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Structural and metabolic changes in rhizophores of the Cerrado species Chrysolaena obovata (Less.) Dematt. as influenced by drought and re-watering.

Garcia PM, Hayashi AH, Silva EA, Figueiredo-Ribeiro Rde C, Carvalho MA - Front Plant Sci (2015)

Bottom Line: Inulin sphero-crystals accumulated in parenchymatic cells of the cortex, vascular tissues and pith were reduced under drought and accompanied anatomical changes, starting from day 10.At 22 days of drought, the cortical and vascular tissues were collapsed, and inulin sphero-crystals and inulin content were reduced.The localization of inulin sphero-crystals in vascular tissues of C. obovata, as well as the decrease of total inulin and the increase in oligo:polysaccharide ratio in water stressed plants is consistent with the role of fructans in protecting plants against drought.

View Article: PubMed Central - PubMed

Affiliation: Núcleo de Pesquisa em Fisiologia e Bioquímica, Instituto de Botânica São Paulo, Brazil ; Programa de Pós-Graduação em Biodiversidade Vegetal e Meio Ambiente, Instituto de Botânica São Paulo, Brazil.

ABSTRACT
The high fructan contents in underground organs of Cerrado species, high water solubility, and fast metabolism of these compounds highlight their role as carbon storage and as an adaptive feature in plants under drought. In this study, we showed that anatomical structure, in association with soluble compounds and metabolism of inulin-type fructans were modified in rhizophores of Crysolaena obovata submitted to water suppression and recovery after re-watering. Plants were subjected to daily watering (control), suppression of watering for 22 days (water suppression) and suppression of watering followed by re-watering after 10 days (re-watered). Plants were collected at time 0 and after 3, 7, 10, 12, 17, and 22 days of treatment. In addition to changes in fructan metabolism, high proline content was detected in drought stressed plants, contributing to osmoregulation and recovery after water status reestablishment. Under water suppression, total inulin was reduced from approx. 60 to 40%, mainly due to exohydrolase activity. Concurrently, the activity of fructosyltransferases promoted the production of short chain inulin, which could contribute to the increase in osmotic potential. After re-watering, most parameters analyzed were similar to those of control plants, indicating the resumption of regular metabolism, after water absorption. Inulin sphero-crystals accumulated in parenchymatic cells of the cortex, vascular tissues and pith were reduced under drought and accompanied anatomical changes, starting from day 10. At 22 days of drought, the cortical and vascular tissues were collapsed, and inulin sphero-crystals and inulin content were reduced. The localization of inulin sphero-crystals in vascular tissues of C. obovata, as well as the decrease of total inulin and the increase in oligo:polysaccharide ratio in water stressed plants is consistent with the role of fructans in protecting plants against drought.

No MeSH data available.


Related in: MedlinePlus

Scanning electron microscopy from rhizophores of Chrysolaena obovata submitted to daily watering—control (A), water suppression—day 10 (B), day 12 (C), day 22 (D), and re-watering—day 12 (E), day 22 (F). Note the altered distribution of inulin (*), mainly after 22 days of water suppression (D), and restoration of outermost tissues (arrows) after re-watering (E,F). Details: (A) Cluster of inulin globules. (B) Isolated inulin globules. C, cortex; P, pith; VB, vascular bundle.
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Figure 5: Scanning electron microscopy from rhizophores of Chrysolaena obovata submitted to daily watering—control (A), water suppression—day 10 (B), day 12 (C), day 22 (D), and re-watering—day 12 (E), day 22 (F). Note the altered distribution of inulin (*), mainly after 22 days of water suppression (D), and restoration of outermost tissues (arrows) after re-watering (E,F). Details: (A) Cluster of inulin globules. (B) Isolated inulin globules. C, cortex; P, pith; VB, vascular bundle.

Mentions: Structural analyses of the rhizophores (Figures 3, 4, 5) highlighted changes in plants subjected to water suppression and re-watering in relation to those daily watered (Figure 2). Rhizophores wilted in WS plants and recovered the initial morphological aspect after re-watering (Figures 2C,D,E,F). Structurally, rhizophores of control plants showed intact organization (Figure 3A) and the beginning of anatomical changes were visualized in WS plants collected at day 10 (Figure 3B), followed by progressive flatness of outermost tissues of the organ (Figures 3C,D) and structure restoration after re-watering (Figures 3E,F). Rhizophores of plants collected at day zero (control) presented a uniseriate epidermis with stomata and glandular and non-glandular trichomes. Sclereids were observed among the parenchymatic cells of the cortex. The endodermal cells were larger than the other cells of the cortical parenchyma. Vascular tissues are organized in bundles and the parenchymatic pith occupies the center of the rhizophore (Figure 3A). Rhizophores collected at 12 and 22 days from plants re-watered at day 10 (Figures 3E,F) showed anatomical characteristics similar to those of control plants (Figure 3A). Gradual changes in the structure of rhizophores were observed in plants undergoing 10, 12, and 22 days of water suppression (Figures 3B,C,D). At day 10, the cell walls of the epidermis, cortex and vascular tissues became sinuous, promoting cell flatness (Figure 3B). At day 12, this flatness was more evident since cell collapsing reached the outer layers of the pith (Figure 3C). At day 22 of WS, the epidermis, the cortex and the vascular tissues were completely collapsed, and the innermost cells of the pith featured sinuous walls (Figure 3D). The collapse of tissues from the outermost to the innermost region of the organ reduced tissues storing inulin sphaero-crystals (Figures 4C,D, 5C,D) which were restored after re-watering (Figures 4E,F, 5E,F). Inulin sphero-crystals were observed in the parenchyma cells of the cortex, vascular tissues and pith in control plants (Figures 4A, 5A), in WS plants after 10 days (Figures 4B, 5B), and in RW plants collected at 12 and 22 days after re-watering at day 10 (Figures 4E,F, 5E,F). Only rhizophores of WS plants showed a structurally compressed cortex at days 12 and 22 after water suppression, and a reduced amount of inulin sphero-crystals in this region (Figures 4C,D, 5C,D).


Structural and metabolic changes in rhizophores of the Cerrado species Chrysolaena obovata (Less.) Dematt. as influenced by drought and re-watering.

Garcia PM, Hayashi AH, Silva EA, Figueiredo-Ribeiro Rde C, Carvalho MA - Front Plant Sci (2015)

Scanning electron microscopy from rhizophores of Chrysolaena obovata submitted to daily watering—control (A), water suppression—day 10 (B), day 12 (C), day 22 (D), and re-watering—day 12 (E), day 22 (F). Note the altered distribution of inulin (*), mainly after 22 days of water suppression (D), and restoration of outermost tissues (arrows) after re-watering (E,F). Details: (A) Cluster of inulin globules. (B) Isolated inulin globules. C, cortex; P, pith; VB, vascular bundle.
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Related In: Results  -  Collection

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Figure 5: Scanning electron microscopy from rhizophores of Chrysolaena obovata submitted to daily watering—control (A), water suppression—day 10 (B), day 12 (C), day 22 (D), and re-watering—day 12 (E), day 22 (F). Note the altered distribution of inulin (*), mainly after 22 days of water suppression (D), and restoration of outermost tissues (arrows) after re-watering (E,F). Details: (A) Cluster of inulin globules. (B) Isolated inulin globules. C, cortex; P, pith; VB, vascular bundle.
Mentions: Structural analyses of the rhizophores (Figures 3, 4, 5) highlighted changes in plants subjected to water suppression and re-watering in relation to those daily watered (Figure 2). Rhizophores wilted in WS plants and recovered the initial morphological aspect after re-watering (Figures 2C,D,E,F). Structurally, rhizophores of control plants showed intact organization (Figure 3A) and the beginning of anatomical changes were visualized in WS plants collected at day 10 (Figure 3B), followed by progressive flatness of outermost tissues of the organ (Figures 3C,D) and structure restoration after re-watering (Figures 3E,F). Rhizophores of plants collected at day zero (control) presented a uniseriate epidermis with stomata and glandular and non-glandular trichomes. Sclereids were observed among the parenchymatic cells of the cortex. The endodermal cells were larger than the other cells of the cortical parenchyma. Vascular tissues are organized in bundles and the parenchymatic pith occupies the center of the rhizophore (Figure 3A). Rhizophores collected at 12 and 22 days from plants re-watered at day 10 (Figures 3E,F) showed anatomical characteristics similar to those of control plants (Figure 3A). Gradual changes in the structure of rhizophores were observed in plants undergoing 10, 12, and 22 days of water suppression (Figures 3B,C,D). At day 10, the cell walls of the epidermis, cortex and vascular tissues became sinuous, promoting cell flatness (Figure 3B). At day 12, this flatness was more evident since cell collapsing reached the outer layers of the pith (Figure 3C). At day 22 of WS, the epidermis, the cortex and the vascular tissues were completely collapsed, and the innermost cells of the pith featured sinuous walls (Figure 3D). The collapse of tissues from the outermost to the innermost region of the organ reduced tissues storing inulin sphaero-crystals (Figures 4C,D, 5C,D) which were restored after re-watering (Figures 4E,F, 5E,F). Inulin sphero-crystals were observed in the parenchyma cells of the cortex, vascular tissues and pith in control plants (Figures 4A, 5A), in WS plants after 10 days (Figures 4B, 5B), and in RW plants collected at 12 and 22 days after re-watering at day 10 (Figures 4E,F, 5E,F). Only rhizophores of WS plants showed a structurally compressed cortex at days 12 and 22 after water suppression, and a reduced amount of inulin sphero-crystals in this region (Figures 4C,D, 5C,D).

Bottom Line: Inulin sphero-crystals accumulated in parenchymatic cells of the cortex, vascular tissues and pith were reduced under drought and accompanied anatomical changes, starting from day 10.At 22 days of drought, the cortical and vascular tissues were collapsed, and inulin sphero-crystals and inulin content were reduced.The localization of inulin sphero-crystals in vascular tissues of C. obovata, as well as the decrease of total inulin and the increase in oligo:polysaccharide ratio in water stressed plants is consistent with the role of fructans in protecting plants against drought.

View Article: PubMed Central - PubMed

Affiliation: Núcleo de Pesquisa em Fisiologia e Bioquímica, Instituto de Botânica São Paulo, Brazil ; Programa de Pós-Graduação em Biodiversidade Vegetal e Meio Ambiente, Instituto de Botânica São Paulo, Brazil.

ABSTRACT
The high fructan contents in underground organs of Cerrado species, high water solubility, and fast metabolism of these compounds highlight their role as carbon storage and as an adaptive feature in plants under drought. In this study, we showed that anatomical structure, in association with soluble compounds and metabolism of inulin-type fructans were modified in rhizophores of Crysolaena obovata submitted to water suppression and recovery after re-watering. Plants were subjected to daily watering (control), suppression of watering for 22 days (water suppression) and suppression of watering followed by re-watering after 10 days (re-watered). Plants were collected at time 0 and after 3, 7, 10, 12, 17, and 22 days of treatment. In addition to changes in fructan metabolism, high proline content was detected in drought stressed plants, contributing to osmoregulation and recovery after water status reestablishment. Under water suppression, total inulin was reduced from approx. 60 to 40%, mainly due to exohydrolase activity. Concurrently, the activity of fructosyltransferases promoted the production of short chain inulin, which could contribute to the increase in osmotic potential. After re-watering, most parameters analyzed were similar to those of control plants, indicating the resumption of regular metabolism, after water absorption. Inulin sphero-crystals accumulated in parenchymatic cells of the cortex, vascular tissues and pith were reduced under drought and accompanied anatomical changes, starting from day 10. At 22 days of drought, the cortical and vascular tissues were collapsed, and inulin sphero-crystals and inulin content were reduced. The localization of inulin sphero-crystals in vascular tissues of C. obovata, as well as the decrease of total inulin and the increase in oligo:polysaccharide ratio in water stressed plants is consistent with the role of fructans in protecting plants against drought.

No MeSH data available.


Related in: MedlinePlus