Genome-Wide Identification, Expression, and Functional Analysis of the Sugar Transporter Gene Family in Cassava (Manihot esculenta)

Abstract

The sugar transporter (STP) gene family encodes monosaccharide transporters that contain 12 transmembrane domains and belong to the major facilitator superfamily. STP genes play critical roles in monosaccharide distribution and participate in diverse plant metabolic processes. To investigate the potential roles of STPs in cassava (Manihot esculenta) tuber root growth, genome-wide identification and expression and functional analyses of the STP gene family were performed in this study. A total of 20 MeSTP genes (MeSTP1–20) containing the Sugar_tr conserved motifs were identified from the cassava genome, which could be further classified into four distinct groups in the phylogenetic tree. The expression profiles of the MeSTP genes explored using RNA-seq data showed that most of the MeSTP genes exhibited tissue-specific expression, and 15 out of 20 MeSTP genes were mainly expressed in the early storage root of cassava. qRT-PCR analysis further confirmed that most of the MeSTPs displayed higher expression in roots after 30 and 40 days of growth, suggesting that these genes may be involved in the early growth of tuber roots. Although all the MeSTP proteins exhibited plasma membrane localization, variations in monosaccharide transport activity were found through a complementation analysis in a yeast (Saccharomyces cerevisiae) mutant, defective in monosaccharide uptake. Among them, MeSTP2, MeSTP15, and MeSTP19 were able to efficiently complement the uptake of five monosaccharides in the yeast mutant, while MeSTP3 and MeSTP16 only grew on medium containing galactose, suggesting that these two MeSTP proteins are transporters specific for galactose. This study provides significant insights into the potential functions of MeSTPs in early tuber root growth, which possibly involves the regulation of monosaccharide distribution.

Sugar transporter proteins in Capsicum: identification, characterization, evolution and expression patterns

“…Two genes (CaSTP5 and CaSTP17) demonstrated similarity tissue-specific expression pattern, being mainly expressed in flowers and leaves. These results were consistent with previous findings on other species [8,37]. In addition, we found that the CaSTP3 and CaSTP5 genes, which are expressed in vegetative organs, are not expressed in reproductive organs ( Figure 5).…”

“…The STP subfamily expanded significantly in pepper compared to Arabidopsis [36]. This result supported previous reports [15,37]. Meanwhile, Clade I, Clade III, and Clade IV displayed significant expansion compared to Clade II.…”

“…It should be noted that CaSTP9 and CaSTP10 were significantly upregulated in roots but down-regulated in leaves. Previous studies also indicated that some STP genes play significant roles in stresses responses [7,8,37]. In addition, the expression of most other STP genes did not change significantly under salt stress.…”

Genome-Wide Identification and Expression Analysis of Sugar Transporter (ST) Gene Family in Longan (Dimocarpus longan L.)

“…In plants, sugar transporters are divided into three major types: sucrose transporters (SUTs), also called sucrose carriers (SUCs), monosaccharide transporters (MSTs), and sugars will eventually be exported transporters (SWEETs) [13,14]. In addition to transporting sugar, sugar transporters also play an important role in plant growth and development [15][16][17]. SWEETs represent a new class of sugar transporters belonging to the MtN3-like clan and are characterized by seven transmembrane domains (TMDs) [13].…”

Heterologous Expression of SvMBD5 from Salix viminalis L. Promotes Flowering in Arabidopsis thaliana L.

“…MEME and Pfam programs were used for the motif analysis of SvMBD5 [37]. A phylogenetic tree was constructed based on protein sequence alignment of MBD5 proteins from S. viminalis, Populus trichocarpa L., S. lycopersicum, Paeonia suffruticosa L., Vitis vinifera L., Gossypium arboretum L., Morus notabilis L., Triticum aestivum L., Helianthus annuus L., and Arabidopsis thaliana L. with the PHYML program [38]. Phylogenetic trees of the MBD protein sequences were constructed using MEGA6 [38].…”