Alpha-Glucan, Water Dikinase 1 Affects Starch Metabolism and Storage Root Growth in Cassava (Manihot esculenta Crantz)

Abstract

AbstarctRegulation of storage root development by source strength remains largely unknown. The cassava storage root delay (srd) T-DNA mutant postpones storage root development but manifests normal foliage growth as wild-type plants. The SRD gene was identified as an orthologue of α-glucan, water dikinase 1 (GWD1), whose expression is regulated under conditions of light/dark cycles in leaves and is associated with storage root development. The GWD1-RNAi cassava plants showed both retarded plant and storage root growth, as a result of starch excess phenotypes with reduced photosynthetic capacity and decreased levels of soluble saccharides in their leaves. These leaves contained starch granules having greatly increased amylose content and type C semi-crystalline structures with increased short chains that suggested storage starch. In storage roots of GWD1-RNAi lines, maltose content was dramatically decreased and starches with much lower phosphorylation levels showed a drastically reduced β-amylolytic rate. These results suggested that GWD1 regulates transient starch morphogenesis and storage root growth by decreasing photo-assimilation partitioning from the source to the sink and by starch mobilization in root crops.

Production of very‐high‐amylose cassava by post‐transcriptional silencing of branching enzyme genes

“…Mature leaves of field‐grown cassava were harvested from three independent plants at 6‐h intervals for 2 d. Sugar extraction and content analysis using HPAEC/PAD (Dionex ICS 5000; Thermo Scientific, Waltham, USA) were described by Zhou et al (2017). Briefly, after extraction with ethanol and chloroform, centrifuged supernatant was used for HPAEC/PAC analysis of each sugar component according to retention time of the standards, and the sample concentration was calculated from the external standard curve.…”

Mutations in Glucan, Water Dikinase Affect Starch Degradation and Gametophore Development in the Moss Physcomitrella patens

“…A recent phylogeny of GWD sequences has been published 47 , but this only included three of the five Physcomitrella sequences, and none from other non-vascular plants. To examine the relationships of the five sequences identified from the Physcomitrella genome with other GWD genes and proteins, we have produced new phylogenetic trees including all Physcomitrella sequences as well as others from a number of red and green algae, non-vascular and vascular plants.…”

“…Three of these have been identified in angiosperms: GWD1 is localized to the plastid and phosphorylates glucose residues within amylopectin at the 6-position 20,24 . Mutations in this gene lead to starch without covalently bound phosphate and a large decrease in leaf starch degradation 25,26,44–47 . GWD3 is also plastidial and phosphorylates glucose residues within starch at the 3-position 20 .…”

De novo transcriptome provides insights into the growth behaviour and resveratrol and trans-stilbenes biosynthesis in Dactylorhiza hatagirea - An endangered alpine terrestrial orchid of western Himalaya

“…In this regard, DEGs of β-glucosidase, trehalose phosphatase, GMMT, glucuronate 4 epimerase; and those involved in signal-transduction, phytohormone activation, metabolite-synthesis, cell-wall-remodeling, lignification, carbohydrate synthesis and stress tolerance were up-regulated and enriched in D. hatagirea tuber as compared to shoot. Water dikinases regulate the growth of storage roots and also facilitate β-amylase mediated conversion of starch into maltose and other transient forms during early stages of cold shock 49 . Thus, a glucan water dikinase (GWD3) was enriched.…”