. 2021 May 18;11(5):756. doi: 10.3390/biom11050756

Table 1.

Overview of N- and O-glycosylation-related enzymes whose mutants display relevant phenotypes for plant development.

Enzyme	Activity	Role during Glycosylation	Mutant	Phenotype	Sources
ALG10	α-1,2-glucosyltransferase	N-glycan precursor synthesis	alg10	Dwarfism	[118]
ALG11	α-1,2-mannosyltransferase		lew3	Aberrant distribution of glycans, reduced cellulose synthesis, abnormal cell walls, reduced fertility	[119]
APTG1	mannosyltransferase		aptg1	Pollen tube is unable to penetrate the style; embryo lethality	[120]
CYT1	GTP:α-D-mannose-1-phosphate guanylyltransferase		cyt1	Disrupted embryonal development	[121]
DPMS1	dolichol phosphate mannose synthase 1		dpms1	Embryo lethality, wrinkled seed coats	[122]
EVN	dolichol kinase		evn	Pollen degeneration before pollen germination	[123]
GlcNA.UT	GlcNAc-phosphate UDP transferase		glcna.ut1/2	Aberrant gametogenesis, reduced fertilization, shorter siliques	[124]
DGL1	Subunit of OST complex	En bloc transfer	dgl1	Altered cell wall composition, embryo lethality, reduced growth of hypocotyls and roots, dense packed root hairs	[125]
HAP6			hap6	Shorter pollen tube	[126]
OST3/6			ost3/6	Enhanced salt sensitivity resulting in decreased root growth and root swelling	[127,128,129]
STT3a			stt3a		[127,128,129]
TUN	UDP-glycosyltransferase		tun	Pollen defects, premature pollen rupture	[123]
GCSI	α-glucosidase I	N-glycan processing in the ER	gcs1	Embryo lethality, wrinkled seed coats	[130,131]
GCSII	α-glucosidase II		gcs2, rsw3	Embryo lethality, radially swollen roots, modified seed set	[132,133]
MOGS	mannosyloligosaccharide glucosidase		mogs	Reduced growth of primary and lateral roots, abnormal root hair initiation and elongation	[134]
UGGT	UDP-glucose:glycoprotein glucosyltransferase	ERAD	-	No mutant	[135]
PNGase	peptide-N⁴-(N-acetyl-β-D-glucosaminyl) asparagine amidase	ERAD	-	No mutant	[78,136,137]
ENGase	endo-N-acetyl-β-D-glucosaminidase	De-N-glycosylation	-	No mutant	[78,136,137]
α-MAN	α-mannosidase		-	No mutant	[138,139]
β-NAHase	β-D-N-acetylhexosaminidase		-	No mutant	[138,139]
FucT	α-1,3-fucosyltransferase	N-glycan maturation in the Golgi apparatus	fuct	Reduced seed set	[140]
FUCTc	α-1,4-fucosyltransferase		fuctc	Increased root hair length, early root hair elongation	[141]
GALT	β-1,3-galactosyl-transferase		galt	Increased root hair length, early root hair elongation	[141]
GnT1	N-acetylglucosaminyl transferase I		gnt1	Cell wall shortcomings: reduced thickness and cellulose content; lethality	[140,142]
				Necrosis on fruits, incomplete fruit ripening, early fruit drop	[143]
				Increased root hair length, early root hair elongation, salt sensitivity resulting in altered root tip morphology	[141,144]
MANII	α-mannosidase II		manII	Increased root hair length, early root hair elongation, salt sensitivity resulting in altered root tip morphology	[141]
MNS1	mannosidase I		mns1	Reduced germination capacity	[140]
MNS2			mns1, mns2, mns3	Shorter roots	[145]
MNS3			mns1, mns2, mns3	Shorter roots	[145]
XylT	β-1,2-xylosyltransferase		rcn11	Postponed seed germination	[140,146,147]
GFAT1	Glutamine:fructose-6-phosphate amidotransferase 1	Sugar delivery	gfat1	Aberrant pollen cell wall	[148]
USP	UDP-sugar pyrophosphorylase		usp	Infertile pollen, improper pollen sac development	[112]
ROCK1	UDP-GlcNAc transferase, UDP-GalNAc transferase		rock1	Cytokinin shortage-like phenotype, increased organ formation rate, increased UPR	[117]
GlcNAc.UT	UDP-GlcNAc transferase		glcna.ut1, glcna.ut2	Severe developmental shortcomings. Disturbed gametogenesis of male and female gametes. Embryonal problems, shorter siliques with fewer and shrunken seeds in double mutant	[149]
OFT	O-fucosyltransferase	O-glycan modification	oft	Impaired pollen tube penetration ability	[150]
SEC	O-GlcNAc transferase		sec	Nonviable seeds, decreased number of leaves	[90,151]
SPY	O-fucosyltransferase		spy	Germination in presence of germination inhibitors	[152]
SPY	O-fucosyltransferase		spy	Enhanced trichome branching, reduced leaf serration size and number of leaf serrations	[153,154]
PSL	β-1,6-GlcNAc-transferase		psl	Early leaf senescence, enhanced ethylene production	[155]
BZ1	UDP-Gal/Glu epimerase		bz1	Abnormal cell walls, abnormal chloroplast membranes	[156]
P4H1	Prolyl-4-hydroxylase	Hydroxyproline production	p4h1	Lack of trichomes, large leaves	[157,158]
P4H2			p4h2	Short root hairs	[94,159,160]
P4H5			p4h5
P4H13			p4h13
P4H7			p4h7	Large leaves	[158]
P4H9			p4h9	Large leaves	[158]
HPAT1	Hydroxyproline O-β-arabinosyltransferase	O-arabinosylation of extensins	hpat1	Decreased number of leaves, accelerated leaf senescence, short root hairs	[161,162]
HPAT2			hpat2
HPAT3			hpat3
RRA1	β-1,2-arabinosyltransferase		rra1	Short root hairs	[95]
RRA2			rra2
RRA3			rra3
XEG113	β-1,2-arabinosyltransferase		xeg113	Larger petioles, short root hairs	[95,163]
ExAD	α-1,3-arabinosyltransferase			Short root hairs	[164]
SGT1	Serine O-α-galactosyltransferase	O-galactosylation of extensins	sgt1	Larger leaf rosette, longer roots	[91]
RAY1	β-arabinofuranosyltransferase	O-arabinosylation of arabinogalactan proteins	ray1	Short primary root, reduced leaf rosette size	[165]
GALT2	Hydroxyproline-O-β-galactosyltransferase	O-galactosylation of arabinogalactan proteins	galt2	Reduced seed coat mucilage, reduced seed set; pleiotropic effects on roots, leaves and root hairs in different single or multiple mutants	[162,166,167,168,169]
GALT3			galt3
GALT4			galt4
GALT5			galt5
GALT6			galt6
HPGT1			hpgt1
HPGT2			hpgt2
HPGT3			hpgt3
GLCAT14a	β-1,6-glucuronosyltransferase	O-glucuronidation of arabinogalactan proteins	glcat14a	Reduced trichome size, branching in double (glcat14a/glcat14b) and triple mutant	[169]
GLCAT14b			glcat14b
GLCAT14c			glcat14c