Expression of a fungal exo-β-1,3-galactanase in Arabidopsis reveals a role of type II arabinogalactans in the regulation of cell shape

Yoshimi, Yoshihisa; Hara, Katsuya; Yoshimura, Mami; Tanaka, Nobukazu; Higaki, Takumi; Tsumuraya, Yoichi; Kotake, Toshihisa

doi:10.1093/jxb/eraa236

Cited by 12 publications

(17 citation statements)

References 52 publications

(77 reference statements)

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“…On the other hand, the expression of a fungal exo1,3GAL in A. thaliana leads to a decrease in AGPs reactive to β-Glc Yariv and a severe tissue disorganization in hypocotyl and cotyledons. Furthermore, oligosaccharides released from AG type II were detected in the soluble fraction of transgenic plants ( Yoshimi et al, 2020 ). Thus, hydrolysis of the carbohydrate component of AGPs by hydrolytic enzymes secreted by fungi and bacteria during penetration of the PCW would have consequences for the mechanisms of detection and monitoring of the integrity of the cell wall, favoring infection by pathogens.…”

Section: Ags Hydrolysis and Plant-microbe Interactionsmentioning

confidence: 99%

The Role of Arabinogalactan Type II Degradation in Plant-Microbe Interactions

et al. 2021

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Arabinogalactans (AGs) are structural polysaccharides of the plant cell wall. A small proportion of the AGs are associated with hemicellulose and pectin. Furthermore, AGs are associated with proteins forming the so-called arabinogalactan proteins (AGPs), which can be found in the plant cell wall or attached through a glycosylphosphatidylinositol (GPI) anchor to the plasma membrane. AGPs are a family of highly glycosylated proteins grouped with cell wall proteins rich in hydroxyproline. These glycoproteins have important and diverse functions in plants, such as growth, cellular differentiation, signaling, and microbe-plant interactions, and several reports suggest that carbohydrate components are crucial for AGP functions. In beneficial plant-microbe interactions, AGPs attract symbiotic species of fungi or bacteria, promote the development of infectious structures and the colonization of root tips, and furthermore, these interactions can activate plant defense mechanisms. On the other hand, plants secrete and accumulate AGPs at infection sites, creating cross-links with pectin. As part of the plant cell wall degradation machinery, beneficial and pathogenic fungi and bacteria can produce the enzymes necessary for the complete depolymerization of AGs including endo-β-(1,3), β-(1,4) and β-(1,6)-galactanases, β-(1,3/1,6) galactanases, α-L-arabinofuranosidases, β-L-arabinopyranosidases, and β-D-glucuronidases. These hydrolytic enzymes are secreted during plant-pathogen interactions and could have implications for the function of AGPs. It has been proposed that AGPs could prevent infection by pathogenic microorganisms because their degradation products generated by hydrolytic enzymes of pathogens function as damage-associated molecular patterns (DAMPs) eliciting the plant defense response. In this review, we describe the structure and function of AGs and AGPs as components of the plant cell wall. Additionally, we describe the set of enzymes secreted by microorganisms to degrade AGs from AGPs and its possible implication for plant-microbe interactions.

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Section: Ags Hydrolysis and Plant-microbe Interactionsmentioning

confidence: 99%

The Role of Arabinogalactan Type II Degradation in Plant-Microbe Interactions

et al. 2021

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“…In suspension cultured tobacco cells, cell bulging is caused by treatment with β-Yariv reagent, a glycosyl-phenylazo compound specifically binding to type II AGs (Sardar et al 2006). In addition, drastic in vivo degradation of type II AGs by expression of fungal glycoside hydrolase results in severe tissue disorganization in hypocotyls of Arabidopsis (Yoshimi et al 2020). On the basis of previous studies, type II AGs are expected to be necessary for the functioning of AGPs.…”

mentioning

confidence: 99%

“…The resulting Gal and oligosaccharides were coupled at their reducing terminals with p-aminobenzoic acid ethyl ester (ABEE) as described (Matsuura and Imaoka 1988;Tsumuraya et al 2019). To remove nonreducing terminal α-L-arabinofuranosyl and 4-Omethyl-β-glucuronosyl residues attached to β-1,6galactooligosaccharides, ABEE-labelled saccharides were further digested with α-L-arabinofuranosidase (α-L-Arafase) from Aspergillus niger (Megazyme), and recombinant β-glucuronidase from Aspergillus niger (rAnGlcAase) in 50 mM acetate buffer (pH 4.6) at 37°C for 12 h (Konishi et al 2008;Yoshimi et al 2020), and then analyzed on an HPLC system equipped with a TSKgel Amide-80 column (4.6×250 mm; Tosoh, Tokyo, Japan) in accordance with a previous study (Tsumuraya et al 2019). Here, Gal is derived from β-galactosyl residues of the β-1,3-galactan backbone where there is no side chain attached, while β-1,6-galactooligosaccharides are those having side chains.…”

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confidence: 99%

Structural features conserved in subclass of type II arabinogalactan

Ito

Fukuoka

Nishigaki

et al. 2020

Plant Biotechnology

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Arabinogalactan-proteins (AGPs) are extracellular proteoglycans, which are presumed to participate in the regulation of cell shape, thus contributing to the excellent mechanical properties of plants. AGPs consist of a hydroxyprolinerich core-protein and large arabinogalactan (AG) sugar chains, called type II AGs. These AGs have a β-1,3-galactan backbone and β-1,6-galactan side chains, to which other sugars are attached. The structure of type II AG differs depending on source plant, tissue, and age. Type II AGs obtained from woody plants in large quantity as represented by gum arabic and larch AG, here designated gum arabic-subclass, have a β-1,3;1,6-galactan structure in which the β-1,3-galactan backbone is highly substituted with short β-1,6-galactan side chains. On the other hand, it is unclear whether type II AGs found as the glycan part of AGPs from herbaceous plants, here designated AGP-subclass, also have conserved β-1,3:1,6-galactan structural features. In the present study we explore similarities of type II AG structures in the AGP-subclass. Type II AGs in fractions obtained from spinach, broccoli, bok choy, komatsuna, and cucumber were hydrolyzed into galactose and β-1,6-galactooligosaccharides by specific enzymes. Based on the proportion of these sugars, the substitution ratio of the β-1,3-galactan backbone was calculated as 46-58% in the five vegetables, which is consistently lower than what is seen in gum arabic and larch AG. Although most side chains were short, long chains such as β-1,6-galactohexaose chains were also observed in these vegetables. The results suggest a conserved β-1,3;1,6-galactan structure in the AGP-subclass that distinguishes it from the gum arabic-subclass.

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“…The enzyme can specifically remove long β-1,6-galactan side chains from β-1,3:1,6-galactan, leaving only stubs of short side chains such as β-1,6-Gal on the main chain ( Okemoto et al., 2003 ; Kotake et al., 2004 ) ( Figure 1 ). Thus, these specific fungal GHs are reliable tools for structural and functional analysis of type II AGs ( Kitazawa et al., 2013 ; Yoshimi et al., 2020 ).…”

Section: Introductionmentioning

confidence: 99%

“…We have recently developed a novel system to study type II AGs in Arabidopsis, in which type II AGs are specifically hydrolyzed into oligosaccharides by an exo-β-1,3-galactanase, Il3GAL, in vivo ( Yoshimi et al., 2020 ). In Dex::Il3GAL plants, we have observed severe tissue disorganization caused by expression of the Il3GAL gene in hypocotyls and cotyledons, demonstrating the importance of type II AGs in the regulation of cell shape.…”

Section: Introductionmentioning

confidence: 99%

In vivo structural modification of type II arabinogalactans with fungal endo-β-1, 6-galactanase in Arabidopsis

Kikuchi

Hara²,

Yoshimi³

et al. 2022

Front. Plant Sci.

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Arabinogalactan-proteins (AGPs) are mysterious extracellular glycoproteins in plants. Although AGPs are highly conserved, their molecular functions remain obscure. The physiological importance of AGPs has been extensively demonstrated with β-Yariv reagent, which specifically binds to AGPs and upon introduction into cells, causes various deleterious effects including growth inhibition and programmed cell death. However, structural features of AGPs that determine their functions have not been identified with β-Yariv reagent. It is known that AGPs are decorated with large type II arabinogalactans (AGs), which are necessary for their functions. Type II AGs consist of a β-1,3-galactan main chain and β-1,6-galactan side chains with auxiliary sugar residues such as L-arabinose and 4-O-methyl-glucuronic acid. While most side chains are short, long side chains such as β-1,6-galactohexaose (β-1,6-Gal6) also exist in type II AGs. To gain insight into the structures important for AGP functions, in vivo structural modification of β-1,6-galactan side chains was performed in Arabidopsis. We generated transgenic Arabidopsis plants expressing a fungal endo-β-1,6-galactanase, Tv6GAL, that degrades long side chains specifically under the control of dexamethasone (Dex). Two of 6 transgenic lines obtained showed more than 40 times activity of endo-β-1,6-galactanase when treated with Dex. Structural analysis indicated that long side chains such as β-1,6-Gal5 and β-1,6-Gal6 were significantly reduced compared to wild-type plants. Tv6GAL induction caused retarded growth of seedlings, which had a reduced amount of cellulose in cell walls. These results suggest that long β-1,6-galactan side chains are necessary for normal cellulose synthesis and/or deposition as their defect affects cell growth in plants.

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Expression of a fungal exo-β-1,3-galactanase in Arabidopsis reveals a role of type II arabinogalactans in the regulation of cell shape

Cited by 12 publications

References 52 publications

The Role of Arabinogalactan Type II Degradation in Plant-Microbe Interactions

The Role of Arabinogalactan Type II Degradation in Plant-Microbe Interactions

Structural features conserved in subclass of type II arabinogalactan

In vivo structural modification of type II arabinogalactans with fungal endo-β-1, 6-galactanase in Arabidopsis

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