Investigating the effect of Glomus etunicatum colonization on structure and phloem transport in roots of Eragrostis curvula (Umgeni)
- Authors: Skinner, Amy
- Date: 2007
- Subjects: Glomus (Fungi) , Phloem , Plant translocation , Weeping lovegrass , Vesicular-arbuscular mycorrhizas , Mycorrhizal fungi , Mycorrhizas
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4227 , http://hdl.handle.net/10962/d1003796 , Glomus (Fungi) , Phloem , Plant translocation , Weeping lovegrass , Vesicular-arbuscular mycorrhizas , Mycorrhizal fungi , Mycorrhizas
- Description: The symbiotic unit of an arbuscular mycorrhizal fungus and its host is able toachieve and maintain far higher inflow of nutrients than non-mycorrhizal roots. The colonization strategy of the mycobiont within the plant is intrinsic to the symbiosis with respect to both structural adaptations and nutrient exchange. An investigation into the effect of Glomus etunicatum colonization on the structure and phloem transport in Eragrostis curvula (Umgeni) allowed for greater insight into the dynamic of the symbiosis. The combined use of stains (such as Trypan Blue, Chlorazol Black, Safranin and Fast Green), and techniques, (such as freeze-microtome transverse sectioning and permanent slide preparations) contributed to a successful general observation of an intermediate colonization strategy using light microscopy methods. However, clarity into structural detail of mycorrhizal forms required electron microscopy studies. The SEM method used with freeze fracture was a relatively quick and simple method allowing for the observation of surface and internal features. The TEM method allowed for highresolution images providing insight into the variations in the apoplasmic compartmental form, and how this may relate to the function of the symbiosis with regard to fungal coils or arbuscules. The apoplasmic nature of mycorrhizas was substantiated and no symplasmic connections were found between symbionts. Fluorescence studies demonstrated that 5,6-carboxyfluorescein was transported through the phloem into the roots of E. curvula, but remained predominantly in the root phloem. Unloading only occurred in optimal nutrient exchange areas of meristimatic lateral or apical growth regions. It was not possible, using fluorescence techniques and related equipment available, to conclusively establish if there were symplasmic connections between the mycobiont and its host or if bidirectional transfer of nutrients occurred at the same interface.
- Full Text:
- Authors: Skinner, Amy
- Date: 2007
- Subjects: Glomus (Fungi) , Phloem , Plant translocation , Weeping lovegrass , Vesicular-arbuscular mycorrhizas , Mycorrhizal fungi , Mycorrhizas
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4227 , http://hdl.handle.net/10962/d1003796 , Glomus (Fungi) , Phloem , Plant translocation , Weeping lovegrass , Vesicular-arbuscular mycorrhizas , Mycorrhizal fungi , Mycorrhizas
- Description: The symbiotic unit of an arbuscular mycorrhizal fungus and its host is able toachieve and maintain far higher inflow of nutrients than non-mycorrhizal roots. The colonization strategy of the mycobiont within the plant is intrinsic to the symbiosis with respect to both structural adaptations and nutrient exchange. An investigation into the effect of Glomus etunicatum colonization on the structure and phloem transport in Eragrostis curvula (Umgeni) allowed for greater insight into the dynamic of the symbiosis. The combined use of stains (such as Trypan Blue, Chlorazol Black, Safranin and Fast Green), and techniques, (such as freeze-microtome transverse sectioning and permanent slide preparations) contributed to a successful general observation of an intermediate colonization strategy using light microscopy methods. However, clarity into structural detail of mycorrhizal forms required electron microscopy studies. The SEM method used with freeze fracture was a relatively quick and simple method allowing for the observation of surface and internal features. The TEM method allowed for highresolution images providing insight into the variations in the apoplasmic compartmental form, and how this may relate to the function of the symbiosis with regard to fungal coils or arbuscules. The apoplasmic nature of mycorrhizas was substantiated and no symplasmic connections were found between symbionts. Fluorescence studies demonstrated that 5,6-carboxyfluorescein was transported through the phloem into the roots of E. curvula, but remained predominantly in the root phloem. Unloading only occurred in optimal nutrient exchange areas of meristimatic lateral or apical growth regions. It was not possible, using fluorescence techniques and related equipment available, to conclusively establish if there were symplasmic connections between the mycobiont and its host or if bidirectional transfer of nutrients occurred at the same interface.
- Full Text:
Observations of selective feeding of the aphid, Sitobion yakini (eastop) on leaf blades of barley (Hordeum vulgare L)
- Authors: Matsiliza, Babalwa
- Date: 2000
- Subjects: Aphids , Phloem , Barley
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4212 , http://hdl.handle.net/10962/d1003781 , Aphids , Phloem , Barley
- Description: Penetration of leaves of barley (Hordeum vulgare L.) plants grown under normal conditions and those exposed to physiological stress, by the aphid, Sitobion yakini was investigated using light and electron microscope techniques. This was carried out to determine if there was evidence of preferential feeding on either thin- or thick-walled sieve tubes in the barley leaf. Under both stress and non-stress conditions, preliminary results of an electron microscope investigation showed that penetration of the epidermis and mesophyll was largely intercellular, becoming partly intercellular and in part intracellular inside the vascular bundle. A total of 317 stylets and stylet tracks were encountered during the examination of 2000 serial sections. In non-stressed plant material, 293 (92%) terminated in thin-walled sieve tubes and only 24 (8%) in thick-walled sieve tubes. Investigation of 1000 serial sections using stressed plant material showed, that 84 of 89 (94%) stylets and stylet tracks encountered terminated in thin-walled sieve tubes. Furthermore, 90 of 94 (96%) stylets and stylet tracks encountered in 1000 serial sections from the second experiment of control non-stressed plant material (control) terminated in thin-walled sieve tubes. The thin-walled sieve tubes were significantly more visited (probed) by the aphid than the thick-walled sieve tubes. Under stress conditions, 50 of 89 (56%) stylets and stylet tracks which terminated in thin-walled sieve tubes were associated with the small longitudinal bundles. Under normal conditions, 65 of 94 (69%) stylets and stylet tracks which terminated in thin-walled sieve tubes were associated with the small longitudinal bundles. There were no significant differences on the number of probes of sieve elements between the two treatments. These data suggest that the aphid S. yakini feeds preferentially on the thin-walled sieve tubes of the small longitudinal vascular bundles in plants grown under normal conditions and those exposed to physiological stress, such as water stress. This further suggests that the thin-walled sieve tubes in barley leaf blades are more attractive to the aphid and are probably most functional in terms of phloem loading and transport.
- Full Text:
- Authors: Matsiliza, Babalwa
- Date: 2000
- Subjects: Aphids , Phloem , Barley
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4212 , http://hdl.handle.net/10962/d1003781 , Aphids , Phloem , Barley
- Description: Penetration of leaves of barley (Hordeum vulgare L.) plants grown under normal conditions and those exposed to physiological stress, by the aphid, Sitobion yakini was investigated using light and electron microscope techniques. This was carried out to determine if there was evidence of preferential feeding on either thin- or thick-walled sieve tubes in the barley leaf. Under both stress and non-stress conditions, preliminary results of an electron microscope investigation showed that penetration of the epidermis and mesophyll was largely intercellular, becoming partly intercellular and in part intracellular inside the vascular bundle. A total of 317 stylets and stylet tracks were encountered during the examination of 2000 serial sections. In non-stressed plant material, 293 (92%) terminated in thin-walled sieve tubes and only 24 (8%) in thick-walled sieve tubes. Investigation of 1000 serial sections using stressed plant material showed, that 84 of 89 (94%) stylets and stylet tracks encountered terminated in thin-walled sieve tubes. Furthermore, 90 of 94 (96%) stylets and stylet tracks encountered in 1000 serial sections from the second experiment of control non-stressed plant material (control) terminated in thin-walled sieve tubes. The thin-walled sieve tubes were significantly more visited (probed) by the aphid than the thick-walled sieve tubes. Under stress conditions, 50 of 89 (56%) stylets and stylet tracks which terminated in thin-walled sieve tubes were associated with the small longitudinal bundles. Under normal conditions, 65 of 94 (69%) stylets and stylet tracks which terminated in thin-walled sieve tubes were associated with the small longitudinal bundles. There were no significant differences on the number of probes of sieve elements between the two treatments. These data suggest that the aphid S. yakini feeds preferentially on the thin-walled sieve tubes of the small longitudinal vascular bundles in plants grown under normal conditions and those exposed to physiological stress, such as water stress. This further suggests that the thin-walled sieve tubes in barley leaf blades are more attractive to the aphid and are probably most functional in terms of phloem loading and transport.
- Full Text:
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