Systematic Characterization of the Monosaccharide Transporter (MST) Gene Family in Citrus and Identification of Candidate Members Associated with Sugar Accumulation
Jul 2026· Horticulturae· Vol 12, pp. 833· 0 citations
TL;DR
This work provides a comprehensive characterization of the MST family in citrus and highlights candidate genes for future functional dissection of sugar transport and fruit quality improvement.
Abstract
The monosaccharide transporter (MST) family mediates soluble sugar transport and distribution, playing critical roles in plant growth, development, and fruit sugar accumulation. Citrus is a globally important fruit crop whose organoleptic quality depends heavily on sugar content. However, a systematic genome-wide analysis of MST genes in citrus is lacking. In this study, we identified 68 MST genes in the Citrus sinensis genome and classified them into seven subfamilies based on phylogenetic analysis. Chromosomal localization revealed uneven distribution across all nine chromosomes. Conserved motif, domain, and gene structure analyses further supported the evolutionary conservation and functional divergence. Syntenic analysis identified segmental duplication as the main driver for family expansion, and interspecific comparisons with Arabidopsis thaliana, Solanum lycopersicum, and Malus domestica provided evolutionary insights. Promoter cis-regulatory element analysis indicated that CsMSTs may respond to light, phytohormones, and stress signals, with several members carrying sugar-responsive elements potentially involved in sugar–acid metabolism. Moreover, by integrating soluble sugar content and transcriptome data across three fruit developmental stages, we performed a correlation analysis and identified 6 CsMST members showing high correlation with sucrose, glucose, and fructose simultaneously based on the Mantel test. qRT-PCR validation and linear correlation analysis confirmed that three of these members were significantly negatively correlated with sugar levels, whereas one was significantly positively correlated. This work provides a comprehensive characterization of the MST family in citrus and highlights candidate genes for future functional dissection of sugar transport and fruit quality improvement.
Sugar transporter proteins (STPs) play pivotal roles in hexose allocation and plant stress responses. However, systematic characterization of the STP family in tobacco (Nicotiana tabacum) and its involvement in Ralstonia solanacearum resistance remains unclear. In this study, 37 NtSTP genes were identified and classified into six groups, with Group VI being the most conserved and Group V exhibiting dicot-specific expansion. Gene structure and conserved motif analyses revealed that most NtSTP members possess the typical MFS_STP domain, although variations in exon–intron organization and motif composition suggested functional divergence. Tandem duplication (TD) served as the primary driver of NtSTP family expansion, and Ka/Ks values of all paralogous pairs were less than 1, indicative of purifying selection. Promoter cis-element analysis revealed a complex regulatory network involving hormone signaling (ABA, JA, SA, GA, ET), stress responses, and light signaling. RT-qPCR expression profiling revealed that ten NtSTP genes (NtSTP1, 5, 7, 21, 22, 24, 26, 27, 28, and 29) exhibited significant transcriptional upregulation upon R. solanacearum infection. Specifically, NtSTP5, NtSTP7, NtSTP21, NtSTP22, NtSTP24, NtSTP26, and NtSTP27 peaked at 12 h post-inoculation (hpi), whereas NtSTP1, NtSTP28, and NtSTP29 reached their highest expression levels at 24 hpi. By contrast, NtSTP6, NtSTP13, and NtSTP30 displayed reduced expression upon R. solanacearum infection. These expression patterns indicate functional diversification within the NtSTP family and imply that these members may be transcriptionally modulated during plant responses to R. solanacearum. The present work provides preliminary and valuable candidate gene resources that may facilitate future disease resistance breeding programs in tobacco.
Hua Xuan, Da-Yin Liu, Ren-Ying Xu et al.· Frontiers in Plant Science· 0 citations
The cultivated peanut (Arachis hypogaea L.) is an important oilseed and economic crop worldwide, with seed protein content being a key target for quality improvement. The Sugars Will Eventually be Exported Transporter (SWEET) gene family encodes sugar transporters that play crucial roles in plant growth and development, stress tolerance, pathogen interactions, and seed filling. In this study, 43 AhSWEET genes were identified in the cultivated peanut genome and classified into four phylogenetic clades. Members within the same clade generally show similar exon-intron structures and conserved motif compositions, suggesting evolutionary conservation within subgroups. Promoter cis-regulatory elements analysis indicated that AhSWEET genes contain multiple elements associated with light response, hormone signaling, stress response, and growth and development, implying their potential involvement in diverse biological processes. Subcellular localization predictions indicated that most AhSWEET proteins are likely localized to the plasma membrane, consistent with their putative roles in transmembrane sugar transport. This was further supported by transient expression analysis of selected AhSWEET-eGFP fusion proteins in Nicotiana benthamiana leaves. Comparative phylogenetic and synteny analyses reveal that AhSWEET5, AhSWEET21, AhSWEET27, and AhSWEET43 are closely related to soybean GmSWEET10a and GmSWEET10b, which are known to regulate seed size and storage-compound accumulation. Transcriptome data and quantitative reverse transcriptase PCR analysis showed that these candidate genes are preferentially expressed in seed-related tissues, particularly the testa and embryo, suggesting possible sugar allocation during peanut seed development. Overall, this study provides a systematic characterization of the AhSWEET gene family and identifies several candidate genes for future functional studies aimed at improving peanut seed quality, including protein accumulation.
Lina He, Pengyu Qu, Xiaona Li et al.· International Journal of Mol...· 0 citations
Overall, this study identifies EnSWEET15 as a positive regulator of salt tolerance via modulating ROS homeostasis, providing novel insights into SWEET-mediated salt stress response in perennial forages and valuable genetic resources for salt-tolerant breeding of E. nutans.
UDP-dependent glycosyltransferases (UGTs) are a large and diverse enzyme family involved in the modification and diversification of plant secondary metabolites, including flavonoids associated with fruit nutritional value and quality traits. However, the evolutionary organization of UGT families and their associations with flavonoid metabolism remain insufficiently characterized in tropical monocot fruit crops. Here, we performed a genome-wide characterization of the UGT family in pineapple (Ananas comosus) and integrated transcriptomic and metabolomic information to prioritize AcUGT candidates associated with flavonoid accumulation. A total of 68 AcUGT genes were identified and classified into 16 phylogenetic clades. Comparative genomic analyses demonstrated conserved syntenic relationships with other monocots, while tandem and segmental duplication contributed to AcUGT family expansion under predominant purifying selection. Structural analyses revealed conservation of the C-terminal plant secondary product glycosyltransferase (PSPG) motif involved in UDP-sugar recognition, whereas N-terminal sequence diversification distinguished AcUGT members. Promoter analysis identified cis-regulatory elements associated with hormone, developmental, environmental, and secondary metabolism responses. Integration of transcriptomic and metabolomic datasets revealed stage- and cultivar-associated AcUGT expression patterns that were statistically associated with flavonoid profiles. Candidate prioritization based on phylogeny, developmental or cultivar specificity and transcript–metabolite associations highlighted AcUGT29, AcUGT02, and AcUGT51 as high-priority candidates for future functional investigation. This study provides a genomic and metabolic framework for investigating UGT-associated flavonoid diversification and for guiding subsequent functional and fruit-quality studies in pineapple.
Meng-Jie Ge, Xin-Ni Jiang, Qiu-Yu Lu et al.· Agronomy· 0 citations
Carotenoid cleavage dioxygenases (CCDs) play critical roles in plant growth, development, and abiotic stress responses, yet their genome-wide identification and drought response mechanisms remain unexplored in wheat. In this study, 34 TaCCD genes were identified in wheat, distributed across 15 chromosomes and phylogenetically classified into five subfamilies. Gene structure analysis indicated that members within each subfamily shared conserved motifs and similar intron-exon arrangements. Cis-regulatory element analysis suggested the potential roles of these genes in stress adaptation, developmental processes, and hormone signaling. Moreover, prediction of tertiary structures and protein-protein interactions revealed unique structural features and potential interacting partners of the TaCCD proteins. In addition, TaNCED9a, a member of the TaCCD family, showed the highest transcript level in wheat roots among all detected TaCCD genes and was significantly induced by drought stress. Subcellular localization assay indicated that TaNCED9a was located in chloroplasts. Downregulation of TaNCED9a expression led to reduced drought resistance in wheat, accompanied by an accumulation of reactive oxygen species and a decrease in endogenous abscisic acid levels. Using yeast one-hybrid, dual-luciferase, and tobacco transient co-expression assays, the upstream regulatory factor TaDREB-7A was identified, which can regulate the expression of TaNCED9a. Additionally, a KASP molecular marker was developed to identify the superior haplotype TaNCED9a-HapI, which exhibited a significantly higher germination rate compared to TaNCED9a-HapII under drought conditions, and was predominant in wheat. These results offer valuable insights into the TaCCD gene family's response mechanisms to drought stress in wheat, simultaneously identifying promising genetic resources for enhancing drought tolerance through molecular breeding.
Ya-Ning Bu, Zi-Han Liu, Jian-Fei Zhou et al.· Plant physiology and biochem...· 0 citations
Inositol monophosphatase (IMP) is a key enzyme in the inositol signaling pathway and ascorbic acid (AsA) biosynthesis, playing crucial roles in plant growth, development, and abiotic stress responses. Sorghum (
S. bicolor
) is an important cereal crop with remarkable drought and salinity tolerance, yet a systematic analysis of the IMP gene family in sorghum has been lacking. In this study, we identified eight IMP genes (
SbIMP-1–SbIMP-8
) in the sorghum genome. Phylogenetic analysis classified them into six subfamilies, consistent with rice and maize, suggesting a common ancestral origin. Gene structure and motif composition were highly conserved within each subfamily but varied among subfamilies, indicating functional divergence. Synteny analysis revealed strong collinearity between sorghum and maize with mostly one-to-one orthologous relationships, whereas complex one-to-many correspondences were observed with the polyploid
S. spontaneum
, highlighting lineage-specific expansion driven by whole-genome duplication. Promoter cis-element analysis identified numerous stress-related and hormone-responsive elements, including ABRE, DRE, MYB and MYC binding sites. Transcriptome and qRT-PCR analyses under salt (NaCl) and osmotic (PEG) stresses revealed distinct expression patterns:
SbIMP-1
,
SbIMP-3
,
SbIMP-6
,
SbIMP-7
and
SbIMP-8
acted as salt responders. In particular,
SbIMP-4
exhibited a strong salt-specific induction. Promoter enrichment of MYB and MYC binding sites was associated with rapid salt response, whereas the combination of DRE, ABRE and MYB sites in
SbIMP-4
likely underpinned its unique expression profile. This study provides preliminary insights into the expression profiles of SbIMP genes under salt and osmotic stresses, offering a theoretical foundation for molecular breeding aimed at improving abiotic stress response in sorghum and other crops.
Ling Zheng, Xiao-Yu Zhou, Fei Wei et al.· Frontiers in Plant Science· 0 citations
We use cookies to run the site and, with your consent, for analytics and to show ads.
See our Cookie Policy.
