Utjecaj nanočestica i iona srebra na nakupljanje i transport auksina u korijenu uročnjaka Arabidopsis thaliana

master's thesis

• Title (english): The effect of silver nanoparticles and ions on the auxin accumulation and transport in Arabidopsis thaliana root
• Author: Bruno Komazec
• Mentor: Petra Peharec Štefanić (mentor)
• Committee member: Petra Peharec Štefanić (predsjednik povjerenstva)
• Committee member: Željka Vidaković-Cifrek (član povjerenstva)
• Committee member: Andreja Brigić (član povjerenstva)
• Committee member: Ivana Šola (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2020-02-28, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Nanočestice srebra (AgNP) se koriste zbog protubakterijskog djelovanja u mnogim
komercijalno dostupnim proizvodima, uključujući pesticide, ali predstavljaju potencijalnu
opasnost za okoliš zbog svoje toksičnosti, reaktivnosti i akumuliranja u biljkama. Zbog svoje
velike površine u odnosu na volumen, AgNP su vrlo reaktivne i podložne otpuštanju iona
srebra što potencijalno povećava njihovu toksičnost. Biljni hormoni su uvelike zaslužni za
normalan rast biljaka, a auksin je jedan od važnijih fitohormona koji ima ulogu u brojnim,
metabolički važnim biljnim procesima. Uročnjak (Arabidopsis thaliana) je uvriježen modelni
organizam u molekularnoj i staničnoj biologiji. U ovome diplomskom radu istražio sam
utjecaj PVP-AgNP i ionskog srebra (AgNO3) na klijance uročnjaka nakon prvog, trećeg,
petog, sedmog, devetog i jedanaestog dana tretmana. Sjemenke sam isklijavao četiri dana na
krutoj MS hranjivoj podlozi, a potom sam klijance prebacio na modificiranu krutu ½ MS
hranjivu podlogu s dodatkom PVP-AgNP ili ionskog srebra konačnih koncentracija 25, 50 i
100 μM te kontrolne klijance na krutu podlogu bez dodataka srebra. U krutoj podlozi s
dodatkom AgNO3 primijetio sam stvaranje AgNP koje su se stabilizirale već trećeg dana
tretmana. Od trećeg dana pa do jedanaestog dana apsorbancija novonastalih AgNP u podlozi
polako je opadala. Nasuprot tome, PVP-AgNP su se u krutoj podlozi u potpunosti stabilizirale
tek oko osmog dana. PVP-AgNP i novonastale AgNP utjecale su na duljinu korijena, a
lokalizirane su u korijenovoj kapi te međustaničnom prostoru i staničnoj stijenci vrška
korijena. Značajne promjene u strukturi korijena i kotiledona nisu zamijećene, no promjene u
ultrastrukturi kloroplasta primijećene su na tretmanu sa 100 μM AgNO3 nakon jedanaestog
dana. Kod svih tretmana uočena je promjena akumulacije i transporta auksina koja je ovisila o
koncentraciji i trajanju tretmana što pokazuje da se biljka prilagođavala na stres AgNP.

Abstract (english)

Silver nanoparticles (AgNPs) are used for their antimicrobial properties in many
commercially available products, including pesticides, but they can pose a risk to the
environment due to their toxicity, reactivity and accumulation in plants. Due to their large
surface area to volume ratio, AgNPs are highly reactive and susceptible to the release of silver
ions, which potentially increases their toxicity. Plant hormones are largely responsible for the
normal growth of plants, and auxin is one of the most important phytohormones that play a
role in many metabolically important plant processes. The Arabidopsis thaliana is an
established model organism in molecular and cellular biology. In this thesis, the effects of
PVP-AgNPs and silver ions (AgNO3) on Arabidopsis seedlings after one, three, five, seven,
nine, and eleven days of treatment were investigated. The seeds were germinated for four
days on a solid MS medium and afterwards on a modified solid ½ MS medium supplemented
with PVP-AgNPs or silver ions at final concentrations of 25, 50 and 100 μM. Control
seedlings were transferred to silver-free solid medium. In AgNO3-supplemented solid
medium, the formation of AgNPs was noticed which were stabilized on the third day. After
the third day and until the eleventh day, the absorbance of the newly formed AgNPs in
medium slowly decreased. In contrast, PVP-AgNPs were stabilized in the solid medium
around the eighth day. PVP-AgNPs and newly formed AgNPs affected the root length and
were localized in the root cap and in the intercellular space and cell wall of the root tip. No
significant changes in root and cotyledon structures were observed, but changes in chloroplast
ultrastructure were observed on treatment with 100 μM AgNO3 after the eleventh day. A
change in the accumulation and transport of auxin was observed in all treatments, which
depended on the concentration and length of treatment, indicating that the plant adjusted to
the AgNPs stress.

• Keywords: nanočestice srebra; Arabidopsis thaliana; duljina korijena; auksin; lokalizacija; ultrastruktura; stabilnost
• Keywords (english): silver nanoparticles; Arabidopsis thaliana; root length; auxin; localization; ultrastructure; stability
• Language: croatian
• URN:NBN: urn:nbn:hr:217:336077
• Study programme: Title: Molecular Biology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra molekularne biologije (magistar/magistra molekularne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 2020-08-28
• Created on: 2020-07-13 07:19:30