Molecular Cloning of Three UDP-Glucuronate Decarboxylase Genes That Are Preferentially Expressed In Gossypium Fibers From Elongation to Secondary Cell Wall Synthesis

Abstract

UDP-xylose (UDP-Xyl) is a nucleotide sugar used as substrate for producing non-cellulose materials, e. g., hemicellulose and pectic polysaccharide, in the fibers of cotton (Gossypium). Its biosynthesis is catalyzed from UDP-glucuronic acid (UDP-GlcA) by UDP-glucuronate decarboxylase (UXS). Here, we first cloned GhUXS1 in Gossypium hirsutum and Gossypium barbadense based on a transcript-derived fragment that originated from our cDNA-AFLP transcriptome profiling in cotton. GhUXS2 and GhUXS3 were also isolated via homology-based cloning. GhUXS nucleotide sequences were identical between the two species, and the deduced amino acid residues had the conserved motif of the UXS family, i.e., GxxGxxG, Ser residues, and YxxxK. GhUXS1 was expressed in Escherichia coli and generated UXS activity that converted UDP-GlcA to UDP-Xyl. Semiquantitative RT-PCR results showed that GhUXSs transcripts were preferentially expressed during fiber development, from elongation through the stage of secondary cell wall synthesis. Although at the same number of days postanthesis they were more abundant in G. hirsutum, expression was sustained for a longer period in G. barbadense. These different patterns of expression may affect quality and partially explain why the latter species has better fiber strength.

Antisense expression of Gossypium hirsutum UDP-glucuronate decarboxylase in Arabidopsis leads to changes in cell wall components

“…At least three GhUXS genes are involved in the biosynthesis of fiber cell walls in cotton. Results from our previous reverse transcriptase-PCR analysis suggested that these genes were preferentially expressed during the different developmental stages, from elongation to secondary cell wall synthesis, with trace levels of transcripts being detected in the roots, hypocotyls, and leaves (Pan et al, 2010). Here, we confirmed that GhUXS3 encodes a cytoplasmic protein.…”

“…We previously proposed a model describing how GhUXS expression influenced fiber quality in cotton (Pan et al, 2010). UDP-XYL synthase 5 (UXS5) was down-regulated during the elongation stage in fuzzless-lintless ovules of a cotton fl mutant (Padmalatha et al, 2012).…”

“…We previously isolated three UXS genes, GhUXS1 to 3, from cotton (Pan et al, 2010). Their roles in affecting the biosynthesis of cell wall polysaccharides and fiber traits are not well understood.…”

Identification and Profiling of microRNAs Expressed in Elongating Cotton Fibers Using Small RNA Deep Sequencing

“…Among the targets of Class B miRNAs, the expression levels of which increased from 5 DPA and reached peak levels at 10 DPA, the expression of UXS2 was reduced from 5 to 10 DPA and subsequently up-regulated at 20 DPA ( Figure 4 ). Interestingly, UXS2 has been found to be closely correlated with UDP-xylose synthesis, a process that is critical to the development of primary walls in fiber cells (Pan et al, 2010). Thus, GhmiR164 may serve as a key regulator of fiber elongation.…”

The UDP-Glucuronate Decarboxylase Gene Family in Populus: Structure, Expression, and Association Genetics

“…Thus, UXS represents a key enzyme for partitioning glycosyl residues between the hexosyl and pentosyl residues. In addition, because of its central role in sugar nucleotide interconversion, UXS is likely ubiquitous among plants and a target for regulatory control during cell wall biosynthesis [8]. The first UXS gene was identified from Cryptococcus neoformans by bioinformatics methods [6].…”