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Asparagine-linked glycosylation (ALG, N-glycosylation) is one of the most prevalent protein modifications in eukaryotes and regulates protein folding, trafficking and function. Recently, we reported that the mutation of N154Q significantly led to the ER retention of brassinosteroids insensitive 1 (BRI1), the receptor of brassinosteroids (BRs). However, the mechanism of how the N154 site affects BRI1 structure is still not completely clear. In current study, we found that the removal of N

N-glycans play a protective or monitoring role according to the folding state of associated protein or the distance from structural defects. Asparagine-linked (Asn/N-) glycosylation is one of the most prevalent and complex protein modifications and the associated N-glycans play crucial roles on protein folding and secretion. The studies have shown that many glycoproteins hold multiple N-glycans, yet little is known about the redundancy of N-glycans on a protein. In this study, we used BRI1 to decipher the roles of N-glycans on protein secretion and function. We found that all 14 potential N-glycosylation sites on BRI1 were occupied with oligosaccharides. The elimination of single N-glycan had no obvious effect on BRI1 secretion or function except N154-glycan, which resulted in the retention of BRI1 in the endoplasmic reticulum (ER), similar to the loss of multiple highly conserved N-glycans. To misfolded bri1, the absence of N-glycans next to local structural defects enhanced the ER retention and the artificial addition of N-glycan could help the misfolded bri1-GFPs exiting from the ER, indicating that the N-glycans might serve as steric hindrance to protect the structure defects from ER recognition. We also found that the retention of misfolded bri1-9 by lectins and chaperones in the ER relied on the presence of multiple N-glycans distal to the local defects. Our findings revealed that the N-glycans might play a protective or monitoring role according to the folding state of associated protein or the distance from structural defects.

Many pieces of evidence show that the adaptive response of plants to salt stress requires the maturation of N-glycan on associated proteins. However, it is still little known about the salt-responsive glycoproteins that function in this process. In the present study, we identified salt-responsive glycoproteins in wild-type (WT) Arabidopsis and two mutants defective in N-glycan maturation, mns1 mns2 and cgl1. A total of 97 proteins with abundance changes of >1.5‐ or mns1 mns2 hardly form functional regulatory networks in STRING analysis. Comparably, the regulatory network in cgl1 was visible and shared overlapping with that in WT. Such difference may supply the evidence to partially explain the lower salt sensitivity of mutant cgl1 than mns1 mns2. We further confirmed that two N-glycosylation clients, peroxidases PRX32 and PRX34, were involved in the salt stress response since the double mutants showed enhanced salt sensitivity. Together, our study provided proteomic evidence that N-glycans are crucial for modulating stress-responsive protein levels, and several novel glycoproteins responsible for salt stress tolerance in Arabidopsis were listed. Data are available via ProteomeXchange with identifier PXD006893.

We employed hi-TAIL-PCR to identify T-DNA loci in our Arabidopsis activation tagging library and only a total of 28 (39%) insertion sites from 72 samples were characterized when the recommended primer pools, C1 and C2 were used. By comparison, we found C1 harboring relatively low degeneracy was more efficient to amplify the flanking sequences of T-DNA insertion than C2. We replaced the degenerate sequences in long arbitrary degenerate (LAD) primers with a piece of 16-bp degenerate sequence originally used in TAIL-PCR, which had the relatively low degeneracy. Our results showed that the new LAD primer pool N increased the valid amplifications and a total of 37 (51%) T-DNA loci were identified, indicating a more effective amplification of T-DNA flanking sequences in A. thaliana.

Asparagine (Asn/N)-linked glycans are important for protein folding, trafficking, and endoplasmic reticulum-associated degradation in eukaryotes. The maturation of glycoproteins involves the trimming of mannosyl residues by mannosidases and addition of other sugar molecules to three-branched N-glycans in the Golgi. However, the biological importance of Golgi-mediated mannose trimming is not fully understood. Here, we show that abolishment of two functionally redundant mannosidases, MNS1 and MNS2, responsible for α-1,2-mannose trimming on the A and C branches of plant N-glycans lead to severe root growth inhibition under salt stress conditions in Arabidopsis. In contrast, mutants with defects in the biosynthesis of the oligosaccharide precursor displayed enhanced salt tolerance in the absence of mannose trimming. However, mutation in EBS3, which is required for the formation of the branched N-glycan precursor, suppressed the salt-sensitive phenotype of mns1 mns2 double mutant. Interestingly, we observed that cellulose biosynthesis was compromised in mns1 mns2 roots under high salinity. Consistently, abundance of a membrane anchored endo-β-1,4-endoglucanase (RSW2/KOR) that plays a key role in cellulose biosynthesis and its mutant variant rsw2-1 were modulated by α-1,2-mannose trimming under salt stress. Overexpression of RSW2 could partially rescue the salt-sensitive phenotype of mns1 mns2. Taken together, these results suggest that MNS1/2-mediated mannose trimming of N-glycans is crucial in modulating glycoprotein abundance to withstand salt stress in plants.

In this study, a sonochemical approach is developed to prepare rare-earth (Y $$^{3+}$$ , Tb $$^{3+}$$ , or Er $$^{3+})$$ -doped zinc oxide nanocrystals in an ionic liquid: 1-butyl-3-methylimidazolium tetrafluoroborate. The nanomaterials are characterized by transmission electron microscopy and X-ray diffraction. The results show that the crystalline samples have a spherical shape with a diameter around 7.5 nm. In the band-edge transition region, the photoacoustic (PA) intensity of the samples changes remarkably. Different PA intensities of the samples are interpreted by comparison with their luminescence spectra. The results indicate that the luminescence properties of zinc oxide can be tuned by rare-earth doping. The luminescence quantum yields have been determined to be 12 %, 9.3 %, and 1.1 % for Tb $$^{3+}$$ -, Y $$^{3+}$$ -, and Er $$^{3+}$$ -doped ZnO samples, respectively. Moreover, a possible mechanism is proposed to interpret the formation of the nanocrystals.

In this work, lanthanide $$\beta $$ -diketonate complexes Ln(btfa) $${}_{3} \cdot 2\hbox {H}_{2}$$ O (Ln $$^{3+}$$ : Eu $$^{3+}$$ , Sm $$^{3+ }$$ , and Tb $$^{3+}$$ ; btfa: 4,4,4-trifluoro-l-phenyl-1,3-butanedione) were incorporated into silica gels by a sol–gel method. Photoacoustic (PA) spectra of these complex-doped silica samples were measured and studied. The PA intensity of the $$\beta $$ -diketonate ligand is nearly the same for lanthanide complexes in wet gels. After heat treatment at 150 $$^{\circ }$$ C, however, the PA intensity of the ligand increases for Eu $$^{3+}$$ , Sm $$^{3+}$$ , and Tb $$^{3+}$$ complexes in silica gels, respectively. Different PA intensities of the samples are interpreted by comparison with their luminescence spectra. The luminescence result is consistent with the PA spectra. The result indicates that lanthanide $$\beta $$ -diketonate complexes cannot be formed in silica gels without a suitable heat treatment. Moreover, the relaxation process model is proposed based on the PA and luminescence results.

In this work, $$\hbox {Pr}^{3+}$$ -doped titania nanomaterials were prepared by a sol–gel method. The structural variations of the samples during the phase transitions were studied by using the $$\hbox {Pr}^{3+}$$ ion as a photoacoustic spectral probe. The result shows that for the gel sample heated at $$80\,^{\circ }\hbox {C}$$ , the coordination environment of $$\hbox {Pr}^{3+}$$ is similar to that of its aqueous ion. The f–f transitions of $$\hbox {Pr}^{3+}$$ exhibit a continuous red shift along with the gel-to-anatase transition, indicating an increase of the ‘degree of covalency’ for the $$\hbox {Pr}^{3+}$$ bonding. For the sample calcined at $$1100\,^{\circ }\hbox {C}$$ , however, the f–f transitions of $$\hbox {Pr}^{3+}$$ show obvious blue shift. This can be attributed to the segregation of $$\hbox {Pr}^{3+}$$ ions to the external surface during the anatase-to-rutile transition, forming $$\hbox {Pr}_{4}\hbox {Ti}_{9}\hbox {O}_{24}$$ . The stabilization effect of the doped $$\hbox {Pr}^{3+ }$$ ions on the anatase phase of the samples is also discussed.