Composition and susceptibility to rumen microbial degradation of nonmesophyll cell walls isolated from Caucasian bluestem [Bothriochloa caucasica (Trin)] leaf tissue

1991 ◽  
Vol 39 (3) ◽  
pp. 473-477 ◽  
Author(s):  
Edward J. Piwonka ◽  
Jennifer W. MacAdam ◽  
Monty S. Kerley ◽  
John A. Paterson
Keyword(s):  
Microbial Degradation ◽  
Cell Walls ◽  
Leaf Tissue

A freeze-etch study of plant cell walls for ectodesmata

1974 ◽  
Vol 52 (9) ◽  
pp. 2033-2036 ◽  
Author(s):  
N. C. Lyon ◽  
W. C. Mueller
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Leaf Tissue ◽  
Physicochemical Characteristics ◽  
Outer Cell ◽  
Plantago Major ◽  
Plant Cell Walls ◽  
Phaseolus Vulgaris L ◽  
Epidermal Cell Wall ◽  
Outer Cell Wall

Leaf tissue of Phaseolus vulgaris L. and Plantago major L. was prepared by the freeze-etch technique and examined in the electron microscope for the presence of ectodesmata. No structures analagous to ectodesmata observed with light microscopy could be found in freeze-etched preparations of chemically unfixed material or in material fixed only in glutaraldehyde. Objects appearing as broad, shallow, granular areas in the epidermal cell wall beneath the cuticle were observed in leaf replicas after fixation in complete sublimate fixative, the acid components of the sublimate fixative, or mercuric chloride alone. Because of their distribution and location, these objects can be considered analagous to ectodesmata observed by light microscopists. Because these areas occur only in chemically fixed walls and are localized within the walls in discrete areas, their presence supports the contention that ectodesmata are sites in the outer cell wall with defined physicochemical characteristics.

UV Absorption Microspectrophotometry and Histochemistry of Flax and Kenaf

1998 ◽  
Vol 4 (S2) ◽  
pp. 846-847
Author(s):  
D.E. Akin
Keyword(s):  
Microbial Degradation ◽  
Linum Usitatissimum ◽  
Cell Walls ◽  
Industrial Applications ◽  
Hibiscus Cannabinus ◽  
Fiber Cell ◽  
The Other ◽  
Uv Absorption ◽  
Bast Fibers ◽  
Histochemical Tests

Flax (Linum usitatissimum L.) and kenaf (Hibiscus cannabinus L.) are the sources of fibers used for textiles and other industrial applications. Both flax and kenaf produce fibers in the bast region (Fig. 1, 2) which must be separated from other tissues by retting. Although both flax and kenaf are bast fibers, their properties are vastly different. UV absorption microspectrophotometry and histochemistry elucidate their chemistry and structure related to enzymatic retting.Aromatics such as lignins are produced by plants for protection and strength, but their presence inhibits microbial degradation, which is necessary in retting. Histochemical tests indicated variations in the site and type of aromatics within these two plants (1,2). In flax, acid phloroglucinol but not chlorine-sulfite gave positive reactions occasionally in fiber cell walls in the bast. The other cell walls in the bast did not contain aromatics by these tests, although aromatics occurred in the cuticle.

Photosynthetic Acclimation of Alocasia macrorrhiza (L.) G. Don

1988 ◽  
Vol 15 (2) ◽  
pp. 107 ◽  
Author(s):  
WS Chow ◽  
L Qian ◽  
DJ Goodchild ◽  
JM Anderson
Keyword(s):  
Charge Density ◽  
Leaf Area ◽  
Cell Walls ◽  
Surface Charge Density ◽  
Leaf Tissue ◽  
O2 Evolution ◽  
Palisade Cell ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Growth Irradiance

The photosynthetic acclimation of Alocasia macrorrhiza (L.) G. Don, a species naturally occurring in deep shade in rainforests, has been studied in relation to a wide range of controlled irradiances during growth (~3-780 �mol photons m-2 s-1 of fluorescent or incandescent light, 10 h light/ 14 h dark). At the maximum growth irradiances, the light- and CO2-saturated rates of O2 evolution per unit leaf area were ~4 times as high as at low irradiance, and approached those of glasshouse-grown spinach. Growth at maximum irradiances reduced the quantum yield of O2 evolution only slightly. Changes in the anatomy of leaf tissue, the ultrastructure of chloroplasts and the composition of chloroplast components accompanied the changes in photosynthetic functional characteristics. At low growth irradiance, palisade cell chloroplasts were preferentially located adjacent to the distal periclinal cell walls and had large granal stacks, and the destacked thylakoids had a very low surface charge density. In contrast, at higher growth irradiance, palisade cell chloroplasts were preferentially located adjacent to the anticlinal cell walls; they had small granal stacks, large stromal space, and a high surface charge density on the destacked thylakoids. The number of chloroplasts per unit section length increased with growth irradiance. Ribulosebisphosphate carboxylase activity per unit leaf area increased markedly with irradiance. Photosystem II, cytochrome f and latent ATPase activity per unit chlorophyll increased to a lesser extent. While the chlorophyll a/chlorophyll b ratio increased substantially with growth irradiance, the chlorophyll content per unit leaf area declined slightly. Our results show that coordinated changes in the structure of leaf tissue, and the organisation and composition of chloroplast components are responsible for Alocasia being capable of acclimation to high as well as low irradiance.

CALCIUM RETARDS PHYSIOLOGICAL COLLAPSE AND SUBSEQUENT MICROBIAL DEGRADATION OF MUNG BEAN (Vigna radiata L. Wilczek) SPROUTS

1987 ◽  
Vol 67 (2) ◽  
pp. 537-548 ◽  
Author(s):  
A. LIPTAY ◽  
P. VANDIERENDONCK
Keyword(s):  
Microbial Degradation ◽  
Vigna Radiata ◽  
Mung Bean ◽  
Cell Walls ◽  
Scanning Electron Micrographs ◽  
Hypocotyl Growth ◽  
Mineral Supplement ◽  
Mung Bean Sprouts ◽  
Bean Sprouts ◽  
Scanning Electron

Mung bean (Vigna radiata L. Wilczek) sprouts, when germinated in water with no added calcium, were prone to physiological collapse of the cell walls below the cotyledonary hook. Growth of the collapsing hypocotyls gradually decreased until it stopped completely as the collapsed area extended cross-sectionally. Scanning electron micrographs indicated that extensive microbial degradation of the collapsed area of the low-calcium hypocotyl ensued by day 4 of germination. In contrast, at the same stage of germination, bacteria were essentially absent on sprouts germinated with calcium added to the water either as CaCl2, or Ca(NO3)2. Even by day 7 the calcium-treated hypocotyls remained intact and without any visual microbial degradation although bacteria were present on the surface of the seedlings. It is concluded that mung bean sprouts are very sensitive to physiological collapse with subsequent microbial degradation of the hypocotyl especially at temperatures above 20 °C. Therefore, it is recommended that water used for germinating the sprouts has sufficient calcium added (e.g. 5 × 10−3 M CaCl2) to maintain the integrity of the hypocotyls and reduce the microbial flora on the sprouts.Key words: Hypocotyl, growth, deterioration, mineral supplement

scholarly journals Microscopic Aspects of Silicon-Mediated Rice Resistance to Leaf Scald

2016 ◽  
Vol 106 (2) ◽  
pp. 132-141 ◽  
Author(s):  
Leonardo Araujo ◽  
Rayane Silva Paschoalino ◽  
Fabrício Ávila Rodrigues
Keyword(s):  
Cell Walls ◽  
Leaf Surface ◽  
Leaf Tissue ◽  
Phenylpropanoid Pathway ◽  
Microscopic Level ◽  
High Concentration ◽  
Great Abundance ◽  
Leaf Scald ◽  
X Ray ◽  
Fungal Hyphae

This study investigated the effect of silicon (Si) on the potentiation of rice resistance against leaf scald at the microscopic level. Rice plants (‘Primavera’) were grown in a nutrient solution containing 0 (−Si) or 2 mM (+Si) Si. The foliar Si concentration of the +Si plants (3.6 dag/kg) increased in comparison with the −Si plants (0.3 dag/kg). An X-ray microanalysis revealed that the leaf tissue of +Si plants infected with Microdochium oryzae had higher peaks and deposition of insoluble Si than that of −Si plants. The high foliar Si concentration for the +Si plants reduced the expansion of leaf scald lesions. Scanning electron microscopy revealed that fungal hyphae and appressorium-like structures of M. oryzae were more abundant in the leaf surface of −Si plants relative to +Si plants. At both histopathological and ultrastructural levels, fungal hyphae grew abundantly into the leaf tissue of −Si plants. By contrast, rice cell walls were rarely degraded and fungal hyphae were often surrounded by amorphous granular material in the leaf tissue of +Si plants. Conidiophores emerged from stomata 36 h after fungal penetration, and conidia were noticed inside the leaf tissue of the −Si plants in great abundance. The collective results of the present study showed a high concentration and deposition of Si and a considerable deposition of phenolic-like compounds in the leaf tissue of +Si plants. These results indicate that the potentiation of the phenylpropanoid pathway in these plants supplied with Si was favorable for the increase in rice resistance to leaf scald.

Physiological mechanisms of tolerance to high boron concentration in Brassica rapa

2006 ◽  
Vol 33 (10) ◽  
pp. 973 ◽  
Author(s):  
Sukhjiwan Kaur ◽  
Marc E. Nicolas ◽  
Rebecca Ford ◽  
Robert M. Norton ◽  
Paul W. J. Taylor
Keyword(s):  
Brassica Rapa ◽  
Cell Walls ◽  
Boron Concentration ◽  
Leaf Tissue ◽  
Boron Uptake ◽  
Tolerance Mechanism ◽  
Physiological Mechanisms ◽  
Boron Tolerance ◽  
High Boron ◽  
Sensitive Genotype

Tolerance to high boron concentration in Brassica rapa was primarily due to low net boron uptake by the roots. However, in the two tolerant genotypes, 39–43% of boron uptake was retained in the tap roots, which limited boron accumulation in the leaves, and also contributed to boron tolerance. In the sensitive genotype, 99% of the increase in boron uptake caused by high soil boron accumulated in the leaves, particularly in the leaf margins. Despite higher transpiration rates, lower net boron uptake occurred in the tolerant genotypes. This result cannot be explained by passive boron uptake alone. Active boron efflux was probably responsible for differences in net boron uptake among tolerant and sensitive genotypes. Boron concentration was much lower in the cell walls than in the cell sap of leaves, indicating that storage of boron in the cell walls was not a tolerance mechanism. Despite high boron concentrations in the leaf symplasm, rates of photosynthesis, transpiration and growth were almost unaffected in the tolerant genotypes. The results demonstrate that boron tolerance in Brassica rapa involves boron exclusion at the root level, boron partitioning away from leaves and, as boron accumulates in leaves despite the first two mechanisms, boron tolerance of the leaf tissue itself.

scholarly journals Characterization of SNP1, a Cell Wall-Degrading Trypsin, Produced During Infection by Stagonospora nodorum

2000 ◽  
Vol 13 (5) ◽  
pp. 538-550 ◽  
Author(s):  
A. J. Carlile ◽  
L. V. Bindschedler ◽  
A. M. Bailey ◽  
P. Bowyer ◽  
J. M. Clarkson ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Cell Walls ◽  
Fluorescent Protein ◽  
Sodium Dodecyl ◽  
Leaf Tissue ◽  
Pcr Primers ◽  
Exchange Chromatography ◽  
Infected Leaf ◽  
In Planta ◽  
Ph Optimum

Stagonospora (= Septoria) nodorum when grown in liquid culture with wheat cell walls as the sole carbon and nitrogen source secretes numerous extracellular depoly-merases, including a rapidly produced, alkaline, trypsin-like protease (SNP1). The enzyme was purified 417-fold by cation exchange chromatography and has a molecular mass of 25 kDa on sodium dodecyl sulfate gels, pI 8.7, and pH optimum of 8.5. It cleaved peptide bonds on the carboxyl side of lysine or arginine, was strongly inhibited by the trypsin inhibitors aprotinin and leupeptin and weakly by phenylmethylsulfonyl fluoride, and its activity was stimulated by calcium. SNP1 has the characteristic, conserved, fungal, trypsin N terminus. Polymerase chain reaction (PCR) primers based on this sequence and the conserved trypsin active site were used to amplify a DNA fragment that facilitated isolation of the corresponding genomic clone from a lambda library of S. nodorum. The full-length sequence confirmed its identity as a trypsin-like protease containing the N-terminal sequence of the previously purified enzyme. Infected leaf tissue contained a protease, not present in controls, that coeluted with the fungal trypsin from cation exchange, and had properties (pI and inhibitor characteristics) similar to those of the fungal trypsin. SNP1 expression in planta was detected by Northern (RNA) blotting, reverse transcription PCR, and green fluorescent protein confocal microscopy. SNP1 released hydroxyproline from wheat cell walls. The release of hydroxyproline, together with its early expression in planta, suggests that SNP1 participates in the degradation of host cell walls during infection.

In vivo and in sacco digestibility and rumen microbial degradation of cell walls of soyabean and rape integuments and of dehydrated beet pulp in sheep, observed by scanning electron microscopy

1990 ◽  
Vol 115 (3) ◽  
pp. 429-435 ◽  
Author(s):  
E. Grenet ◽  
P. Barry
Keyword(s):  
Microbial Degradation ◽  
Cell Walls ◽  
Cell Layer ◽  
Aleurone Layer ◽  
Palisade Layer ◽  
Cell Layers ◽  
Beet Pulp ◽  
A Cell ◽  
In Sacco

SUMMARYThe in vivo digestibility of soyabean integuments, rape integuments and dehydrated beet pulp was determined in sheep in the Centre de Recherches de Clermont-Ferrand-Theix, in 1985. Organic matter digestibility was 83·5, 59·6 and 85·0%, respectively, for the three feeds. The nylon bag method was used to determine the disappearance of dry matter (DM) in the rumen. After 72 h, 89 and 96% DM had disappeared for soyabean integuments and beet pulp, respectively, but only 61% for rape integuments. The DM disappearance rate was slowest (P < 0·05) for soyabean integuments. Microscopic examination showed that the different layers of the soyabean integument could be ranked in increasing order of resistance to microbial degradation as follows: parenchyma, aleurone layer, column cell layer, palisade layer and epidermis. The hilum area was the most resistant and the only one lignified. The cell layers of the rape integument could be ranked in increasing order of resistance as follows: epidermis, aleurone layer and palisade layer. The last was highly lignified and not degradable. Degradation of beet pulp was fast, occurring first in the parenchyma. The vessels resisted degradation but were only a small part of the feed. This study shows why beet pulp has a low fill value and allows high intake. The soyabean integument is very digestible and is degraded slowly, whereas almost half of the rape integument is made up of a cell layer that is not degradable.

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