Microbes and climate change: insights from plant-microbe interactions in rice phyllosphere and soil microbiomes in subarctic grasslands
Date
2024-07-12
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Abstract
Inimtegevuse, eriti fossiilsete kütuste põletamise ja tööstuse tõttu, on kasvuhoonegaasid tase atmosfääris märkimisväärselt suurenenud. See põhjustab kliimamuutusi, nagu globaalne soojenemine, põud ja ekstreemsed ilmastikunähtused. Prognoosid näitavad, et 2100. aastaks võib globaalne temperatuur tõusta 3–5 °C, millel võivad olla pöördumatud tagajärjed ökosüsteemidele. Kliimamuutuste tagajärjel väheneb paljudes maailma piirkondades sademete hulk ja õhuniiskus, mis viib mulla niiskuse vähenemiseni ja seega põllukultuuride, eriti teraviljade, saagikuse vähenemiseni. Mikroorganismid on olulised ökosüsteemide funktsioneerimisel, osaledes ainete ringes ja säilitades mulla stabiilsust. Taimede ja mikroorganismide kooseksisteerimine hõlmab nii mutualistlikke kui ka parasiitlikke suhteid. Mikroorganismid elavad nii lehtede pinnal (epifüütsed mikroobid) kui ka taime sees (endofüüdid) ja juurte ümbruses (risosfääri mikroobid). Reaktsioon kliimamuutustele ei toimu taim-mikroob-muld süsteemis sünkroonselt, sest muutused mõjutavad taimi ja mulda erinevalt. Doktoritöö eesmärk oli uurida taimedega seotud mikroobikoosluste omadusi kliimamuutuste kontekstis. Töö tulemused põhinevad kahel kompleksel uurimusel. Esimene uuring keskendus põuakindla riisi lehtedelt eraldatud bakterite võimele suurendada riisitaimede osmotolerantsust ja saagikust põua tingimustes. Uuringute tulemused näitasid, et kõrge osmotolerantsus oli iseloomulik peamiselt Bacillus perekonda kuuluvatele bakteritele, mis säilitasid taimedele kasulikul tasemel taimehormoonide sünteesi osmootse stressi tingimustes. Eriti efektiivne oli Bacillus megaterium tüvi PB50, mis parandas taimede stressitaluvust. Teises uuringus uuriti mulla soojenemise mõju risosfääri ja juurevaba mulla mikroobikooslustele subarktilistel rohumaadel. Leiti, et mulla soojenemine mõjutas oluliselt mikroobikoosluse struktuuri ja funktsioneerimist. Pikemal soojenemisel täheldati muutusi denitrifikatsiooniga seotud geenide osakaalus nii risosfääris kui juurevabas mullas, mis võib suurendada N₂O emissiooni mullast. Need uuringud aitavad paremini mõista kliimamuutuste mõju taim-mikroob-muld süsteemidele ja võimaldavad ennustada ning vähendada kliimamuutuste negatiivseid mõjusid põllumajandusele.
Human activities, particularly fossil fuel burning and industrial processes, have elevated greenhouse gas levels in the atmosphere, driving climate change, including global warming, droughts, and extreme weather events. Projections indicate a potential global temperature rise of 3–5 °C by 2100, posing irreversible threats to ecosystems. Climate change is reducing precipitation and air humidity in many regions, leading to decreased soil moisture and lower agricultural crop yields, especially cereals. Soil microorganisms, essential for nutrient cycling and stability, support plant health but may be disrupted by climate change, increasing greenhouse gas emissions from soil and causing plant diseases. This doctoral thesis explores the effect of climate change on microbial communities associated with plants and soil through two detailed studies. The first study examined how bacteria from the leaf surfaces of drought-resistant rice could protect more vulnerable rice varieties from brief, moderate droughts. The results showed that most stress-tolerant bacteria belong to Bacillus species, with Bacillus megaterium strain PB50 particularly effective in enhancing the drought tolerance and yield of susceptible rice. The second study investigated how warming impacts microbial communities in the soils of subarctic grasslands, specifically in root-free soil and rhizosphere (soil around the root). The findings indicated that warming significantly alters the composition and function of these microbes, notably increasing the proportion of genes involved in denitrification in both the rhizosphere and root-free soil. This shift could lead to higher emissions of nitrous oxide, a potent greenhouse gas, from the soil. These studies enhance our understanding of the impact of climate change on plant-soil-microbe systems and help predict and mitigate the negative effects of climate change on agriculture.
Human activities, particularly fossil fuel burning and industrial processes, have elevated greenhouse gas levels in the atmosphere, driving climate change, including global warming, droughts, and extreme weather events. Projections indicate a potential global temperature rise of 3–5 °C by 2100, posing irreversible threats to ecosystems. Climate change is reducing precipitation and air humidity in many regions, leading to decreased soil moisture and lower agricultural crop yields, especially cereals. Soil microorganisms, essential for nutrient cycling and stability, support plant health but may be disrupted by climate change, increasing greenhouse gas emissions from soil and causing plant diseases. This doctoral thesis explores the effect of climate change on microbial communities associated with plants and soil through two detailed studies. The first study examined how bacteria from the leaf surfaces of drought-resistant rice could protect more vulnerable rice varieties from brief, moderate droughts. The results showed that most stress-tolerant bacteria belong to Bacillus species, with Bacillus megaterium strain PB50 particularly effective in enhancing the drought tolerance and yield of susceptible rice. The second study investigated how warming impacts microbial communities in the soils of subarctic grasslands, specifically in root-free soil and rhizosphere (soil around the root). The findings indicated that warming significantly alters the composition and function of these microbes, notably increasing the proportion of genes involved in denitrification in both the rhizosphere and root-free soil. This shift could lead to higher emissions of nitrous oxide, a potent greenhouse gas, from the soil. These studies enhance our understanding of the impact of climate change on plant-soil-microbe systems and help predict and mitigate the negative effects of climate change on agriculture.
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