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The UDP-glucose: glycoprotein glucosyltransferase (UGGT), a key enzyme in ER quality control, plays a significant role in plant growth as well as biotic and abiotic stress in Arabidopsis thaliana.

Blanco-Herrera F, Moreno AA, Tapia R, Reyes F, Araya M, D'Alessio C, Parodi A, Orellana A - BMC Plant Biol. (2015)

Bottom Line: Here, we show that two mutant alleles in the At1g71220 locus have none or reduced UGGT activity.These results show that a lack of UGGT activity alters plant vegetative development and impairs the response to several abiotic and biotic stresses.Moreover, our results uncover an unexpected role of UGGT in the incorporation of UDP-Glucose into the ER lumen in Arabidopsis thaliana.

View Article: PubMed Central - PubMed

Affiliation: Centro de Biotecnología Vegetal, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Avenida República 217, Santiago, 837-0146, RM, Chile. mblanco@unab.cl.

ABSTRACT

Background: UDP-glucose: glycoprotein glucosyltransferase (UGGT) is a key player in the quality control mechanism (ER-QC) that newly synthesized glycoproteins undergo in the ER. It has been shown that the UGGT Arabidopsis orthologue is involved in ER-QC; however, its role in plant physiology remains unclear.

Results: Here, we show that two mutant alleles in the At1g71220 locus have none or reduced UGGT activity. In wild type plants, the AtUGGT transcript levels increased upon activation of the unfolded protein response (UPR). Interestingly, mutants in AtUGGT exhibited an endogenous up-regulation of genes that are UPR targets. In addition, mutants in AtUGGT showed a 30% reduction in the incorporation of UDP-Glucose into the ER suggesting that this enzyme drives the uptake of this substrate for the CNX/CRT cycle. Plants deficient in UGGT exhibited a delayed growth rate of the primary root and rosette as well as an alteration in the number of leaves. These mutants are more sensitive to pathogen attack as well as heat, salt, and UPR-inducing stressors. Additionally, the plants showed impairment in the establishment of systemic acquired resistance (SAR).

Conclusions: These results show that a lack of UGGT activity alters plant vegetative development and impairs the response to several abiotic and biotic stresses. Moreover, our results uncover an unexpected role of UGGT in the incorporation of UDP-Glucose into the ER lumen in Arabidopsis thaliana.

No MeSH data available.


Related in: MedlinePlus

AtUGGT mutant plants are less tolerant to biotic stress. Whole leaves of four-week-old soil grown WT and mutant plants were infiltrated with Pst AvrRpm1 (OD600 = 0.001) to trigger SAR; a solution of 10 mM MgCl2 served as the mock. Twenty-four hours later the systemic leaves were infiltrated with Pst DC3000 (OD600 = 0.001). Bacterial growth (Pst DC3000) was monitored 3 days post infection. Error bars represent standard deviation from 6 samples. Different letters statically represent differences between the genotypes (lowercase for –AvrRpm1; uppercase for + AvrRpm1) at p < 0.05 (Tukey’s test). The experiments were performed at least three times with similar results
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Fig6: AtUGGT mutant plants are less tolerant to biotic stress. Whole leaves of four-week-old soil grown WT and mutant plants were infiltrated with Pst AvrRpm1 (OD600 = 0.001) to trigger SAR; a solution of 10 mM MgCl2 served as the mock. Twenty-four hours later the systemic leaves were infiltrated with Pst DC3000 (OD600 = 0.001). Bacterial growth (Pst DC3000) was monitored 3 days post infection. Error bars represent standard deviation from 6 samples. Different letters statically represent differences between the genotypes (lowercase for –AvrRpm1; uppercase for + AvrRpm1) at p < 0.05 (Tukey’s test). The experiments were performed at least three times with similar results

Mentions: Multiple lines of evidence suggest that UGGT is involved in pathogen response [15, 16]. Therefore, we decided to test the sensitivity to pathogens on mutants that have residual or no detectable UGGT activity. We infected UGGT mutant plants with Pseudomona syringae pv tomato DC3000 (Pst) and assessed the number of bacteria infecting the leaves after 3 days. A higher number of bacteria were recovered from the leaves of mutants in comparison to those obtained from wild type suggesting that mutants in AtUGGT have an altered basal defense response (Fig. 6). Furthermore, a similar phenotype was observed when plants were first infected with Pst avrRpm1 to induce the systemic acquired resistance followed by infection with the virulent strain (Pst DC3000) (Fig. 6). These results indicate that both basal and systemic resistance responses are compromised in the AtUGGT mutants.Fig. 6


The UDP-glucose: glycoprotein glucosyltransferase (UGGT), a key enzyme in ER quality control, plays a significant role in plant growth as well as biotic and abiotic stress in Arabidopsis thaliana.

Blanco-Herrera F, Moreno AA, Tapia R, Reyes F, Araya M, D'Alessio C, Parodi A, Orellana A - BMC Plant Biol. (2015)

AtUGGT mutant plants are less tolerant to biotic stress. Whole leaves of four-week-old soil grown WT and mutant plants were infiltrated with Pst AvrRpm1 (OD600 = 0.001) to trigger SAR; a solution of 10 mM MgCl2 served as the mock. Twenty-four hours later the systemic leaves were infiltrated with Pst DC3000 (OD600 = 0.001). Bacterial growth (Pst DC3000) was monitored 3 days post infection. Error bars represent standard deviation from 6 samples. Different letters statically represent differences between the genotypes (lowercase for –AvrRpm1; uppercase for + AvrRpm1) at p < 0.05 (Tukey’s test). The experiments were performed at least three times with similar results
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4465474&req=5

Fig6: AtUGGT mutant plants are less tolerant to biotic stress. Whole leaves of four-week-old soil grown WT and mutant plants were infiltrated with Pst AvrRpm1 (OD600 = 0.001) to trigger SAR; a solution of 10 mM MgCl2 served as the mock. Twenty-four hours later the systemic leaves were infiltrated with Pst DC3000 (OD600 = 0.001). Bacterial growth (Pst DC3000) was monitored 3 days post infection. Error bars represent standard deviation from 6 samples. Different letters statically represent differences between the genotypes (lowercase for –AvrRpm1; uppercase for + AvrRpm1) at p < 0.05 (Tukey’s test). The experiments were performed at least three times with similar results
Mentions: Multiple lines of evidence suggest that UGGT is involved in pathogen response [15, 16]. Therefore, we decided to test the sensitivity to pathogens on mutants that have residual or no detectable UGGT activity. We infected UGGT mutant plants with Pseudomona syringae pv tomato DC3000 (Pst) and assessed the number of bacteria infecting the leaves after 3 days. A higher number of bacteria were recovered from the leaves of mutants in comparison to those obtained from wild type suggesting that mutants in AtUGGT have an altered basal defense response (Fig. 6). Furthermore, a similar phenotype was observed when plants were first infected with Pst avrRpm1 to induce the systemic acquired resistance followed by infection with the virulent strain (Pst DC3000) (Fig. 6). These results indicate that both basal and systemic resistance responses are compromised in the AtUGGT mutants.Fig. 6

Bottom Line: Here, we show that two mutant alleles in the At1g71220 locus have none or reduced UGGT activity.These results show that a lack of UGGT activity alters plant vegetative development and impairs the response to several abiotic and biotic stresses.Moreover, our results uncover an unexpected role of UGGT in the incorporation of UDP-Glucose into the ER lumen in Arabidopsis thaliana.

View Article: PubMed Central - PubMed

Affiliation: Centro de Biotecnología Vegetal, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Avenida República 217, Santiago, 837-0146, RM, Chile. mblanco@unab.cl.

ABSTRACT

Background: UDP-glucose: glycoprotein glucosyltransferase (UGGT) is a key player in the quality control mechanism (ER-QC) that newly synthesized glycoproteins undergo in the ER. It has been shown that the UGGT Arabidopsis orthologue is involved in ER-QC; however, its role in plant physiology remains unclear.

Results: Here, we show that two mutant alleles in the At1g71220 locus have none or reduced UGGT activity. In wild type plants, the AtUGGT transcript levels increased upon activation of the unfolded protein response (UPR). Interestingly, mutants in AtUGGT exhibited an endogenous up-regulation of genes that are UPR targets. In addition, mutants in AtUGGT showed a 30% reduction in the incorporation of UDP-Glucose into the ER suggesting that this enzyme drives the uptake of this substrate for the CNX/CRT cycle. Plants deficient in UGGT exhibited a delayed growth rate of the primary root and rosette as well as an alteration in the number of leaves. These mutants are more sensitive to pathogen attack as well as heat, salt, and UPR-inducing stressors. Additionally, the plants showed impairment in the establishment of systemic acquired resistance (SAR).

Conclusions: These results show that a lack of UGGT activity alters plant vegetative development and impairs the response to several abiotic and biotic stresses. Moreover, our results uncover an unexpected role of UGGT in the incorporation of UDP-Glucose into the ER lumen in Arabidopsis thaliana.

No MeSH data available.


Related in: MedlinePlus