Dynamics of structural and functional changes in the thylakoid membrane of maize inbred lines resistant and adapted to high temperature and drought

Abstract

The delayed chlorophyll fluorescence method, as a non-invasive bioluminescence method, is recommended for the application in maize breeding and seed production in order to evaluate maize inbred lines for their resistance and adaptability to increased and high temperatures, as well as, to drought. The following thermal properties of the photosynthetic apparatus of the observed maize inbred lines: the temperature dependence within a range of 25-60°C, critical temperatures at which phase transitions occur in the thylakoid membrane were discovered and by means of it significant functional changes in the photosynthetic apparatus of observed maize inbred lines were detected. activation energies (Ea, kJ mol-1) alongside the straight lines prior and after critical temperatures were calculated. Ea are a measure of occurrence of chlorophyll DF recombination processes and by that a measure of the total changes in structure and functioning of the thylakoid membranes. Thylakoid membranes underwent significant conformational changes in the part following the maximum intensity, i.e. in the part of its sharp linear decline. Such a state fits more to a non-living than a living organism in relation to its both, structure and functions. Results and the discussion of presented parameters of total thermal processes of chlorophyll DF, such as: temperature dependence, critical temperatures and activation energy, can be an important factor for a more exact characterization of maize inbred lines in relation to their resistance and adaptation to temperature and drought, contributing to a rapider and more rational development of the selection process.

Utvrđene su termalne karakteristike fotosintetičnog aparata proučavanih samooplodnih linija kukuruza, i to: određena je dinamika temperaturne zavisnosit u opsegu od 25 do 60°C, otkrivene su kritične temperature na kojima dolazi do faznih transformacija u tilakoidnoj membrani, a time i do značajnih strukturnih i funkcionalnih promena u fotosintetičnom aparatu ispitivanih samooplodnih linija kukuruza, obračunate su energije aktivacije (Ea, kJ/mol) duž pravih linija pre i posle nastanka kritične temperature. Energija aktivacije je mera nastajanja rekombinacionih reakcija povezanih sa uspostavljanjem zakasnele fluorescencije (ZF) hlorofila, a time i ukupnih promena u strukturi i funkciji tilakodinih membrana. Rezultati i diskusija izloženih parametara ukupnih terminalnih procesa ZF hlorofila, kao što su: temperaturna zavisnost, kritične temperature i energija aktivacije mogu doprineti egzaktnijem karakterisanju samooplodnih linija kukuruza u odnosu na njihovu otpornost i adaptivnost prema višoj i visokoj temperaturi i suši, što doprinosi egzaktnijem i racionalnijem odvijanju procesa oplemenjivanja.