Publications of NIPGR Scientists

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Subject: search.filters.subject.Sugar transporters

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    Genome wide investigation and transcriptional profiling of SWEET genes in two contrasting cultivars of foxtail millet under abiotic stresses
    (Elsevier B.V., 2025) Singh, Jitender; Singh, Kajol BM.; Sutar, Rashmi Ranjan; Kumar, Angad; Prasad, Manoj; Thakur, Jitendra K.
    The SWEET (Sugars will eventually be exported transporter) gene family is an important class of sugar transporters that regulates diverse aspects of plant physiology such as apoplastic phloem loading, plant-pathogen interactions and plant responses to abiotic stresses. While majority of the studies on SWEET family in plants have been performed in C3 species, there are limited reports on C4 plants. In this study we conducted genome wide investigation of the SWEET gene family in foxtail millet, a naturally stress tolerant C4 crop. In-silico analysis identified 24 SWEET genes in foxtail millet genome that were classified into 4 distinct clades. Domain analysis revealed the presence of conserved MtN3_slv/PQ-loop domains in all identified SWEET proteins. Interestingly, many SWEET proteins also harboured the prokaryotic SemiSWEET/PQ-loop domain suggesting an evolutionary link to their prokaryotic Semi-SWEET ancestors. In-silico analysis predicted the presence of abscisic acid and drought responsive cis-elements in the promoter region of SWEET genes. Transcriptional analysis under control, drought, and salinity stress revealed differential expression patterns of SWEET genes in stress resistant and stress susceptible foxtail millet cultivars. Moreover, the differential expression of SWEET genes altered the soluble sugar content in leaves and roots under stress conditions suggesting altered carbon re-allocation between source and sink tissues. This study significantly advances our understanding of the SWEET gene family in C4 plants, particularly in foxtail millet, and provides insights into its role in stress tolerance mechanisms and carbohydrate re-allocation under stress conditions.
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    Physiological implications of SWEETs in plants and their potential applications in improving source-sink relationships for enhanced yield
    (John Wiley & Sons, 2023) Singh, Jitender; Das, Shubhashis; Gupta, Kapuganti Jagadis; Ranjan, Aashish; Foyer, Christine H; Thakur, Jitendra K.
    The SWEET (SUGARS WILL EVENTUALLY BE EXPORTED TRANSPORTERS) family of transporters in plants is identified as a novel class of sugar carriers capable of transporting sugars, sugar alcohols, and hormones. Functioning in intercellular sugar transport, SWEETs influence a wide range of physiologically important processes. SWEETs regulate the development of sink organs by providing nutritional support from source leaves, responses to abiotic stresses by maintaining intracellular sugar concentrations, and host-pathogen interactions through the modulation of apoplastic sugar levels. Many bacterial and fungal pathogens activate the expression of SWEET genes in species such as rice and Arabidopsis to gain access to the nutrients that support virulence. The genetic manipulation of SWEETs has led to the generation of Bacterial Blight (BB) resistant rice varieties. Similarly, while the overexpression of the SWEETs involved in sucrose export from leaves and pathogenesis led to growth retardation and yield penalties, plants overexpressing SWEETs show improved disease resistance. Such findings demonstrate the complex functions of SWEETs in growth and stress tolerance. Here, we review the importance of SWEETs in plant-pathogen and source-sink interactions and abiotic stress resistance. We highlight the possible applications of SWEETs in crop improvement programs aimed at improving sink and source strengths important for enhancing the sustainability of yield. We discuss how the adverse effects of the overexpression of SWEETs on plant growth may be overcome.
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    The ins and outs of SWEETs in plants: current understanding of the basics and their prospects in crop improvement
    (Springer Nature Publishing AG, 2021) Anjali, Anjali; Fatima, Urooj; Senthil-Kumar, Muthappa
    Sugar will eventually be exported transporters (SWEETs), a newly discovered class of sugar transporters, play a significant role in sugar efflux processes across various kingdoms of life. In fact, SWEETs have a long evolutionary path from prokaryotes to higher plants. In plants, they are involved in developmental processes, including nectar secretion, pollen nutrition, and seed filling. While the role of SWEETs has been well studied in biotic stresses, particularly their manipulation by pathogens for sugar acquisition, they have also been linked to many abiotic stresses. Although the phylogenetic relationships and solved structures of SWEETs in different plants have been revealed, their regulation remains unexplored. The current review deals with all the exciting discoveries around SWEETs, including their classification and diversity, and bridges the gaps in their evolutionary story, from bacterial semiSWEETs to eukaryotic SWEETs. We also critically examine SWEETs at genomic, transcriptomic, and proteomic levels, as evinced by recently published examples from grain, millet, and horticultural crops. In addition, we highlight the possibilities of utilizing SWEETs in applications such as bioethanol production and disease diagnostic markers. We attempt to elucidate and unify findings related to the yet unsolved puzzle of SWEET regulation in plants to improve crop production and protection for sustainable agriculture.
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    Structure and regulation of SWEET transporters in plants: An update
    (Elsevier B.V., 2020) Anjali, Anjali; Fatima, Urooj; Manu, M.S.; Ramasamy, Sureshkumar; Senthil-Kumar, Muthappa
    Sugar will eventually be exported transporters (SWEETs), a novel family of sugar transporters found in both eukaryotes and prokaryotes, facilitate sugar flux across the cell membrane. Although these transporters were first discovered in plants, their homologs have been reported in different organisms. SWEETs have critical roles in various developmental processes, including phloem loading, nectar secretion, and pathogen nutrition. The structure of bacterial homologs, called SemiSWEETs, has been well studied thus far. Here, we provide an overview of SWEET protein structure and dynamic function by analyzing the solved crystal structures and predicted models that are available for a few SWEETs in a monocot plant (rice) and dicot plant (Arabidopsis thaliana). Despite the advancement in structure-related studies, the regulation of SWEETs remains unknown. In light of reported regulatory mechanisms of a few other sugar transporters, we propose the regulation of SWEETs at the post-translational level. We then enumerate the potential post-translational modification sites in SWEETs using computational tools. Overall, in this review, we critically analyze SWEET protein structure in plants to predict the post-translational regulation of SWEETs. Such findings have a direct bearing on plant nutrition and defense and targeting the regulation at these levels will be important in crop improvement.
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    Identification of candidate pathogenicity determinants of Rhizoctonia solani AG1-IA, which causes sheath blight disease in rice
    (Springer Nature, 2018) Ghosh, Srayan; Kanwar, Poonam; Jha, Gopaljee
    Sheath blight disease is one of the predominant diseases of rice and it is caused by the necrotrophic fungal pathogen Rhizoctonia solani. The mechanistic insight about its widespread success as a broad host range pathogen is limited. In this study, we endeavor to identify pathogenicity determinants of R. solani during infection process in rice. Through RNAseq analysis, we identified a total of 65 and 232 R. solani (strain BRS1) genes to be commonly upregulated in three different rice genotypes (PB1, Tetep, and TP309) at establishment and necrotrophic phase, respectively. The induction of genes encoding extracellular protease, ABC transporter, and transcription factors were notable during establishment phase. While during necrotrophic phase, several CAZymes, sugar transporters, cellular metabolism, and protein degradation-related genes were prominently induced. We have also identified few putative secreted effector encoding genes that were upregulated during pathogenesis. The qPCR analysis further validated the phase-specific expression dynamics of some selected putative effectors and pathogenicity-associated genes. Overall, the present study reports identification of key genes and processes that might be crucial for R. solani pathogenesis. The ability to effectively damage host cell wall and survive in hostile plant environment by managing oxidative stress, cytotoxic compounds, etc. is being proposed to be important for pathogenesis of R. solani in rice. The functional characterization of these genes would provide key insights about this important pathosystem and facilitate development of strategies to control this devastating disease.