Abstract
Carbohydrates are nutrients and important signal molecules in higher plants. Sugar transporters (ST) play important role not only in long-distance transport of sugar, but also in sugar accumulations in sink cells. Longan (Dimocarpus longan L.) is one of the most important commercial tropical/subtropical evergreen fruit species in Southeast Asia. In this study, a total of 52 longan sugar transporter (DlST) genes were identified and they were divided into eight clades according to phylogenetic analysis. Out of these 52 DlST genes, many plant hormones (e.g., MeJA and gibberellin), abiotic (e.g., cold and drought), and biotic stress responsive element exist in their promoter region. Gene structure analysis exhibited that each of the clades have closely associated gene architectural features based on similar number or length of exons. The numbers of DlSTs, which exhibited alternative splicing (AS) events, in flower bud is more than that in other tissues. Expression profile analysis revealed that ten DlST members may regulate longan flowerbud differentiation. In silico expression profiles in nine longan organs indicated that some DlST genes were tissue specificity and further qRT-PCR analysis suggested that the transcript level of seven DlSTs (DlINT3, DlpGlcT1, DlpGlcT2, DlPLT4, DlSTP1, DlVGT1 and DlVGT2) was consistent with sugar accumulation in fruit, indicating that they might be involved in sugar accumulations during longan fruit development. Our findings will contribute to a better understanding of sugar transporters in woody plant.
Highlights
Carbohydrates are the main components that provide energy sources and building blocks for cell and constitute osmotic and act as signaling molecules throughout the physiological process and corresponding both abiotic and biotic stress responses in higher plants [1]
The content of sucrose was higher than glucose and fructose after 60 days after flowering (DAF)
The results showed that the transcript abundance of 11 genes
Summary
Carbohydrates are the main components that provide energy sources and building blocks for cell and constitute osmotic and act as signaling molecules throughout the physiological process and corresponding both abiotic and biotic stress responses in higher plants [1]. Two kinds of carbohydrates related to sugars, polyols and organic acids, have complementary roles in plant growth and development. Sugars are the main products of photosynthesis, which are synthesized de novo in leaves (source) and translocated into fruits, roots, and stems (sink) to supply the carbon substrate for plant growth and/or storage. Plants 2020, 9, 342 between source and sink [3]. Sucrose is the main transport sugar in the phloem in many plants [4,5]
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