Metabolni odziv plodov jablane (Malus domestica Borkh.) na fiziološke motnje

Čebulj, Anka (author), Veberič, Robert (mentor)

V nalogi smo želeli z analizo metabolitov preveriti odziv plodov jablane (Malus domestica Borkh.) na izbrane fiziološke motnje (sončni ožigi, steklavost, grenka pegavost in skald). Pri nekaterih fizioloških motnjah smo določili tudi encimsko aktivnost in izražanje genov fenilpropanoidne/flavonoidne poti ter določili aktivnost polifenol oksidaz (PPO) in peroksidaz (POX). V raziskavah smo za določanje vsebnosti metabolitov uporabili metode UV-VIS, HPLC in HPLC-MS, aktivnost encimov smo določali s pomočjo spektrofotometrije, radiografskega skeniranja TLC in izražanja genov z metodo RT-qPCR. Ugotovili smo, da odziv plodov na fiziološke motnje ni enoten. Pri skoraj vseh fizioloških motnjah se je vsebnost hidroksicimetnih kislin povečala v prizadetem tkivu, razen pri steklavosti. Splošno večjo vsebnost vseh fenolnih spojin smo opazili v pegah grenke pegavosti, medtem ko je bila vsebnost antocianinov in flavonolov v kožici nad pego manjša, je bila vsebnost slednjih pri ožigih močno povečana. Med najbolj zanimivimi in hkrati najmanj raziskanimi odzivi je vsebnost dihidrohalkonov v povezavi s fiziološkimi motnjami. Pri steklavosti, sončnih ožigih in v pegi pri grenki pegavosti je bila njihova vsebnost v prizadetem tkivu večja od vsebnosti v neprizadetem tkivu. Izkazalo se je, da je bila tudi aktivnost encima P2'GT večja v plodu s steklavostjo v primerjavi s plodovi brez steklavosti. Pri ostalih določenih encimih fenilpropanoidne/flavonoidne poti (PAL, CHS/CHI, FHT, FLS in F3’GT) v poskusu s steklavostjo nismo ugotovili razlik v aktivnosti med obravnavanji. Razvoj steklavosti se odraža tudi v kožici prizadetih plodov, kar lahko služi v pomoč pri razvijanju cenovno ugodnih metod razvrščanja plodov. Najbolj neenoten odziv na fiziološke motnje je bil v skupini flavanolov. Pri skaldu smo ugotovili povečano izražanje genov fenilpropanoidne/flavonoidne poti (MdCHS, MdCHI, MdFHT, MdANS in MdUFGT) v kožici s skaldom, ki pa se ni odražala v večji aktivnosti encimov (PAL, FHT, CHS/CHI, DFR). Pri nastanku fizioloških motenj smo ugotovili tudi večjo aktivnost POX v steklavem mesu ter na mestu sončnih ožigov, medtem ko je bila aktivnost POX pri skaldu manjša. Aktivnost encima PPO smo določali pri nastanku skalda in steklavosti in v obeh primerih smo ugotovili večjo aktivnost v prizadetem tkivu.

• Language: Slovenian
• Keywords: jabolka, fiziološke motnje, primarni metaboliti, sekundarni metaboliti, sončni ožigi, steklavost, grenka pegavost, skald
• Work type: Doctoral dissertation
• Organization: BF - Biotechnical Faculty
• Year: 2018
• PID: 20.500.12556/RUL-105288
• Publication date in RUL: 21.11.2018

Secondary language

• Language: English
• Title: Metabolic response of apple fruits (Malus domestica Borkh.) to physiological disorders

Abstract

The aim of this PhD thesis was to evaluate the response of apple fruits (Malus domestica Borkh.) to selected physiological disorders (sunburn, watercore, bitter pit and scald) through metabolite analysis. Additionally, gene expression and enzyme activity of phenylpropanoid and flavonoid pathway plus polyphenol oxidase (PPO) and peroxidase (POX) activity were determined for certain disorders. Metabolites were analysed using UV-VIS, HPLC and HPLC-MS, gene expression with RT-qPCR and enzyme activities with UV-VIS and radiographic TLC scan. The response of apple fruits to different physiological disorders was not uniform. The affected tissues from all physiological disorders except watercore had higher contents of hydroxycinnamic acids. Generally higher contents of phenolic compounds were observed in the pits of bitter pit, whereas peels above the pit contained lower amounts of anthocyanins and flavonols. The latter were strongly increased in sunburned peels. One of the most notable results and yet least researched responses was the content of dihydrochalcones in connection to physiological disorders. Their content was higher in sunburned peels, flesh with watercore and in the pits of bitter pit in comparison to unaffected tissue. The P2'GT enzyme activity was also higher in the flesh of apples with watercore in comparison to flesh of apples without watercore. No statistically significant differences were observed in the activity of the rest of the enzymes of phenylpropanoid and flavonoid pathway (PAL, CHS/CHI, FHT, FLS in F3’GT) between treatments. Watercore incidence is reflected in the apple peel, which could aid in developing cost-efficient methods of fruit sorting. The most unequal response to physiological disorders was in the group of flavanols. Higher gene expression (MdCHS, MdCHI, MdFHT, MdANS and MdUFGT) was observed with scald development, but was not reflected in enzyme activity (PAL, FHT, CHS/CHI and DFR). Higher activity of POX was determined in flesh affected with watercore and sunburned peel, whereas it was lower in peel affected with scald in comparison to unaffected tissues. Comparing to unaffected tissues, PPO activity was higher in flesh with watercore and peel with scald.

• Keywords: apples, physiological disorders, sunburn, watercore, bitter pit, scald, primary metabolites, secondary metabolites