XYLEM CYSTEINE PEPTIDASE 1 and its inhibitor CYSTATIN 6 regulate pattern-triggered immunity by modulating the stability of the NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D.

Plants produce a burst of reactive oxygen species (ROS) after pathogen infection to successfully activate immune responses. During pattern-triggered immunity (PTI), ROS are primarily generated by the NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D (RBOHD). RBOHD is degraded in the resting state to avoid inappropriate ROS production; however, the enzyme mediating RBOHD degradation and how to prevent RBOHD degradation after pathogen infection is unclear. In this study, we identified an Arabidopsis (Arabidopsis thaliana) vacuole-localized papain-like cysteine protease, XYLEM CYSTEINE PEPTIDASE 1 (XCP1), and its inhibitor CYSTATIN 6 (CYS6). Pathogen-associated molecular pattern-induced ROS burst and resistance were enhanced in the xcp1 mutant but were compromised in the cys6 mutant, indicating that XCP1 and CYS6 oppositely regulate PTI responses. Genetic and biochemical analyses revealed that CYS6 interacts with XCP1 and depends on XCP1 to enhance PTI. Further experiments showed that XCP1 interacts with RBOHD and accelerates RBOHD degradation in a vacuole-mediated manner. CYS6 inhibited the protease activity of XCP1 toward RBOHD, which is critical for RBOHD accumulation upon pathogen infection. As CYS6, XCP1, and RBOHD are conserved in all plant species tested, our findings suggest the existence of a conserved strategy to precisely regulate ROS production under different conditions by modulating the stability of RBOHD.

Structural basis of salicylic acid perception by Arabidopsis NPR proteins.

Salicylic acid (SA) is a plant hormone that is critical for resistance to pathogens1-3. The NPR proteins have previously been identified as SA receptors4-10, although how they perceive SA and coordinate hormonal signalling remain unknown. Here we report the mapping of the SA-binding core of Arabidopsis thaliana NPR4 and its ligand-bound crystal structure. The SA-binding core domain of NPR4 refolded with SA adopts an α-helical fold that completely buries SA in its hydrophobic core. The lack of a ligand-entry pathway suggests that SA binding involves a major conformational remodelling of the SA-binding core of NPR4, which we validated using hydrogen-deuterium-exchange mass spectrometry analysis of the full-length protein and through SA-induced disruption of interactions between NPR1 and NPR4. We show that, despite the two proteins sharing nearly identical hormone-binding residues, NPR1 displays minimal SA-binding activity compared to NPR4. We further identify two surface residues of the SA-binding core, the mutation of which can alter the SA-binding ability of NPR4 and its interaction with NPR1. We also demonstrate that expressing a variant of NPR4 that is hypersensitive to SA could enhance SA-mediated basal immunity without compromising effector-triggered immunity, because the ability of this variant to re-associate with NPR1 at high levels of SA remains intact. By revealing the structural mechanisms of SA perception by NPR proteins, our work paves the way for future investigation of the specific roles of these proteins in SA signalling and their potential for engineering plant immunity.

A rapid and highly efficient sorghum transformation strategy using GRF4-GIF1/ternary vector system.

Sorghum is an important crop for food, forage, wine and biofuel production. To enhance its transformation efficiency without negative developmental by-effects, we investigated the impact of GRF4-GIF1 chimaera and GRF5 on sorghum transformation. Both GRF4-GIF1 and GRF5 effectively improved the transformation efficiency of sorghum and accelerated the transformation process of sorghum to less than 2 months which was not observed when using BBM-WUS. As agrobacterium  effectors increase the ability of T-DNA transfer into plant cells, we checked whether ternary vector system can additively enhance sorghum transformation. The combination of GRF4-GIF1 with helper plasmid pVS1-VIR2 achieved the highest transformation efficiency, reaching 38.28%, which is 7.71-fold of the original method. Compared with BBM-WUS, overexpressing GRF4-GIF1 caused no noticeable growth defects in sorghum. We further developed a sorghum CRISPR/Cas9 gene-editing tool based on this GRF4-GIF1/ternary vector system, which achieved an average gene mutation efficiency of 41.36%, and null mutants were created in the T0 generation.

ERAD-related E2 and E3 enzymes modulate the drought response by regulating the stability of PIP2 aquaporins.

Endoplasmic reticulum-associated degradation (ERAD) is known to regulate plant responses to diverse stresses, yet its underlying molecular mechanisms and links to various stress signaling pathways are poorly understood. Here, we show that the ERAD component ubiquitin-conjugating enzyme UBC32 positively regulates drought tolerance in Arabidopsis thaliana by targeting the aquaporins PIP2;1 and PIP2;2 for degradation. Furthermore, we demonstrate that the RING-type ligase Rma1 acts together with UBC32 and that the E2 activity of UBC32 is essential for the ubiquitination of Rma1. This complex ubiquitinates a phosphorylated form of PIP2;1 at Lys276 to promote its degradation, thereby enhancing plant drought tolerance. Extending these molecular insights into crops, we show that overexpression of Arabidopsis UBC32 also improves drought tolerance in rice (Oryza sativa). Thus, beyond uncovering the molecular basis of an ERAD-regulated stress response, our study suggests multiple potential strategies for engineering crops with improved drought tolerance.

Nitrate Reduction by NiFe-LDH/CeO2: Understanding the Synergistic Effect between Dual-Metal Sites and Dual Adsorption.

Electrocatalytic nitrate reduction reaction (EC-NITRR) shows a significant advantage for green reuse of the nitrate (NO3-) pollutant. However, the slow diffusion reaction limits the reaction rate in practical EC-NITRR, causing an unsatisfactory ammonia (NH3) yield. In this work, a multifunctional NiFe-LDH/CeO2 with the dual adsorption effect (physisorption and chemisorption) and dual-metal sites (Ce3+ and Fe2+) was fabricated by the electrodeposition method. NiFe-LDH/CeO2 performed an expected ability of enrichment for NO3- through the pseudo-first-order and pseudo-second-order kinetic models, and the polymetallic structure provided abundant sites for effective reaction of NO3-. At-0.6 V vs RHE, the ammonia (NH3) yield of NiFe-LDH/CeO2 reached 335.3 µg h-1 cm-2 and the selectivity of NH3 was 24.2 times that of NO2-. The nitrogen source of NH3 was confirmed by 15NO3- isotopic labeling. Therefore, this work achieved the recycling of the NO3- pollutant by synergy of enrichment and catalysis, providing an alternative approach for the recovery of NO3- from wastewater.

The Impact of Doctor-Nurse Complementary Model Combined with Disease Tracking on Stroke Patients.

Objective: The incidence of stroke worldwide is increasing year by year. With the enhancement of public health awareness, people's demand for the quality of stroke rehabilitation is getting higher and higher, so better quality care measures are needed in the treatment of stroke. Based on this, this paper explores the impact of a new type of nursing care measure, the complementary health care model combined with condition tracking, on stroke patients. Methods: 238 stroke patients were randomly divided into a conventional group (n=119) and a combined group (n=119). 238 stroke patients were randomly divided into conventional group (n=119) and combined group (n=119). The conventional group received routine care, in which doctors and nursing carried out their own work without cooperation after the patients were admitted to the hospital; the combined group received a complementary health care model and condition tracking, in which doctors and nurses jointly checked the rooms, discussed cases, jointly formulated treatments and nursing care plans, and jointly formulated the patients' discharge and rehabilitation plans after the patients were admitted to the hospital. Before the intervention, at the time of discharge, and 6 months after discharge, the neurological function of the patients in both groups was assessed using the National Institutes of Health Stroke Scale (NIHSS) and the Fugl-Meyer (FMA) scale, the cognitive function of the patients in both groups was assessed using the Montreal Cognitive Assessment (MoCA) scale and the Measured Mental State Examination (MMSE), and the cognitive function of the patients in both groups was assessed using the General Self-Efficacy Scale (GSS) and the Montreal Cognitive Assessment (MCA) scale. General Self-Efficacy Scale (GSES) to assess self-efficacy, Exercise Adherence Questionnaire (EAQ) to assess adherence to functional exercise and Specific Quality of Life Scale (SSQoL-12) to assess the quality of life of patients in both groups, and the self-developed satisfaction with nursing care to assess patients' satisfaction with the care model. Results: Before the intervention, there was no difference in the National Institutes of Health Stroke Scale (NIHSS), the Fugl-Meyer Assessment (FMA), the Montreal Cognitive Assessment (MoCA), the Mental State Examination (MMSE), the General Self-Efficacy Scale (GSES), the Exercise Adherence Questionnaire (EAQ) and the Stroke-Specific Quality of Life Scale-12 (SSQoL-12) scores between the two groups (P > .05). At discharge and six months later, NIHSS scores continued to decrease in both groups, with the joint group being lower than the conventional group (P < .05); scores for all other items continued to increase, with the joint being higher than the conventional group (P < .05). Satisfaction with care was higher in the combined group than in the conventional group (P < .05). Conclusion: The complementary healthcare model combined with condition tracking can effectively promote the prognosis of rehabilitation of stroke patients, and has a positive effect in promoting the recovery of neurological and cognitive functions, strengthening self-efficacy, and improving the quality of life, which can be promoted in the clinic.

Common Driving Forces of Provincial-Level Greenhouse Gas and Air Pollutant Emissions in China.

By developing a filtering framework and a sector-level multi-regional input-output structural decomposition model, this study identifies key common emission sources, motivation sources, and inter-provincial emission flows of both GHGs and air pollutants and reveals the key driving forces of changes in different emissions from 2012 to 2017. Results show that key common emission sources are electricity sector, non-metallic mineral products, and smelting and processing of metals in Shandong and Hebei. However, key common motivation sources are the construction sectors in Guangdong, Henan, Jiangsu, Zhejiang, and Shandong. The key inflow regions include Guangdong and Zhejiang and key outflow regions include Jiangsu and Hebei. The emission reductions are attributed to the emission intensity effect of the construction sector; contrastingly, the emission increase is from the investment scale of the construction sector. Here, Jiangsu could be a key target for future emission reduction because of its high absolute emissions and low past reduction. The scale of investment in construction might be a significant factor in reducing emissions in Shandong and Guangdong. Henan and Zhejiang could concentrate on sound new building planning and resource recycling.

Global translational reprogramming is a fundamental layer of immune regulation in plants.

In the absence of specialized immune cells, the need for plants to reprogram transcription to transition from growth-related activities to defence is well understood. However, little is known about translational changes that occur during immune induction. Using ribosome footprinting, here we perform global translatome profiling on Arabidopsis exposed to the microbe-associated molecular pattern elf18. We find that during this pattern-triggered immunity, translation is tightly regulated and poorly correlated with transcription. Identification of genes with altered translational efficiency leads to the discovery of novel regulators of this immune response. Further investigation of these genes shows that messenger RNA sequence features are major determinants of the observed translational efficiency changes. In the 5' leader sequences of transcripts with increased translational efficiency, we find a highly enriched messenger RNA consensus sequence, R-motif, consisting of mostly purines. We show that R-motif regulates translation in response to pattern-triggered immunity induction through interaction with poly(A)-binding proteins. Therefore, this study provides not only strong evidence, but also a molecular mechanism, for global translational reprogramming during pattern-triggered immunity in plants.

uORF-mediated translation allows engineered plant disease resistance without fitness costs.

Controlling plant disease has been a struggle for humankind since the advent of agriculture. Studies of plant immune mechanisms have led to strategies of engineering resistant crops through ectopic transcription of plants' own defence genes, such as the master immune regulatory gene NPR1 (ref. 1). However, enhanced resistance obtained through such strategies is often associated with substantial penalties to fitness, making the resulting products undesirable for agricultural applications. To remedy this problem, we sought more stringent mechanisms of expressing defence proteins. On the basis of our latest finding that translation of key immune regulators, such as TBF1 (ref. 3), is rapidly and transiently induced upon pathogen challenge (see accompanying paper), we developed a 'TBF1-cassette' consisting of not only the immune-inducible promoter but also two pathogen-responsive upstream open reading frames (uORFsTBF1) of the TBF1 gene. Here we demonstrate that inclusion of uORFsTBF1-mediated translational control over the production of snc1-1 (an autoactivated immune receptor) in Arabidopsis thaliana and AtNPR1 in rice enables us to engineer broad-spectrum disease resistance without compromising plant fitness in the laboratory or in the field. This broadly applicable strategy may lead to decreased pesticide use and reduce the selective pressure for resistant pathogens.

The UBC27-AIRP3 ubiquitination complex modulates ABA signaling by promoting the degradation of ABI1 in Arabidopsis.

Abscisic acid (ABA) is the key phytohormone in plant drought tolerance and stress adaptation. The clade A protein phosphatase 2Cs (PP2Cs) like ABI1 (ABA-INSENSITIVE 1) work as coreceptors of ABA and regulate multiple ABA responses. Ubiquitination of ABI1 has been proven to play important regulatory roles in ABA signaling. However, the specific ubiquitin conjugating enzyme (E2) involved is unknown. Here, we report that UBC27 is an active E2 that positively regulates ABA signaling and drought tolerance. UBC27 forms the E2-E3 pair with the drought regulator RING E3 ligase AIRP3. Both UBC27 and AIRP3 interact with ABI1 and affect the ubiquitination and degradation of ABI1. ABA activates the expression of UBC27, inhibits the proteasome degradation of UBC27, and enhances the interaction between UBC27 and ABI1 to increase its activity. These findings uncover a regulatory mechanism in ABA signaling and drought response and provide a further understanding of the plant ubiquitination system and ABA signaling pathway.

Adaptive Changes in Detoxification Metabolism and Transmembrane Transport of Bombyx mori Malpighian Tubules to Artificial Diet.

The high adaptability of insects to food sources has contributed to their ranking among the most abundant and diverse species on Earth. However, the molecular mechanisms underlying the rapid adaptation of insects to different foods remain unclear. We explored the changes in gene expression and metabolic composition of the Malpighian tubules as an important metabolic excretion and detoxification organ in silkworms (Bombyx mori) fed mulberry leaf and artificial diets. A total of 2436 differentially expressed genes (DEGs) and 245 differential metabolites were identified between groups, with the majority of DEGs associated with metabolic detoxification, transmembrane transport, and mitochondrial function. Detoxification enzymes, such as cytochrome P450 (CYP), glutathione-S-transferase (GST), and UDP-glycosyltransferase, and ABC and SLC transporters of endogenous and exogenous solutes were more abundant in the artificial diet group. Enzyme activity assays confirmed increased CYP and GST activity in the Malpighian tubules of the artificial diet-fed group. Metabolome analysis showed increased contents of secondary metabolites, terpenoids, flavonoids, alkaloids, organic acids, lipids, and food additives in the artificial diet group. Our findings highlight the important role of the Malpighian tubules in adaptation to different foods and provide guidance for further optimization of artificial diets to improve silkworm breeding.

The novel pathogen-responsive glycosyltransferase UGT73C7 mediates the redirection of phenylpropanoid metabolism and promotes SNC1-dependent Arabidopsis immunity.

Recent studies have shown that global metabolic reprogramming is a common event in plant innate immunity; however, the relevant molecular mechanisms remain largely unknown. Here, we identified a pathogen-induced glycosyltransferase, UGT73C7, that plays a critical role in Arabidopsis disease resistance through mediating redirection of the phenylpropanoid pathway. Loss of UGT73C7 function resulted in significantly decreased resistance to Pseudomonas syringae pv. tomato DC3000, whereas constitutive overexpression of UGT73C7 led to an enhanced defense response. UGT73C7-activated immunity was demonstrated to be dependent on the upregulated expression of SNC1, a Toll/interleukin 1 receptor-type NLR gene. Furthermore, in vitro and in vivo assays indicated that UGT73C7 could glycosylate p-coumaric acid and ferulic acid, the upstream metabolites in the phenylpropanoid pathway. Mutations that lead to the loss of UGT73C7 enzyme activities resulted in the failure to induce SNC1 expression. Moreover, glycosylation activity of UGT73C7 resulted in the redirection of phenylpropanoid metabolic flux to biosynthesis of hydroxycinnamic acids and coumarins. The disruption of the phenylpropanoid pathway suppressed UGT73C7-promoted SNC1 expression and the immune response. This study not only identified UGT73C7 as an important regulator that adjusts phenylpropanoid metabolism upon pathogen challenge, but also provided a link between phenylpropanoid metabolism and an NLR gene.

Transcriptome analysis provides insights into the bases of salicylic acid-induced resistance to anthracnose in sorghum.

Key Message Transcriptome analysis of SA sensitive and tolerant lines indicates that SA enhances anthracnose resistance in sorghum by upregulating the expression of some immune-related genes and pathways.Abstract Anthracnose caused by the hemibiotrophic pathogen Colletotrichum sublineolum is one of the most destructive diseases of sorghum, the fifth most important cereal crop in the world. Salicylic acid (SA) is a phytohormone essential for plant immunity; however, the role of SA in sorghum resistance to anthracnose has not been well explored. In this study, we found that Colletotrichum sublineolum infection induced the expression of SA-responsive genes and that exogenous SA enhanced resistance to anthracnose in the sorghum line BTx623. To rule out the possibility that SA triggers anthracnose resistance in sorghum by its direct toxic function on pathogen, an SA-tolerant line, WHEATLAND, was identified, and we found that SA treatment could not induce anthracnose resistance in WHEATLAND. Then, SA-induced transcriptome changes during Colletotrichum sublineolum infection in BTx623 and WHEATLAND were analyzed to explore the molecular mechanism of SA-triggered resistance. SA pretreatment regulated the expression of 2125 genes in BTx623 but only 524 genes in WHEATLAND during Colletotrichum sublineolum infection. The cutin, suberine and wax biosynthesis pathway involved in the plant immune response and the flavonoid biosynthesis pathway involved in anthracnose resistance were enriched in BTx623-specifically upregulated genes. Additionally, some immune-related genes, including multiple resistance genes, were differentially expressed in BTx623 and WHEATLAND. Taken together, our results revealed the mechanisms of SA-induced anthracnose resistance in sorghum at the transcriptional level and shed light on the possibility of enhancing sorghum resistance to anthracnose by activating the SA signaling pathway by molecular breeding.

GLABRA2-based selection efficiently enriches Cas9-generated nonchimeric mutants in the T1 generation.

The CRISPR/Cas9 system is a widely used tool for genome editing in plants. In Arabidopsis (Arabidopsis thaliana), egg cell-specific promoters driving Cas9 expression have been applied to reduce the proportion of T1 transformants that are chimeras; however, this approach generally leads to relatively low mutagenesis rates. In this study, a GLABRA2 mutation-based visible selection (GBVS) system was established to enrich nonchimeric mutants among T1 plants generated by an egg cell-specific CRISPR/Cas9 system. GBVS generally enhanced mutation screening, increasing the frequency by 2.58- to 7.50-fold, and 25%-48.15% of T1 plants selected through the GBVS system were homozygous or biallelic mutants, which was 1.71- to 7.86-fold higher than the percentage selected using the original system. The mutant phenotypes of T2 plants were not obviously affected by the glabrous background for all four target genes used in this study. Additionally, the nonchimeric pyrabactin resistance 1 (PYR1)/PYR1-like 1 (PYL1) and PYL2 triple mutant pyr1/pyl1/pyl2 could be obtained in the T1 generation with a ratio of 26.67% when GBVS was applied. Collectively, our results show that compared with the known CRISPR/Cas9 systems, the GBVS system described here saves more time and labor when used for the obtainment of homozygous or biallelic monogenic mutants and nonchimeric polygenic mutants in Arabidopsis.

Arabidopsis Cys2/His2 Zinc Finger Transcription Factor ZAT18 Modulates the Plant Growth-Defense Tradeoff.

Plant defense responses under unfavorable conditions are often associated with reduced growth. However, the mechanisms underlying the growth-defense tradeoff remain to be fully elucidated, especially at the transcriptional level. Here, we revealed a Cys2/His2-type zinc finger transcription factor, namely, ZAT18, which played dual roles in plant immunity and growth by oppositely regulating the signaling of defense- and growth-related hormones. ZAT18 was first identified as a salicylic acid (SA)-inducible gene and was required for plant responses to SA in this study. In addition, we observed that ZAT18 enhanced the plant immunity with growth penalties that may have been achieved by activating SA signaling and repressing auxin signaling. Further transcriptome analysis of the zat18 mutant showed that the biological pathways of defense-related hormones, including SA, ethylene and abscisic acid, were repressed and that the biological pathways of auxin and cytokinin, which are growth-related hormones, were activated by abolishing the function of ZAT18. The ZAT18-mediated regulation of hormone signaling was further confirmed using qRT-PCR. Our results explored a mechanism by which plants handle defense and growth at the transcriptional level under stress conditions.

Antiviral strategies: What can we learn from natural reservoirs?

Viruses cause many severe diseases in both plants and animals, urging us to explore new antiviral strategies. In their natural reservoirs, viruses live and replicate while causing mild or no symptoms. Some animals, such as bats, are the predicted natural reservoir of multiple viruses, indicating that they possess broad-spectrum antiviral capabilities. Mechanisms of host defenses against viruses are generally studied independently in plants and animals. In this article, we speculate that some antiviral strategies of natural reservoirs are conserved between kingdoms. To verify this hypothesis, we created null mutants of 10-formyltetrahydrofolate synthetase (AtTHFS), an Arabidopsis thaliana homologue of methylenetetrahydrofolate dehydrogenase, cyclohydrolase and formyltetrahydrofolate synthetase 1 (MTHFD1), which encodes a positive regulator of viral replication in bats. We found that disruption of AtTHFS enhanced plant resistance to three different types of plant viruses, including the tomato spotted wilt virus (TSWV), the cucumber mosaic virus (CMV) and the beet severe curly top virus (BSCTV). These results demonstrate a novel antiviral strategy for plant breeding. We further discuss the approaches used to identify and study natural reservoirs of plant viruses, especially those hosting many viruses, and highlight the possibility of discovering new antiviral strategies from them for plant molecular breeding and antiviral therapy.

The THO/TREX Complex Active in Alternative Splicing Mediates Plant Responses to Salicylic Acid and Jasmonic Acid.

Salicylic acid (SA) and jasmonic acid (JA) are essential plant immune hormones, which could induce plant resistance to multiple pathogens. However, whether common components are employed by both SA and JA to induce defense is largely unknown. In this study, we found that the enhanced disease susceptibility 8 (EDS8) mutant was compromised in plant defenses to hemibiotrophic pathogen Pseudomonas syringae pv. maculicola ES4326 and necrotrophic pathogen Botrytis cinerea, and was deficient in plant responses to both SA and JA. The EDS8 was identified to be THO1, which encodes a subunit of the THO/TREX complex, by using mapping-by-sequencing. To check whether the EDS8 itself or the THO/TREX complex mediates SA and JA signaling, the mutant of another subunit of the THO/TREX complex, THO3, was tested. THO3 mutation reduced both SA and JA induced defenses, indicating that the THO/TREX complex is critical for plant responses to these two hormones. We further proved that the THO/TREX interacting protein SERRATE, a factor regulating alternative splicing (AS), was involved in plant responses to SA and JA. Thus, the AS events in the eds8 mutant after SA or JA treatment were determined, and we found that the SA and JA induced different alternative splicing events were majorly modulated by EDS8. In summary, our study proves that the THO/TREX complex active in AS is involved in both SA and JA induced plant defenses.

[Determination of polychlorinated biphenyls in water by stable isotope dilution through automatic solid-phase extraction membrane coupled to gas chromatography-mass spectrometry].

OBJECTIVE: The method for analyzing of 20 polychlorinated biphenyls(PCBs) in water by stable isotope internal standard-automatic solid-phase extraction membrane(auto SPEM) coupled to gas chromatography-mass spectrometer(GC-MS) was established, and applied to the analysis of trace PCBs in water samples. METHODS: The sample backgrounds of bottled mineral water production in Fuzhou(groundwater), inland water in Fuzhou university city(surface water), tap water(pipe tip water) and stream water in Xiyuan Gong(water source of life) were analyzed by GC-MS. Surrogate solution(SS)internal standards including ~(13)C_(12 )PCBs stable isotope was used for quantification. The method was confirmed by calculating recovery rate(RR) and relative standard deviation(RSD) of spiked water samples(20, 40 and 80 ng/L, n=7). And recovery rates of SS were used to evaluate the effect of the pretreatment. And the method was used to determine PCBs of a total of 17 cross-sectiona river water in minjiang river tributaries upstream to the downstream estuary. RESULTS: The method detection limits(MDL) were 1. 9-6. 6 ng/L, and RRs were 70. 9%-127%, and RSDs were 0. 5%-13%. The RRs of SS were 40%-90%. Positive sample was not detected. CONCLUSION: The method of auto SPEM is less solvent, more automatic than traditional manual SPE. And the method is more accurate and reliable by stable isotope internal standard coupled to GC-MS. Therefore, it is useful for the trace PCBs determination of waters.

The RING finger ubiquitin E3 ligase SDIR1 targets SDIR1-INTERACTING PROTEIN1 for degradation to modulate the salt stress response and ABA signaling in Arabidopsis.

The plant hormone abscisic acid (ABA) regulates many aspects of plant development and the stress response. The intracellular E3 ligase SDIR1 (SALT- AND DROUGHT-INDUCED REALLY INTERESTING NEW GENE FINGER1) plays a key role in ABA signaling, regulating ABA-related seed germination and the stress response. In this study, we found that SDIR1 is localized on the endoplasmic reticulum membrane in Arabidopsis thaliana. Using cell biology, molecular biology, and biochemistry approaches, we demonstrated that SDIR1 interacts with and ubiquitinates its substrate, SDIRIP1 (SDIR1-INTERACTING PROTEIN1), to modulate SDIRIP1 stability through the 26S proteasome pathway. SDIRIP1 acts genetically downstream of SDIR1 in ABA and salt stress signaling. In detail, SDIRIP1 selectively regulates the expression of the downstream basic region/leucine zipper motif transcription factor gene ABA-INSENSITIVE5, rather than ABA-RESPONSIVE ELEMENTS BINDING FACTOR3 (ABF3) or ABF4, to regulate ABA-mediated seed germination and the plant salt response. Overall, the SDIR1/SDIRIP1 complex plays a vital role in ABA signaling through the ubiquitination pathway.

CRISPR/Cas9-Mediated Mutagenesis of Carotenoid Cleavage Dioxygenase 8 (CCD8) in Tobacco Affects Shoot and Root Architecture.

Strigolactones (SLs) are a class of phytohormones that regulate plant architecture. Carotenoid cleavage dioxygenase (CCD) genes are involved in the biosynthesis of SLs and are identified and characterized in many plants. However, the function of CCD genes in tobacco remains poorly understood. In this study, two closely related genes NtCCD8A and NtCCD8B were cloned from tobacco (Nicotiana tabacum L.). The two NtCCD8 genes are orthologues of the tomato (Solanum lycopersicum) carotenoid cleavage dioxygenase 8 (SlCCD8) gene. NtCCD8A and NtCCD8B were primarily expressed in tobacco roots, but low expression levels of these genes were detected in all plant tissues, and their transcript levels significantly increased in response to phosphate limitation. NtCCD8A and NtCCD8B mutations were introduced into tobacco using the CRISPR/Cas9 system and transgenic tobacco lines for both ntccd8 mutant alleles were identified. The ntccd8a and ntccd8b mutant alleles were inactivated by a deletion of three nucleotides and insertion of one nucleotide, respectively, both of which led to the production of premature stop codons. The ntccd8 mutants had increased shoot branching, reduced plant height, increased number of leaves and nodes, and reduced total plant biomass compared to wild-type plants; however, the root-to-shoot ratio was unchanged. In addition, mutant lines had shorter primary roots and more of lateral roots than wild type. These results suggest that NtCCD8 genes are important for changes in tobacco plant architecture.