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Three SAUR proteins SAUR76, SAUR77 and SAUR78 promote plant growth in Arabidopsis.

Li ZG, Chen HW, Li QT, Tao JJ, Bian XH, Ma B, Zhang WK, Chen SY, Zhang JS - Sci Rep (2015)

Bottom Line: Compared with wild type, SAUR-overexpressing plants exhibit reduced ethylene sensitivity, while SAUR-RNAi lines exhibit enhanced ethylene sensitivity.Overexpressing the three SAURs partially complements the phenotype of subfamily II ethylene receptor loss-of-function double mutant etr2-3ein4-4, which has increased ethylene response and small cotyledon and rosette. saur76 mutation partially suppresses the reduced ethylene sensitivity of etr2-2.These findings suggest that SAUR76-78 may affect ethylene receptor signaling and promote plant growth in Arabidopsis.

View Article: PubMed Central - PubMed

Affiliation: State Key Lab of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.

ABSTRACT
Ethylene perceived by a family of five receptors regulates many developmental processes in Arabidopsis. Here we conducted the yeast two-hybrid assay to screen for additional unidentified proteins that interact with subfamily II ethylene receptor ETR2. Three SAUR proteins, named SAUR76, 77 and 78, were identified to associate with both ETR2 and EIN4 in different assays. Interaction of SAUR76 and SAUR78 with ETR2 was further verified by co-immunoprecipitation and bimolecular fluorescence complementation (BiFC) assays. Expressions of SAUR76-78 are induced by auxin and ethylene treatments. Compared with wild type, SAUR-overexpressing plants exhibit reduced ethylene sensitivity, while SAUR-RNAi lines exhibit enhanced ethylene sensitivity. Overexpressing the three SAURs partially complements the phenotype of subfamily II ethylene receptor loss-of-function double mutant etr2-3ein4-4, which has increased ethylene response and small cotyledon and rosette. saur76 mutation partially suppresses the reduced ethylene sensitivity of etr2-2. SAUR76/78 proteins are regulated by 26S proteasome system and larger tag increases their protein stability. These findings suggest that SAUR76-78 may affect ethylene receptor signaling and promote plant growth in Arabidopsis.

No MeSH data available.


SAUR76-78 gene expressions.(a) SAUR76-78 expressions in response to ethylene by quantitative PCR. Six-day-old seedlings were used. Bars indicate SD (n = 3). (b) SAUR76-78 expressions upon NAA treatments. Others are as in (a). (c). Expressions of three SAUR genes in different plant organs. Bars indicate SD (n = 3). (d) Promoter-GUS analysis of the three SAUR genes. The 2.3 ~ 2.5 kb promoter regions of the three SAUR76-78 genes were used to drive the GUS gene. From top to bottom, SAUR76 to 78 promoters were analyzed. From left to right, seedling, root tip, leaf, flowers and siliques were stained for GUS activity. (e) Detection of GUS activity in eight-day-old PSAUR78-GUS transgenic seedlings treated with 10 μM ethylene and 50 μM NAA for 1 h. Representative pictures of seedling, aerial parts and root tip are shown. Lower panel: quantitation of GUS activity. Bars indicate SD (n = 4).
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f3: SAUR76-78 gene expressions.(a) SAUR76-78 expressions in response to ethylene by quantitative PCR. Six-day-old seedlings were used. Bars indicate SD (n = 3). (b) SAUR76-78 expressions upon NAA treatments. Others are as in (a). (c). Expressions of three SAUR genes in different plant organs. Bars indicate SD (n = 3). (d) Promoter-GUS analysis of the three SAUR genes. The 2.3 ~ 2.5 kb promoter regions of the three SAUR76-78 genes were used to drive the GUS gene. From top to bottom, SAUR76 to 78 promoters were analyzed. From left to right, seedling, root tip, leaf, flowers and siliques were stained for GUS activity. (e) Detection of GUS activity in eight-day-old PSAUR78-GUS transgenic seedlings treated with 10 μM ethylene and 50 μM NAA for 1 h. Representative pictures of seedling, aerial parts and root tip are shown. Lower panel: quantitation of GUS activity. Bars indicate SD (n = 4).

Mentions: Expressions of SAURs were investigated in six-day-old Arabidopsis seedlings in relation to ethylene as well as auxin treatments. The three SAURs were rapidly induced to peak levels within 15 min after treatment with high concentration of ethylene (10 ppm) (Fig. 3a). With lower concentrations of ethylene (0.1 ~ 1 ppm), the inductions reached peaks at 30 to 60 min after initiation (Fig. 3a). The different peak values for various concentrations of ethylene probably reflected different dynamics of inductions. Upon NAA treatment, the three SAUR transcripts accumulated to the highest levels at different time points (Fig. 3b). Because auxin can induce ethylene production, we further examined whether ethylene mediates auxin-induced gene expressions. AVG (an ethylene biosynthesis inhibitor) or 1-MCP (an ethylene perception inhibitor) treatments did not abolish the auxin inductions of these SAURs (Fig. S7), suggesting that the effects of auxin on SAUR76-78 were mainly not dependent on ethylene biosynthesis and/or signaling.


Three SAUR proteins SAUR76, SAUR77 and SAUR78 promote plant growth in Arabidopsis.

Li ZG, Chen HW, Li QT, Tao JJ, Bian XH, Ma B, Zhang WK, Chen SY, Zhang JS - Sci Rep (2015)

SAUR76-78 gene expressions.(a) SAUR76-78 expressions in response to ethylene by quantitative PCR. Six-day-old seedlings were used. Bars indicate SD (n = 3). (b) SAUR76-78 expressions upon NAA treatments. Others are as in (a). (c). Expressions of three SAUR genes in different plant organs. Bars indicate SD (n = 3). (d) Promoter-GUS analysis of the three SAUR genes. The 2.3 ~ 2.5 kb promoter regions of the three SAUR76-78 genes were used to drive the GUS gene. From top to bottom, SAUR76 to 78 promoters were analyzed. From left to right, seedling, root tip, leaf, flowers and siliques were stained for GUS activity. (e) Detection of GUS activity in eight-day-old PSAUR78-GUS transgenic seedlings treated with 10 μM ethylene and 50 μM NAA for 1 h. Representative pictures of seedling, aerial parts and root tip are shown. Lower panel: quantitation of GUS activity. Bars indicate SD (n = 4).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4513569&req=5

f3: SAUR76-78 gene expressions.(a) SAUR76-78 expressions in response to ethylene by quantitative PCR. Six-day-old seedlings were used. Bars indicate SD (n = 3). (b) SAUR76-78 expressions upon NAA treatments. Others are as in (a). (c). Expressions of three SAUR genes in different plant organs. Bars indicate SD (n = 3). (d) Promoter-GUS analysis of the three SAUR genes. The 2.3 ~ 2.5 kb promoter regions of the three SAUR76-78 genes were used to drive the GUS gene. From top to bottom, SAUR76 to 78 promoters were analyzed. From left to right, seedling, root tip, leaf, flowers and siliques were stained for GUS activity. (e) Detection of GUS activity in eight-day-old PSAUR78-GUS transgenic seedlings treated with 10 μM ethylene and 50 μM NAA for 1 h. Representative pictures of seedling, aerial parts and root tip are shown. Lower panel: quantitation of GUS activity. Bars indicate SD (n = 4).
Mentions: Expressions of SAURs were investigated in six-day-old Arabidopsis seedlings in relation to ethylene as well as auxin treatments. The three SAURs were rapidly induced to peak levels within 15 min after treatment with high concentration of ethylene (10 ppm) (Fig. 3a). With lower concentrations of ethylene (0.1 ~ 1 ppm), the inductions reached peaks at 30 to 60 min after initiation (Fig. 3a). The different peak values for various concentrations of ethylene probably reflected different dynamics of inductions. Upon NAA treatment, the three SAUR transcripts accumulated to the highest levels at different time points (Fig. 3b). Because auxin can induce ethylene production, we further examined whether ethylene mediates auxin-induced gene expressions. AVG (an ethylene biosynthesis inhibitor) or 1-MCP (an ethylene perception inhibitor) treatments did not abolish the auxin inductions of these SAURs (Fig. S7), suggesting that the effects of auxin on SAUR76-78 were mainly not dependent on ethylene biosynthesis and/or signaling.

Bottom Line: Compared with wild type, SAUR-overexpressing plants exhibit reduced ethylene sensitivity, while SAUR-RNAi lines exhibit enhanced ethylene sensitivity.Overexpressing the three SAURs partially complements the phenotype of subfamily II ethylene receptor loss-of-function double mutant etr2-3ein4-4, which has increased ethylene response and small cotyledon and rosette. saur76 mutation partially suppresses the reduced ethylene sensitivity of etr2-2.These findings suggest that SAUR76-78 may affect ethylene receptor signaling and promote plant growth in Arabidopsis.

View Article: PubMed Central - PubMed

Affiliation: State Key Lab of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.

ABSTRACT
Ethylene perceived by a family of five receptors regulates many developmental processes in Arabidopsis. Here we conducted the yeast two-hybrid assay to screen for additional unidentified proteins that interact with subfamily II ethylene receptor ETR2. Three SAUR proteins, named SAUR76, 77 and 78, were identified to associate with both ETR2 and EIN4 in different assays. Interaction of SAUR76 and SAUR78 with ETR2 was further verified by co-immunoprecipitation and bimolecular fluorescence complementation (BiFC) assays. Expressions of SAUR76-78 are induced by auxin and ethylene treatments. Compared with wild type, SAUR-overexpressing plants exhibit reduced ethylene sensitivity, while SAUR-RNAi lines exhibit enhanced ethylene sensitivity. Overexpressing the three SAURs partially complements the phenotype of subfamily II ethylene receptor loss-of-function double mutant etr2-3ein4-4, which has increased ethylene response and small cotyledon and rosette. saur76 mutation partially suppresses the reduced ethylene sensitivity of etr2-2. SAUR76/78 proteins are regulated by 26S proteasome system and larger tag increases their protein stability. These findings suggest that SAUR76-78 may affect ethylene receptor signaling and promote plant growth in Arabidopsis.

No MeSH data available.