Ted Botha
Rhodes University, Botany, Emeritus
- Professor Emeritus, Botany, Rhodes Universityedit
This indispensable textbook provides a comprehensive, up-to-date overview of all aspects of plant anatomy. * Emphasizes the application of plant anatomy and its relevance to modern botanical research. * Features expanded... more
This indispensable textbook provides a comprehensive, up-to-date overview of all aspects of plant anatomy.
* Emphasizes the application of plant anatomy and its relevance to modern botanical research.
* Features expanded treatment on vegetative anatomy and additional material on functional anatomy.
* Includes a CD ROM of high quality photographs and scanning electron microscope images giving students access to the microscopic detail of plant structures essential to gaining a real understanding of the subject.
* Exercises for the laboratory are also included on the CD ROM making this work an indispensable resource for lectures and laboratory classes.
“The book is very attractively priced, benefits from many excellent colour images and extra material on the enclosed CD, and takes a practical hands-on approach that will win many friends. Plant anatomy: an applied approach deserves to do well!” (Annals of Botany, 2008)
A Network version of the Virtual Plant CD-ROM that accompanies the book is available for separate purchase.
* Emphasizes the application of plant anatomy and its relevance to modern botanical research.
* Features expanded treatment on vegetative anatomy and additional material on functional anatomy.
* Includes a CD ROM of high quality photographs and scanning electron microscope images giving students access to the microscopic detail of plant structures essential to gaining a real understanding of the subject.
* Exercises for the laboratory are also included on the CD ROM making this work an indispensable resource for lectures and laboratory classes.
“The book is very attractively priced, benefits from many excellent colour images and extra material on the enclosed CD, and takes a practical hands-on approach that will win many friends. Plant anatomy: an applied approach deserves to do well!” (Annals of Botany, 2008)
A Network version of the Virtual Plant CD-ROM that accompanies the book is available for separate purchase.
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There is a large body of information relating to the ontogeny, development and the vasculature of eudicotyledonous leaves. However, there is less information available concerning the vascular anatomy of monocotyledonous leaves. This is... more
There is a large body of information relating to the ontogeny, development and the vasculature of eudicotyledonous leaves. However, there is less information available concerning the vascular anatomy of monocotyledonous leaves. This is surprising, given that there are two uniquely different phloem systems present in large groups such as grasses and sedges. Monocotyledonous leaves contain marginal, large, intermediate, and small longitudinal veins that are interconnected by numerous transverse veins. The longitudinal veins contain two metaphloem sieve tube types, which, based upon their ontogeny and position within the phloem, are termed early (thin-walled) and late (thick-walled) sieve tubes. Early metaphloem comprises sieve tubes, companion cells and vascular parenchyma (VP) cells, whilst the late metaphloem, contains thick-walled sieve tubes (TSTs) that lack companion cells. TSTs are generally adjacent to, or no more than one cell removed from the metaxylem. Unlike thin-walled sie...
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Research Interests: Plant Biology and Ecology
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ABSTRACT We investigated the comparative effects of the feeding damage caused by two Russian wheat aphid (RWA, Diuraphis noxia Kurdjumov) biotypes, RWASA1 and RWASA2, on leaves of three RWA-resistant barley (Hordeum vulgare L.) lines from... more
ABSTRACT We investigated the comparative effects of the feeding damage caused by two Russian wheat aphid (RWA, Diuraphis noxia Kurdjumov) biotypes, RWASA1 and RWASA2, on leaves of three RWA-resistant barley (Hordeum vulgare L.) lines from the USDA-ARS, and used a South African non-resistant cultivar as control. The relationship between aphid breeding capacity and the structural damage inflicted by the aphids was studied, using wide-field fluorescence and transmission electron microscopy (TEM). Colonies of the two biotypes grew rapidly on all four barley lines during a 10day feeding exposure but as expected, population size and density were generally lower on the resistant lines than on the non-resistant cultivar. The new South African biotype, RWASA2, bred significantly faster than the original RWASA1 biotype. The feeding and water uptake-related damage sustained by phloem and xylem tissues of the resistant lines suggest that RWASA2 was a more aggressive feeder and caused substantially more cell damage than RWASA1. Examination of wound callose distribution after aphid feeding revealed that high levels of wound callose occurred in non-resistant and in resistant lines. Reduction in aphid population size, as well as ultrastructural damage during feeding by RWA biotypes on resistant lines, signals potential antibiotic and tolerant responses of the barley lines to aphid feeding. We infer from callose distribution and ultrastructural studies, that phloem transport would be substantially reduced in the non-resistant PUMA and to a lesser extent in the resistant STARS lines, which suggests that the STARS lines may be a potential source of RWASA1 and RWASA2-resistance.
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Summary Two free-space marker procedures (Prussian blue and lanthanum nitrate) were employed to determine the pathway(s) followed by water and solutes in the transpiration stream after their introduction into the xylem of small and... more
Summary Two free-space marker procedures (Prussian blue and lanthanum nitrate) were employed to determine the pathway(s) followed by water and solutes in the transpiration stream after their introduction into the xylem of small and intermediate bundles, and the effectiveness of the suberin lamellae of the bundle-sheath cells as a barrier to the movement of tracer ions (Fe3+ and La3+). Judged
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Summary Penetration of the stems and leaves ofGomphocarpus physocarpus (E.Mey) by the aphid,Aphis nerii (B. de F.) was studied with light and phase microscopes. Penetration of the epidermis and ground tissues was largely intercellular,... more
Summary Penetration of the stems and leaves ofGomphocarpus physocarpus (E.Mey) by the aphid,Aphis nerii (B. de F.) was studied with light and phase microscopes. Penetration of the epidermis and ground tissues was largely intercellular, that of the phloem tissues partly intercellular and in part intracellular. In the large majority of penetrations the external phloem was bypassed, the stylet tracks terminating in the sieve tubes of the internal phloem. Of 75 pairs of stylet tips encountered in presumably functional sieve tubes 73 were lodged in sieve tubes of the internal phloem. This confirms observations of a preliminary study which indicated thatA. nerii feeds preferentially on sieve tubes of the internal phloem. A satisfactory explanation of this preferential feeding has yet to be provided.
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Large, intermediate, and small bundles and contiguous tissues of the leaf blade of Hordeum tvulgare L. ‘Morex’ were examined with the transmission electron microscope to determine their cellular composition and the distribution and... more
Large, intermediate, and small bundles and contiguous tissues of the leaf blade of Hordeum tvulgare L. ‘Morex’ were examined with the transmission electron microscope to determine their cellular composition and the distribution and frequency of the plasmodesmata between the various cell combinations. Plasmodesmata are abundant at the mesophyll/parenchymatous bundle sheath, parenchymatous bundle sheath/mestome sheath, and mestome sheath/vascular parenchyma cell interfaces. Within the bundles, plasmodesmata are also abundant between vascular parenchyma cells, which occupy most of the interface between the sieve tube-companion cell complexes and the mestome sheath. Other vascular parenchyma cells commonly separate the thick-walled sieve tubes from the sieve tube-companion cell complexes. Plasmodesmatal frequencies between all remaining cell combinations of the vascular tissues are very low, even between the thin-walled sieve tubes and their associated companion cells. Both the sieve tube-companion cell complexes and the thick-walled sieve tubes, which lack companion cells, are virtually isolated symplastically from the rest of the leaf. Data on plamodesmatal frequency between protophloem sieve tubes and other cell types in intermediate and large bundles indicate that they (and their associated companion cells, when present) are also isolated symplastically from the rest of the leaf. Collectively, these data indicate that both phloem loading and unloading in the barley leaf involve apoplastic mechanisms.
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The role of the sucrose transporter OsSUT1 in assimilate retrieval via the xylem, as a result of damage to and leakage from punctured phloem was examined after rusty plum aphid (Hysteroneura setariae, Thomas) infestation on leaves from... more
The role of the sucrose transporter OsSUT1 in assimilate retrieval via the xylem, as a result of damage to and leakage from punctured phloem was examined after rusty plum aphid (Hysteroneura setariae, Thomas) infestation on leaves from 3-week-old rice (Oryza sativa L. cv Nipponbare) plants. Leaves were examined over a 1- to 10-day infestation time course, using a combination of gene expression and β-glucuronidase (GUS) reporter gene analyses. qPCR and Western blot analyses revealed differential expression of OsSUT1 during aphid infestation. Wide-field fluorescence microscopy was used to confirm the expression of OsSUT1-promoter::GUS reporter gene in vascular parenchyma associated with xylem elements, as well as in companion cells associated with phloem sieve tubes of large, intermediate and small vascular bundles within the leaf blade, in regions where the aphids had settled and were feeding. Of great interest was up-regulation of OsSUT1 expression associated with the xylem parenchyma cells, abutting the metaxylem vessels, which confirmed that OsSUT1 was not only involved in loading of sugars into the phloem under normal physiological conditions, but was apparently involved in the retrieval of sucrose leaked into the xylem conduits, which occurred as a direct result of aphid feeding, probing and puncturing of vascular bundles. The up-regulation of OsSUT1 in xylem vascular parenchyma thus provides evidence in support of the location within the xylem parenchyma cells of an efficient mechanism to ensure sucrose recovery after loss to the apoplast (xylem) after aphid-related feeding damage and its transfer back to the symplast (phloem) in O. sativa leaves.
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Whilst the structure of higher plant plasmodesmata was first described by Robards (1963. Desmotubule-a plasmodesmatal substructure. Nature 218, 784), and despite many subsequent intensive investigations, there is still much that remains... more
Whilst the structure of higher plant plasmodesmata was first described by Robards (1963. Desmotubule-a plasmodesmatal substructure. Nature 218, 784), and despite many subsequent intensive investigations, there is still much that remains unclear relating to their ultrastructure and functioning in higher plants. We have examined chemically fixed plant material, and suggest that the conformational changes seen in plasmodesmatal substructure, particularly the deposition of electron-dense extra-plasmodesmal material, is linked to either manipulation of the hormonal balance (as in Avocado fruit), or of osmotic potential in leaf blade material. These changes result in the deposition of beta 1,3-glucan (callose) at the neck region of these plasmodesmata. This electron-dense material is deposited at the neck region of plasmodesmata, and forms a collar-like structure. The formation of a collar is shown to be coupled with loss of lucence within the cytoplasmic sleeve. The formation of a collar at the plasmodesmatal orifice thus results in encapsulation and closure of the plasmodesmatal orifice. Closure of the orifice coincides with a loss of electron-lucence and a lack of resolution of the desmotubule. These ultrastructural changes are potentially significant and could contribute to, result in, or assist in the down-regulation of cell to cell trafficking via plasmodesmata.
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... an enzyme that degrades callose), which has been shown to accumulate to a greater extent in the resistant cultivars (Van der Westhuizen et al ... The authors thank the following: Dr. Vicky Tolmay of the ARC Bethlehem, South Africa for... more
... an enzyme that degrades callose), which has been shown to accumulate to a greater extent in the resistant cultivars (Van der Westhuizen et al ... The authors thank the following: Dr. Vicky Tolmay of the ARC Bethlehem, South Africa for the supply of aphids and seeds used in this ...