OsMOGS is required for N‐glycan formation and auxin‐mediated root development in rice (Oryza sativa L.)

Abstract

SUMMARY N-glycosylation is a major modification of glycoproteins in eukaryotic cells. In Arabidopsis, great progress has been made in functional analysis of N-glycan production; however, there are few studies in monocotyledons. Here, we characterized a rice (Oryza sativa L.) osmogs mutant with shortened roots and isolated a gene coding a putative mannosyl-oligosaccharide glucosidase (OsMOGS), an ortholog of α-glucosidase I in Arabidopsis, which trims the terminal glucosyl residue of the oligosaccharide chain of nascent peptides in the endoplasmic reticulum (ER). OsMOGS is strongly expressed in rapidly cell-dividing tissues and OsMOGS protein is localized in the ER. Mutation of OsMOGS entirely blocked N-glycan maturation and inhibited high-mannose N-glycan formation. The osmogs mutant exhibited severe defects in root cell division and elongation, resulting in a short-root phenotype. In addition, osmogs plants had impaired root hair formation and elongation, and reduced root epidemic cell wall thickness due to decreased cellulose synthesis. Further analysis showed that auxin content and polar transport in osmogs roots were reduced due to incomplete N-glycosylation of the B subfamily of ATP-binding cassette transporter proteins (ABCBs). Our results demonstrate that involvement of OsMOGS in N-glycan formation is required for auxin-mediated root development in rice.

The auxin influx carrier, OsAUX3, regulates rice root development and responses to aluminium stress

“…Japonica wild‐type rice Hwayoung (WT/HY) and Dongjin (WT/DJ), OsAUX3 ‐related transgenic mutants, and OsAUX3 overexpression lines were planted in nutrient solution as previously described (Wang et al, ; Xu et al, ). Phytohormone treatment was performed with 1 μM of indole‐3‐acetic acid (IAA), or 0.01 μM of 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 0.01 μM of 1‐naphthylacetic acid (NAA) for 7 days.…”

The Interaction between Rice ERF3 and WOX11 Promotes Crown Root Development by Regulating Gene Expression Involved in Cytokinin Signaling

“…Arabidopsis lateral root regulatory genes LATERAL ORGAN BOUNDARIES-DOMAIN16/ASYMMETRIC LEAVES2-LIKE18 (LBD16/ASL18) and LBD29/ASL16 are reported to function downstream of AUXIN RESPONSE FACTOR7 (ARF7)-and ARF19-dependent auxin signaling (Okushima et al, 2007;Lee et al, 2009;Goh et al, 2012). In rice, mutants or knockdown transgenic plants of genes involved in auxin signaling pathways and/or polar auxin transport (e.g., CROWN ROOTLESS1 [CRL1]/ADVENTITIOUS ROOTLESS1 [ARL1], CRL4/ GNOM1, CAND1, PIN1, CRL5, Aux/IAA3, and MANNOSYL-OLIGOSACCHARIDE GLUCOSIDASE) display reduced or no crown root phenotypes Liu et al, 2005;Xu et al, 2005;Nakamura et al, 2006;Liu et al, 2009;Kitomi et al, 2011a;Wang et al, 2011;Zhu et al, 2012;Wang et al, 2014). In addition, a gain-of-function mutation of IAA11 affects lateral root development in rice (Nakamura et al, 2006;Zhu et al, 2012).…”

Review/N-glycans: The making of a varied toolbox

“…There is also a link between high-mannoseN-glycan synthesis and auxin signaling in root cell formation in rice [140].O. sativaplants mutated in an ortholog of the A. thaliana-glucosidase I, the so-called osmogs mutants,the levels of high-mannose (ER-derived) and complex (Golgiderived) N-glycans were greatly reduced compared to the levels in wild type plants.…”

“…Additionally, these osmogs mutants were impaired in cellulose formation and had a short-root phenotype with defects in root hair formation and reduced auxin content [140]. The mutants were also insensitive to exogenous auxin due to impaired polar auxin transport in the roots [140].Local auxin levels and regional auxin concentration gradients control root cell fate and differentiation [141].Directional auxin transport and establishment of auxin gradients across tissues rely on auxin transporters like the glycosylated ABCB proteins [142].…”

“…The mutants were also insensitive to exogenous auxin due to impaired polar auxin transport in the roots [140].Local auxin levels and regional auxin concentration gradients control root cell fate and differentiation [141].Directional auxin transport and establishment of auxin gradients across tissues rely on auxin transporters like the glycosylated ABCB proteins [142]. In the osmogs mutants, these ABCB transporters were under-glycosylated compared to wild type plants, resulting in a significantly diminished and restricted auxin distribution pattern in osmogs roots explaining the observed mutant phenotypes [140].…”