Limits...
AXY3 encodes a α-xylosidase that impacts the structure and accessibility of the hemicellulose xyloglucan in Arabidopsis plant cell walls.

Günl M, Pauly M - Planta (2010)

Bottom Line: The data support the hypothesis that AXY3/XYL1 is an essential component of the apoplastic xyloglucan degradation machinery and as a result of the lack of function in the various axy3-alleles leads not only to an altered xyloglucan structure but also a xyloglucan that is less tightly associated with other wall components.However, the plant can cope with the excess xyloglucan relatively well as the mutant does not display any visible growth or morphological phenotypes with the notable exception of shorter siliques and reduced fitness.Taken together, these results demonstrate that plant apoplastic hydrolases have a larger impact on wall polymer structure and function than previously thought.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, USA.

ABSTRACT
Xyloglucan is the most abundant hemicellulose in the walls of dicots such as Arabidopsis. It is part of the load-bearing structure of a plant cell and its metabolism is thought to play a major role in cell elongation. However, the molecular mechanism by which xyloglucan carries out this and other functions in planta is not well understood. We performed a forward genetic screen utilizing xyloglucan oligosaccharide mass profiling on chemically mutagenized Arabidopsis seedlings to identify mutants with altered xyloglucan structures termed axy-mutants. One of the identified mutants, axy3.1, contains xyloglucan with a higher proportion of non-fucosylated xyloglucan subunits. Mapping revealed that axy3.1 contains a point mutation in XYLOSIDASE1 (XYL1) known to encode for an apoplastic glycoside hydrolase releasing xylosyl residues from xyloglucan oligosaccharides at the non-reducing end. The data support the hypothesis that AXY3/XYL1 is an essential component of the apoplastic xyloglucan degradation machinery and as a result of the lack of function in the various axy3-alleles leads not only to an altered xyloglucan structure but also a xyloglucan that is less tightly associated with other wall components. However, the plant can cope with the excess xyloglucan relatively well as the mutant does not display any visible growth or morphological phenotypes with the notable exception of shorter siliques and reduced fitness. Taken together, these results demonstrate that plant apoplastic hydrolases have a larger impact on wall polymer structure and function than previously thought.

Show MeSH
Silique phenotype in axy3 mutants. a Mature siliques of 6 weeks’ old plants from Col0, axy3.1, axy3.2, axy3.3 and complemented axy3.1 line (pXYL1::XYL1). b Average silique length (n = 10–12, ±SD) of mature siliques from 6 weeks old plants. c Average number of seeds per silique (n = 24, ±SD) of siliques from 2-month-old plants. *** Indicates significant differences between mutant and wild-type/complemented axy3.1 line (p = 0.001)
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3064893&req=5

Fig4: Silique phenotype in axy3 mutants. a Mature siliques of 6 weeks’ old plants from Col0, axy3.1, axy3.2, axy3.3 and complemented axy3.1 line (pXYL1::XYL1). b Average silique length (n = 10–12, ±SD) of mature siliques from 6 weeks old plants. c Average number of seeds per silique (n = 24, ±SD) of siliques from 2-month-old plants. *** Indicates significant differences between mutant and wild-type/complemented axy3.1 line (p = 0.001)

Mentions: In general, plants of all three axy3 alleles did not exhibit any growth or morphological phenotypical differences compared to wild type and complemented plants under the growth conditions used (data not shown) with one exception. All axy3 mutants had significant shorter siliques (25% reduction) than both Col0 and complemented mutant (Fig. 4a, b). Moreover, the fitness of axy3 mutant plants was reduced as shown by a decreased number of produced seeds per silique (Fig. 4c). The amount of seeds per silique was reduced from about 60 seeds per silique in Col0 and complemented line to less than 50 seeds in axy3 mutants. This reduction in seed number could be a consequence of reduced silique length. The axy3 XyG oligo phenotype was confirmed on cell wall preparations from mature siliques showing a similar change in oligo distribution as OLIMP on etiolated seedlings (data not shown) indicating that the observed slique/seed number phenotype could be related to the change in XyG structure.Fig. 4


AXY3 encodes a α-xylosidase that impacts the structure and accessibility of the hemicellulose xyloglucan in Arabidopsis plant cell walls.

Günl M, Pauly M - Planta (2010)

Silique phenotype in axy3 mutants. a Mature siliques of 6 weeks’ old plants from Col0, axy3.1, axy3.2, axy3.3 and complemented axy3.1 line (pXYL1::XYL1). b Average silique length (n = 10–12, ±SD) of mature siliques from 6 weeks old plants. c Average number of seeds per silique (n = 24, ±SD) of siliques from 2-month-old plants. *** Indicates significant differences between mutant and wild-type/complemented axy3.1 line (p = 0.001)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3064893&req=5

Fig4: Silique phenotype in axy3 mutants. a Mature siliques of 6 weeks’ old plants from Col0, axy3.1, axy3.2, axy3.3 and complemented axy3.1 line (pXYL1::XYL1). b Average silique length (n = 10–12, ±SD) of mature siliques from 6 weeks old plants. c Average number of seeds per silique (n = 24, ±SD) of siliques from 2-month-old plants. *** Indicates significant differences between mutant and wild-type/complemented axy3.1 line (p = 0.001)
Mentions: In general, plants of all three axy3 alleles did not exhibit any growth or morphological phenotypical differences compared to wild type and complemented plants under the growth conditions used (data not shown) with one exception. All axy3 mutants had significant shorter siliques (25% reduction) than both Col0 and complemented mutant (Fig. 4a, b). Moreover, the fitness of axy3 mutant plants was reduced as shown by a decreased number of produced seeds per silique (Fig. 4c). The amount of seeds per silique was reduced from about 60 seeds per silique in Col0 and complemented line to less than 50 seeds in axy3 mutants. This reduction in seed number could be a consequence of reduced silique length. The axy3 XyG oligo phenotype was confirmed on cell wall preparations from mature siliques showing a similar change in oligo distribution as OLIMP on etiolated seedlings (data not shown) indicating that the observed slique/seed number phenotype could be related to the change in XyG structure.Fig. 4

Bottom Line: The data support the hypothesis that AXY3/XYL1 is an essential component of the apoplastic xyloglucan degradation machinery and as a result of the lack of function in the various axy3-alleles leads not only to an altered xyloglucan structure but also a xyloglucan that is less tightly associated with other wall components.However, the plant can cope with the excess xyloglucan relatively well as the mutant does not display any visible growth or morphological phenotypes with the notable exception of shorter siliques and reduced fitness.Taken together, these results demonstrate that plant apoplastic hydrolases have a larger impact on wall polymer structure and function than previously thought.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, USA.

ABSTRACT
Xyloglucan is the most abundant hemicellulose in the walls of dicots such as Arabidopsis. It is part of the load-bearing structure of a plant cell and its metabolism is thought to play a major role in cell elongation. However, the molecular mechanism by which xyloglucan carries out this and other functions in planta is not well understood. We performed a forward genetic screen utilizing xyloglucan oligosaccharide mass profiling on chemically mutagenized Arabidopsis seedlings to identify mutants with altered xyloglucan structures termed axy-mutants. One of the identified mutants, axy3.1, contains xyloglucan with a higher proportion of non-fucosylated xyloglucan subunits. Mapping revealed that axy3.1 contains a point mutation in XYLOSIDASE1 (XYL1) known to encode for an apoplastic glycoside hydrolase releasing xylosyl residues from xyloglucan oligosaccharides at the non-reducing end. The data support the hypothesis that AXY3/XYL1 is an essential component of the apoplastic xyloglucan degradation machinery and as a result of the lack of function in the various axy3-alleles leads not only to an altered xyloglucan structure but also a xyloglucan that is less tightly associated with other wall components. However, the plant can cope with the excess xyloglucan relatively well as the mutant does not display any visible growth or morphological phenotypes with the notable exception of shorter siliques and reduced fitness. Taken together, these results demonstrate that plant apoplastic hydrolases have a larger impact on wall polymer structure and function than previously thought.

Show MeSH