| 1. |
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| 2. |
- Prashant, S., et al.
(författare)
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Down-regulation of Leucaena leucocephala cinnamoyl CoA reductase (LlCCR) gene induces significant changes in phenotype, soluble phenolic pools and lignin in transgenic tobacco
- 2011
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Ingår i: Plant Cell Reports. - : Springer Nature. - 0721-7714 .- 1432-203X. ; 30:12, s. 2215-2231
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Tidskriftsartikel (refereegranskat)abstract
- cDNA and genomic clones of cinnamoyl CoA reductase measuring 1011 and 2992 bp were isolated from a leguminous pulpwood tree Leucaena leucocephala, named as LlCCR. The cDNA exhibited 80–85% homology both at the nucleotide and amino acid levels with other known sequences. The genomic sequence contained five exons and four introns. Sense and antisense constructs of LlCCR were introduced in tobacco plants to up and down-regulate this key enzyme of lignification. The primary transformants showed a good correlation between CCR transcript levels and its activity. Most of the CCR down-regulated lines displayed stunted growth and development, wrinkled leaves and delayed senescence. These lines accumulated unusual phenolics like ferulic and sinapic acids in cell wall. Histochemical staining suggested reduction in aldehyde units and increased syringyl over guaiacyl (S/G) ratio of lignin. Anatomical studies showed thin walled, elongated xylem fibres, collapsed vessels with drastic reduction of secondary xylem. The transmission electron microscopic studies revealed modification of ultrastructure and topochemical distribution of wall polysaccharides and lignin in the xylem fibres. CCR down-regulated lines showed increased thickness of secondary wall layers and poor lignification of S2 and S3 wall layers. The severely down-regulated line AS17 exhibited 24.7% reduction of Klason lignin with an increase of 15% holocellulose content. Contrarily, the CCR up-regulated lines exhibited robust growth, development and significant increase in lignin content. The altered lignin profiles observed in transgenic tobacco lines support a role for CCR down-regulation in improving wood properties of L. leucocephala exclusively used in the pulp and paper industry of India.
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| 3. |
- Kumar, S. Anil, et al.
(författare)
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Beyond just being foot soldiers : osmotin like protein ( OLP ) and chitinase ( Chi11 ) genes act as sentinels to confront salt, drought, and fungal stress tolerance in tomato
- 2016
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Ingår i: Environmental and Experimental Botany. - : Elsevier. - 0098-8472 .- 1873-7307. ; 132, s. 53-65
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Tidskriftsartikel (refereegranskat)abstract
- Osmotin like protein (OLP) and chitinase (Chi11) belong to pathogenesis-related (PR) class of proteins and are induced during both biotic and abiotic stresses. Transgenic tomato was developed with OLP and Chi11 via in vitro and in planta transformation methods. Transgenes integration and transcript levels were confirmed by multiplex PCR, DNA blot, and multiplex reverse transcriptase PCR. Homozygous T2 transgenics when evaluated for salt, drought, and fungal stresses showed enhanced tolerance compared to untransformed controls (UC). Transgenics showed enhanced endochitinase activity and root biomass under normal conditions. Transformants also displayed higher proline content, K+, relative water content, chlorophyll fluorescence, total biomass, vascular conductivity, and fruit yield than the UC under stress conditions. Co-immunoprecipitation revealed that Chi11 co-expresses with phosphofructokinase2 (PFK2), which may play a role in enhanced root biomass. qPCR analysis resulted in higher transcript levels of OLP, Chi11, and PFK2 in transgenics as compared to the untransformed controls. Our findings suggest the use of multiples genes to confer multiple stress tolerance for enhanced crop productivity. This work unveils a new molecular player PFK2, which may play a role in enhanced root biomass.
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| 4. |
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| 5. |
- Sirisha, V. L., et al.
(författare)
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Cloning, characterization and impact of up- and down-regulating subabul cinnamyl alcohol dehydrogenase (CAD) gene on plant growth and lignin profiles in transgenic tobacco
- 2011
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Ingår i: Plant growth regulation (Print). - : Springer Nature. - 0167-6903 .- 1573-5087. ; 66:3, s. 239-253
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Tidskriftsartikel (refereegranskat)abstract
- Both cDNA including 5′UTR and 3′UTR and genomic clones of cinnamyl alcohol dehydrogenase (CAD) were isolated and characterized from a pulp-yielding leguminous tree Leucaena leucocephala (LlCAD1). The deduced amino acid sequence shared high identity with orthologous sequences of Acacia mangium × Acacia auriculiformis (83%), Medicago sativa (83%), Nicotiana tabaccum (83%) and Aralia cordata (81%). Full length cDNA contained 78 bases of 5′UTR and 283 bases of 3′UTR, while the genomic clone contained 5 exons and 4 introns. Western blot analysis revealed elevated expression of LlCAD1 in seedling roots and shoots compared to leaves. Sense and antisense CAD tobacco transgenics showed increased and reduced CAD activity accompanied by a change in monomeric lignin composition. Histochemical staining of lignin in down-regulated plants suggested an increase in aldehyde units and a decrease in S/G ratio. Down-regulation of CAD resulted in accumulation of syringic, ferulic, p-coumaric and sinapic acids compared to untransformed controls. These observations were validated by anatomical studies of down-regulated transgenic stems which showed thin walled, elongated phloem and xylem fibres, accompanied by a reduction in the density of vessel elements and amount of secondary xylem when compared to untransformed plants. Furthermore, Klason lignin analysis of CAD antisense transgenics showed 7–32% reduced lignin and normal phenotype as compared to untransformed plants. Such a reduction was not noticed in up-regulated transgenics. These results demonstrate a unique opportunity to explore the significant role that down-regulation of CAD gene plays in reducing lignin content thereby offering potential benefits to the pulp and paper industry.
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| 6. |
- Chen, J. Y., et al.
(författare)
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High-resolution 3D imaging uncovers organ-specific vascular control of tissue aging
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- Blood vessels provide supportive microenvironments for maintaining tissue functions. Age-associated vascular changes and their relation to tissue aging and pathology are poorly understood. Here, we perform 3D imaging of young and aging vascular beds. Multiple organs in mice and humans demonstrate an age-dependent decline in vessel density and pericyte numbers, while highly remodeling tissues such as skin preserve the vasculature. Vascular attrition precedes the appearance of cellular hallmarks of aging such as senescence. Endothelial VEGFR2 loss-of-function mice demonstrate that vascular perturbations are sufficient to stimulate cellular changes coupled with aging. Age-associated tissue-specific molecular changes in the endothelium drive vascular loss and dictate pericyte to fibroblast differentiation. Lineage tracing of perivascular cells with inducible PDGERB and NG2 Cre mouse lines demonstrated that increased pericyte to fibroblast differentiation distinguishes injury-induced organ fibrosis and zymosan-induced arthritis. To spur further discoveries, we provide a freely available resource with 3D vascular and tissue maps.
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| 7. |
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| 8. |
- Koyani, Rina D., et al.
(författare)
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Anatomical Characterisation and In Vitro Laboratory Decay Test of Different Woods Decayed by Xylaria hypoxylon
- 2017
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Ingår i: Wood is Good. - Singapore : Springer. ; , s. 93-103
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Bokkapitel (refereegranskat)abstract
- Different species of Xylaria are often reported as an endophyte in different groups of plants starting from liverworts to angiosperms. In the present study, Xylaria hypoxylon isolated from branch stubs of living trees was utilised for in vitro decay test to investigate the pattern of cell wall alterations in sound wood blocks of Azadirachta indica, Leucaena leucocephala, and Tectona grandis. Naturally infected as well as in vitro decayed wood showed cavities and erosion troughs at the lumen surface. In laboratory decay test, vertical invasion of mycelia occurred through the lateral wall pits of the vessels and vessel-associated parenchyma while ray cells enabled radial movement of mycelia. At the end of 60 days, the progression of degradation in the fibre cell wall was evident by the formation of transverse boreholes in the cell walls, erosion troughs at the lumen surface, and larger cavities in the S2 layer of secondary wall. The erosion channels were angular to round (i.e. V-shaped or U-shaped). Fungus was also tested for polyphenol oxidase (Bavandemm's test) production by on-plate assay and was found to be positive. Confocal microscopy revealed delignification pattern during degradation of cell wall of different cell types in all the three woody species. The SEM analysis of degraded wood showed the ultrastructural changes in the cell wall particularly penetration of hyphae through the S2 layer of the cell walls forming tunnels through it.
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| 9. |
- Koyani, Rina D., et al.
(författare)
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The Delignification Pattern of Ailanthus excelsaWood by Inonotus hispidus (Bull.: Fr.) P. Karst.
- 2015
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Ingår i: Journal of Sustainable Forestry. - : Informa UK Limited. - 1054-9811 .- 1540-756X. ; 34:5, s. 502-515
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Tidskriftsartikel (refereegranskat)abstract
- AbstractIn vitro laboratory decay tests on Ailanthus excelsa Roxb. wood revealed that I. hispidus exhibits a combination of both white-rot and soft-rot patterns of wood decay. Early stages of wood decay showed dissolution of the middle lamella as well as defibration and localized delignification of fiber walls; vessels, axial, and ray parenchyma remained unaltered. Delignification commenced from the middle lamellae at the cell corners without any marked effect on the primary and secondary wall layers. In later stages of growth, the species produces typical soft-rot decay pattern by forming erosion channels through the S2 layers of fiber walls, transverse bore holes in the cell walls, and erosion channels alongside/following the orientation of cellulose microfibrils. The rays showed signs of cell wall alterations only after the extensive damage to the fiber walls. After 120 days of incubation, the vessels also showed localized delignification, the erosion of pits, and separation from associated xylem elements. The extensive weight losses under natural and in vitro decayed wood as well as the very soft nature of severely degraded wood indicate that I. hispidus alters wood strength and stiffness.
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| 10. |
- Kumari, P. Hima, et al.
(författare)
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Overexpression of a Plasma Membrane Bound Na+/H+ Antiporter-Like Protein (SbNHXLP) Confers Salt Tolerance and Improves Fruit Yield in Tomato by Maintaining Ion Homeostasis
- 2017
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Ingår i: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- A Na+/H+ antiporter-like protein (NHXLP) was isolated from Sorghum bicolor L. (SbNHXLP) and validated by overexpressing in tomato for salt tolerance. Homozygous T2 transgenic lines when evaluated for salt tolerance, accumulated low Na+ and displayed enhanced salt tolerance compared to wild-type plants (WT). This is consistent with the amiloride binding assay of the protein. Transgenics exhibited higher accumulation of proline, K+, Ca2+, improved cambial conductivity, higher PSII, and antioxidative enzyme activities than WT. Fluorescence imaging results revealed lower Na+ and higher Ca2+ levels in transgenic roots. Co-immunoprecipitation experiments demonstrate that SbNHXLP interacts with a Solanum lycopersicum cation proton antiporter protein2 (SlCHX2). qRT-PCR results showed upregulation of SbNHXLP and SlCHX2 upon treatment with 200 mM NaCl and 100 mM potassium nitrate. SlCHX2 is known to be involved in K+ acquisition, and the interaction between these two proteins might help to accumulate more K+ ions, and thus maintain ion homeostasis. These results strongly suggest that plasma membrane bound SbNHXLP involves in Na+ exclusion, maintains ion homeostasis in transgenics in comparison with WT and alleviates NaCl stress.
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| 11. |
- Sivan, Pramod, 1984-, et al.
(författare)
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Anatomy and cell wall chemistry of tension wood in Hibiscus cannabinus
- 2021
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Ingår i: Bosque (Valdivia). - : SciELO Agencia Nacional de Investigacion y Desarrollo (ANID). - 0304-8799 .- 0717-9200. ; 42:1, s. 99-110
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Tidskriftsartikel (refereegranskat)abstract
- Hibiscus cannabinus (kenaf) is well known as a source for textile fibers and as an alternate source for cellulosic fibers for paper and pulp industry. Formation of reaction xylem alters the chemical properties of fibers, which may affect its uses. To the best of our knowledge, there are no reports on the occurrence of reaction xylem in kenaf. The present study examines reaction xylem (i.e. tension wood and its opposite side) formed in response to bending of stems in Kenaf by anatomical, histochemical and biochemical methods. The reaction xylem found on the upper side of leaning stems showed an eccentric growth pattern, thin walls, shorter and wider fibers without gelatinous layer, decrease of vessel or ray density as compared to wood formed on opposite sides. Histochemical localization of lignin using Weisner reaction and Maule’s test indicated presence of more syringyl units in the fiber wall of tension wood. Gravimetric quantification of cell wall polymers showed relatively more amount of holocellulose and hemicellulose in tension wood (69 and 46 %, respectively) compared to those of opposite wood (63 and 42 %, respectively). There was no significant difference noticed in the klason lignin content between opposite (17.4 %) and tension wood (16.7 %). Lignin characterization by the thioacidolysis method revealed that the tension wood lignin in kenaf was composed of more amount of syringyl and p-hydroxyphenyl monomers compared to that of opposite side wood. This analysis also suggests that the tension wood lignin is rich in β-aryl ether linkages in syringyl units resulting in high S/G ratio.
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| 12. |
- Sivan, Pramod, 1984-, et al.
(författare)
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Chemical Composition in Juvenile and Mature Wood of Branch and Main Trunk of Leucaena leucocephala (Lam.) de Wit
- 2023
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Ingår i: PLANTS. - : MDPI AG. - 2223-7747. ; 12:23
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Tidskriftsartikel (refereegranskat)abstract
- Secondary growth is the most dynamic developmental aspect during the terrestrialization of plants. The development of secondary xylem tissue composed of thick-walled cells with characteristic changes in its structure and chemistry facilitates the growth and development of woody plants. In the present study, the chemical composition of the secondary xylem of juvenile and mature wood from the branch and main trunk of Leucaena leucocephala, has been investigated and the differences established. The biochemical analysis of different cell wall components in the mature wood of the main trunk revealed high holocellulose and α-cellulose and less lignin content in the juvenile wood while its syringyl/guaiacyl (S/G) ratio was less than for the mature wood. As compared to the branch xylem, concentration of cell wall polysaccharides and lignin content was higher in both juvenile and mature wood collected from the main trunk. Thioacidolysis and GC-MS analysis of wood lignin from juvenile and mature wood showed that an increased concentration in lignin content in mature wood is associated with a corresponding increase in S/G ratio. The structural information of the acetylated lignin was investigated by 1H NMR spectroscopy. Our results indicate that the mature wood from the main trunk is superior in pulp yielding and lignin degradability as compared to the juvenile wood of the branch and trunk.
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| 13. |
- Sivan, Pramod, 1984-, et al.
(författare)
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Dieback of Gmelina arborea Trees and Structural Alterations Induced in the Wood Cell Walls by Alternaria alternata
- 2022
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Ingår i: FORESTIST. - : AVES YAYINCILIK A.Ş.. - 2602-4039. ; 72:1, s. 2-9
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Tidskriftsartikel (refereegranskat)abstract
- The death and structural alterations in the secondary xylem of Gmelina arborea trees in response to fungal invasion were investigated by light and electron microscopy methods. In vivo experiments indicate that Alternaria alternata is an aggressive pathogen which invades the deeper part of the wood in the branches-up to 4 cm from the site of infection--within 10 days of inoculation. The mycelial invasion occurred through pits and boreholes formed by the fungus in the vessels, fibers, and axial and ray parenchyma cells. Scanning electron microscopy also revealed the colonization of fungus through pit and vessel elements. In vitro studies showed that ray cells and fibers were more prone to cell wall damage in contrast to vessels during the initial stage of infection. The etiology of infection found in the infected samples collected from the living trees and samples of in vivo and in vitro experiments showed similar patterns of infection and confirmed that A. alternata is responsible for the mortality and decay in Gmelina trees. It causes a typical soft-rot pattern with cell wall alterations such as cavity formation by "L" bending. The separation of fibers at the compound middle lamella region indicated that the fungus is capable of degrading both lignin-rich regions of cell walls. The boreholes in the fiber wall also showed distinct variations in size and shape. The penetration of fungal hyphae through the middle lamella and removal of lignin from the cell walls was also confirmed with transmission electron microscopy studies.
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| 14. |
- Sivan, Pramod, 1984-, et al.
(författare)
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Distribution of tension wood like gelatinous fibres in the roots of Acacia nilotica (Lam.) Willd
- 2014
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Ingår i: Planta. - : Springer. - 0032-0935 .- 1432-2048. ; 240:6, s. 1191-1202
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Tidskriftsartikel (refereegranskat)abstract
- The present study was aimed to investigate the anatomy of reaction xylem in the positively gravitropic roots of Acacia nilotica growing in compact and waterlogged soils. The roots collected from the two different sites showed occurrence of gelatinous fibres throughout xylem radii from a distance of 4 cm from the soil surface. The thickness of gelatinous layer (G-layer) increased in the root collected from the deeper soil. Further, the ultrastructural studies revealed a complete replacement of S2 and S3 layers in G-fibres nearer to root tip region as compared to the root portion close to upper part of the soil surface. In addition, these fibres demonstrated intense lignification in compound middle lamellae region of G-fibre walls. Moreover, the vessel density and their width increased considerably near the root tip region. The immunofluorescence analysis suggested that the β-1,4-galactans were prevalent in G-layer, whereas the xylan was restricted to only regions of lignified secondary wall. The similarities in distribution pattern and anatomical features of G-fibres in waterlogged and non-waterlogged roots suggest the occurrence of G-fibres as inherent characteristics in the roots of Acacia nilotica.
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| 15. |
- Sivan, Pramod, 1984-, et al.
(författare)
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Histological and ultrastructural alterations in the Ailanthus excelsa wood cell walls by Bjerkandera adusta (Willd.) P. Karst
- 2015
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier. - 0964-8305 .- 1879-0208. ; 100, s. 124-132
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Tidskriftsartikel (refereegranskat)abstract
- Ailanthus excelsa Roxb. requires less care than other species and thrives in arid and semi-arid regions. Therefore, it becomes an important choice for forestry programs. Young branches of these trees are frequently invaded by the fungus Bjerkandera adusta (Willd.) P. Karst. The main aims of this study were to characterize the wood decay pattern and evaluate the extent of damage caused by the fungus. Infected samples were studied using light microscopy, confocal laser scanning microscopy, transmission electron microscopy, and scanning electron microscopy. Wood of the dead branches became pale white and very soft. In vitro decayed wood showed extensive weight loss of wood blocks (68.6%) at the end of three months. In the xylem, fibres were the most severely affected cell types, whereas wall structure of the axial parenchyma remained virtually unaltered. Unlike axial parenchyma, walls of the ray cells formed several boreholes and finally collapsed in the advanced stage of decay. By contrast, the middle lamella of all the xylem elements remained intact even at the end of three months. In the early stages of infection, vessels appeared to be resistant to the fungal action but they also became eroded at the advanced stage. The degradation pattern showed anatomical characteristics of both the white-rot and soft-rot type of decay. Thinning of walls from the lumen side and appearance of U-notches resembles white-rot decay, while tunnels through the S2 layer of the fibre wall added the characteristics of the soft-rot decay pattern. Extensive weight loss of wood blocks following infection suggests B. adusta is an aggressive wood-degrading fungus.
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| 16. |
- Sivan, Pramod, 1984-, et al.
(författare)
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Immunofluorescence Localization of β-(1-4)-d-Galactan and Xylans in Tension Wood and Normal Wood Fibres of Leucaena leucocephala
- 2017
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Ingår i: Wood is Good. - Singapore : Springer. ; , s. 63-71
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Bokkapitel (refereegranskat)abstract
- The distribution pattern of β-(1-4)-D-galactan and xylans in the fibres of tension wood and normal wood of Leucaena leucocephala was investigated using immunofluorescence microscopy. Light microscopic observation of tension wood fibres revealed that they are characterized by the presence of typical non-lignified, tertiary wall layer. LM-5 labelling of normal fibres showed weak labelling from the cell wall, indicating less concentration of β-(1-4)-D-galactans or masking effect due to co-polymerization of other polymers. Both less substituted (LM-10) and highly substituted (LM-11) xylans found to be distributed more in the secondary wall region, while compound middle lamella showed weak labelling. In tension wood fibres, LM-5 labelling revealed strong signals from tertiary wall layer, indicating that gelatinous layer contains more amount of β-(1-4)-D-galactans. The lignified secondary wall and compound middle lamellae showed weak labelling with LM-5. Labelling of xylans with LM-10 showed intense fluorescence signals from the lignified secondary wall, while gelatinous layer showed weak labelling, indicating less concentration of xylans in the gelatinous layer. In conclusion, in addition to the generalized concept that the G-layer in tension wood fibre is rich in cellulose, our results showed that constitution of pectins and xylans is also different compared to the secondary wall of normal wood fibres.
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| 17. |
- Sivan, Pramod, 1984-, et al.
(författare)
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Immunolocalization of β-(1–4)-D-galactan, xyloglucans and xylans in the reaction xylem fibres of Leucaena leucocephala (Lam.) de Wit
- 2019
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Ingår i: Plant physiology and biochemistry (Paris). - : Elsevier. - 0981-9428 .- 1873-2690. ; 142, s. 217-223
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Tidskriftsartikel (refereegranskat)abstract
- Cell wall architecture of tension wood fibres represents a suitable biological system to study the mechanism of growth and maintenance of posture of trees growing under various physical and physiological growth constraints. In the present study, we investigated the spatial distributions of β-(1–4)-D-galactan, xyloglucan and xylans (both less and highly substituted) in the opposite and tension wood fibres of bent Leucaena leucocephala by immunolabelling with monoclonal antibodies LM5, CCRCM1, LM10 and LM11 specific to these carbohydrate epitopes. The presence of non-lignified, tertiary wall layer is the typical tension wood characteristic associated with the reaction xylem fibres in Leucaena. LM5 labelling of opposite fibres showed weak labelling in the cell walls indicating less concentration of β-(1–4)-D-galactans while tension wood showed strong labelling in the tertiary wall layer suggesting the gelatinous layer (G-layer) has a strong cross linking with β-(1–4)-D-galactans. Xyloglucan distribution was more in the compound middle lamellae and the primary wall-S1 layer boundary of tension wood fibres as compared to that of opposite wood. A weak labelling was also evident near the boundary between the G-layer and the secondary wall of tension wood fibres. The secondary wall of opposite and tension wood fibres showed a strong distribution of both ls ACG Xs (LM10) and hs ACG Xs (LM11) while a weak labelling was noticed in the compound middle lamella. Tension wood fibres also showed strong xylan labelling mainly confined to the lignified secondary walls while the G-layer showed weak xylan labelling. In conclusion, our results suggest that β-(1–4)-D-galactans and xyloglucans could be implicated in the tensile stress generation within the G-layer of tension wood fibres of Leucaena leucocephala.
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| 18. |
- Bhatt, Isha M, et al.
(författare)
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Anatomical changes in the cell-wall structure of Leucaena leucocephala(Lam.) de Wit as caused by the decay fungi Trametes versicolorandTrametes hirsuta
- 2015
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Ingår i: Southern Forests, a journal of forest science. - : National Inquiry Services Center (NISC). - 2070-2620 .- 2070-2639. ; 77:4, s. 297-303
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Tidskriftsartikel (refereegranskat)abstract
- The structural changes in the cell wall and delignification pattern caused by Trametes versicolor and Trametes hirsuta in the sap wood of Leucaena leucocephala were examined by light and confocal laser scanning microscopy. The in vitro decay test was conducted for 12 weeks. Both species of Trametes used in this study caused anatomical characteristics specific to simultaneous white rot. Formation of boreholes, erosion troughs, erosion channels with U-shaped notches in tangential sections and thinning of cell walls were evident in the wood inoculated with each of the fungal species. Cell separation due to removal of middle lamellae occurred at the early stages of infection (30 d) with T. versicolor. In contrast, middle lamellae remained intact in wood inoculated with T. hirsuta and showed cell separation due to degradation of the outer layer of the secondary wall and degradation of the middle lamellae observed only in severely decayed wood at late stages. Confocal microscopy revealed the delignification pattern particularly from cell corners and vessel walls at an advanced stage of decay, indicating strong ligninolytic activity of both species in the sapwood of L. leucocephala.
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| 19. |
- Bhatt, I.M., et al.
(författare)
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Anatomical characterization of Eucalyptus globulus wood decay by two white rot species of Trametes
- 2016
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Ingår i: Journal of plant pathology. - : Springer. - 1125-4653 .- 2239-7264. ; 98:2, s. 227-234
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Tidskriftsartikel (refereegranskat)abstract
- Application of ligninolytic enzymes in paper and pulp industry has opened a new avenue to overcome the problems associated with mechanical and chemical pulping. The present study was therefore aimed to investigate the anatomical alterations in the cell wall of eucalyptus sap wood inoculated with Trametes hirsuta (Fr.) Pilat and T. versicolor (Fr.) Pilat. T. hirsuta caused cell separation, formation of oval shaped cavities rich in cellulosic polysaccharides and pit erosion during early stages of decay, suggesting selective delignification pattern. However, degradation of carbohydrate components resulting in large void areas was detected during advanced stages of decay. Thinning of cell wall was detected in the fibres of wood blocks colonized by T. versicolor, indicating simultaneous white rot decay. The degradation occurred preferentially to the middle layers of secondary wall, while compound middle lamellae and S₃ layer resisted degradation during early stages of decay. Confocal microscopy revealed strong delignification from vessel wall and separation of fibres following delignification of compound middle lamellae. The degradation of lignin rich vessel wall during advanced stages of decay by both species suggests their strong ligninolytic properties suitable for its use in paper and pulp industry.
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| 20. |
- Bhatt, Isha M., et al.
(författare)
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Histological changes in the cell wall structure during wood decay by Trametes hirsuta and Trametes versicolor in neem (Azadirachta Indica A. Juss)
- 2016
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Ingår i: Journal of Sustainable Forestry. - : Informa UK Limited. - 1054-9811 .- 1540-756X. ; 35:8, s. 578-590
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Tidskriftsartikel (refereegranskat)abstract
- Structural alterations in the wood cell walls of neem inoculated with by Trametes hirsuta and T. versicolor were studied by microscopic methods. In vitro decayed wood showed extensive weight loss of test blocks (26.7 and 41.38% by T. versicolor and T. hirsuta, respectively) at the end of 3 months. Selective delignification in the initial phase followed by simultaneous removal of lignin was evident in test blocks inoculated with both the species. The separation of middle lamellae and patches of cellulosic polysaccharides stained blue with Astra blue in the delignified region of the fiber wall during early stages indicates selective mode of decay. In contrast, the occurrence of erosion troughs with characteristic U-notch in tangential sections is a characteristic feature of simultaneous rot that was apparent after 3 months of incubation. The decay pattern occurred concomitantly in all the xylem elements irrespective of general resistance pattern shown by vessel and axial parenchyma cells. At an advance stage, both species of Trametes showed formation of erosion channels along the microfibrils angle of cellulose which is considered as characteristics of soft rot decay type. The sharing of white rot and soft rot decay pattern by both the fungi suggest a phylogenetic link between both groups of fungi.
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| 21. |
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| 22. |
- Karumanchi, Appa Rao, et al.
(författare)
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Root and Leaf Anatomy, Ion Accumulation, and Transcriptome Pattern under Salt Stress Conditions in Contrasting Genotypes of Sorghum bicolor
- 2023
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Ingår i: PLANTS. - : MDPI AG. - 2223-7747. ; 12:13
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Tidskriftsartikel (refereegranskat)abstract
- Roots from salt-susceptible ICSR-56 (SS) sorghum plants display metaxylem elements with thin cell walls and large diameter. On the other hand, roots with thick, lignified cell walls in the hypodermis and endodermis were noticed in salt-tolerant CSV-15 (ST) sorghum plants. The secondary wall thickness and number of lignified cells in the hypodermis have increased with the treatment of sodium chloride stress to the plants (STN). Lignin distribution in the secondary cell wall of sclerenchymatous cells beneath the lower epidermis was higher in ST leaves compared to the SS genotype. Casparian thickenings with homogenous lignin distribution were observed in STN roots, but inhomogeneous distribution was evident in SS seedlings treated with sodium chloride (SSN). Higher accumulation of K+ and lower Na+ levels were noticed in ST compared to the SS genotype. To identify the differentially expressed genes among SS and ST genotypes, transcriptomic analysis was carried out. Both the genotypes were exposed to 200 mM sodium chloride stress for 24 h and used for analysis. We obtained 70 and 162 differentially expressed genes (DEGs) exclusive to SS and SSN and 112 and 26 DEGs exclusive to ST and STN, respectively. Kyoto Encyclopaedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analysis unlocked the changes in metabolic pathways in response to salt stress. qRT-PCR was performed to validate 20 DEGs in each SSN and STN sample, which confirms the transcriptomic results. These results surmise that anatomical changes and higher K+/Na+ ratios are essential for mitigating salt stress in sorghum apart from the genes that are differentially up- and downregulated in contrasting genotypes.
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| 23. |
- Mishra, Preeti, et al.
(författare)
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Effect of exogenous growth regulators on secondary vascular tissue differentiation in the twigs of Kigelia africana
- 2013
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Ingår i: Phyton - Annales Rei Botanicae. - Horn, Austria : Verlag Berger. - 0079-2047. ; 53:1, s. 133-149
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Tidskriftsartikel (refereegranskat)abstract
- The effect of gibberellic acid (GA), naphthalene acetic acid (NAA) and ethephon on dormant and actively growing twigs of was studied by histological and histochemical staining methods. Application of GA and ethephon alone on dormant twigs did not initiate cambial cell division and differentiation, while application of NAA lead to cambial cell division but failed to differentiate cells towards xylem and phloem. Application of GA together with NAA and the combination of GA, NAA and ethephon induced rapid cambial cell division and differentiation of xylem and phloem elements. In the upper portion of twigs close to the point of GA, NAA and ethephon application the cell walls of cambium and phloem elements underwent lignification, while formation of earlywood and latewood was observed in the lower portion. Moreover the application of this hormone combination on actively growing twigs resulted in the formation of tyloses in vessels and differentiation of parenchyma cells with intercellular spaces towards phloem. The combination of GA-NAA promoted rapid cambial cell division and differentiation towards xylem. Maule’s reaction revealed increase in ‘S’ type of lignin in the walls of newly formed vessels and associated parenchyma cells following GA+NAA treatment.
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- Patel, Vinay, et al.
(författare)
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Development of vascular cambium in the leaf rachis of Kigelia Africana (Lam.) Benth
- 2010
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Ingår i: PRAJÑĀ - Journal of Pure and Applied Sciences. - Gujarat, India : Sardar Patel University. - 0975-2595. ; 18:1-4, s. 40-43
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Tidskriftsartikel (refereegranskat)abstract
- The structural changes during the vascular cambium development from procambium in the leaf rachis of Kigelia africana bearing leaflets of different developmental stages (young, mature and old rachis) were investigated. The different regions from the internodes of rachis bearing young, copper brown coloured leaves revealed the sequential stages of cambial development. Terminal region of the rachis showed developing procambium along with protoxylem and protopholem derivatives, middle regions exhibited the development of interfascicular cambium whereas basal region showed complete ring of vascular cambium with secondary phloem derivatives. Rachis bearing brownish coloured leaflets showed an active cambium with both secondary xylem and phloem derivatives indicating bidirectional cambial growth. Rachis with fully matured dark green leaflets was characterized by the presence of dormant cambium surrounded by mature xylem and phloem elements and occurrence of calcium oxalate crystals in the phloem parenchyma cells. The study also describes the pattern of vascular cambial development in the leaf rachis of Kigelia, a deciduous tree and it was compared with development of vascular cambium in the leaves of conifers and evergreen dicotyledons. Influence of leaf maturity on cambial activity and secondary xylem development is discussed.
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