Native Glycoprotein II (Phaseolin, G-II), the major 7S storage protein from <i>Phaseolus vulgaris</i> seeds, var. 'Processor' is known to be resistant to <i>in vitro</i> proteolysis by most endopeptidases. On sequential treatments with pepsin and a mixture of trypsin and chymotrypsin, the sub-unit polypeptides of G-II were split midchain. The fragments produced however, retained reactivity with the antibody raised against native G-II quantitatively. When measured by rocket immunoelectrophoresis, the extent of <i>in vitro</i> degradation of G-II by these endopeptidases was negligible. This procedure was used for monitoring the <i>in vivo</i> or <i>in vitro</i> degradation of G-II by gut enzymes other than trypsin or chymotrypsin. Diets containing 10% of a highly purified G-II preparation, did not support growth of rats adequately. Faecal N outputs were elevated and the true N digestibility based on Kjeldhal estimation was only 37%. In contrast, the true GII-N digestibility, based on immunological estimations, was high. It is suggested that G-II and/or its limited breakdown fragments (by trypsin or chymotrypsin) are stimulants of endogenous N secretion in the small intestine. The higher extent of the degradation of G-II in the small intestine of rats <i>in vivo</i> than that obtained by pure endopeptidases <i>in vitro</i> suggested the presence in this tissue of other enzymes capable to act upon and modify the structure of G-II, prior to the action of trypsin and chymotrypsin. These other modifying proteolytic enzymes render the G-II molecule more negatively charged and more susceptible to the subsequent action of trypsin and chymotrypsin. It is suggested that protease content and the ratio of the concentration of the GII-modifying protease(s) to that of trypsin and chymotrypsin may vary appreciably along the small intestine. Accordingly, the dependence of the degradation of G-II <i>in vivo</i> on the competition between all the enzymes capable of attacking it during its passage through the gut may explain the variability of GII breakdown <i>in vivo</i>.

This study has examined the rate at which the seeds of certain species disappear from woodland soils, and whether the composition of the seed banks beneath stands of known age can be used to reveal management history. Associated with this is an investigation of the spatial distribution of the stored propagules. A question arises as to whether species with long lived seeds can survive as buried seed long enough to take advantage of the opening of the canopy and soil disturbance resulting from the falling of old trees. Given the great life span of most trees, this is a strategy open only to species with exceptionally long lived seed banks. One such species is Hypericum pulchrum, which, as the seed bank surveys carried out in this study show, can exist as viable seeds beneath woodlands of great age in the Tavistock Woodland Estate in Devon. Is this germination and reproduction on tree falls sufficient to maintain Hypericum in the seed bank indefinitely ? To answer this question, a computer model was developed to examine the effect of various parameters on the survival time of a Hypericum seed bank beneath a simulated woodland. The model allowed prediction of both the mean density of buried seeds in a unit area, and the development of pattern within the seed bank. Analysis of the simulation results established that the dispersal of Hypericum was insufficient to maintain a seed bank by a &quot;chain reaction&quot; of windthrown reinforcement. The implications of this are discussed with respect to pioneer species within both temperate and tropical forests.

The aim of this work was to study the effect of the herbicide, 2,4-D on a mono- cot (Lolium temulentum Linn.) and a dicot (Raphanus sativus Linn.) in relation to drought stress, in order to elucidate if the combined treatments altered the survival of the plants. Herbicide effects were investigated on a number of plant developmental stages; germination, seedling growth, mature leaves and root function, and were combined with various water stress regimes.2,4-D did not alter the germination percentage in either species when applied singly or with polyethylene glycol (PEG) induce water stress. However, rate of seedling emergence and accumulation of chlorophyll, protein and proline were inhibited. Foliar application of 2,4-D at selective concentrations showed that in addition to induced growth distortion the herbicide reduced the survivial capacity of radish but enhanced that of rye grass to later drought stress. Analysis of the content of proline (a stress metabolite) in both species indicated that the accumulation of this compound was reduced in radish but enhanced in rye grass. In contrast, when 2,4-,VJ)&amp;^Dlapplied via the roots, from water culture, the selectivity of effect was lost since proline accumulation was reduced in both species. Use of (^14)C-2,4-D showed that the herbicide remained in the roots when applied in water culture and that since a major response was seen in the roots this implied that some signalling was occuring between the two organs. From the results it would appear that the use of low doses of herbicides such as 2,4-D may be valuable in protecting certain plants from drought stress, whilst the susceptability of other plants could be increased hence making the herbicide more effective at low concentrations.

No description available.

Micropropagated potato (Solanum tuberosum L.) plantlets are routinely used for producing specific pathogen tested minitubers in the Canadian seed tuber certification industry. In vitro hardening methods for micropropagated 'Norland' were investigated, involving full and half strength Murashige and Skoog (1962) based propagation medium supplemented with NaCl, KCl, CaCl2, polyethyleneglycol, or paclobutrazol. Ten different media treatments were compared for their effect on stomatal function and early transplant performance using porometry, microscopy, and direct ex vitro transplanting. PEG, NaCl and 1/2 MS + 3 mM Ca treatments did lead to decreased leaf water losses. However, these treatments did not improve ex vitro transplant performance compared to controls. Minituber production was investigated using ex vitro plantlets in a rockwool-based hydroponic system. Productivity was evaluated for treatments involving photoperiod pretreatment, planting orientation, planting density, and hilling. No difference in total yield was detected when plantlets were exposed to 12 compared with 16 hour photoperiod pretreatments. However, short photoperiod pretreatment increased the number of minitubers in the most desirable size range. Increased planting density reduced yield per plant. However, small increases in yield per m2 occurred with increased planting density. Hilling, pinching, and planting orientation had no effect upon minituber size, number, or overall fresh weight yield. Significant differences in minituber yield occurred in field experiments. Larger minitubers (10--40 g) had larger yields compared with smaller minitubers (1--5 g). These results will contribute to improved minituber production technology for the Canadian certified potato seed tuber industry.

Within the Australian wet tropics bioregion, only 900 000 hectares of once continuous rainforest habitat between Townsville and Cooktown now remains. While on the Atherton Tableland, only 4% of the rainforest that once occurred there remains today with remnant vegetation now forming a matrix of rainforest dispersed within agricultural land (sugarcane, banana, orchard crops, townships and pastoral land). Some biologists have suggested that remnants often support both faunal and floral communities that differ significantly from remaining continuous forest. Australian tropical forests possess a relatively high diversity of native small mammal species particularly rodents, which unlike larger mammalian and avian frugivores elsewhere, have been shown to be resilient to the effects of fragmentation, patch isolation and reduction in patch size. While small mammals often become the dominant mammalian frugivores, in terms of their relative abundance, the relationship that exists between habitat diversity and structure, and the impacts of small mammal foraging within fragmented habitat patches in Australia, is still poorly understood. The relationship between foraging behaviour and demography of two small mammal species, Rattus fuscipes and Melomys cervinipes, and food resources in fragmented rainforest sites, were investigated in the current study. Population densities of both species were strongly related with overall density of seed resources in all rainforest fragments. The distribution of both mammal species however, was found to be independent of the distribution of seed resources. Seed utilisation trials indicated that M.cervinipes and R.fuscipes had less impact on seed resources (extent of seed harvesting) than did other rainforest frugivores. Experimental feeding trials demonstrated that in 85% of fruit species tested, rodent feeding increased seed germination by a factor of 3.5 suggesting that in Australian tropical rainforest remnants, small mammals may play a significant role in enhancing germination of large seeded fruits. This study has emphasised the role of small mammals in tropical rainforest systems in north eastern Australia, in particular, the role that they play within isolated forest fragments where larger frugivorous species may be absent.

Apomixis is an intriguing and agronomically valuable asexual reproductive pathway resulting in seeds that give rise to plants that are identical in genotype to the female parent. Apomixis is absent in agriculturally important seed crops and our work has focused on the analysis of apomixis in the daisy-like genus Hieracium which contains sexual and apomictic species. Prior studies have shown that apomixis in Hieracium is controlled by two dominant loci. The LOA controls the avoidance of meiosis during female gametophyte (embryo sac) formation and the LOP locus is required for fertilization independent embryo formation during seed initiation. The genes conferring apomixis are unknown. In this study we focused on the events of autonomous seed initiation. Cytological examination of apomictic mutants that have lost LOA or LOP and analysis of their progeny enabled us to characterize developmental aspects associated with the function of these loci. Upon removal of LOA meiosis occurs normally and LOP segregates with a 1:1 ratio in the progeny, characterizing maternal gametophytic control. We also show that autonomous embryo formation segregates with autonomous endosperm formation, suggesting that these two loci are closely linked. However, upon meiotic division, embryo lethal components arise and embryo development in apomeiosis mutants was generally defective and seed set was low. Similarly, upon removal of LOP, apomixis initiation occurs normally and unreduced embryo sacs can only form seeds if pollinated. Autonomous seed initiation is actively repressed in the sexual model plant Arabidopsis by the action of a chromatin remodelling complex encoded by the FERTILIZATION INDEPENDENT SEED (FIS)-class genes. These genes are homologues of the Drosophila PcG complex that also repress gene expression throughout Drosophila development. Mutations in the FIS-class genes lead to elements of apomixis, such as autonomous endosperm, and in one particular mutant, autonomous egg cell development. Given the similarity in apomictic and FISclass gene mutant phenotype we isolated three homologues from sexual and apomictic Hieracium plants: FERTILIZATION INDEPENDENT ENDOSPERM (FIE), MULTICOPY SUPPRESSOR OF IRA1 (MSI1) AND RETINOBLASTOMA (RBR). FIS-class genes from sexual and apomicit Hieracium and examined their expression, interaction and function during seed initiation. The isolated Hieracium FIS-class genes were highly conserved in sexual and apomictic plants in terms of gene sequence and temporal and spatial expression pattern. Analysis of protein interactions by yeast-two hybrid showed that the HFIE gene from sexual and apomictic plants does not interact with other complex members in the same manner found in Arabidopsis. Protein modelling uncovered structural differences between the Arabidopsis and Hieracium FIE proteins. RNAi- mediated down-regulation of HFIE in sexual Hieracium did not lead to autonomous seed initiation indicating HFIE was not part of a repressive complex. Down-regulation of HFIE in sexual and apomictic plants revealed the gene was essential for embryo growth and viability. Therefore, FIS-complex genes interact differently in Arabidopsis and Hieracium and have different developmental roles. In summary, the results presented here suggest that the FIS-genes are not mutated in apomictic Hieracium plants, but they interact differently relative to the Arabidopsis counterparts and play a fundamental role in embryogenesis. Thus, engineering autonomous seed into crops will not depend on mutating these genes but rather in uncovering the molecular signal that triggers apomictic development. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1337073 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2008

Thesis (Th. M.)--Dallas Theological Seminary, 1988. / Includes bibliographical references (leaves [87]-94).

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Literatures in English." Includes bibliographical references.

Thesis (M.S.)--Brigham Young University. Dept. of Plant and Animal Sciences, 2006. / Includes bibliographical references (p. 31-37).