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Modification of xylan in secondary walls alters cell wall biosynthesis and wood formation programs and improves saccharification
Full text linkWood of broad-leaf tree species is a valued source of renewable biomass for biorefinery and a target for genetic improvement efforts to reduce its recalcitrance. Glucuronoxylan (GX) plays a key role in recalcitrance through its interactions with cellulose and lignin. To reduce recalcitrance, we modified wood GX by expressing GH10 and GH11 endoxylanases from Aspergillus nidulans in hybrid aspen (Populus tremula L. x tremuloides Michx.) and targeting the enzymes to cell wall. The xylanases reduced tree height, modified cambial activity by increasing phloem and reducing xylem production, and reduced secondary wall deposition. Xylan molecular weight was decreased, and the spacing between acetyl and MeGlcA side chains was reduced in transgenic lines. The transgenic trees produced hypolignified xylem having thin secondary walls and deformed vessels. Glucose yields of enzymatic saccharification without pretreatment almost doubled indicating decreased recalcitrance. The transcriptomics, hormonomics and metabolomics data provided evidence for activation of cytokinin and ethylene signalling pathways, decrease in ABA levels, transcriptional suppression of lignification and a subset of secondary wall biosynthetic program, including xylan glucuronidation and acetylation machinery. Several candidate genes for perception of impairment in xylan integrity were detected. These candidates could provide a new target for uncoupling negative growth effects from reduced recalcitrance. In conclusion, our study supports the hypothesis that xylan modification generates intrinsic signals and evokes novel pathways regulating tree growth and secondary wall biosynthesis.Fungal xylanases expressed in aspen decreased lignin content in the wood of transgenic lines due to downregulation of a subset of lignin biosynthetic genes. This greatly increased saccharification potential. Transgenic plants exhibited altered growth and several signaling and regulatory genes were found affected that could mediate these effects via xylobiose signaling
Microbial assisted alleviation of nickel toxicity in plants: A review
Full text linkNickel (Ni) is required in trace amounts (less than 500 µg kg−1) in plants to regulate metabolic processes, the immune system, and to act as an enzymatic catalytic cofactor. Conversely, when nickel is present in high concentration, it is considered as a toxic substance. Excessive human nickel exposure occurs through ingestion, inhalation, and skin contact, ultimately leading to respiratory, cardiovascular, and chronic kidney diseases. Due to anthropogenic activities, the nickel concentrations in various environmental scenarios have progressively risen to levels as high as 26,000 ppm in soil and 0.2 mg L−1 in water; surpassing the established safety threshold limits of 100 ppm for soil and 0.005 ppm for surface water. Nickel is required by various plant species for facilitating biological processes; in the range of 0.01–5 µg g−1 (dry weight). When present in excess, nickel toxicity in plants (10–1000 mg kg−1 dry weight mass) causes many disrupted metabolic processes; leading to lower growth, altered development, hindered seed germination, chlorosis, and necrosis. To tackle any metal-linked pollution issues, various remediation approaches are employed to remove heavy metals (especially nickel) and metalloids including physicochemical, and biological methods. Based on literature, the physicochemical methods are not commonly used due to their costly nature and the potential for producing secondary pollutants. Interestingly, bioremediation is considered by many practitioners as an easy-to-handle, efficient, and cost-effective approach, encompassing techniques such as phytoremediation, bioleaching, bioreactors, green landforming, and bio-augmentation. Operationally, phytoremediation is widely utilized for cleaning up contaminated sites. To support the phytoremediative processes, numerous nickel hyperaccumulating plants have been identified; these species can absorb from their surroundings and store high concentrations of nickel (through various mechanisms) in their biomass, thereby helping to detoxify nickel-contaminated soils via phytoextraction. The microbe-assisted phytoremediation further optimizes the nickel detoxification processes by fostering beneficial interactions between microbes and the nickel-hyperaccumulators; promoting enhanced metal uptake, transformation, and sequestration. Microbe-assisted phytoremediation can be categorized into four subtypes: bacterial-assisted phytoremediation, cyanoremediation, mycorrhizal-assisted remediation, and rhizoremediation. These diverse approaches are likely to offer more effective and sustainable remediative strategy to ecologically restore the nickel-contaminated environments
Losing lemurs: Declining populations and land cover changes over space and time
Full text linkForest loss and degradation due to land cover changes imperil biodiversity worldwide. Subtropical and tropical ecosystems experience high deforestation rates, negatively affecting species like primates. Madagascar's endemic lemurs face exceptionally high risks of population declines and extirpation. We examined how short-term land cover changes within a fragmented landscape in southeastern Madagascar impacted the density of lemur species. Using line transects, we assessed density changes in nine lemur species across five forest fragments. Diurnal surveys were conducted monthly from 2015 to 2019 on 35 transects (total effort = 1268 km). Additionally, 21 transects were surveyed nocturnally in 2015 and 2016 (total effort = 107.5 km). To quantify forest cover changes, we generated land use/land cover (LULC) maps from Sentinel-2 imagery using supervised classification for each year. For the LULC maps, we overlayed species-specific buffers around all transects and calculated the proportion of land cover classes within them. We observed declines in the annual densities of four diurnal and cathemeral lemur species between 2015 and 2019, with species-specific declines of up to 80% (Varecia variegata). While the density of two nocturnal species decreased, one increased fivefold (Cheirogaleus major) between 2015 and 2016. By 2019, Grassland was the dominant land type (50%), while Paddy Fields had the smallest coverage (1.03%). Mature Agricultural Land increased the most (63.37%), while New Agricultural Land decreased the most (-66.36%). Unexpectedly, we did not find evidence that higher forest cover supported a higher lemur population density within sampled areas, but we found support for the negative impact of degraded land cover types on three lemur species. Our study underscores the urgent need to address land-use changes and their repercussions for primate populations in tropical ecosystems. The diverse responses of lemur species to modified habitats highlight the complexity of these impacts and emphasize the importance of targeted conservation efforts.Losing lemurs: declining populations and land cover changes over space and time. imageKianjavato experienced a substantial loss of forest cover between 2015 and 2019, with an average annual forest loss (3.4%) that is considerably higher than the national average (1.1%). We observed a decrease in the density of six out of seven lemur species in the Kianjavato forest fragments. Structurally simpler land cover types such as grasslands emerged as a factor negatively influencing the density of three lemur species, while tree fallow positively influenced three species
Svenska laxbestånd i Östersjön
Full text linkDe vilda laxbestånden i Bottniska viken har generellt uppvisat en positiv utveckling sedan slutet av 1990-talet, och flera älvbestånd uppnår idag det MSY-baserade förvaltningsmålet. Laxens överlevnad i havet har dock försämrats under de senaste 2-3 åren. Bakomliggande orsaker till nedgången är oklara, men forskning pågår för att öka kunskapen om faktorer som påverkar laxens överlevnad i havet. Om den låga överlevnaden i havet fortsätter under en längre period förväntas detta resultera i kraftigt försämrad tillgång på lax vilket kommer påverka fiskemöjligheterna i både havet och älvarna.Laxbestånden i södra Östersjön har sedan slutet av 1990-talet inte uppvisat samma positiva utvecklingstrend som laxen i Bottniska viken, och flera av de sydliga bestånden bedöms fortfarande ha låg status.Fisket efter lax har förändrats under de senaste årtiondena, från att ha varit ett utpräglat blandbeståndsfiske i havet och längs kusterna, till att ske framförallt längs kusterna i Bottniska viken och i älvarna. Ett stort inslag av blandbeståndsfiske finns dock fortfarande i form av yrkes- och fritidsfiske längs Sveriges och Finlands kuster, samt som fritidsfiske i södra Östersjön. Exploateringsgraden (andel av den fiskbara resursen som fiskas upp) under 2022 beräknades till mellan 1 och 3 % i södra Östersjön, medan exploateringsgraden längs Sveriges och Finlands kuster samma år varierade mellan bestånd med ett genomsnitt på 12 %. Mer osäkra skattningar av exploateringsgraden i älvfisket indikerar att odlade bestånd genomgående exploateras relativt hårt (medelvärde på 16 % under 2022) medan exploateringsgraden av vild lax är betydligt lägre men varierar kraftigt mellan älvar (0-15 % med medelvärde på 3 % under 2022).En nationell indelning av laxbestånden i förvaltningskategorier, baserad på status och förväntad framtida utveckling (samt eventuell annan information), bedöms kunna underlätta anpassningen av fiskeregler till beståndssituationen. I detta underlag presenteras ett uppdaterat förslag på hur ett sådant system kan utformas. Den uppdaterade modellen för indelning av bestånden i förvaltningskategorier har breddats till att omfatta även åtgärdsbehov i sötvatten utöver fiskeregleringar, exempelvis behov av habitatrestaureringar eller förbättrade möjligheter för fiskvandring.Det är önskvärt att utvecklingen av en beståndsanpassad fiskeförvaltning fortsätter för att i högre grad kunna styra fisket mot odlad lax och starkare vildlaxbestånd i syfte att förbättra möjligheterna till återhämtning för svagare vilda bestånd. Sådana möjligheter bedöms finnas på nationell svensk nivå, även om detta kan kräva kompletterande data och analyser. Det finns även behov av att implementera ekosystemansatsen i fiskeförvaltningen i stort, för att i högre omfattning än hittills kunna ta hänsyn till artinteraktioner och fiskets påverkan på ekosystemen
A longitudinal study of the dynamics of Mycoplasma bovis antibody status in primiparous cows and bulk tank milk in Swedish dairy herds
Full text linkMycoplasma bov/s is an important pathogen causing pneumonia, mastitis, and arthritis in cattle all over the world entailing reduced animal welfare and economic losses. In this longitudinal study, we investigated the presence ofM. bov/s antibodies in bulk tank milk (BTM) and in milk from primiparous (PP) cows at 4 sampling occasions over 2 yr. Herd characteristics associated with a positive antibody test result in PP cows were investigated. The participating dairy herds (n = 149) were situated in southern Sweden, samples were collected and analyzed with ID Screen antibody ELISA. Information on herd characteristics was retrieved from the national DHI database. To identify herd characteristics associated with the presence of antibodies in PP cows, mixed linear regression with herd and sample as random factors were used. The apparent herd-level prevalence of M. bov/s infection based on antibodies in BTM was 17%, but with the addition of PP cows, the prevalence increased to 28%. The results showed that larger herds and introduction of cattle was associated with higher antibody levels in PP cows. In conclusion, this study showed a clear difference in the apparent prevalence ofM. bov/s infection based on antibodies in BTM or in PP cows: The number of positive herds was almost doubled when including PP cows. This motivates repeated sampling of a few PP cows to find newly infected herds in an early stage. Finally, the results showed that introduction of cattle influences the level of M. bov/s antibodies. This is important in the control and prevention of further spread of the infection. It is essential for free herds to know their M. bov/s status, and antibody testing is highly recommended if introducing cattle
Grazing at high latitudes
Full text linkThe intensification of the dairy industry has led to less reliance on grazing as a primary animal feed source in both Norway and Sweden. The livestock sector is also under considerable societal pressure to reduce its climate footprint. Indeed, enteric methane is an important source of greenhouse gas emissions and there are ongoing investigations to find mitigation strategies. The aim of this thesis was to assess various grazing management systems with different levels of herbage intake in a cow’s diet. Implemented as a collection of four papers, this thesis investigates dairy cows' performances (intake, milk production), behavioural responses, and enteric methane emissions as effects of their consumption of herbage on pasture and grass silage indoors. Two GreenFeed units, both indoors and outdoors, were employed to investigate enteric methane emissions in part-time grazing systems. This thesis highlights that energy corrected milk remains at the same level with a high proportion of herbage intake as compared to indoor feeding during the summer in Norway and Sweden. The implementation of minor changes in grazing management, such as aligning the provision of fresh pasture with the animals' behavioural preferences, yields promising results if grass intake remains the main source of feed, as the enteric methane emissions recorded from cows fed fresh grass on pasture were significantly lower (20-28%) compared to cows fed silage indoors. This underscores the possibility to use grazing as an enteric methane mitigation strategy
Storskarv i Sverige
Full text linkEfter att tidigare varit utrotad har storskarv (Phalacrocorax carbo) häckat i Sverige sedan mitten av 1900-talet. De flesta storskarvar anländer till Sverige på våren inför häckningssäsongen. Kolonier med häckande storskarvar finns i samtliga län längs kusten men med stora skillnader i antalet häckande par mellan olika geografiska områden. Efter avslutad häckning sprider skarvarna ut sig och flyttar till andra områden. Under hösten lämnar de flesta storskarvarna landet och spenderar en stor del av vinterhalvåret i Europa. Antalet storskarvar som stannar kvar och övervintrar i Sverige varierar mellan år, beroende på hur kallt det är. Hur många storskarvar det finns i olika geografiska områden i Sverige varierar alltså stort, både under året och mellan år.Rikstäckande inventeringar av storskarv under häckningssäsongen genomfördes senast 2023 och antalet häckande storskarvar hade ökat sedan den tidigare riksinventeringen 2012, främst i södra delen av landet. Övervintrande storskarvar räknas tillsammans med andra sjöfåglar i januari varje år och inventeringsresultaten visar att antalet storskarvar ökade i de flesta områden under 1970-, 1980- och 1990-talet, framför allt i södra Sverige. Sedan år 2000 är bilden mer otydlig och variationen mellan år är stor.Storskarvar äter främst fisk och antas vara generalister och opportunister vilket innebär att de anpassar sig till nya förhållanden och födoresurser. Det är därför problematiskt att basera slutsatser om skarvars födoval (diet, d.v.s. de fiskar som skarvarna äter) på underlag som är begränsade i tid och rum. I detta uppdrag har vi därför fokuserat på att analysera tidsserier i födoval som i framtiden kan jämföras med motsvarande tidsserier från provfisken.Förändringar i storskarvens födoval över en period på cirka tio år har studerats i 8-fjordarområdet på västkusten och i Karlskrona skärgård på ostkusten. Utöver dessa två områden har vi även analyserat prover från Öresund för åren 2023 och 2024. Resultaten visar att art- och storlekssammansättningen av storskarvens födoval skiljer sig mellan områden, mellan år och mellan säsonger. Resultat om skarvars födoval kan påverkas av vilken typ av dietprover som samlas in och vilken dietanalysmetod som används.I 8-fjordarområdet dominerar fiskar tillhörande bytesgrupperna flundrefiskar, torskfiskar och smörbultsfiskar födovalet både i antal och vikt, men den relativa andelen varierar stort mellan år. Arter från samma bytesgrupper dominerar också födovalet i Öresund där torskfiskar utgör huvuddelen av födan viktmässigt. Bytesgruppen torskfiskar består till största delen av arten torsk, men artsammansättningen i gruppen skiljer sig åt betydligt mellan undersökningsområdena. I Karlskrona domineras födovalet av spigg till antal och viktmässigt har det i området skett en förskjutning från en mer varierad sammansättning av födan till en dominerad av abborre. Förutsatt att tillgängliga provfiskedata kan ge en representativ bild av fisksamhällets art- och storlekssammansättning i området kan mer detaljerade analyser av skarvdiet- och provfiskedata förhoppningsvis öka förståelsen för hur storskarvars födoval i de tre områdena varierar i relation till bytesförekomst.Toppskarven (Gulosus aristotelis) ökar snabbt i antal och utbredning längs västkusten i Sverige och dess utbredning i både tid och rum ser ut att överlappa allt mer med storskarvens utbredning. Kunskapsläget om de olika arternas relativa förekomst i olika områden under olika tidsperioder, samt vilka likheter och skillnader de uppvisar i sin ekologi, till exempel häckningsplatser, födoval, födosöksområden, rörelsemönster och beteende samt migrationer och övervintringsområden är dock Sammanfattning mycket begränsat. Med rådande kunskapsbrist finns det en risk att förvaltningsåtgärder riktade mot storskarv också påverkar toppskarv.Trots den korta tiden som erbjöds kan de resultat som tagits fram inom uppdraget ge en fingervisning om var, när och hur fortsatt forskning och övervakning bör bedrivas och utvecklas för ökad förståelse om skarvars predation och för att ta fram adekvat underlag till förvaltningsrelaterade frågor
A trans-Atlantic perspective on successful plantation establishment in boreal ecosystems: lessons learned and research opportunities
Full text linkBoreal forests, which account for one-third of the world's forested areas, play a crucial role in global climate regulation and provide significant ecological, economic, and cultural benefits. However, boreal ecosystems face substantial threats from climate change, leading to increased disturbances such as wildfires, insect outbreaks, and disease. In response, reforestation emerges as a vital strategy for maintaining and restoring forest cover. In this perspective paper, we summarize some recent research on plantation establishment in boreal ecosystems of eastern North America and Scandinavia, emphasizing the effectiveness of mechanical site preparation (MSP), species-specific responses, and soil nutrient dynamics. We suggest key areas for future research, including the long-term sustainability of MSP, the development of adaptive strategies to climate variability, species-specific optimization of planting techniques, and integration of technological advances. Addressing these research needs will support the development of adaptive silviculture practices that enhance boreal stands resilience and productivity, helping to meet reforestation objectives and mitigate the impacts of climate change. We aim to stimulate regional, national, and international research initiatives, contributing to the resilience and sustainability of boreal ecosystems
A long- distance inhibitory system regulates haustoria numbers in parasitic plants
Full text linkThe ability of parasitic plants to withdraw nutrients from their hosts depends on the formation of an infective structure known as the haustorium. How parasites regulate their haustoria numbers is poorly understood, and here, we uncovered that existing haustoria in the facultative parasitic plants Phtheirospermum japonicum and Parentucellia viscosa suppressed the formation of new haustoria located on distant roots. Using Phtheirospermum, we found that this effect depended on the formation of mature haustoria and could be induced through the application of external nutrients. To understand the molecular basis of this root plasticity, we analyzed hormone response and found that existing infections upregulated cytokinin- responsive genes first at the haustoria and then more distantly in Phtheirospermum shoots. We observed that infections increased endogenous cytokinin levels in Phtheirospermum roots and shoots, and this increase appeared relevant since local treatments with exogenous cytokinins blocked the formation of both locally and distantly formed haustoria. In addition, local overexpression of a cytokinin- degrading enzyme in Phtheirospermum prevented this systemic interhaustoria repression and increased haustoria numbers locally. We propose that a long- distance signal produced byhaustoria negatively regulates future haustoria, and in Phtheirospermum, such a signaling system is mediated by a local increase in cytokinin to regulate haustoria numbers and balance nutrient acquisition
Ground lichen development and consultation between reindeer husbandry and forestry
Full text linkSamråd has long been the policy instrument for consultation between forestry and reindeer husbandry in Sweden. Natural pasture-based reindeer husbandry is crucial to the Sami culture, and ground lichen is the key winter grazing resource for the reindeer, while forestry has great economic significance. In recent decades the volume and denseness of the forest have significantly increased, contributing to a strong decline in lichen-abundant forest. The aim of this thesis is to investigate what could contribute to a more balanced development of the two key resources, timber and ground lichen, taking its departure in samråd as the instrument for consultation.Results show that reindeer husbandry’s expectations regarding samråd have differed from forestry’s, and that samråd has mainly become an instrument for information exchange. Analysis of Swedish National Forest Inventory data shows that ground lichen cover declined by 57% from 1993 to 2015, while there was no declining trend from 2015 to 2023. Results also show that a significant increase in lichen cover could be possible using conventional forestry methods adapted in timing and intensity. Scenario analyses were used to show how lichen habitat could increase in the future through specific forest management strategies, and also showed the resulting decrease in economic output for the forest company.The thesis discusses reasons why this new knowledge might not be implemented. These include that consensus in samråd is voluntary, the reindeer herders have low levels of influence and power, and the decisions governing samråd are made at a higher level. Implementing the results of the thesis in the forest companies’ strategic planning could to some extent replace samråd and guarantee a certain lichen habitat development. However, this is not likely in today’s context, and might require changes in areas such as legislation, certification, or international/national societal pressure