Although N-acetylglucosamine-1-P uridylyltransferase (GlcNAc1pUT) that catalyzes the final step of the hexosamine biosynthetic pathway and is conserved among, organisms, produces UDP-N-acetylglucosamine (UDP-GlcNAc), an essential sugar moiety involved in protein glycosylation and structural polymers, its biological function in plants remains unknown. In this study, two GlcNA.UT genes were characterized in Arabidopsis thaliana. The single mutants glcna.ut1 and glcna.ut2 revealed no obvious phenotype, but their homozygous double mutant was lethal, reflecting the functional redundancy of these genes in being essential for plant growth. Mutant plants, GlcNA.UT1/glcna.ut1 glcna.ut2/ glcna.ut2, obtained from an F2-segregating population following reciprocal crosses of glcna.ut1 with glcna.ut2, displayed shorter siliques and fewer seed sets combined with impaired pollen viability and unfertilized ovules. Genetic analyses further demonstrated that the progeny of the GlcNA.UT1/glcna.ut1 glcna.ut2/glcna.ut2 mutant plants, but not those of the glcna.ut1/glcna.ut1 GlcNA.UT2/glcna.ut2 mutant plants, suffer from the aberrant transmission of (glcna.ut1 glcna.ut2) gametes. In parallel, cell biology analyses revealed a substantial defect in male gametophytes appearing during the late vacuolated or pollen mitosis I stages and that the female gametophyte is arrested during the uninucleate embryo sac stage in GlcNA.UT1/glcna.ut1 glcna.ut2/glcna.ut2 mutant plants. Nevertheless, although the glcna.ut1/glcna.ut1 GlcNA.UT2/glcna.ut2 mutant plants exhibited a normal transmission of (glcna.ut1 glcna.ut2) gametes and gametophytic development, the development of numerous embryos was arrested during the early globular stage within the embryo sacs. Collectively, despite having overlapping functions, the GlcNA.UT genes play an indispensable role in the unique mediation of gametogenesis and embryogenesis.
Although the nucleolus is involved in ribosome biogenesis, the functions of numerous nucleolus-localized proteins remain unclear. In this study, we genetically isolated Arabidopsis thaliana salt hypersensitive mutant 1 (sahy1), which exhibits slow growth, short roots, pointed leaves, and sterility. SAHY1 encodes an uncharacterized protein that is predominantly expressed in root tips, early developing seeds, and mature pollen grains and is mainly restricted to the nucleolus. Dysfunction of SAHY1 primarily causes the accumulation of 32S, 18S-A3, and 27SB pre-rRNA intermediates. Coimmunoprecipitation experiments further revealed the interaction of SAHY1 with ribosome proteins and ribosome biogenesis factors. Moreover, sahy1 mutants are less sensitive to protein translation inhibitors and show altered expression of structural constituents of ribosomal genes and ribosome subunit profiles, reflecting the involvement of SAHY1 in ribosome composition and ribosome biogenesis. Analyses of ploidy, S-phase cell cycle progression, and auxin transport and signaling indicated the impairment of mitotic activity, translation of auxin transport carrier proteins, and expression of the auxin-responsive marker DR5::GFP in the root tips or embryos of sahy1 plants. Collectively, these data demonstrate that SAHY1, a nucleolar protein involved in ribosome biogenesis, plays critical roles in normal plant growth in association with auxin transport and signaling.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.