A heterodimeric 60 kDa lectin was isolated from the ground bean ( Vigna sesquipedalis cv ground bean). Its hemagglutinating activity was inhibited by polygalacturonic acid and not by galacturonic acid and other simple monosaccharides. Ground bean lectin exhibited mitogenic activity on murine splenocytes, reduced the viability of hepatoma and leukemia cells, and exerted an inhibitory activity toward HIV-1 reverse transcriptase. / A homodimeric 30-kDa glucose/mannose-specific lectin was purified from emperor banana. In contrast to Con A, the mitogenic activity of emperor banana lectin (EBL) toward mouse splenocytes but not its NO stimulatory effect toward mouse macrophages could be abrogated by 200 mM glucose. It also inhibited proliferation of tumor cells and inhibited HIV-1 reverse transcriptase. / A homodimeric 60-kDa lectin with specificity toward mannose, glucose and rhamnose and substantial N-terminal sequence to Concanavalin A has been isolated from Canavalia gladiata legumes. In contrast to Con A, the mitogenic activity of knife bean lectin toward mouse splenocytes but not its antiproliferative activity toward tumor cells could be abrogated by 200 mM glucose. The lectin inhibited HIV-1 reverse transcriptase, but did not exhibit antifungal activity. / A homotetrameric 120-kDa agglutinin was isolated from haricot bean seeds. It manifested a weaker mitogenic activity than concanavalin A toward mouse splenocytes and exhibited antiproliferative activity toward several tumor cell lines. / A plant defensin-like peptide, with a molecular mass around 6-kDa, was purified from the seeds of Chinese lima beans (Phaseolus lunatus L. ). Phld exerted an antifungal activity and an antibacterial action. Phld could reduce the activity of HIV-1 reverse transcriptase and inhibit translation in a cell-free rabbit reticulocyte lysate system. (Abstract shortened by UMI.) / Defense proteins are produced by a wide range of organisms including mammals, insects, plants, fungi and bacteria. In this study, focus was placed on 2 kinds of defense proteins in plants, namely, lectins/hemagglutinins and defensin-like peptides/defensins. Three lectins, one hemagglutinin (i.e. lectin whose hemagglutinating activity cannot be inhibited by simple saccharides), one defensin and two defensin-like peptides were isolated from 5 species of plants. The isolation procedure included different chromatographic techniques, involving ion exchange chromatography, affinity chromatography and gel filtration. / Wong Ho. / "August 2005." / Adviser: Tzi Bun Ng. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3785. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. i-xxvii). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

The worldwide utilisation of Vicia species as forage and green manure crops is well established. Except for V. faba L., the utilisation of Vicia species as grain legumes is of minor global economic importance and mainly restricted to the Mediterranean region and South - West Asia, where the grain is used primarily as seed and in ruminant diets. In Australia, the comparatively high seed yields and low production costs for genotypes from species such as V. narbonensis L. (narbon bean or moor's pea) and V. sativa L. (common vetch) have provided an attractive alternative grain legume option for dryland farming and have thus stimulated an interest in markets for the grain. Monogastric animals (incl. humans) are the major global end-users for grain legume products. Because of the well known toxicity of Vicia spp. seeds to mono gastric animals in particular, this thesis has focused on those major toxic chemical seed components which are perceived as major constraints to the wider utilisation of these promising crops as grain legumes. A thorough examination of current and past practices of vetch cultivation and utilisation was undertaken to complement this approach. The two major aims were, first to elucidate the nature of the factors responsible for the low palatability of carbon beans to pigs, and second to review the available information about the toxicity of Vicia species and their utilisation as grain legumes. The potent feed inhibitory activity of Namoi vetch (V. villosa Roth cv. Namoi) provided a useful model for the initial age of this study. Its antifeedant activity was shown to he due to the toxic amino acid canavanine. Inclusion of canavanine in pig diets at a concentration equivalent to that found in Namoi vetch seed accounted fully for the feed inhibitory activity of this legume. The novel effect of this well known arginine analogue may well be explicable in terms of the inhibition of the argmine pathway leading to nitric oxide which is now known to be involved in the control of peristalsis. The experience gained with Namoi vetch in the feed-intake bioassay proved to be invaluable for the isolation of the much less potent y- glutamyl-S-ethenyl-cysteine feed inhibitor from the narbon bean. A quantitative assessment of this factor's feed inhibitory activity was not permitted due to the untimely death of our veterinary colleague, Dr. Richard Davies. There is, however, a clear correlation between the total S-ethenyl cysteine content of the tested diets and the negative porcine feed intake responses. An important difference between V. villosa and V. narbonensis was noted, as demonstrated by the rate at which the pigs reduced their feed intake. It is remarkable, that the effect of canavanine - containing diets becomes evident only after the second meal, whereas the pigs immediately restrict their feed intake when presented with diets containing S-ethenyl-cysteine. Such a clear delineation of feed-intake responses provides a simple and general classification for feed-intake inhibitors, and may be worthy of further detailed physiological studies. The antifeedant effects of these compounds suggest that they have evolved as part of the plants' anti-predator defence strategy. Particular attention, including a detailed review of its economic botany, has been given to V. narbonensis, a relatively unknown but promising grain crop for Australia. With the chemical identity of the unpalatability established, the selection of more palatable genotypes is likely to provide access for the grain to monogastric feed markets. The historical evidence suggests that V. narbonensis is a niche crop of particular value for specific agricultural applications, its conversion into a broad acre crop is a challenge for the future. V. sativa was investigated as a direct consequence of a request to chemically examine the toxin content of the cultivar Blanche Fleur. By the time that investigation commenced, Blanche Fleur, which was originally introduced to Australia as a hay, forage and green manure crop, had already been prematurely promoted and exported as a cheap replacement for red lentils (Lens culinaris Med.) in ignorance of this species' well documented content of y- glutamyl-β-cyanoalanine and the favism toxin, vicine. A 1992 commentary article to Nature on our observations led to a ban on its importation by India and Egypt. Subsequent poultry bioassays established that the cyano- alanine content was substantially altered by cooking to produce some as yet un-identified nitrile component, but the feed inhibitory activity of the cooked grain was undiminished. Acid hydrolysis of Blanche Fleur, however, removed both, the readily detectable nitrile absorbance as well as the poultry feed-intake inhibition. This observation could potentially form the basis for a simple post-harvest detoxification process for V. sativa and other feed stuffs containing acid labile antinutritive factors. Unfortunately, cases of poisoning by Vicia species continue to be reported. These can be grouped into those caused by V. sativa and its related species (cyanogenic glycoside Vicianine: HCN poisoning; and anti- nutritional effects of (β- cyanoalanine )and those caused by canavanine containing species ( V. villosa, V. benghalensis, V. ervilia etc.). Farmers need to be made aware of the well documented biochemical distinctions between Vicia cultivars to prevent the accidental intoxication of their livestock with seeds containing high concentrations of canavanine orvicianine. Finally, an overview of the voluminous and widely dispersed vetch literature, coupled with the observations in this thesis, suggest that the utility and value of each of the three Vicia model species examined in this thesis can be markedly enhanced by the following strategies : 1. Provision of sufficient alternative feed sources to allow feed intake to be regulated by palatability, thus rninirnising toxin ingestion. 2. Adaptation to Vicia toxins a) through selection of a digestive flora capable of detoxification (in the case of ruminants) and b) through selection or modification of animal genotypes with improved biochemical tolerance or even resistance to toxicity. 3. Detoxification prior to ingestion (Post - harvest detoxification) 4. Plant selection or genetic modification of specific toxin biosynthetic pathways to provide cultivars with optimum toxin concentration and distribution in strategic tissues (minimisation of toxins in the end product). The inevitable conclusion from this thesis is that by incrementing our current fundamental knowledge of the biological chemistry of their naturally occurring anti-predator metabolites, we will promote the intelligent usage of Vicia species as highly nutritious grains for a sustainable agriculture. This thesis has resulted in 2 publications in referred journals. / Thesis (Ph.D.)--Department of Plant Science, 1994.

Bibliography: leaves 162-186.

Abstract To assess the symbiotic dependency of grain and shrub/tree legumes within five agro-ecological zones of Botswana, fully expanded leaves of the test species were sampled from about 26 study sites within Ngwaketse, Gaborone, Central, Ghanzi and Kalahari agro-ecological zones. Isotopic analysis revealed significant differences in 1)15N values of the grain legumes [cowpea (Vigna unguiculata L. Walp), Bambara groundnut (Vigna subterranea L. Verde.), and groundnut (Arachis hypogaea L.)] from the 26 farming areas in both 2005 and 2006. Estimates of %Ndfa of leaves also showed significant differences between farming areas, with cowpea deriving more than 50% of its N nutrition from symbiotic fixation. In terms of distribution, many more symbiotic shrub/tree species were found in the wetter Ngwaketse agro-zone compared to the fewer numbers in the drier Kalahari region. Acacias were the more dominant species at all sites. Leaf 1)15N values of shrub/tree species also varied strongly across Botswana, with 11 out of 18 of these legumes deriving about 50%, or more, of their N from symbiotic Nz fixation. Acacia caffra, in particular, obtained as much as 93.6% of its N nutrition from symbiotic fixation in the wetter Ngwaketse agro-zone. This study has shown that grain legumes sampled from farmer's fields in Botswana obtained considerable amounts of their N from symbiotic fixation. We have also shown that shrub and tree legumes probably play an important role in the N economy of the savanna ecosystems in Botswana. However, the decline in the number of functional Ny-fixing shrub/tree legumes along an aridity gradient suggests that soil moisture is a major constraint to Nz fixation in the tree legumes of Botswana.

Abstract Data collated from around the world indicate that, for every tonne of shoot dry matter produced by crop legumes, the symbiotic relationship with rhizobia is responsible for fixing, on average on a whole plant basis (shoots and nodulated roots), the equivalent of 30-40 kg of nitrogen (N). Consequently, factors that directly influence legume growth (e.g. water and nutrient availability, disease incidence and pests) tend to be the main determinants of the amounts of N2 fixed. However, practices that either limit the presence of effective rhizobia in the soil (no inoculation, poor inoculant quality), increase soil concentrations of nitrate (excessive tillage, extended fallows, fertilizer N), or enhance competition for soil mineralN (intercropping legumes with cereals) can also be critical. Much of the N2 fixed by the legume is usually removed at harvest in high-protein seed so that the net residual contributions of fixed N to agricultural soils after the harvest of legume grain may be relatively small. Nonetheless, the inclusion of legumes in a cropping sequence generally improves the productivity of following crops. Whilesome of these rotational effects may be associated with improvements in availability ofN in soils, factors unrelated to N also play an important role. Recent results suggest that one such non-N benefit may be due to the impact on soil biology of hydrogen emitted from nodules as a by-product of'N, fixation.

Abstract To assess the symbiotic dependency of grain and shrub/tree legumes within five agro-ecological zones of Botswana, fully expanded leaves of the test species were sampled from about 26 study sites within Ngwaketse, Gaborone, Central, Ghanzi and Kalahari agro-ecological zones. Isotopic analysis revealed significant differences in 1)15N values of the grain legumes [cowpea (Vigna unguiculata L. Walp), Bambara groundnut (Vigna subterranea L. Verde.), and groundnut (Arachis hypogaea L.)] from the 26 farming areas in both 2005 and 2006. Estimates of %Ndfa of leaves also showed significant differences between farming areas, with cowpea deriving more than 50% of its N nutrition from symbiotic fixation. In terms of distribution, many more symbiotic shrub/tree species were found in the wetter Ngwaketse agro-zone compared to the fewer numbers in the drier Kalahari region. Acacias were the more dominant species at all sites. Leaf 1)15N values of shrub/tree species also varied strongly across Botswana, with 11 out of 18 of these legumes deriving about 50%, or more, of their N from symbiotic Nz fixation. Acacia caffra, in particular, obtained as much as 93.6% of its N nutrition from symbiotic fixation in the wetter Ngwaketse agro-zone. This study has shown that grain legumes sampled from farmer's fields in Botswana obtained considerable amounts of their N from symbiotic fixation. We have also shown that shrub and tree legumes probably play an important role in the N economy of the savanna ecosystems in Botswana. However, the decline in the number of functional Ny-fixing shrub/tree legumes along an aridity gradient suggests that soil moisture is a major constraint to Nz fixation in the tree legumes of Botswana.

Abstract Data collated from around the world indicate that, for every tonne of shoot dry matter produced by crop legumes, the symbiotic relationship with rhizobia is responsible for fixing, on average on a whole plant basis (shoots and nodulated roots), the equivalent of 30-40 kg of nitrogen (N). Consequently, factors that directly influence legume growth (e.g. water and nutrient availability, disease incidence and pests) tend to be the main determinants of the amounts of N2 fixed. However, practices that either limit the presence of effective rhizobia in the soil (no inoculation, poor inoculant quality), increase soil concentrations of nitrate (excessive tillage, extended fallows, fertilizer N), or enhance competition for soil mineralN (intercropping legumes with cereals) can also be critical. Much of the N2 fixed by the legume is usually removed at harvest in high-protein seed so that the net residual contributions of fixed N to agricultural soils after the harvest of legume grain may be relatively small. Nonetheless, the inclusion of legumes in a cropping sequence generally improves the productivity of following crops. Whilesome of these rotational effects may be associated with improvements in availability ofN in soils, factors unrelated to N also play an important role. Recent results suggest that one such non-N benefit may be due to the impact on soil biology of hydrogen emitted from nodules as a by-product of'N, fixation.

No description available.

The synthesis of isoflavonoid phytoalexins in legumes is relatively well understood, but far less is known about how these phytotoxic compounds are metabolised by the plant when no longer required. In this project medicarpin, the major isoflavonoid phytoalexin in alfalfa, was prepared in radiolabelled form and fed to cell cultures and seedlings of alfalfa. The metabolism of the radioactive phytoalexin was then studied by characterising the radiolabelled metabolites formed. Uptake of radiolabelled phytoalexin by cells was faster in elicitor-treated cultures than in untreated cultures. However, there was little difference in pattern or speed of metabolism in treated or untreated cultures. Labelled medicarpin was rapidly metabolised to a complex range of extractable medicarpin products (MPs). A very small proportion of the dose was broken down to (^14)C02. A total of 8 MPs could be resolved as distinct metabolites by HPLC and TLC. However, as incubation time increased the radioactivity became associated with multiple minor components which could not be identified. The 8 MPs were characterised by UV and mass-spectrometry and where possible by co- chromatography with authentic standards by TLC and HPLC. Four MPs were unambiguously identified as medicarpin-3-0-glucoside-6"-O-malonate (MGM), the isoflavans vestitol and sativan and the pterocarpan 6a-hydroxy-3,4'- dimethoxypterocarpan (variabilin). In addition a hydroxylated derivative of medicarpin, termed pseudomedicarpin was also tentatively identified. Of the four remaining metabolites MPl had a relative molecular mass of 166 but remained unidentified. MP2 was formed from pseudomedicarpin, but could not be characterised due to its labile nature. Similarly MP3 and MP6 remained unidentified, though the evidence suggested that MPS was a demethylated product of medicarpin. The metabolism of medicarpin in seedlings resembled that of cell cultures with the exception that rather more of the medicarpin was conjugated to form MGM.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1990. / Includes bibliographical references (leaves 164-173) / Microfiche. / xi, 173 leaves, bound ill. 29 cm