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Constitutive Expresser of Pathogenesis Related Genes 1 Is Required for Pavement Cell Morphogenesis in Arabidopsis.

Han B, Chen L, Wang J, Wu Z, Yan L, Hou S - PLoS ONE (2015)

Bottom Line: These results suggest that the abnormal PC morphogenesis in cpr1 is accompanying with the aberrant arrangement of cytoskeleton.Site-directed mutagenesis and knockout within the F-box-associated (FBA) domain, which is reported to be a motif for recognizing particular substrates of CPR1, proved that the FBA domain is indispensable for normal CPR1 regulation of the PC morphogenesis.Our results provide further insights into the relationship between the cytoskeleton and PC morphogenesis, and suggest that the cytoskeleton-mediated PC morphogenesis control might be tightly linked to plant defense responses.

View Article: PubMed Central - PubMed

Affiliation: Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, People's Republic of China.

ABSTRACT
For over 50 years, researchers have focused on the mechanisms underlying the important roles of the cytoskeleton in controlling the cell growth direction and cell expansion. In our study, we performed ethyl methane sulfonate mutagenesis on Col-0 background and identified two new CONSTITUTIVE EXPRESSER OF PATHOGENESIS RELATED GENES 1 (CPR1) alleles with pavement cell (PC) morphogenetic defects. Morphological characterizations showed that polar growth initiation and expansion of PCs are seriously suppressed in cpr1. Closer cytoskeleton investigation showed that the directional arrangement of microtubules (MTs) during PC development is defective and the cortical fine actin filaments cannot be aggregated effectively to form actin cable networks in cpr1 mutants. These results suggest that the abnormal PC morphogenesis in cpr1 is accompanying with the aberrant arrangement of cytoskeleton. Site-directed mutagenesis and knockout within the F-box-associated (FBA) domain, which is reported to be a motif for recognizing particular substrates of CPR1, proved that the FBA domain is indispensable for normal CPR1 regulation of the PC morphogenesis. Further genetic analysis indicated that the defects on PC morphogenesis of cpr1 depend on two lipase-like proteins, ENHANCED DISEASE SUSCEPTIBILITY 1 and PHYTOALEXIN DEFICIENT 4. Our results provide further insights into the relationship between the cytoskeleton and PC morphogenesis, and suggest that the cytoskeleton-mediated PC morphogenesis control might be tightly linked to plant defense responses.

No MeSH data available.


Related in: MedlinePlus

Phenotypic analysis in Col, 35S::CPR1, 35S::CPR1I247V and 35S::CPR1∆FBA transgenic plants.(A) Two-week-old seedlings of Col, 35S::CPR1, three 35S::CPR1I247V transgenic lines and three 35S::CPR1∆FBA transgenic lines. Bar = 1 cm. (B) Mature PC shape of Col, 35S::CPR1, three 35S::CPR1I247V transgenic lines and three 35S::CPR1∆FBA transgenic lines. Bars = 50 μm. (C–F) Quantitative analysis of the PC in the Col, 35S::CPR1, three 35S::CPR1I247V transgenic lines and three 35S::CPR1∆FBA transgenic lines. PC area (C), lobe length (D), circularity (E), and lobe number (F). Error bars indicate s.e.m.; **, P<0.01 by Student’s test.
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pone.0133249.g006: Phenotypic analysis in Col, 35S::CPR1, 35S::CPR1I247V and 35S::CPR1∆FBA transgenic plants.(A) Two-week-old seedlings of Col, 35S::CPR1, three 35S::CPR1I247V transgenic lines and three 35S::CPR1∆FBA transgenic lines. Bar = 1 cm. (B) Mature PC shape of Col, 35S::CPR1, three 35S::CPR1I247V transgenic lines and three 35S::CPR1∆FBA transgenic lines. Bars = 50 μm. (C–F) Quantitative analysis of the PC in the Col, 35S::CPR1, three 35S::CPR1I247V transgenic lines and three 35S::CPR1∆FBA transgenic lines. PC area (C), lobe length (D), circularity (E), and lobe number (F). Error bars indicate s.e.m.; **, P<0.01 by Student’s test.

Mentions: To investigate the function of the FBA domain in CPR1, two CPR1 overexpression constructs with mutations in the FBA domain were used. The first construct had a point mutation (35S::CPR1I247V) and the second lacked the FBA domain (35S::CPR1ΔFBA). Both constructs were expressed under a cauliflower mosaic virus 35S (CaMV35S) promoter in Col-0 background. Transgenic lines of both 35S::CPR1I247V and 35S::CPR1ΔFBA exhibited similar phenotypes to those observed in cpr1-j594 and cpr1-j2928 (Fig 6A and 6B). Quantitative PC shape analysis showed that PCs in 35S::CPR1I247V and 35S::CPR1ΔFBA lines are small, have short and reduced lobes, and large values of circularity (Fig 6C–6F). However, plants overexpressing the normal CPR1 exhibited phenotypes similar to those observed in wild-type plants and PCs (Fig 6A and 6B). Meanwhile, expression of exogenous CPR1 did not affect the transcription level of endogenous CPR1 (S1 Fig). Thus, we concluded that 35S::CPR1I247V and 35S::CPR1ΔFBA could imitate the phenotypes of cpr1 loss-of-function mutants, suggesting that the overexpression of these mutated CPR1 has impact on the normal function of endogenous CPR1.


Constitutive Expresser of Pathogenesis Related Genes 1 Is Required for Pavement Cell Morphogenesis in Arabidopsis.

Han B, Chen L, Wang J, Wu Z, Yan L, Hou S - PLoS ONE (2015)

Phenotypic analysis in Col, 35S::CPR1, 35S::CPR1I247V and 35S::CPR1∆FBA transgenic plants.(A) Two-week-old seedlings of Col, 35S::CPR1, three 35S::CPR1I247V transgenic lines and three 35S::CPR1∆FBA transgenic lines. Bar = 1 cm. (B) Mature PC shape of Col, 35S::CPR1, three 35S::CPR1I247V transgenic lines and three 35S::CPR1∆FBA transgenic lines. Bars = 50 μm. (C–F) Quantitative analysis of the PC in the Col, 35S::CPR1, three 35S::CPR1I247V transgenic lines and three 35S::CPR1∆FBA transgenic lines. PC area (C), lobe length (D), circularity (E), and lobe number (F). Error bars indicate s.e.m.; **, P<0.01 by Student’s test.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4508093&req=5

pone.0133249.g006: Phenotypic analysis in Col, 35S::CPR1, 35S::CPR1I247V and 35S::CPR1∆FBA transgenic plants.(A) Two-week-old seedlings of Col, 35S::CPR1, three 35S::CPR1I247V transgenic lines and three 35S::CPR1∆FBA transgenic lines. Bar = 1 cm. (B) Mature PC shape of Col, 35S::CPR1, three 35S::CPR1I247V transgenic lines and three 35S::CPR1∆FBA transgenic lines. Bars = 50 μm. (C–F) Quantitative analysis of the PC in the Col, 35S::CPR1, three 35S::CPR1I247V transgenic lines and three 35S::CPR1∆FBA transgenic lines. PC area (C), lobe length (D), circularity (E), and lobe number (F). Error bars indicate s.e.m.; **, P<0.01 by Student’s test.
Mentions: To investigate the function of the FBA domain in CPR1, two CPR1 overexpression constructs with mutations in the FBA domain were used. The first construct had a point mutation (35S::CPR1I247V) and the second lacked the FBA domain (35S::CPR1ΔFBA). Both constructs were expressed under a cauliflower mosaic virus 35S (CaMV35S) promoter in Col-0 background. Transgenic lines of both 35S::CPR1I247V and 35S::CPR1ΔFBA exhibited similar phenotypes to those observed in cpr1-j594 and cpr1-j2928 (Fig 6A and 6B). Quantitative PC shape analysis showed that PCs in 35S::CPR1I247V and 35S::CPR1ΔFBA lines are small, have short and reduced lobes, and large values of circularity (Fig 6C–6F). However, plants overexpressing the normal CPR1 exhibited phenotypes similar to those observed in wild-type plants and PCs (Fig 6A and 6B). Meanwhile, expression of exogenous CPR1 did not affect the transcription level of endogenous CPR1 (S1 Fig). Thus, we concluded that 35S::CPR1I247V and 35S::CPR1ΔFBA could imitate the phenotypes of cpr1 loss-of-function mutants, suggesting that the overexpression of these mutated CPR1 has impact on the normal function of endogenous CPR1.

Bottom Line: These results suggest that the abnormal PC morphogenesis in cpr1 is accompanying with the aberrant arrangement of cytoskeleton.Site-directed mutagenesis and knockout within the F-box-associated (FBA) domain, which is reported to be a motif for recognizing particular substrates of CPR1, proved that the FBA domain is indispensable for normal CPR1 regulation of the PC morphogenesis.Our results provide further insights into the relationship between the cytoskeleton and PC morphogenesis, and suggest that the cytoskeleton-mediated PC morphogenesis control might be tightly linked to plant defense responses.

View Article: PubMed Central - PubMed

Affiliation: Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, People's Republic of China.

ABSTRACT
For over 50 years, researchers have focused on the mechanisms underlying the important roles of the cytoskeleton in controlling the cell growth direction and cell expansion. In our study, we performed ethyl methane sulfonate mutagenesis on Col-0 background and identified two new CONSTITUTIVE EXPRESSER OF PATHOGENESIS RELATED GENES 1 (CPR1) alleles with pavement cell (PC) morphogenetic defects. Morphological characterizations showed that polar growth initiation and expansion of PCs are seriously suppressed in cpr1. Closer cytoskeleton investigation showed that the directional arrangement of microtubules (MTs) during PC development is defective and the cortical fine actin filaments cannot be aggregated effectively to form actin cable networks in cpr1 mutants. These results suggest that the abnormal PC morphogenesis in cpr1 is accompanying with the aberrant arrangement of cytoskeleton. Site-directed mutagenesis and knockout within the F-box-associated (FBA) domain, which is reported to be a motif for recognizing particular substrates of CPR1, proved that the FBA domain is indispensable for normal CPR1 regulation of the PC morphogenesis. Further genetic analysis indicated that the defects on PC morphogenesis of cpr1 depend on two lipase-like proteins, ENHANCED DISEASE SUSCEPTIBILITY 1 and PHYTOALEXIN DEFICIENT 4. Our results provide further insights into the relationship between the cytoskeleton and PC morphogenesis, and suggest that the cytoskeleton-mediated PC morphogenesis control might be tightly linked to plant defense responses.

No MeSH data available.


Related in: MedlinePlus