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1.
Mol Ecol ; 30(20): 5164-5178, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34398981

RESUMO

Various hypotheses have been proposed regarding the origin of the plant pathogen Phytophthora cinnamomi. P. cinnamomi is a devastating, highly invasive soilborne pathogen associated with epidemics of agricultural, horticultural and forest plantations and native ecosystems worldwide. We conducted a phylogeographic analysis of populations of this pathogen sampled in Asia, Australia, Europe, southern and northern Africa, South America, and North America. Based on genotyping-by-sequencing, we observed the highest genotypic diversity in Taiwan and Vietnam, followed by Australia and South Africa. Mating type ratios were in equal proportions in Asia as expected for a sexual population. Simulations based on the index of association suggest a partially sexual, semi-clonal mode of reproduction for the Taiwanese and Vietnamese populations while populations outside of Asia are clonal. Ancestral area reconstruction provides new evidence supporting Taiwan as the ancestral area, given our sample, indicating that this region might be near or at the centre of origin for this pathogen as speculated previously. The Australian and South African populations appear to be a secondary centre of diversity following migration from Taiwan or Vietnam. Our work also identified two panglobal, clonal lineages PcG1-A2 and PcG2-A2 of A2 mating type found on all continents. Further surveys of natural forests across Southeast Asia are needed to definitively locate the actual centre of origin of this important plant pathogen.


Assuntos
Phytophthora , Austrália , Ecossistema , Especificidade de Hospedeiro , Filogeografia , Phytophthora/genética , Doenças das Plantas
2.
J Paediatr Child Health ; 57(11): 1741-1744, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34792233

RESUMO

Humans in their increasing numbers and wealth are changing ecosystems through accelerated consumption of food, natural resources and energy which continue to cause significant damage to the planet. Using 'stunting in children' as a case study, we show how the traditional siloed (specialist) approaches have failed to reduce stunting world-wide. Despite significant effort, traditional approaches fail to appreciate the interconnectedness of the multiple factors that underpin stunting. We will not improve the lives of the millions of children living in poverty by doing the same things we have always done, rather we need to adopt approaches that recognise the interconnectedness of all the component parts and apply One Health methods designed to solve these intractable problems.


Assuntos
Saúde Única , Criança , Ecossistema , Transtornos do Crescimento , Humanos , Lactente , Planetas , Pobreza
3.
J Occup Organ Psychol ; 93(1): 110-133, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32139980

RESUMO

In this study, we explore different pathways during organizational socialization through the lens of the psychological contract using in-depth longitudinal qualitative methods. Analysis of 112 critical incident interviews with 27 newcomers across their first year of work reveals five distinct psychological contract pathways through socialization, within which fulfilment and breach influence adjustment by facilitating or restricting opportunities to learn and integrate, as well as influencing attitudes and behaviour. The analysis reveals that whilst perceived psychological contract fulfilment facilitates newcomer adjustment, perceived breach can disrupt the process. We provide a detailed account of the way socialization and the psychological contract unfold for newcomers over time, and show that psychological contract events can significantly alter the course of adjustment. PRACTITIONER POINTS: Delivery of perceived promises that are of particular importance to newcomers during early tenure can accelerate adjustment. Managers should therefore attempt to find out which promised contributions are important to employees and prioritize their delivery.The negative effects of perceptions of broken promises on newcomer adjustment may be reversed by later delivery. Managers should explain the reasons for any broken promises and seek to fulfil them in the future.Ongoing support from managers can help newcomers to negotiate the difficult period after organizational entry, even where promises are perceived to have been broken.Direct managers should be made aware of information provided and promises made to newcomers by those responsible for recruitment.

4.
Phytopathology ; 109(8): 1331-1343, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31115251

RESUMO

Theobroma cacao, the source of chocolate, is affected by destructive diseases wherever it is grown. Some diseases are endemic; however, as cacao was disseminated from the Amazon rain forest to new cultivation sites it encountered new pathogens. Two well-established diseases cause the greatest losses: black pod rot, caused by several species of Phytophthora, and witches' broom of cacao, caused by Moniliophthora perniciosa. Phytophthora megakarya causes the severest damage in the main cacao producing countries in West Africa, while P. palmivora causes significant losses globally. M. perniciosa is related to a sister basidiomycete species, M. roreri which causes frosty pod rot. These Moniliophthora species only occur in South and Central America, where they have significantly limited production since the beginnings of cacao cultivation. The basidiomycete Ceratobasidium theobromae causing vascular-streak dieback occurs only in South-East Asia and remains poorly understood. Cacao swollen shoot disease caused by Cacao swollen shoot virus is rapidly spreading in West Africa. This review presents contemporary research on the biology, taxonomy and genomics of what are often new-encounter pathogens, as well as the management of the diseases they cause.


Assuntos
Agaricales , Cacau , Chocolate , Agaricales/patogenicidade , Basidiomycota , Cacau/microbiologia , Doenças das Plantas/microbiologia
5.
Phytopathology ; 108(5): 627-640, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29231777

RESUMO

Austropuccinia psidii, causal agent of myrtle rust, was discovered in Australia in 2010 and has since become established on a wide range of species within the family Myrtaceae. Syzygium luehmannii, endemic to Australia, is an increasingly valuable berry crop. Plants were screened for responses to A. psidii inoculation, and specific resistance, in the form of localized necrosis, was determined in 29% of individuals. To understand the molecular basis underlying this response, mRNA was sequenced from leaf samples taken preinoculation, and at 24 and 48 h postinoculation, from four resistant and four susceptible plants. Analyses, based on de novo transcriptome assemblies for all plants, identified significant expression changes in resistant plants (438 transcripts) 48 h after pathogen exposure compared with susceptible plants (three transcripts). Most significantly up-regulated in resistant plants were gene homologs for transcription factors, receptor-like kinases, and enzymes involved in secondary metabolite pathways. A putative G-type lectin receptor-like kinase was exclusively expressed in resistant individuals and two transcripts incorporating toll/interleukin-1, nucleotide binding site, and leucine-rich repeat domains were up-regulated in resistant plants. The results of this study provide the first early gene expression profiles for a plant of the family Myrtaceae in response to the myrtle rust pathogen.


Assuntos
Basidiomycota/patogenicidade , Resistência à Doença/genética , Doenças das Plantas/genética , Syzygium/genética , Transcriptoma , Austrália , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Doenças das Plantas/microbiologia , Syzygium/microbiologia
6.
Phytopathology ; 104(9): 933-44, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24624956

RESUMO

Leaf rust (Puccinia triticina) is a major disease of wheat. We tested aqueous leaf extracts of Jacaranda mimosifolia (Bignoniaceae), Thevetia peruviana (Apocynaceae), and Calotropis procera (Apocynaceae) for their ability to protect wheat from leaf rust. Extracts from all three species inhibited P. triticina urediniospore germination in vitro. Plants sprayed with extracts before inoculation developed significantly lower levels of disease incidence (number of plants infected) than unsprayed, inoculated controls. Sprays combining 0.6% leaf extracts and 2 mM salicylic acid with the fungicide Amistar Xtra at 0.05% (azoxystrobin at 10 µg/liter + cyproconazole at 4 µg/liter) reduced disease incidence significantly more effectively than sprays of fungicide at 0.1% alone. Extracts of J. mimosifolia were most active, either alone (1.2%) or in lower doses (0.6%) in combination with 0.05% Amistar Xtra. Leaf extracts combined with fungicide strongly stimulated defense-related gene expression and the subsequent accumulation of pathogenesis-related (PR) proteins in the apoplast of inoculated wheat leaves. The level of protection afforded was significantly correlated with the ability of extracts to increase PR protein expression. We conclude that pretreatment of wheat leaves with spray formulations containing previously untested plant leaf extracts enhances protection against leaf rust provided by fungicide sprays, offering an alternative disease management strategy.


Assuntos
Apocynaceae/química , Basidiomycota/fisiologia , Bignoniaceae/química , Doenças das Plantas/prevenção & controle , Extratos Vegetais/farmacologia , Triticum/genética , Eletroforese em Gel Bidimensional , Fungicidas Industriais/farmacologia , Doenças das Plantas/microbiologia , Extratos Vegetais/isolamento & purificação , Folhas de Planta/química , Folhas de Planta/genética , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ácido Salicílico/farmacologia , Esporos Fúngicos , Triticum/metabolismo , Triticum/microbiologia
7.
J Healthc Prot Manage ; 28(2): 59-64, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22970624

RESUMO

In this basic introduction and refresher to the art of report writing, the author points out that, besides the importance of the report to the successful handling on an incident, public safety officer reports have a direct relationship to their professionalism. He stresses that sloppy, incomplete and/or incorrect reports can further a perception that the officer is an incompetent and/or ineffective public safety officer.


Assuntos
Documentação/normas , Polícia , Redação/normas , Instalações de Saúde , Competência Profissional , Medidas de Segurança
8.
J Healthc Prot Manage ; 28(1): 59-71, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22423522

RESUMO

The recruiting and selection of professional public safety officers is the first step in developing and maintaining a world class public safety service. Working closely with the human resources department, and utilizing techniques developed by the law enforcement community, the public safety director can build a strong foundation for future growth. This is the first of a series of articles on all aspects of public safety personnel administration.


Assuntos
Administração Hospitalar , Seleção de Pessoal , Gestão da Segurança , Humanos , Aplicação da Lei , Medidas de Segurança
9.
BMC Med Educ ; 11: 13, 2011 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-21473749

RESUMO

BACKGROUND: The professional development of under-represented faculty may be enhanced by mentorship, but we understand very little about the mechanisms by which mentoring brings about change. Our study posed the research question, what are the mechanisms by which mentoring may support professional development in under-represented groups? The study aims to: (i) to pilot a mentoring scheme for female academics; (ii) to compare various health-related and attitudinal measures in mentees at baseline, 6 months, and 1 year into the mentoring relationship and, (iii) to compare pre-mentoring expectations to outcomes at 6 months and 1 year follow-up for mentees and mentors. METHODS: Female academic mentees were matched 1:1 or 2:1 with more senior academic mentors. Online surveys were conducted to compare health-related and attitudinal measures and expectations of mentoring at baseline with outcomes at 6 months and 1 year using paired t-tests and McNemar's test for matched cohort data. RESULTS: N = 46 mentoring pairs, 44 (96%) mentees completed the pre-mentoring survey, 37 (80%) at 6 months and 30 (65%) at 1 year. Job-related well-being (anxiety-contentment), self-esteem and self-efficacy all improved significantly and work-family conflict diminished at 1 year. Highest expectations were career progression (39; 89%), increased confidence (38; 87%), development of networking skills (33; 75%), better time-management (29; 66%) and better work-life balance (28; 64%). For mentees, expectations at baseline were higher than perceived achievements at 6 months or 1 year follow-up. For mentors (N = 39), 36 (92%) completed the pre-mentoring survey, 32 (82%) at 6 months and 28 (72%) at 1 year. Mentors' highest expectations were of satisfaction in seeing people progress (26; 69%), seeing junior staff develop and grow (19; 53%), helping solve problems (18; 50%), helping women advance their careers (18; 50%) and helping remove career obstacles (13; 36%). Overall, gains at 6 months and 1 year exceeded pre-mentoring expectations. CONCLUSIONS: This uncontrolled pilot study suggests that mentoring can improve aspects of job-related well-being, self-esteem and self-efficacy over 6 months, with further improvements seen after 1 year for female academics. Work-family conflict can also diminish. Despite these gains, mentees' prior expectations were shown to be unrealistically high, but mentors' expectations were exceeded.


Assuntos
Mobilidade Ocupacional , Docentes , Mentores , Desenvolvimento de Pessoal , Mulheres Trabalhadoras/psicologia , Adaptação Psicológica , Adulto , Conflito Psicológico , Relações Familiares , Feminino , Humanos , Satisfação no Emprego , Londres , Estudos Longitudinais , Projetos Piloto , Autoimagem , Autoeficácia
10.
Glob Public Health ; 16(11): 1741-1756, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-33091327

RESUMO

ABSTRACTA pilot village volunteer programme (VVP) was implemented to produce new knowledge about the extent to which 24 trained village volunteers, taking an integrated One Health approach, could assist their communities by disseminating information on better agricultural and health practices. Just prior to the six-month pilot, the volunteers were mentored in a four-day training programme by local agricultural extension and public health experts. On returning to their villages, contacts and activities by volunteers with local community members were monitored using a CommCare application, enabling uploaded data to be accessed in real-time. The six volunteers in each village coordinated activities to address concerns of households. The VVP resulted in 960 actions (356 agricultural; 604 health), helping in 97% of contacts, most (55-61%) by providing information and others by advising community members where appropriate information could be sourced. Focus group meetings with village leaders, community health staff and local extension officers supported continuation of the VVP through local funding. Six months after the pilot, volunteers were continuing their activities and assisting with other government measures, such as district programmes to reduce childhood stunting and improve waste disposal. Community empowerment using local human resources is sustainable and could be supportive in government programmes.


Assuntos
Saúde Única , Criança , Promoção da Saúde , Humanos , Indonésia , Projetos Piloto , Voluntários
11.
BMJ Glob Health ; 5(8)2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32843525

RESUMO

Half the children under the age of 5 years in Papua New Guinea (PNG) are undernourished, more than double the global average with rural areas disproportionately affected. This study examines factors associated with stunting, wasting and underweight in cocoa growers' children (<5 years) in the Autonomous Region of Bougainville (ARoB), using data from a comprehensive 2017 cross-sectional livelihoods survey. Sixteen independent predictors for stunting, wasting and underweight were selected based on the UNICEF Conceptual Framework of Determinants of Undernutrition. We used multilevel logistic mixed regression models to measure the association of the explanatory variables with stunting, wasting and underweight. At the household level, the adjusted OR (aOR) of stunting (aOR=1.71,95% CI 1.14 to 2.55) and underweight (aOR=2.11, 95% CI 1.16 to 3.82) increased significantly among children from households with unimproved toilet facilities. The aOR for underweight also increased among children from households without access to clean drinking water (aOR=1.97, 95% CI 1.19 to 3.29). Short maternal stature was significantly associated with child stunting, the odds increased as maternal height decreased (from 150 to <155 cm, aOR=1.52, 95% CI 1.02 to 2.26) (<150 cm, aOR=2.37, 95% CI 1.29 to 4.35). At the individual level, the odds of a child being underweight increased with birth order (second born, aOR=1.92, 95% CI 1.09 to 3.36; third born, aOR=6.77, 95% CI 2.00 to 22.82). Compared with children less than 6 months, children aged 6-23 months and 24-59 months had a higher odds of being stunted (aOR=3.27, 95% CI 1.57 to 6.78 and aOR=2.82, 95% CI 1.40 to 5.67) and underweight (aOR=4.83, 95% CI 1.36 to 17.24 and aOR=4.59, 95% CI 1.29 to 16.26). No variables were found to be significant for wasting. Interventions that simultaneously target key life stages for women and children and the underlying social and environmental determinants are required for sustained improvements to undernutrition.


Assuntos
Desnutrição , Criança , Pré-Escolar , Estudos Transversais , Feminino , Transtornos do Crescimento/epidemiologia , Humanos , Desnutrição/epidemiologia , Prevalência , Magreza/epidemiologia
12.
One Health ; 10: 100143, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32518813

RESUMO

Cocoa production is the major contributor to livelihoods for farming families that constitute nearly two-thirds of the population of the Autonomous Region of Bougainville, a Province in Papua New Guinea (PNG). These families, living mostly in subsistence poverty as a result of the Bougainville Civil War (1988-98), have significantly reduced cocoa production. Efforts to rebuild the industry have not been realised, due to known agricultural factors such as labour shortages, pests and diseases, poor support for farmers from trained agricultural extension officers and inefficient cocoa supply chains. But cocoa production involves factors other than agricultural ones. This article describes how we applied One Health methods to design and undertake a 6-year research project in Bougainville to improve cocoa productivity. Maximising the health and wellbeing of farming families and increasing agricultural productivity we argue, requires an in-depth understanding of the non-linear interactions between health, labour, household decision-making, yields and incomes.

13.
One Health ; 10: 100142, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32509957

RESUMO

BACKGROUND: Bougainville, an autonomous region of Papua New Guinea (PNG) is slowly improving services and infrastructure destroyed 20 years ago during the ten year civil war. However, the region still faces significant constraints to economic growth and human development and remains under-developed compared to PNG and close Pacific neighbours. PNG's 2017 Human Development Category (HDC) was one of the lowest at 0.544. The Bougainville Strategic Development Plan 2018-2022 noted significant gaps in health services and infrastructure, had inadequate water and waste disposal and experienced weak markets and cocoa quality. This research examines domestic conditions and the extent to which they impact on livelihoods. METHOD: A cross-sectional livelihood survey was administered to cocoa growing households in 33 Village Assemblies (VAs) with 11 VAs in each of the three regions. RESULTS: Data was collected from 5172 individuals. A significant majority of households reported multiple health issues, rudimentary housing, unimproved sanitation and unimproved water. Over two-thirds of cocoa growers did not sell any cocoa bags in 2014-2016 resulting in low incomes and greater food insecurity compared to families selling cocoa. Families that produced no saleable cocoa were more likely to have rudimentary housing, unimproved toilet facilities and unsafe water, factors that increase the likelihood of chronic disease and exacerbate malnutrition and poor labour productivity. CONCLUSION: This study provides key information about the health and livelihood status of cocoa growers in Bougainville. If productivity is to increase, farmer health needs to improve including improving water and sanitation practices and diets. Building a responsive health system for the community is a challenge when a majority of the population live in small villages with difficult access to health centres. Establishing and integrating outreach village health clinics will enable health care to be more accessible to these remote communities.

14.
Artigo em Inglês | MEDLINE | ID: mdl-31583107

RESUMO

BACKGROUND: Ceratobasidium theobromae, a member of the Ceratobasidiaceae family, is the causal agent of vascular-streak dieback (VSD) of cacao, a major threat to the chocolate industry in the South-East Asia. The fastidious pathogen is very hard to isolate and maintain in pure culture, which is a major bottleneck in the study of its genetic diversity and genome. RESULT: This study describes for the first time, a 33.90 Mbp de novo assembled genome of a putative C. theobromae isolate from cacao. Ab initio gene prediction identified 9264 protein-coding genes, of which 800 are unique to C. theobromae when compared to Rhizoctonia spp., a closely related group. Transcriptome analysis using RNA isolated from 4 independent VSD symptomatic cacao stems identified 3550 transcriptionally active genes when compared to the assembled C. theobromae genome while transcripts for only 4 C. theobromae genes were detected in 2 asymptomatic stems. De novo assembly of the non-cacao associated reads from the VSD symptomatic stems uniformly produced genes with high identity to predicted genes in the C. theobromae genome as compared to Rhizoctonia spp. or genes found in Genbank. Further analysis of the predicted C. theobromae transcriptome was carried out identifying CAZy gene classes, KEGG-pathway associated genes, and 138 putative effector proteins. CONCLUSION: These findings put forth, for the first time, a predicted genome for the fastidious basidiomycete C. theobromae causing VSD on cacao providing a model for testing and comparison in the future. The C. theobromae genome predicts a pathogenesis model involving secreted effector proteins to suppress plant defense mechanisms and plant cell wall degrading enzymes.

15.
One Health ; 8: 100107, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31890845

RESUMO

We conducted an interdisciplinary One Health study of potential links between agricultural, health and associated livelihood factors on the livelihoods of smallholder cocoa-growing families in West Sulawesi. Our 2017 survey of 509 cocoa smallholder family members in 120 households in Polewali-Mandar District, West Sulawesi, Indonesia showed that farmers face many challenges to improving their livelihoods, including land management, agricultural practices, nutrition and human health, animal health, aging and demographic changes. Price fluctuations, limited access to capital and poor health deterred farmers from applying agricultural inputs and resulted in levels of low cocoa production (275 kg/annum per household). While market demand for live goats in the region is substantial and expected to increase, uptake of mixed farming with goats by smallholders was low. However, most households kept chickens. Bank accounts were held by 31% of households. Inadequate sanitation and unsafe water were reported in >50% households. Anthropometric measures showed that 42% of children under five years were significantly stunted and 32% of women were overweight. Joint, back pain and blurry vision were reported by 30% of adult respondents. High blood pressure contributed to complications in 20% of pregnancies. Primary health care provided by district health services mainly focuses on maternal and child health, leaving chronic health problems such as Type 2 diabetes, cataracts, arthritis and mental illness under-diagnosed, and if diagnosed, with inadequate treatment. Availability of food was a source of worry for 58% of households with 63% reporting limited food variety. Dietary diversity was low with an average of four out of ten food categories consumed in each household. Positive correlations were recorded for household cocoa productivity, land size, dietary diversity and perceptions that food availability and variety was sufficient. The results showed that an integrated One Health approach provides deep understanding of priority areas for improving livelihoods.

16.
Phytopathology ; 97(12): 1650-3, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18943728

RESUMO

ABSTRACT Pathogens of the Straminipile genus Phytophthora cause significant disease losses to global cocoa production. P. megakarya causes significant pod rot and losses due to canker in West Africa, whereas P. capsici and P. citrophthora cause pod rots in Central and South America. The global and highly damaging P. palmivora attacks all parts of the cocoa tree at all stages of the growing cycle. This pathogen causes 20 to 30% pod losses through black pod rot, and kills up to 10% of trees annually through stem cankers. P. palmivora has a complex disease cycle involving several sources of primary inoculum and several modes of dissemination of secondary inoculum. This results in explosive epidemics during favorable environmental conditions. The spread of regional pathogens must be prevented by effective quarantine barriers. Resistance to all these Phytophthora species is typically low in commercial cocoa genotypes. Disease losses can be reduced through integrated management practices that include pruning and shade management, leaf mulching, regular and complete harvesting, sanitation and pod case disposal, appropriate fertilizer application and targeted fungicide use. Packaging these options to improve uptake by smallholders presents a major challenge for the industry.

17.
Phytopathology ; 97(12): 1654-7, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18943729

RESUMO

ABSTRACT The basidiomycete Oncobasidium theobromae was identified as the cause of a devastating disease of cacao named vascular-streak dieback (VSD) in Papua New Guinea in the 1960s. VSD now causes losses among cacao seedlings and kills branches in mature cacao trees throughout Southeast Asia and parts of Melanesia. The characteristic symptoms include a green-spotted chlorosis and fall of leaves beginning on the second or third flush behind the stem apex, raised lenticels, and darkening of vascular traces at the leaf scars and infected xylem. Eventually complete defoliation occurs and, if the fungus spreads to the trunk, the tree will die. O. theobromae is a highly specialized, near-obligate parasite of cocoa. It is a windborne, leaf-penetrating, vascular pathogen, and may have evolved as an endophyte on an as yet unidentified indigenous host. The rate of disease spread on cocoa is limited because basidiocarps develop only on fresh leaf scars during wet weather, and basidiospores remain viable for a few hours on the night they are shed. Consequently, very few new infections occur beyond 80-m from diseased trees. Transmission of the disease through seed or infected cuttings has not been demonstrated. Strict quarantine measures applied to the movement of intact plants are crucial in reducing spread of the disease. Integrated management, including the planting of less susceptible genotypes, nursery construction and management, canopy pruning and shade management, provides effective control.

18.
Tree Physiol ; 37(5): 565-582, 2017 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-28338992

RESUMO

Eucalyptus grandis (W. Hill ex Maiden) is an Australian Myrtaceae tree grown for timber in many parts of the world and for which the annotated genome sequence is available. Known to be susceptible to a number of pests and diseases, E. grandis is a useful study organism for investigating defense responses in woody plants. Chitinases are widespread in plants and cleave glycosidic bonds of chitin, the major structural component of fungal cell walls and arthropod exoskeletons. They are encoded by an important class of genes known to be up-regulated in plants in response to pathogens. The current study identified 67 chitinase gene models from two families known as glycosyl hydrolase 18 and 19 (36 GH18 and 31 GH19) within the E. grandis genome assembly (v1.1), indicating a recent gene expansion. Sequences were aligned and analyzed as conforming to currently recognized plant chitinase classes (I-V). Unlike other woody species investigated to date, E. grandis has a single gene encoding a putative vacuolar targeted Class I chitinase. In response to Leptocybe invasa (Fisher & La Salle) (the eucalypt gall wasp) and Chrysoporthe austroafricana (Gryzenhout & M.J. Wingf. 2004) (causal agent of fungal stem canker), this Class IA chitinase is strongly up-regulated in both resistant and susceptible plants. Resistant plants, however, indicate greater constitutive expression and increased up-regulation than susceptible plants following fungal challenge. Up-regulation within fungal resistant clones was further confirmed with protein data. Clusters of putative chitinase genes, particularly on chromosomes 3 and 8, are significantly up-regulated in response to fungal challenge, while a cluster on chromosome 1 is significantly down-regulated in response to gall wasp. The results of this study show that the E. grandis genome has an expanded group of chitinase genes, compared with other plants. Despite this expansion, only a single Class I chitinase is present and this gene is highly up-regulated within diverse biotic stress conditions. Our research provides insight into a major class of defense genes within E. grandis and indicates the importance of the Class I chitinase.


Assuntos
Quitinases/genética , Eucalyptus/genética , Família Multigênica , Estresse Fisiológico , Animais , Ascomicetos/patogenicidade , Austrália , Eucalyptus/enzimologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Regulação para Cima , Vespas
19.
Annu Rev Phytopathol ; 54: 373-95, 2016 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-27491435

RESUMO

The tropics produce a range of fruit from tree crops that cannot be grown in colder climates. Bananas, mangos, several nuts, spices, coffee, and cacao are widely traded and much sought after around the world. However, the sustainable production of these tropical tree fruit crops faces significant challenges. Among these, losses due to pests and diseases play a large part in reducing yields, quality, and profitability. Using bananas and cacao as key examples, we outline some of the reasons fungal and oomycete diseases cause such significant losses to tropical tree crops. Cultivation of monocultures derived from limited genetic diversity, environmental conditions conducive for disease development, high levels of disease incidence and severity, a lack of disease resistance in planting materials, shortages of labor, and inadequate infrastructure and investment pose significant challenges, especially for smallholder producers. The expansion of travel and trade has given rise to emerging infectious plant diseases that add further insecurity and pressure. We conclude that holistic actions are needed on multiple fronts to address the growing problem of disease in tropical fruit tree crops.


Assuntos
Fungos/fisiologia , Musa/microbiologia , Oomicetos/fisiologia , Doenças das Plantas/microbiologia , Produtos Agrícolas/economia , Produtos Agrícolas/genética , Produtos Agrícolas/imunologia , Produtos Agrícolas/microbiologia , Frutas/microbiologia , Musa/genética , Doenças das Plantas/economia , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Árvores/microbiologia , Clima Tropical
20.
Mol Plant Pathol ; 17(5): 783-8, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26575410

RESUMO

Resistance genes (R genes) in plants mediate a highly specific response to microbial pathogens, often culminating in localized cell death. Such resistance is generally pathogen race specific and believed to be the result of evolutionary selection pressure. Where a host and pathogen do not share an evolutionary history, specific resistance is expected to be absent or rare. Puccinia psidii, the causal agent of myrtle rust, was recently introduced to Australia, a continent rich in myrtaceous taxa. Responses within species to this new pathogen range from full susceptibility to resistance. Using the myrtle rust case study, we examine models to account for the presence of resistance to new encounter pathogens, such as the retention of ancient R genes through prolonged 'trench warfare', pairing of resistance gene products and the guarding of host integrity.


Assuntos
Basidiomycota/fisiologia , Resistência à Doença/genética , Myrtus/genética , Myrtus/microbiologia , Doenças das Plantas/microbiologia , Austrália , Genes de Plantas , Interações Hospedeiro-Patógeno
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