Hexose translocation mediated by SlSWEET5b is required for pollen maturation in Solanum lycopersicum

AbstractPollen fertility is critical for successful fertilization and, accordingly, for crop yield. While sugar unloading affects growth and development of all types of sink organs, the molecular nature for sugar import to tomato pollen is poorly understood. However, SWEET transporters have been proposed to function in pollen development. Here, qRT-PCR revealed that SlSWEET5b was markedly expressed in flowers when compared to the remaining tomato SlSWEETs; particularly, in the stamens of maturing flower buds undergoing mitosis. Distinct accumulation of SlSWEET5b-GUS fusion proteins was present in mature flower buds, especially in anther vascular and inner cells, symplasmic isolated pollen cells and styles. The demonstration that GFP fusion proteins located to the plasma membrane support the idea that the SlSWEET5b carrier functions in apoplasmic sugar translocation during pollen maturation. Such function is in line with data from yeast complementation experiments and radiotracer uptakes, showing that SlSWEET5b operates as a low affinity hexose-specific passive facilitator, with a KM of ~36 mM. Most importantly, RNAi-mediated suppression of SlSWEET5b expression resulted in shrunken nucleus-less pollen cells, impaired germination and low seed yield. Interestingly, stamens from SlSWEET5b-silenced tomato mutants contained significantly lower amounts of sucrose and increased invertase activity, pointing to reduced carbon supply and perturbed sucrose homeostasis in this tissue. Taken together, our findings reveal an essential role of SlSWEET5b in mediating apoplasmic hexose import into phloem unloading cells and into developing pollen cells to support pollen mitosis and maturation in tomato flowers.One-sentence SummaryPlasma-membrane-localized SlSWEET5b facilitates a sequential hexose flux, from phloem to anther cells and from anther locule to pollen, to support pollen maturation and fertility in tomato flowers.

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Plasma membrane-localized SlSWEET7a and SlSWEET14 regulate sugar transport and storage in tomato fruits

Horticulture Research ◽

10.1038/s41438-021-00624-w ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Xinsheng Zhang ◽

Chaoyang Feng ◽

Manning Wang ◽

Tianlai Li ◽

Xin Liu ◽

...

Keyword(s):

Plasma Membrane ◽

Sugar Content ◽

Sugar Transport ◽

Invertase Activity ◽

Vascular Bundles ◽

Tomato Fruits ◽

Sugar Transporters ◽

Potential Strategy ◽

And Storage

AbstractSugars, especially glucose and fructose, contribute to the taste and quality of tomato fruits. These compounds are translocated from the leaves to the fruits and then unloaded into the fruits by various sugar transporters at the plasma membrane. SWEETs, are sugar transporters that regulate sugar efflux independently of energy or pH. To date, the role of SWEETs in tomato has received very little attention. In this study, we performed functional analysis of SlSWEET7a and SlSWEET14 to gain insight into the regulation of sugar transport and storage in tomato fruits. SlSWEET7a and SlSWEET14 were mainly expressed in peduncles, vascular bundles, and seeds. Both SlSWEET7a and SlSWEET14 are plasma membrane-localized proteins that transport fructose, glucose, and sucrose. Apart from the resulting increase in mature fruit sugar content, silencing SlSWEET7a or SlSWEET14 resulted in taller plants and larger fruits (in SlSWEET7a-silenced lines). We also found that invertase activity and gene expression of some SlSWEET members increased, which was consistent with the increased availability of sucrose and hexose in the fruits. Overall, our results demonstrate that suppressing SlSWEET7a and SlSWEET14 could be a potential strategy for enhancing the sugar content of tomato fruits.

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Faculty Opinions recommendation of Reassessment of the role of plasma membrane domains in the regulation of vesicular traffic in yeast.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.8911958.10009055 ◽

2011 ◽

Author(s):

Kenneth Sawin

Keyword(s):

Plasma Membrane ◽

Membrane Domains ◽

Vesicular Traffic ◽

Plasma Membrane Domains

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Role of Exosomes in the Exchange of Spermatozoa after Leaving the Seminiferous Tubule: A Review

Current Drug Metabolism ◽

10.2174/1389200221666200520091511 ◽

2020 ◽

Vol 21 (5) ◽

pp. 330-338

Author(s):

Luming Wu ◽

Yuan Ding ◽

Shiqiang Han ◽

Yiqing Wang

Keyword(s):

Drug Delivery ◽

Plasma Membrane ◽

Seminiferous Tubule ◽

Metabolic Diseases ◽

Inflammatory Diseases ◽

Multivesicular Bodies ◽

Extensive Search ◽

Neurological Research ◽

The One

Background: Exosomes are extracellular vesicles (EVs) released from cells upon fusion of an intermediate endocytic compartment with the plasma membrane. They refer to the intraluminal vesicles released from the fusion of multivesicular bodies with the plasma membrane. The contents and number of exosomes are related to diseases such as metabolic diseases, cancer and inflammatory diseases. Exosomes have been used in neurological research as a drug delivery tool and also as biomarkers for diseases. Recently, exosomes were observed in the seminal plasma of the one who is asthenozoospermia, which can affect sperm motility and capacitation. Objective: The main objective of this review is to deeply discuss the role of exosomes in spermatozoa after leaving the seminiferous tubule. Methods: We conducted an extensive search of the literature available on relationships between exosomes and exosomes in spermatozoa on the bibliographic database. Conclusion: : This review thoroughly discussed the role that exosomes play in the exchange of spermatozoa after leaving the seminiferous tubule and its potential as a drug delivery tool and biomarkers for diseases as well.

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Histochemical Examination of Invertase Activities in the Growing Tip of the Plant Root

The Open Plant Science Journal ◽

10.2174/1874294701710010035 ◽

2017 ◽

Vol 10 (1) ◽

pp. 35-45

Author(s):

N.F. Lunkova ◽

N.A. Burmistrova ◽

M.S. Krasavina

Keyword(s):

Plant Root ◽

Invertase Activity ◽

Root Tip ◽

Elongation Zone ◽

Root Tips ◽

Phloem Unloading ◽

Meristem Cell ◽

Transition To Elongation ◽

Different Tissues

Background:A growing part of the root is one of the most active sinks for sucrose coming from source leaves through the phloem. In the root, sucrose is unloaded from conducting bundles and is distributed among the surrounding cells. To be involved in the metabolism, sucrose should disintegrate into hexoses by means of degrading enzymes.Aims:The aim of this research was to explore the possibility of the involvement of one such enzymes, invertase, in phloem unloading as well as distribution of its activity in the functionally different tissues of the plant root tips.Method:To estimate the enzyme activities in root tissues, we applied two techniques: the histochemical method using nitro blue tetrazolium. The localization of phloem unloading was studied with carboxyfluorescein, a fluorescent marker for symplastic transport.Results:Invertase activity was not detected in the apical part of the meristem. It appeared only between the basal part of this zone and the beginning of the elongation zone. There is the root phloem unloading in that area. Invertase activity increased with increasing the distance from the root tip and reached the highest values in the region of cell transition to elongation and in the elongation zone. The activities of the enzyme varied in different tissues of the same zone and sometimes in the neighboring cells of the same tissue. Biochemical determination of invertase activity was made in the maize root segments coincident to the zones of meristem, cell elongation and differentiation. The results of both methods of determination of invertase activity were in agreement.Conclusion:It was concluded that phloem unloading correlated with invertase activity, possibly because of the activation of invertase by unloaded sucrose. Invertase is one of the factors involved in the processes preparing the cells for their transition to elongation because the concentration of osmotically active hexoses increases after cleavage of sucrose, that stimulates water entry into the cells, which is necessary for elongation growth.

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Involvement of Very Short DNA Tandem Repeats and the Influence of the RAD52 Gene on the Occurrence of Deletions in Saccharomyces cerevisiae

Genetics ◽

10.1093/genetics/156.2.549 ◽

2000 ◽

Vol 156 (2) ◽

pp. 549-557 ◽

Cited By ~ 1

Author(s):

Anne J Welcker ◽

Jacky de Montigny ◽

Serge Potier ◽

Jean-Luc Souciet

Keyword(s):

Fusion Proteins ◽

Tandem Repeats ◽

Chromosomal Rearrangements ◽

Reversion Rate ◽

Wild Type ◽

Recombination Mechanism ◽

Nonhomologous Recombination ◽

Deletion Rate ◽

Dna Tandem Repeats

Abstract Chromosomal rearrangements, such as deletions, duplications, or Ty transposition, are rare events. We devised a method to select for such events as Ura+ revertants of a particular ura2 mutant. Among 133 Ura+ revertants, 14 were identified as the result of a deletion in URA2. Of seven classes of deletions, six had very short regions of identity at their junctions (from 7 to 13 bp long). This strongly suggests a nonhomologous recombination mechanism for the formation of these deletions. The total Ura+ reversion rate was increased 4.2-fold in a rad52Δ strain compared to the wild type, and the deletion rate was significantly increased. All the deletions selected in the rad52Δ context had microhomologies at their junctions. We propose two mechanisms to explain the occurrence of these deletions and discuss the role of microhomology stretches in the formation of fusion proteins.

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