17 research outputs found
The stilbene biosynthetic pathway and its regulation in Scots pine
Conifers dominate the boreal forests of the Northern Hemisphere, and especially members of the family Pinaceae have great economic and ecological significance. Part of their success is thought to arise from the vast array of secondary metabolites they produce. The products of secondary metabolism are essential for plants to survive in the ever-changing environment. In Scots pine (Pinus sylvestris L.), two groups of secondary metabolites, stilbenes and resin acids, are crucial for decay resistance of heartwood timber and for active defense responses against herbivores and fungal pathogens. Several studies have shown that stilbenes improve decay resistance of pine heartwood. Since there is wide variation in the concentration of stilbenes between individuals and the trait has high heritability, it may be possible to breed heartwood that is more decay-resistant. However, breeding for heartwood properties is slow, since the decay resistance characteristics can be estimated at the earliest from 30-year-old trees. Early selection methods utilizing genetic markers or chemical screening are needed, but we do not yet understand which genes control the biosynthesis of stilbenes and what the genetic differences are between individuals that explain the variation in the capacity to produce stilbenes. Importantly, there is genetic correlation between stress-induced stilbene biosynthesis in seedlings and the heartwood stilbene content in their adult mother trees.
Here, we examined the pine transcriptional responses under two conditions that were previously known to activate stilbene biosynthesis: heartwood formation in adult trees and ultraviolet (UV)-C treatment of needles in seedlings. We found that these two conditions had very little in common, except for the activation of stilbene pathway genes. For example, the regulators of the two responses seemed not to be shared. The activation of the stilbene pathway in response to UV-C treatment occurred a few hours after the onset of the treatment and was independent of translation. Stilbene biosynthesis seems to be an early defense response in Scots pine.
Heartwood formation, an important developmental process in the senescence of secondary xylem, is poorly understood. Based on transcriptomic analysis, stilbene biosynthesis occurs in situ in the transition zone between the sapwood and heartwood, but resin acids were synthesized primarily in the sapwood. Bifunctional nuclease, an enzyme involved in the process of developmentally programmed cell death (dPCD), is a useful marker for heartwood formation and aided us in defining the timing of the process, from spring to late autumn. Expression of this marker, which is strictly confined to dPCD conditions, further clarified that heartwood formation truly is a process that is initiated by intrinsic programming instead of environmental cues.
The transcriptomic data revealed that the expression of the previously characterized pinosylvin O-methyltransferase gene, PMT1, was not induced under stilbene-forming conditions. A new PMT-encoding gene, PMT2, was identified by coexpression analysis. The gene showed an inducible expression pattern very similar to that of the stilbene synthase gene under all conditions studied. PMT2 furthermore methylated pinosylvin with high specificity, in contrast to PMT1, which accepted several substrates.Pohjoisen pallonpuoliskon kasvillisuus on havumetsien hallitsemaa ja etenkin mÀntykasvien (Pinaceae) heimoon kuuluu taloudellisesti ja ekologisesti merkittÀviÀ lajeja. Yksi selitys havupuiden menestykselle saattaa olla niiden kyky tuottaa laaja kirjo erilaisia sekundaariyhdisteitÀ. MÀnnyn (Pinus sylvestris L.) tÀrkeimpiin sekundaariyhdisteisiin kuuluvat stilbeenit ja terpeenit toimivat puolustuksessa tuholaisia ja patogeenejÀ vastaan. Aikaisemmat tutkimukset ovat osoittaneet, ettÀ aktiivisen puolustuksen lisÀksi etenkin stilbeenit parantavat mÀnnyn sydÀnpuun lahonkestÀvyyttÀ. SydÀnpuun stilbeenien mÀÀrÀ vaihtelee huomattavasti yksilöiden vÀlillÀ ja ominaisuus on periytyvÀ, mikÀ mahdollistaa sydÀnpuun lahonkestÀvyyden parantamisen jalostuksen keinoin. SydÀnpuun laatuominaisuuksien jalostus on kuitenkin hidasta ja varhaisvalintaan soveltuvien geenimerkkien tunnistaminen nopeuttaisi jalostusprosessia. Emme kuitenkaan vielÀ tiedÀ, mitkÀ geenit sÀÀtelevÀt stilbeenien biosynteesiÀ ja selittÀvÀt erot sydÀnpuun stilbeenien mÀÀrÀssÀ. Stilbeenien tuotanto kÀynnistyy erilaisten stressitekijöiden vaikutuksesta neulasissa ja mantopuussa. Indusoituva tuotanto korreloi sydÀnpuun stilbeenien mÀÀrÀn kanssa ja tÀtÀ voidaan mahdollisesti hyödyntÀÀ kemiallisessa seulonnassa taimien varhaisvalinnassa.
TÀssÀ vÀitöskirjassa tutkittiin muutoksia mÀnnyn transkriptomissa sydÀnpuun muodostumisen aikana ja UV-C kÀsittelyn seurauksena. Stilbeenien biosynteesireitin entsyymejÀ koodavat geenit aktivoituivat kummassakin tapauksessa, mutta muuten transkriptomeilla oli hyvin vÀhÀn yhteistÀ. Esimerkiksi yhteisiÀ transkriptiota sÀÀteleviÀ tekijöitÀ ei löydetty ja vaikuttaakin siltÀ, ettÀ eri transkriptiofaktorit sÀÀtelevÀt stilbeenien biosynteesireittiÀ sydÀnpuun kehityksen aikana ja stressitekijöiden vaikutuksesta.
SydÀnpuun muodostumisen aikana puussa tapahtuvat kemialliset ja rakenteelliset muutokset tunnetaan joillakin lajeilla hyvin, mutta itse prosessin ajoittuminen sekÀ kÀynnistymiseen ja sÀÀtelyyn vaikuttavat tekijÀt ovat vielÀ suurelta osin tuntemattomia. Stilbeenin biosynteesistÀ vastaavat geenit ilmenivÀt vaihettumisvyöhykkeellÀ mantopuun ja sydÀnpuun vÀlissÀ, jossa sydÀnpuun muodostuminen kÀynnistyy ja nÀin tukee aiempaa kÀsitystÀ stilbeenien in situ biosynteesistÀ. Hartsihappojen biosynteesistÀ vastaavat geenit taas ilmenivÀt lÀhinnÀ mantopuussa, jolloin ne todennÀköisesti kuljetetaan vaihettumisvyöhykkeelle sen ulkopuolelta. Ohjelmoidulla solukuolemalla on suuri merkitys sekÀ kasvin kehityksessÀ, ettÀ stressivasteissa. Bifunktionaalinen nukleaasi (BFN) on entsyymi, joka on yhdistetty aiemmissa tutkimuksissa spesifisesti kasvien kehityksellisiin tapahtumiin. EntsyymiÀ koodaavan geenin havaittiin ilmenevÀn ainoastaan vaihettumisvyöhykkeellÀ. TÀmÀ tukee hypoteesia, jonka mukaan sydÀnpuun muodostuminen on sisÀisesti sÀÀdelty eikÀ ympÀristötekijöiden laukaisema tapahtuma. Bifunktionaalinen nukleaasi toimi myös hyödyllisenÀ markkerina sydÀnpuun muodostumisen ajoittamisessa kevÀÀstÀ myöhÀiseen syksyyn.
Transkriptiodata paljasti, ettÀ aiemmin tunnistettu stilbeenireitin viimeistÀ reaktiota katalysoiva metyylitransferaasientsyymiÀ (PMT1) koodaava geeni ei indusoitunut tutkituissa stilbeenejÀ tuottavissa olosuhteissa. Tunnistimme uuden metyylitransferaasia koodaavan geenin (PMT2), jonka ekspressioprofiili vastasi stilbeenireitin toisen entsyymin, stilbeenisyntaasin ekspressiota kaikissa tutkituissa olosuhteissa. PMT2 metyloi spesifisesti pinosylviiniÀ kun taas PMT1 metyloi stilbeenien lisÀksi useita rakenteellisesti erilaisia substraatteja
Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017
A double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4% (62.3 (55.1â70.8) million) to 6.4% (58.3 (47.6â70.7) million), but is predicted to remain above the World Health Organizationâs Global Nutrition Target of <5% in over half of LMICs by 2025. Prevalence of overweight increased from 5.2% (30 (22.8â38.5) million) in 2000 to 6.0% (55.5 (44.8â67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic
Integrated satellite microwave and infrared measurements of precipitation during a Bay of Bengal cyclone
115-124In the present paper,
an approach for integrated IR and microwave measurements using various satellite
sensors have been used for the study of a severe cyclone over Bay of Bengal and
adjoining Eastern India and Bangladesh during 24-29 April 1991. The rain estimates
from measurements of brightness temperatures from Special Sensor Microwave/Imager
(SSM/I) and Outgoing
Longwave Radiation (OLR) from IR radiances of polar orbiting and geostationary
satellites have been used. Since the OLR derived rainfall exhibit a larger spatial
spread with lower intensities in rain fall fields, we have followed the above procedure
for optimally combining both the observations for more realistic rainfall o n regional
scale to
study precipitation
fields. Since the OLR rains are well represented spatially and tempo rally by more
frequent observations from both geostationary and polar orbiting satellites, the
algorithm sharpens the IR derived rain s and augments it to the microwave derived
rain. The combined IR and microwave rain algorithm brings out the finer details
of the cyclone structure and precipitation fields, and thus seems to be highly
promising for operational applications. Some aspects of the associated wind fields
are also examined for their relationship with tropical rain intensity in the present
case. A comparison of rainfall is performed with rare in-situ observations
over the coastal regions during the severe cyclone
Sensitivity of brightness temperatures to the oceanic surface roughness and rainfall for TRMM and IRS-P4-MSMR radiometric channels over the Indian Ocean
61-70Upwelling
microwave radiances at the top of the atmosphere originate partly from the
oceanic/land surfaces and partly from atmospheric constituents. Radiative
transfer simulations have been carried out for the Tropical Rainfall Measuring
Mission (TRMM)-Microwave Imager (TMI) and Indian OCEANSAT-Multichannel Scanning
Microwave Radiometer (MSMR) radiometric frequencies for varying winds, under
clear sky (non-raining) and raining conditions. Both emission and scattering
based radiative transfer simulations are carried out for typical atmospheric
profiles over the North Indian Ocean during the monsoon season. The simulation
results match reasonably well with the real observations from TRMMTMI and MSMR
channels that represent a variety of oceanic and atmospheric conditions during
the south-west monsoon season. The main purpose of simulations is to delineate
the frequencies that are most sensitive (as far as brightness
temperatures are
concerned) to the ocean surface and rainfall characteristics. This effort will
contribute for the combined use of different sensors to retrieve geophysical
parameters with better accuracy