understood. ...Here we report that AtNLP7 protein transport from the nucleus to the cytoplasm in response to nitrate deficiency is dependent on the N-terminal GAF domain. With the deletion of the GAF domain, AtNLP7.sup.DELAGAF always remains in the nucleus regardless of nitrate availability. AtNLP7 .sup.DELAGAF also shows reduced activation of nitrate-induced genes due to its impaired binding to the nitrate-responsive cis-element (NRE) as well as decreased growth like nlp7-1 mutant. In addition, AtNLP7.sup.DELAGAF is unable to mediate the reduction of reactive oxygen species (ROS) accumulation upon nitrate treatment. Our investigation shows that the GAF domain of AtNLP7 plays a critical role in the sensing of nitrate deficiency signal and in the nitrate-triggered ROS signaling process.
Abstract Lung cancer has been the leading type of cancers with regard to mortality and mobility. New versions of RNAi-based therapy are greatly required to tackle the challenges of lung cancer. In ...this study, we developed a novel siRNA delivery vector based on our magnetic mesoporous silica nanoparticles (M-MSNs) platform. This nanocarrier was constructed by loading siRNAs into the mesopores of M-MSNs, followed by polyethylenimine (PEI) capping, PEGylation and fusogenic peptide KALA modification. The resultant delivery system exhibited prolonged half-life in bloodstream, enhanced cell membrane translocation and endosomal escapablity, and favorable tissue biocompatibility and biosafety. Systemic application of vascular endothelial growth factor (VEGF) siRNA via this nanocarrier resulted in remarkable tumor suppression, both in subdermal and orthotopic lung cancer models, while tumor metastasis was also significantly reduced, overall leading to improved survival. In addition, the magnetic core of the particles and the functionalized fluorescence markers conveniently enabled in vivo imaging of target tissues. Taken together, this M-MSNs-based siRNA delivery vehicle has shown very favorable applicability for cancer therapy.
Herein, a novel single-atomic Pt doping and interface-rich CoS/Co(OH)
2
(Pt-CoS/Co(OH)
2
/C) electrocatalyst has been successfully prepared. Benefiting from precise regulation of d-orbital electronic ...structure modulation on Co site, Pt-CoS/Co(OH)
2
/C exhibited remarkable HER activity and high stability for hydrogen evolution in splitting both water (73 mV@10 mA·cm
−2
) and seawater (87 mV@10 mA·cm
−2
). Notably, atomic Pt doping was introduced into CoS/Co(OH)
2
, which could produce local unbalanced Coulombic force and significantly increased the number of S vacancies, and then expose abundant Co sites. Meantime, Co(OH)
2
in Pt-CoS/Co(OH)
2
/C could act as the adsorption sites for H
2
O in hydrogen evolution reaction process. Density functional theory results also proved that atomic Pt doping, S vacancies and Co(OH)
2
coupling could result in the formation of enriched electronic Co sites and optimize
d
z
2
orbital electronic structure, and then realize the depth upward shift of d-band center and enhance the adsorption of H* on Co sites.
Graphical abstract
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.
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