Waxy and non-waxy barley cultivars exhibit differences in the targeting and catalytic activity of GBSS1a

Abstract

HighlightThe waxy phenotype of barley CDC_Alamo is associated with a reduction of catalytic activity and deficient targeting of GBSS1a.

Fast and Inexpensive Phenotyping and Genotyping Methods for Evaluation of Barley Mutant Population

“…This suggests that the GBSSI is translated with a truncated C-terminal region consisting of 33 amino acids at the end. This region is different from the catalytic site (residues 81–567) [ 19 ]. However, according to the rice GBSSI protein structure reported by Momma and Fujimoto [ 20 ], the helix of the C-terminal region (residues 569–585) may form a catalytic center together with the N-terminal domain (residues 83–355) and the C-terminal domain (residues 356–568).…”

A mutation in Waxy gene affects amylose content, starch granules and kernel characteristics of barley (Hordeum vulgare)

“…Besides the binding activity of GBSSI with substrates, the combination of GBSSI with starch granules was necessary for GBSSI to function properly. Hebelstrup et al () found that the waxy phenotype of 'CDC Alamo' was associated with deficient targeting of GBSSI into starch granules as well as the significant reduction in GBSSI catalytic activity. GBSSI from 'CDC Alamo' could not be detected on starch granules through western blotting and distributed in unknown subcellular bodies of 0.5–3 µm in size (Hebelstrup et al, ).…”

“…Hebelstrup et al () found that the waxy phenotype of 'CDC Alamo' was associated with deficient targeting of GBSSI into starch granules as well as the significant reduction in GBSSI catalytic activity. GBSSI from 'CDC Alamo' could not be detected on starch granules through western blotting and distributed in unknown subcellular bodies of 0.5–3 µm in size (Hebelstrup et al, ). However, in this study, the G 3935 ‐to‐T in Waxy gene has little effect on the combination of GBSSI protein and starch granules, because relatively higher GBSSI protein content of Z999 was detected on extracted starch granules by 1D‐SDS‐PAGE compared with that of other waxy even normal barleys in previous study (Li et al, ).…”

“…Amylose–free barley 'CDC Alamo' had normal transcript and GBSSI protein level, but significantly lower GBSSI activity (Patron et al, ). It was further proved that three single–nucleotide polymorphism (SNP) mutations in Waxy gene of 'CDC Alamo' decrease GBSSI activity by 90% (Hebelstrup et al, ). Recently, a G 3935 ‐to‐T in Waxy gene resulting in the substitution of Trp for 513th Gly has been found in amylose–free barley 'CDC Fibar' and Z999, which showed unexpectedly elevated transcript level and GBSSI concentration (Asare et al, ; Li et al, ).…”

Natural Polymorphisms in Arabidopsis Result in Wide Variation or Loss of the Amylose Component of Starch

“…The enzyme responsible for amylose synthesis-GRANULE BOUND STARCH SYNTHASE (GBSS)differs from the other isoforms of starch synthase that synthesize amylopectin in being exclusively located within starch granules, where it produces amylose within the amylopectin matrix (Denyer et al, 1999;Tatge et al, 1999;Denyer et al, 2001;Hebelstrup et al, 2017). It does not accumulate in the plastid stroma and appears to be unstable when dissociated from starch granules (Smith et al, 2004;Seung et al, 2015).…”