scholarly journals The Dual Function of OsSWEET3a as a Gibberellin and Glucose Transporter Is Important for Young Shoot Development in Rice

2020 ◽  
Vol 61 (11) ◽  
pp. 1935-1945 ◽  
Author(s):  
Minami Morii ◽  
Akihiko Sugihara ◽  
Sayaka Takehara ◽  
Yuri Kanno ◽  
Kyosuke Kawai ◽  
...  
Keyword(s):  
Glucose Transporter ◽  
Vascular Tissue ◽  
Shoot Development ◽  
Dual Function ◽  
Vascular Bundles ◽  
Long Distance ◽  
Reverse Transcription Pcr ◽  
Long Distance Transport ◽  
Sweet Proteins ◽  
Young Leaves

Abstract Translocation and long-distance transport of phytohormones are considered important processes for phytohormone responses, as well as their synthesis and signaling. Here, we report on the dual function of OsSWEET3a, a bidirectional sugar transporter from clade I of the rice SWEET family of proteins, as both a gibberellin (GA) and a glucose transporter. OsSWEET3a efficiently transports GAs in the C13-hydroxylation pathway of GA biosynthesis. Both knockout and overexpression lines of OsSWEET3a showed defects in germination and early shoot development, which were partially restored by GA, especially GA20. Quantitative reverse transcription PCR, GUS staining and in situ hybridization revealed that OsSWEET3a was expressed in vascular bundles in basal parts of the seedlings. OsSWEET3a expression was co-localized with OsGA20ox1 expression in the vascular bundles but not with OsGA3ox2, whose expression was restricted to leaf primordia and young leaves. These results suggest that OsSWEET3a is expressed in the vascular tissue of basal parts of seedlings and is involved in the transport of both GA20 and glucose to young leaves, where GA20 is possibly converted to the bioactive GA1 form by OsGA3ox2, during early plant development. We also indicated that such GA transport activities of SWEET proteins have sporadically appeared in the evolution of plants: GA transporters in Arabidopsis have evolved from sucrose transporters, while those in rice and sorghum have evolved from glucose transporters.

scholarly journals Boron Deficiency Effects on Sugar, Ionome, and Phytohormone Profiles of Vascular and Non-Vascular Leaf Tissues of Common Plantain (Plantago major L.)

2019 ◽  
Vol 20 (16) ◽  
pp. 3882 ◽  
Author(s):  
Benjamin Pommerrenig ◽  
Kai Eggert ◽  
Gerd P. Bienert
Keyword(s):  
Vascular Tissue ◽  
Nutrient Deficiency ◽  
Distribution Patterns ◽  
Boron Deficiency ◽  
Vascular Bundles ◽  
Plantago Major ◽  
Long Distance ◽  
Long Distance Transport ◽  
Specific Manner ◽  
Organ Specific

Vascular tissues essentially regulate water, nutrient, photo-assimilate, and phytohormone logistics throughout the plant body. Boron (B) is crucial for the development of the vascular tissue in many dicotyledonous plant taxa and B deficiency particularly affects the integrity of phloem and xylem vessels, and, therefore, functionality of long-distance transport. We hypothesize that changes in the plants’ B nutritional status evoke differential responses of the vasculature and the mesophyll. However, direct analyses of the vasculature in response to B deficiency are lacking, due to the experimental inaccessibility of this tissue. Here, we generated biochemical and physiological understanding of B deficiency response reactions in common plantain (Plantago major L.), from which pure and intact vascular bundles can be extracted. Low soil B concentrations affected quantitative distribution patterns of various phytohormones, sugars and macro-, and micronutrients in a tissue-specific manner. Vascular sucrose levels dropped, and sucrose loading into the phloem was reduced under low B supply. Phytohormones responded selectively to B deprivation. While concentrations of abscisic acid and salicylic acid decreased at low B supply, cytokinins and brassinosteroids increased in the vasculature and the mesophyll, respectively. Our results highlight the biological necessity to analyze nutrient deficiency responses in a tissue- rather organ-specific manner.

Regulation of vascular differentiation in leaf primordia during the rhythmic growth of Gnetum africanum

1986 ◽  
Vol 64 (1) ◽  
pp. 208-213 ◽  
Author(s):  
F. Mialoundama ◽  
P. Paulet
Keyword(s):  
Principal Axis ◽  
Vascular Tissue ◽  
Growth Period ◽  
Leaf Primordia ◽  
Single Pair ◽  
Vascular Bundles ◽  
Vascular Differentiation ◽  
Terminal Bud ◽  
Young Leaves ◽  
Rhythmic Growth

The growth of the principal axis of Gnetum africanum Welw. is achieved by successive growth and rest periods. During the phase of growth arrest, the terminal bud produces a single pair of leaf primordia containing no vascular tissue whereas observation of the terminal bud of the vinelike stem reveals that the oldest of the leaf primordia do contain vascular tissue before emerging. The differentiation of vascular bundles in the leaf primordia of the principal axis begins only with the return of the growth period during which time new young leaves are formed. The rhythm of formation of the leaves and their vascularization can be accelerated by removal of the young leaves. A prolonged exogenous treatment with abscisic acid after removal of the young leaves reestablishes the inhibition and prevents initiation of vascularization. It seems, therefore, that in the principal axis young leaves inhibit vascular differentiation of the leaf primordia, which may partly explain the inhibition of growth.

scholarly journals Cloning and Characterization of Deoxymugineic Acid Synthase Genes from Graminaceous Plants

2006 ◽  
Vol 281 (43) ◽  
pp. 32395-32402 ◽  
Author(s):  
Khurram Bashir ◽  
Haruhiko Inoue ◽  
Seiji Nagasaka ◽  
Michiko Takahashi ◽  
Hiromi Nakanishi ◽  
...  
Keyword(s):  
Amino Acids ◽  
Vascular Bundles ◽  
Long Distance ◽  
Mugineic Acid Family Phytosiderophores ◽  
Long Distance Transport ◽  
Shoot Tissue ◽  
Iron Deficient ◽  
Deoxymugineic Acid ◽  
Graminaceous Plants

Graminaceous plants have evolved a unique mechanism to acquire iron through the secretion of a family of small molecules, called mugineic acid family phytosiderophores (MAs). All MAs are synthesized from l-Met, sharing the same pathway from l-Met to 2′-deoxymugineic acid (DMA). DMA is synthesized through the reduction of a 3″-keto intermediate by deoxymugineic acid synthase (DMAS). We have isolated DMAS genes from rice (OsDMAS1), barley (HvDMAS1), wheat (TaD-MAS1), and maize (ZmDMAS1). Their nucleotide sequences indicate that OsDMAS1 encodes a predicted polypeptide of 318 amino acids, whereas the other three orthologs all encode predicted polypeptides of 314 amino acids and are highly homologous (82–97.5%) to each other. The DMAS proteins belong to the aldo-keto reductase superfamily 4 (AKR4) but do not fall within the existing subfamilies of AKR4 and appear to constitute a new subfamily within the AKR4 group. All of the proteins showed DMA synthesis activity in vitro. Their enzymatic activities were highest at pH 8–9, consistent with the hypothesis that DMA is synthesized in subcellular vesicles. Northern blot analysis revealed that the expression of each of the above DMAS genes is up-regulated under iron-deficient conditions in root tissue, and that of the genes OsDMAS1 and TaDMAS1 is up-regulated in shoot tissue. OsDMAS1 promoter-GUS analysis in iron-sufficient roots showed that its expression is restricted to cells participating in long distance transport and that it is highly up-regulated in the entire root under iron-deficient conditions. In shoot tissue, OsDMAS1 promoter drove expression in vascular bundles specifically under iron-deficient conditions.

scholarly journals Shoot-to-root translocation of the jasmonate precursor 12-oxo-phytodienoic acid (OPDA) coordinates plant growth responses following tissue damage

2019 ◽  
Author(s):  
Adina Schulze ◽  
Marlene Zimmer ◽  
Stefan Mielke ◽  
Hagen Stellmach ◽  
Charles W. Melnyk ◽  
...  
Keyword(s):  
Vascular Tissue ◽  
Plant Stress ◽  
Root Growth Inhibition ◽  
Growth Responses ◽  
Mechanical Wounding ◽  
Long Distance ◽  
Long Distance Transport ◽  
Stress Acclimation ◽  
Transcriptional Changes ◽  
Multicellular Organisms

ABSTRACTMulticellular organisms rely upon the movement of signaling molecules across cells, tissues and organs to communicate among distal sites. In plants, herbivorous insects, necrotrophic pathogens and mechanical wounding stimulate the activation of the jasmonate (JA) pathway, which in turn triggers the transcriptional changes necessary to protect plants against those challenges, often at the expense of growth. Although previous evidence indicated that JA species can translocate from damaged into distal sites, the identity of the mobile compound(s), the tissues through which they translocate and the consequences of their relocation remain unknown. Here, we demonstrated that endogenous JA species generated after shoot injury translocate to unharmed roots via the phloem vascular tissue in Arabidopsis thaliana. By wounding wild-type shoots of chimeric plants and by quantifying the relocating compounds from their JA-deficient roots, we uncovered that the JA-Ile precursor 12-oxo-phytodienoic acid (OPDA) is a mobile JA species. Our data also showed that OPDA is a primary mobile compound relocating to roots where, upon conversion to the bioactive hormone, it induces JA-mediated gene expression and root growth inhibition. Collectively, our findings reveal the existence of long-distance transport of endogenous OPDA which serves as a communication molecule to coordinate shoot-to-root responses, and highlight the importance of a controlled distribution of JA species among organs during plant stress acclimation.

The anatomy of the pathway of sucrose unloading within the sugarcane stalk

2005 ◽  
Vol 32 (4) ◽  
pp. 367 ◽  
Author(s):  
Kerry B. Walsh ◽  
Russell C. Sky ◽  
Sharon M. Brown
Keyword(s):  
Cell Layer ◽  
Sink Strength ◽  
Vascular Bundles ◽  
Sucrose Transport ◽  
Long Distance ◽  
Long Distance Transport ◽  
Sugarcane Stalk ◽  
Storage Parenchyma ◽  
Phloem Fibre ◽  
Distance Transport

The physical path of sucrose unloading in the sugarcane stalk is described. About 50% of the vascular bundles in the internodes were located within 3 mm of the outside of the stalk. These bundles were inactive in long distance sucrose transport, as assessed by dye tracers of phloem flow. A sheath of fibres isolates the phloem apoplast from that of the storage parenchyma. In bundles associated with long distance transport (i.e. in the central region), the fibre sheath is narrowest to either side of the phloem fibre cap, and consists of living cells with plasmodesmata within pits in the secondary wall. Plasmodesmata were also arranged into pit fields between cells of the storage parenchyma. Since the vascular apoplast is isolated from the apoplast of the storage parenchyma, sucrose must move through the symplast of the fibre sheath. The calculated flux of sucrose through plasmodesmata of this cell layer was at the low end of reported values in the literature. Sucrose unloading within the storage parenchyma may also follow a symplastic route, with unloading into the apoplast of the storage parenchyma occurring as part of a turgor mechanism to increase sink strength.

The Fine Structure of Phloem Cells

1985 ◽  
Vol 43 ◽  
pp. 632-635
Author(s):  
James Cronshaw
Keyword(s):  
Structural Studies ◽  
High Concentration ◽  
Long Distance ◽  
Phloem Tissue ◽  
Sieve Elements ◽  
Long Distance Transport ◽  
P Protein ◽  
Companion Cells ◽  
Electron Microscopical ◽  
Distance Transport

Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.

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