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Foliar pine pathogens from different kingdoms share defence-eliciting effector proteins
No full textDothistroma needle blight, Cyclaneusma needle blight and red needle cast are devastating foliar pine diseases caused by the fungi Dothistroma septosporum and Cyclaneusma minus and the oomycete Phytophthora pluvialis, respectively. These pathogens colonise the host apoplast, secreting effector proteins to promote infection and disease. If these effectors are recognised by corresponding host resistance proteins, they activate the plant immune system to stop pathogen growth. We aimed to identify and characterise effectors that are common to all three pathogens. Using D. septosporum as a starting point, three candidate effectors (CEs) were investigated: Ds69335 (a CAP protein) and Ds131885, both of which have sequence and structural similarity to CEs of C. minus and P. pluvialis, and Ds74283, which adopts a β-trefoil fold and has structural rather than sequence similarity to CEs from all three pathogens. Notably, of the CEs investigated, Ds74283 and Ds131885, as well as their homologues from C. minus and P. pluvialis, elicited chlorosis or cell death in Nicotiana species, with Ds131885 and its homologues also triggering cell death in Pinus radiata. In line with these observed responses being related to activation of the plant immune system, the chlorosis triggered by Ds131885 and its homologues was compromised in a Nicotiana benthamiana mutant lacking the extracellular immune system co-receptor, SOBIR1. Such cross-kingdom, plant immune system-activating effectors, whether similar in sequence or structure, might ultimately enable the selection or engineering of durable, broad-spectrum resistance against foliar pine pathogen
Species of the botryosphaeriaceae are associated with blackcurrant dieback in New Zealand
No full textDieback of blackcurrants (Ribes nigrum) is an increasing problem worldwide with several pathogens including the Botryosphaeriaceae species, Neofusicoccum ribis, reported as being associated with dieback. To identify the species of Botryosphaeriaceae associated with blackcurrant dieback in New Zealand, isolations were carried out from plant samples with dieback symptoms collected from blackcurrant orchards in the main growing areas in the South Island of New Zealand. For one site, symptomatic grapevines in an adjacent vineyard were also sampled as they are known hosts of these species. The pathogenicity of representative isolates from each of the species recovered was determined on detached blackcurrant shoots. Of the 242 symptomatic plant materials collected, 29% were infected by Botryosphaeriaceae. Species of Botryosphaeriaceae were recovered from plant samples from all four orchards sampled. Of the 70 Botryosphaeriaceae isolates recovered from blackcurrant, Diplodia seriata (43 isolates) and D. mutila (17 isolates) were the most prevalent species, with Neofusicoccum australe (6 isolates), N. cryptoaustrale (3 isolates) and one isolate of D. sapinea also recovered. D. seriata, D. mutila, N. australe and N. cryptoaustrale were also recovered from symptomatic grapevine tissues sampled from the adjacent vineyard and all but N. cryptoaustrale were found in the blackcurrant crop adjacent to this vineyard. All species were pathogenic on detached green shoots, with N. australe and N. cryptoaustrale the most pathogenic, producing the longest lesions compared with D. seriata and D. mutila. This is the first study on the incidence and pathogenicity of species of the Botryosphaeriaceae infecting blackcurrant plants in New Zealand
Phosphorus fertility regulates microbial carbon use efficiency and SOM decomposition in non-allophanic Andosols
No full textPhosphorus (P) availability affects soil carbon (C) cycling such as microbial carbon use efficiency (CUE) and priming effects (PEs). While non-allophanic Andosols are characterized by high organic C content and strong P retention, the effects of different soil P fertility levels on C dynamics in these soils remain poorly understood. In this study, we conducted a 20-day incubation experiment using ¹³C-enriched glucose to investigate how different soil P levels (Truog-P: 157 mg P kg¯¹ and 12 mg P kg¯¹) impacted microbial C dynamics in non-allophanic Andosols under different field management practices. Our results showed that soil organic matter (SOM) priming strongly depends on soil P levels, although total primed CO₂-C emissions were low in these soils. The addition of glucose alone promoted positive PEs compared to the addition of glucose with nitrogen (N). In high P soils, glucose and N addition resulted in negative PEs, whereas in low P soils, the same treatment stimulated microbial SOM mining, resulting in positive PEs. Additionally, higher CUE was found in high P soils than in low P soils after 20 days of incubation. These findings suggest that soil P levels influence both substrate-induced microbial assimilation and SOM decomposition. In P-limited soils, microbial P requirements drive SOM decomposition, which in turn regulates CUE. This study contributes to an understanding of the role of P in soil C cycling and provides insights into soil fertility management strategies for improving C sequestration in non-allophanic Andosols
Promoting diversity of thought: bridging knowledge systems for a pluriverse approach to research
No full textDiversity of thought is vital for research, yet different knowledge systems and disciplines are often viewed as incompatible. Bioprotection Aotearoa (BA), a National Centre of Research Excellence, leads research to protect ecosystems in Aotearoa New Zealand and the Pacific from biological threats such as pathogens, pests and weeds. It centres itself around a research framework led by Indigenous values. We examine whether and how BA’s placement of Indigenous knowledge at its core and its efforts to inspire trans- and interdisciplinary research promotes and sustains a pluriverse perspective. Through thematic analysis of expert interviews, we identify key factors influencing pluriversality and reflect on how these influence diversity, equity and inclusion. Interviewees outline that placing Indigenous and scientific knowledge systems on an equal footing improves diversity practices overall. Essential drivers that encourage pluralism of thought and engagement with multiple knowledges and practices are identified as: intentional community-building efforts, clear operational guidelines and deliberate alignment of research efforts towards a synergy of Indigenous knowledge with Western perspectives. Interviewees point to barriers such as time constraints, limited resources, disciplinary silos and a bias toward the status quo. Our case study highlights the importance of leadership and organizational guidance in embracing a pluriverse approac
In pursuit of water policy nirvana: Examining the role of catchment groups in Aotearoa New Zealand
No full textWater quality decline has proven to be an intractable policy problem worldwide due to the complexity of multiple interests in land and water use. In Aotearoa New Zealand, a proliferation of local catchment groups, including collectives of farmers and other land users and stakeholders, raises important questions about the scope for government to direct collective management towards water policy implementation, and the opportunities and pitfalls of doing so. This paper draws on evidence from a collaborative research project in Aotearoa New Zealand to consider how an emerging catchment-group–led approach might address water policy goals. We examine the emergent policy narrative around catchment groups as a water management solution, and the investment in this approach by government agencies, industry bodies and non-governmental organisations. We then explore a diversity of experiences across four case study catchments. Our focus is on group membership, purpose, relationships, structure and resourcing, with the aim of illustrating how these characteristics of catchment groups influence their ability to carry out policy-relevant actions. We argue that efforts to enlist catchment groups in policy implementation have uneven consequences and that agencies and catchment groups alike should pay attention to the alignment between policy goals and group purpose, to the value of diversity and difference among groups, and to the fine line between supporting and instrumentalising groups towards implementing freshwater policy
Fuel architecture influences interspecific variation in shoot flammability, but not as much as leaf traits
No full text1. Plant flammability is strongly influenced by functional traits, meaning that the quantitative measurement of trait–flammability relationships is key to understanding why some species burn better than others. While relationships between flammability and leaf traits are well-studied, the role of architectural traits has rarely been assessed. Shoots preserve some of the architecture of plants; therefore, shoot-level trait–flammability relationships offer great promise for determining the relative influence of fuel architecture and leaf traits on flammability.
2. We quantified plant flammability by burning 70-cm-long shoot samples from 65 species of indigenous and exotic New Zealand trees and shrubs and measured a range of leaf and fuel architectural traits on the same individuals. The influence of species' evolutionary history on flammability variation was also quantified.
3. Most of the variation in flammability and functional traits was explained by between-species differences. No significant phylogenetic signal was detected for the flammability variables measured in this study. Fuel architecture influenced shoot flammability, and along with leaf traits, explained a high proportion (41%–54%) of flammability variation. Branching patterns (number of ramifications and sub-branches) was the key architectural trait that was strongly positively correlated with flammability. Other architectural traits, such as foliage and twig fraction mass, and fuel bulk density were also significantly associated with some flammability variables. Leaf dry matter content (LDMC; positive relationship) and leaf thickness (negative relationship) were the leaf traits most strongly correlated with shoot flammability.
4. Synthesis. Our study addresses a key knowledge gap by demonstrating the influence of fuel architecture on shoot flammability and improves our understanding of why species with certain architecture (e.g. highly branched) burn better than others. However, leaf traits such as leaf dry matter content (LDMC) and leaf thickness emerged as having a relatively stronger influence on flammability than architectural traits. Where available, traits such as LDMC, leaf thickness and branching pattern can be effective surrogates of plant flammability and can be used to improve global dynamic vegetation models and fire behaviour models. However, several architectural traits are time-consuming to measure, so where they are not available, it will be quicker to simply measure shoot flammability
Gaps in environmental and social evidence base are holding back strategic action on our national food system
No full textWhile there is broad agreement on the challenges facing the Aotearoa New Zealand food system now and in the near future, there is less agreement on the action to be taken. Poor agreement is fuelled by gaps in both our scientific understanding of the food system and data to support our decision making, particularly in the environmental and social spaces. Filling these gaps and being transparent about scientific confidence in future predictions will strengthen the evidence base for action
Psychological and thermal responses to urban green space exposure among elderly: a comparative study of chronic and non-chronic disease populations
No full textWith the intensifying processes of climate change and population aging, elderly populations are increasingly exposed to significant climate-related health risks. Urban green spaces serve as crucial venues for physical activity, social interaction, and mental restoration among the elderly, providing numerous health benefits. This study employed meteorological measurements and questionnaire surveys to investigate older adults' thermal perceptions and psychological responses to winter exposure in green spaces, comparing differences between two groups: those with chronic diseases and those without. The research specifically analyzed changes in thermal and psychological responses as participants transitioned from urban built environments to neighborhood green spaces and then returned to urban built environments. Such alternating experiences of diverse urban environments reflect the authentic Living conditions of urban residents. Findings are as follows: 1) Exposure to green spaces improved the psychological Health of older adults, with more significant and sustained improvements in emotional well-being for the chronic disease group. 2) The cold tolerance of the chronic disease group was inferior to that of the non-chronic disease group. Exposure to green spaces enhanced older adults' thermal comfort, increasing their tolerance to low temperatures, with more pronounced and sustained effects observed in the chronic disease group. 3) Psychological factors influenced older adults' thermal perceptions, with positive emotions serving as the key moderating variable. Urban green spaces could effectively enhance thermal comfort by mediating improvements in positive emotions, a benefit that is especially pronounced among older adults with chronic disease
The effect of medium and cold preconditioning on in vitro carpogenic germination of sclerotia of different Sclerotinia sclerotiorum isolates in New Zealand
No full textSclerotia of Sclerotinia sclerotiorum germinate carpogenically developing apothecia and release ascospores which act as an inoculum in the field. Identifying the factors influencing the carpogenic germination of sclerotia is important in management of the pathogen. This study assessed the effect of medium and cold preconditioning on in vitro carpogenic germination of sclerotia and development of apothecia. Carpogenic germination was tested in sand, water agar and potting mixture and the effect of preconditioning of sclerotia at 4°C was assessed for isolates originating from different locations in New Zealand. Sclerotia germination and number of apothecia per plate were greater in water agar compared with potting mix. Development of stipes into apothecia was greater in compost compared with water agar. The isolates from sub-tropical Auckland region showed greater carpogenic germination than most of the isolates from temperate Canterbury region under the experimental conditions used in the study. A few isolates showed a positive or negative response to cold preconditioning hence, no conclusions as to possible ecological adaptation of S. sclerotiorum to the field conditions in which the isolates originated could be made. The prominent isolate effect on all aspects of carpogenic germination assessed highlights the need to include several isolates in future studies
Low richness of invasive non-native plants in New Zealand indigenous forests may not reflect low impact
No full textAim: Identifying habitats vulnerable to plant invasions is essential for developing efficient management programmes. We assessed trends in richness and cover of non-native plants in indigenous shrublands and forests across New Zealand. We investigated whether species classed as invasive species exhibited higher levels of plant invasion than naturalised species and the extent to which this reflected plant life form.
Location: New Zealand.
Time Period: From January 2009 to March 2014. Major Taxa Studied: Plant.
Methods: We analysed 839 permanent 20 × 20 m plots spread across New Zealand that could be classified to a recognised forest type: mānuka-kānuka shrubland, beech, beech-broadleaved, beech-broadleaved-podocarp and broadleaved-podocarp forests. Generalised additive models were run with native canopy richness or cover and spatial coordinates as co-variables in order to compare non-native plant richness and cover across forest types in relation to their invasive status and growth form. Results: Overall, 35% of the plots had at least one non-native species. Mānuka-kānuka shrubland exhibited the highest mean non-native richness (11 species) and cover (32%) with broadleaved-podocarp forest presenting the next highest invasion level but to a much lesser extent (1.7 species and 3% cover). Despite presenting overall greater non-native richness, naturalised species had lower cover than invasive species (4.2%, 13.5%, respectively). This pattern was mainly related to non-native woody species that, despite their low richness, can reach greater cover than herbaceous species once established.
Main Conclusions: Despite half the New Zealand flora being composed of non-native plant species, relatively few were found in forest habitats. However, indigenous shrubland and early successional forests showed higher vulnerability to plant invasion. Woody species, which are overrepresented among invasive species, had higher cover than herbaceous species and were less limited by native canopy cover. Such findings highlight the threat posed by non-native woody species and the need for more targeted management programmes