Učinak povišene temperature na linije uročnjaka Arabidopsis thaliana (L.) Heynh. s promijenjenom ekspresijom gena DMS3

master's thesis

• Title (english): Effect of high temperature on Arabidopsis thaliana (L.) Heynh. lines with modified DMS3 expression
• Author: Iva Križić
• Mentor: Mirta Tkalec (mentor)
• Committee member: Mirta Tkalec (predsjednik povjerenstva)
• Committee member: Sven Jelaska (član povjerenstva)
• Committee member: Karmen Fio Firi (član povjerenstva)
• Committee member: Mladen Maradin (član povjerenstva)
• Committee member: Dražen Balen (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2022-02-22, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Toplinski stres uzrokuje poremećaje u rastu i razvoju biljaka, inhibira klijanje te štetno utječe
na fotosintetske pigmente i lipidni integritet membrana. U odgovoru na stres biljke
sintetiziraju kompatibilne osmolite kao što je prolin i proteine toplinskog šoka te aktiviraju
antioksidacijske mehanizme i epigenetske promjene među kojima je metilacija molekule
DNA. Protein DMS3 dio je sustava za RNA-posredovanu metilaciju DNA koji sudjeluje u
metilaciji DNA de novo i uključen je u regulaciju genske ekspresije. Cilj ovoga rada bio je
istražiti utjecaj povišenih temperatura (30, 32, 32/24 i 35 °C) na divlji tip uročnjaka
Arabidopsis thaliana, liniju dms3-1 s mutiranim genom DMS3 te transgeničnu liniju oeDMS3
(nazvana 6TV) s pojačanom ekspresijom gena DMS3 kako bi se utvrdilo postoje li među
njima razlike u odgovoru na toplinski stres. Od morfoloških parametara mjereni su klijavost,
duljina korijena i biomasa, a od biokemijskih sadržaj fotosintetskih pigmenata i prolina,
stupanj lipidne peroksidacije (sadržaj malondialdehida) te prisutnost proteina HSP70. Pri
povišenim temperaturama vrijednosti morfoloških parametara bile su značajno smanjene kod
mutanta dms3-1 u odnosu na divlji tip i liniju 6TV. Sadržaj klorofila a i b te karotenoida bio je
značajno snižen pri povišenim temperaturama kod svih linija. Više vrijednosti
malondialdehida zabilježene su kod mutanta dms3-1 na svim temperaturama iznad 30 °C.
Sadržaj prolina nije se značajno razlikovao među linijama. Prisutnost proteina HSP70 bila je
izraženija kod linija dms3-1 i 6TV pri povišenim temperaturama. Rezultati pokazuju da je
linija dms3-1 osjetljivija, a linija 6TV otpornija na toplinski stres, iz čega se može zaključiti da
metilacija DNA posredovana molekulama RNA ima značajnu ulogu u prilagodbi biljaka na
toplinski stres

Abstract (english)

Heat stress causes disorders in plant growth and development, inhibits germination, and
adversely affects photosynthetic pigments and lipid integrity of membranes. In response to
stress, plants synthesize compatible osmolytes such as proline and heat shock proteins, and
activate antioxidant mechanisms and epigenetic changes, including DNA methylation. The
DMS3 protein is part of the RNA-directed DNA methylation system involved in de novo
DNA methylation and is involved in the regulation of gene expression. The aim of this study
was to investigate the effect of elevated temperatures (30, 32, 32/24 and 35 °C) on wild type
plant Arabidopsis thaliana, the dms3-1 line with the mutated DMS3 gene and the oeDMS3
transgenic line (called 6TV) with overexpression of DMS3 gene, in order to determine if there
are differences in their response to heat stress. Germination, radicle length and biomass were
measured as morphological parameters, and content of photosynthetic pigments and proline,
degree of lipid peroxidation (content of malondialdehyde) and presence of HSP70 protein as
biochemical parameters. At elevated temperatures, the values of morphological parameters
were significantly reduced in the dms3-1 mutant, compared to wild-type and 6TV line. The
content of chlorophyll a and b, and carotenoids was significantly reduced at elevated
temperatures in all lines. Higher values of malondialdehyde were observed in the dms3-1
mutant at all temperatures above 30 °C. The proline content did not differ significantly
between the lines. The presence of HSP70 protein was more pronounced in the dms3-1 and
6TV lines at elevated temperatures. The results show that the dms3-1 line is more sensitive
and the 6TV line is more resistant to heat stress, from which it can be concluded that DNA
methylation mediated by RNA molecules plays a significant role in the adaptation of plants to
heat stress.

• Keywords: toplinski stres; metilacija; klijanje; fotosintetski pigmenti; lipidna peroksidacija; prolin; HSP70
• Keywords (english): heat stress; methylation; germination; photosynthetic pigments; lipid peroxidation; proline; HSP70
• Language: croatian
• URN:NBN: urn:nbn:hr:217:752195
• Study programme: Title: Enviromental Sciences; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra struke znanosti o okolišu (magistar/magistra struke znanosti o okolišu)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2022-03-23 13:08:18