395 resultados para Plant-pathogen relationships


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This study investigated relationships between SRL and EF in a sample of 254 school-aged adolescent males. Two hypotheses were tested: that self-reported measures of SRL and EF are closely related and that as different aspects of EF mature during adolescence, the corresponding components of SRL should also improve, leading to an age-related increase in the correlation between EF and SRL. Two self-report instruments were used: the strategies for self-regulated learning survey (SSRLS) and the behavioural rating instrument of executive function (BRIEF). Strong correlations between the measures of EF and SRL were found, especially in areas associated with metacognitive processes. Correlations between EF and SRL were found, with weaker correlations between behavioural regulation and SRL were found to be weaker for the younger participants in the sample while the relationship between EF and SRL appears to grow stronger during the initial years of high school even though self-reported levels of EF along with motivation for SRL and important components of SRL such as goal setting and planning were found to decrease with age. Decreasing levels of motivation for learning during adolescence are speculated to moderate the deployment of SRL and EF in a school context.

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QUT Learning and Teaching Unit Seminar Making a Real Difference: Learning and Teaching Grants Showcase This event recognised and shared teaching innovations, including those from faculty learning and teaching grants. The Showcase featured four ALTC Grant project leaders (Helen Partridge, Sylvia Edwards, Robyn Nash and Mary Ryan) who had recently completed or were about to complete their grants. Each QUT faculty nominated two 2010 faculty teaching and learning grant recipients to showcase grant outcomes via a poster. Poster: Shannon Satherley & Abbe Winter Changing Relationships: Engaging Students and Staff in the Design Studio 'In the design studio learning environment, traditional student and staff expectations are of close contact teaching and learning. However, in recent years increasing class sizes have meant students experiencing reduced personal staff attention, and increasingly feeling “anonymous” and correspondingly disengaged, to the detriment of quality learning (Carbone 1998: 8; Biggs 2003). Concurrently, there has been a necessary increase in teaching by sessional (casual) teaching staff at QUT, with varied levels of experience and assurance. While teachers primarily regard engagement as “cognitive and conative,” for students it is emotional: “... an essential need to feel that they were engaged with the context of their learning and that it was meaningful in some way” (Solomonides and Martin 2008: 18). As a response to these conditions, the Changing Relationships action-research project was run within a QUT School of Design studio unit in 2009 and 2010, based on the premise that engaged teaching can encourage emotionally engaged learning. The project inverted the structure of the traditional QUT studio unit, empowering both students and sessional staff with a sense of increased autonomy: literally changing the relationships within the studio learning environment.'

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This thesis investigates patterns of evolution in a group of native Australo-Papuan rodents. Past climatic change and associated sea level fluctuations, and fragmentation of wet forests in eastern Australia has facilitated rapid radiation, diversification and speciation in this group. This study adds to our understanding of the evolution of Australia’s rainforest fauna and describes the evolutionary relationships of a new genus of Australian rodent.

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We develop a general theoretical framework for exploring the host plant selection behaviour of herbivorous insects. This model can be used to address a number of questions, including the evolution of specialists, generalists, preference hierarchies, and learning. We use our model to: (i) demonstrate the consequences of the extent to which the reproductive success of a foraging female is limited by the rate at which they find host plants (host limitation) or the number of eggs they carry (egg limitation); (ii) emphasize the different consequences of variation in behaviour before and after landing on (locating) a host (termed pre- and post-alighting, respectively); (iii) show that, in contrast to previous predictions, learning can be favoured in post-alighting behaviour--in particular, individuals can be selected to concentrate oviposition on an abundant low-quality host, whilst ignoring a rare higher-quality host; (iv) emphasize the importance of interactions between mechanisms in favouring specialization or learning.

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The polyphagous moth Helicoverpa armigera (Hübner) is one of the world's most important agricultural pests. A number of existing approaches and future designs for management of H. armigera rely on the assumption that moths do not exhibit either genetically and/or non-genetically based variation for host plant utilization. We review recent empirical evidence demonstrating that both these forms of variation influence host plant use in this moth. The significance of this variation in H. armigera in relation to current and future pest management strategies is examined. We provide recommendations on future research needs and directions for sustainable management of H. armigera, under a framework that includes consideration of intra-specific variation for host use relevant in this and other similar pest species.

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Learning can allow individuals to increase their fitness in particular environments. The advantage to learning depends on the predictability of the environment and the extent to which animals can adjust their behaviour. Earlier general models have investigated when environmental predictability might favour the evolution of learning in foraging animals. Here, we construct a theoretical model that predicts the advantages to learning using a specific biological example: oviposition in the Lepidoptera. Our model includes environmental and behavioural complexities relevant to host selection in these insects and tests whether the predictions of the general models still hold. Our results demonstrate how the advantage of learning is maximised when within-generation variability is minimised (the local environment consists mainly of a single host plant species) and between-generation variability is maximised (different host plant species are the most common in different generations). We discuss how our results: (a) can be applied to recent empirical work in different lepidopteran species and (b) predict an important role of learning in lepidopteran agricultural pests.

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It is well established that herbivorous insects respond to changes in plant odour production, but little attention has been given to whether these responses relate to direct fitness costs of plant volatile production on insect growth and survival. Here, we use transgenic Nicotiana tabacum (tobacco) plants that produce relatively large amounts of the volatile (S)-linalool to study whether the responses of egg-laying herbivorous insects to linalool production relate directly to the growth and survival of offspring. In choice tests, fewer eggs were laid on transgenic plants compared with non-transformed controls, indicating that increased linalool emissions have a deterrent effect on Helicoverpa armigera oviposition. Larval survival and larval mass after feeding on transgenic leaves, however, was comparable to non-transformed controls. (S)-linalool, whether in volatile or sequestered form, does not appear to have a direct effect on offspring fitness in this moth. We discuss how the ecology of this polyphagous moth species may necessitate a high tolerance for certain volatiles and their related non-volatile compounds, and suggest that responses by adult female H. armigera moths towards increased linalool production may be context specific and relate to other indirect effects on fitness.

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Plant and machinery valuation is important to every company.s annual financial reporting. It is reported under the non-current assets section, and the valuers are generally employed to provide the up to date valuation of the non-current assets valuation such as property, plant and equipment that can make up to 80% of the total assets of a company. The valuation of plant and machinery is also important for other purposes such as securing loan facilities, sales, takeover, insurance and auction. The application of 2005 International Financial Reporting Standard (IFRS) has a subsequent impact on the financial sector, as a whole. The accountants have to choose between the Historical Cost approach and Market Value approach in determining the value of the client.s assets. In Malaysia, the implementation of IFRS has a domino effect on the financial system, especially for plant and machinery valuation for financial reporting. The comparison data for plant and machinery valuation is limited unlike land and building valuation. The question of Malaysian valuer.s ability to comply with the IFRS standard keeps rising every day, not just to the accountants, but also other related parties such as financial institutions, government agencies and the clients. This is happening because of different interpretations of premise of value for plant and machinery, as well as methods been used and differences in standards of reporting among the valuers conducting plant and machinery valuation. The root of the problem lies in the lack of practical guidelines governing plant and machinery valuation practices and different schools of thought among the valuers. Some follow the United Kingdom.s RICS guidelines, whilst some valuers are more comfortable with the United State.s USPAP rules, especially on the premise of value. This research is to investigate the international best practices of plant and machinery valuation and to establish the common valuation concept, awareness and application of valuation methodology and valuation process for plant and machinery valuation in Malaysia. This research uses a combination of the qualitative and quantitative research approach. In the qualitative approach, the content analyses were conducted from the international practices and current Malaysian implementation of plant and machinery valuation. A survey (quantitative approach) via questionnaire was implemented among the registered and probationary valuers in Malaysia to investigate their understanding and opinion relating to plant and machinery valuation based on the current practices. The significance of this research is the identification of international plant and machinery practices and the understanding of current practices of plant and machinery valuation in Malaysia. It is found that issues embedding plant and machinery valuation practices are limited numbers of resources available either from scholars or practitioner. This is supported by the general finding from the research survey that indicates that there are immediate needs for practical notes or guidelines to be developed and implemented to support the Malaysian valuers practising plant and machinery valuation. This move will lead to a better understanding of plant and machinery valuation, reducing discrepancies in valuation of plant and machinery and increased accuracy among practising valuers.

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A finely-tuned innate immune response plays a pivotal role in protecting host against bacterial invasion during periodontal disease progression. Hyperlipidemia has been suggested to exacerbate periodontal health condition. However, the underlying mechanism has not been addressed. In the present study, we investigated the effect of hyperlipidemia on innate immune responses to periodontal pathogen Porphyromonas gingivalis infection. Apolipoprotein E-deficient and wild-type mice at the age of 20 weeks were used for the study. Peritoneal macrophages were isolated and subsequently used for the study of viable P. gingivalis infection. ApoE−/− mice demonstrated inhibited iNOS production and impaired clearance of P. gingivalis in vitro and in vivo; furthermore, ApoE−/− mice displayed disrupted cytokine production pattern in response to P. gingivalis, with a decreased production of tumor necrosis factor-α, interleukin-6 (IL-6), IL-1β and monocyte chemotactic protein-1. Microarray data demonstrated that Toll-like receptor (TLR) and NOD-like receptor (NLR) pathway were altered in ApoE−/− mice macrophages; further analysis of pattern recognition receptors (PRRs) demonstrated that expression of triggering receptors on myeloid cells-1 (TREM-1), an amplifier of the TLR and NLR pathway, was decreased in ApoE−/− mice macrophages, leading to decreased recruitment of NF-κB onto the promoters of the TNF-α and IL-6. Our data suggest that in ApoE−/− mice hyperlipidemia disrupts the expression of PRRs, and cripples the host’s capability to generate sufficient innate immune response to P. gingivalis, which may facilitate immune evasion, subgingival colonization and establishment of P. gingivalis in the periodontal niche.

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This paper presents an approach for identifying the limit states of resilience in a water supply system when influenced by different types of pressure (disturbing) forces. Understanding of systemic resilience facilitates identification of the trigger points for early managerial action to avoid further loss of ability to provide satisfactory service availability when the ability to supply water is under pressure. The approach proposed here is to illustrate the usefulness of a surrogate measure of resilience depicted in a three dimensional space encompassing independent pressure factors. That enables visualisation of the transition of the system-state (resilience) between high to low resilience regions and acts as an early warning trigger for decision-making. The necessity of a surrogate measure arises as a means of linking resilience to the identified pressures as resilience cannot be measured directly. The basis for identifying the resilience surrogate and exploring the interconnected relationships within the complete system, is derived from a meta-system model consisting of three nested sub-systems representing the water catchment and reservoir; treatment plant; and the distribution system and end-users. This approach can be used as a framework for assessing levels of resilience in different infrastructure systems by identifying a surrogate measure and its relationship to relevant pressures acting on the system.

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Bananas (Musa sp) are one of the most important food crops in the world and provide a staple food and source of income in many households especially in Africa. Diseases are a major constraint to production with bunchy top, caused by Banana bunchy top virus (BBTV) generally considered the most important virus disease of bananas worldwide. Of the fungal diseases, Fusarium wilt, caused by the Fusarium oxysporum f.sp cubense (Foc), and black Sigatoka, caused by Mycosphaerella fijiensis, are arguably two of the most important and cause significant yield losses. The low fertility of commercially important banana cultivars has hampered efforts to generate disease resistance using conventional breeding. Possible alternative strategies to generate or increase disease resistance are through genetic engineering or by manipulation of the innate plant defence mechanisms, namely systemic acquired resistance (SAR). The first research component of this thesis describes attempts to generate BBTV-resistant banana plants using a genetic modification approach. The second research component of the thesis focused on the identification of a potential marker gene associated with SAR in banana plants and a comparison of the expression levels of the marker gene in response to biotic and abiotic stresses, and chemical inducers. Previous research at QUT CTCB showed that replication of BBTV DNA components in banana embryogenic cell suspensions (ECS) was abolished following co-bombardment with 1.1mers of mutated BBTV DNA-R. BBTV DNA-R encodes the master replication protein (Rep) and is the only viral protein essential for BBTV replication. In this study, ECS of banana were stably transformed with the same constructs, each containing a different mutation in BBTV DNA-R, namely H41G, Y79F and K187M, to examine the effect on virus replication in stably transformed plants. Cells were also transformed with a construct containing a native BBTV Rep. A total of 16, 16, 11 and five lines of stably transformed banana plants containing the Y79F, H41G, K187M and native Rep constructs, respectively, were generated. Of these, up to nine replicates from Y79F lines, four H41G lines, seven K187M lines and three native Rep lines were inoculated with BBTV by exposure to viruliferous aphids in two separate experiments. At least one replicate from each of the nine Y79F lines developed typical bunchy top symptoms and all tested positive for BBTV using PCR. Of the four H41G lines tested, at least one replicate from three of the lines showed symptoms of bunchy top and tested positive using PCR. However, none of the five replicates of one H41G line (H41G-3) developed symptoms of bunchy top and none of the plants tested positive for BBTV using PCR. Of the seven K187M lines, at least one replicate of all lines except one (K187M-1) developed symptoms of bunchy top and tested positive for BBTV. Importantly, none of the four replicates of line K187M-1 showed symptoms or tested positive for BBTV. At least one replicate from each of the three native Rep lines developed symptoms and tested positive for BBTV. The H41G-3 and K187M-1 lines possibly represent the first transgenic banana plants generated using a mutated Rep strategy. The second research component of this thesis focused on the identification of SAR-associated genes in banana and their expression levels in response to biotic and abiotic stresses and chemical inducers. The impetus for this research was the observation that tissue-cultured (TC) banana plants were more susceptible to Fusarium wilt disease (and possibly bunchy top disease) than plants grown from field-derived suckers, possibly due to decreased levels of SAR gene expression in the former. In this study, the pathogenesis-related protein 1 (PR-1) gene was identified as a potential marker for SAR gene expression in banana. A quantitative real-time PCR assay was developed and optimised in order to determine the expression of PR-1, with polyubiquitin (Ubi-1) found to be the most suitable reference gene to enable relative quantification. The levels of PR-1 expression were subsequently compared in Lady Finger and Cavendish (cv. Williams) banana plants grown under three different environmental conditions, namely in the field, the glass house and in tissue-culture. PR-1 was shown to be expressed in both cultivars growing under different conditions. While PR-1 expression was highest in the field grown bananas and lowest in the TC bananas in Lady Finger cultivar, this was not the case in the Cavendish cultivar with glass house plants exhibiting the lowest PR-1 expression compared with tissue culture and field grown plants. The important outcomes of this work were the establishment of a qPCR-based assay to monitor PR-1 expression levels in banana and a preliminary assessment of the baseline PR-1 expression levels in two banana cultivars under three different growing conditions. After establishing the baseline PR-1 expression levels in Cavendish bananas, a study was done to determine whether PR-1 levels could be increased in these plants by exposure to known banana pathogens and non-pathogens, and a known chemical inducer of SAR. Cavendish banana plants were exposed to pathogenic Foc subtropical race 4 (FocSR4) and non-pathogenic Foc race 1 (Foc1), as well as two putative inducers of resistance, Fusarium lycopersici (Fol) and the chemical, acibenzolar-S-methyl (BION®). Tissue culture bananas were acclimatised under either glass house (TCS) or field (TCH) conditions and treatments were carried out in a randomised complete block design. PR-1 expression was determined using qPCR for both TCS and TCH samples for the period 12-72h post-exposure. Treatment of TCH plants using Foc1 and FocSR4 resulted in 120 and 80 times higher PR-1 expression than baseline levels, respectively. For TCS plants treated with Foc1, PR-1 expression was 30 times higher than baseline levels at 12h post-exposure, while TCS plants treated with FocSR4 showed the highest PR-1 expression (20 times higher than baseline levels) at 72h post-exposure. Interestingly, when TCS plants were treated with Fol there was a marked increase of PR-1 expression at 12 h and 48 h following treatment which was 4 and 8 times higher than the levels observed when TCS plants were treated with Foc1 and FocSR4, respectively. In contrast, when TCH plants were treated with Fol only a slight increase in PR-1 expression was observed at 12 h, which eventually returned to baseline levels. Exposure of both TCS and TCH plants to BION® resulted in no effect on PR-1 expression levels at any time-point. The major outcome of the SAR study was that the glass house acclimatised tissue culture bananas exhibited lower PR-1 gene expression compared to field acclimatised tissue culture plants and the identification of Fol as a good candidate for SAR induction in banana plants exhibiting low PR-1 levels. A number of outcomes that foster understanding of both pathogen-derived and plant innate resistance strategies in order to potentially improve banana resistance to diseases were explored in this study and include identification of potential inducers of systemic acquired resistance and a promising mutated Rep approach for BBTV resistance. The work presented in this thesis is the first report on the generation of potential BBTV resistant bananas using the mutated Rep approach. In addition, this is the first report on the status of SAR in banana grown under different conditions of exposure to the biotic and abiotic environment. Further, a robust qPCR assay for the study of gene expression using banana leaf samples was developed and a potential inducer of SAR in tissue culture bananas identified which could be harnessed to increase resistance in tissue culture bananas.

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As mentor teachers hold the balance of power in the relationship, how do they build and sustain positive mentor-mentee relationships? This study involved eleven pairs of mentors and mentees (n=22) with audio-recorded interviews to explore their relationships, mentors’ support and mentors’ expectations for mentees’ involvement in the school. Findings suggested ways to build and sustain mentoring relationships (e.g., professionalism, respect, and support). Indeed, support in providing information for planning, access to resources, two-way dialoguing with feedback and reflections, and establishing safe, risk-taking environments to trial and evaluate newly-learnt teaching practices were considered as a ways to build and sustain relationships.

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This article provides a general overview of some of the plant research being conducted by a number of researchers at the Queensland University of Technology (QUT) Brisbane. Details about student projects and research facilities have been limited to those of relevance to plant structure and systematics. Academics, technicians and research students involved in plant research are in the Faculty of Science and Engineering, mainly in the School of Earth, Environment and Biological Sciences (EEBS), with a few exceptions. Our offices and laboratories are housed in a number of different buildings at the Gardens Point campus (e.g., P, Q, R, S, M Blocks) and we have strong collaborative links with Queensland Herbarium (BRI) and Mt Coot-tha Botanic Gardens.

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Plant growth can be limited by resource acquisition and defence against consumers, leading to contrasting trade-off possibilities. The competition-defence hypothesis posits a trade-off between competitive ability and defence against enemies (e.g. herbivores and pathogens). The growth-defence hypothesis suggests that strong competitors for nutrients are also defended against enemies, at a cost to growth rate. We tested these hypotheses using observations of 706 plant populations of over 500 species before and following identical fertilisation and fencing treatments at 39 grassland sites worldwide. Strong positive covariance in species responses to both treatments provided support for a growth-defence trade-off: populations that increased with the removal of nutrient limitation (poor competitors) also increased following removal of consumers. This result held globally across 4 years within plant life-history groups and within the majority of individual sites. Thus, a growth-defence trade-off appears to be the norm, and mechanisms maintaining grassland biodiversity may operate within this constraint.