| Popis: |
Globano zagrijavanje i klimatske promjene zahtijevaju selekciju otpornih biljaka koje unatoč temperaturnim ekstremima i sušnim periodima mogu davati dobre prinose. Raštika (Brassica oleracea var. acephala) je biljka koja odlično uspijeva pri visokim temperaturama i u slanome tlu. U prvom dijelu rada testirana su 33 varijeteta raštike iz različitih dijelova Hrvatske i Hercegovine izlaganjem klijanaca toplinskom stresu (maksimum 38 °C), suši (uz primjenu 0,3 M manitola), te kombinaciji tih stresnih uvjeta. Usporedbom rezultata prirasta korijena, biomase, sadržaja vode i količine prolina odabrana su dva otpornija i dva neotporna kultivara na kojima je u drugom dijelu pokusa mjerena brza fluorescencija klorofila a (metoda OJIP), sadržaj vodikova peroksida, stupanj lipidne peroksidacije i aktivnost katalaze. Zatim je napravljena imunodetekcija proteina HSP70, HSP90 i Rubisco, te je analizirana ekspresija gena NAC041 i NAC084. Pronađeno je da u svim kultivarima raštike osmotski stres uzrokuje veće morfološke promjene klijanaca, veću akumulaciju prolina i veća oksidativna oštećenja nego povišena temperatura. Usporedbom otpornih i manje otpornih kultivara utvrđeno je da otporni prilikom izlaganja osmotskom i toplinskom stresu imaju bolju sposobnost očuvanja fotosintetske učinkovitosti, te da dolazi do povećanja količine proteina HSP70, HSP90 i Rubisco. Kod osjetljivog kultivara raštike ekspresija gena NAC041 smanjena je u osmotskom stresu, a ekspresija gena NAC084 smanjena je primjenom kombinacije toplinskog i osmotskog stresa. Otporan kultivar raštike ne pokazuje statistički značajno odstupanje u ekspresiji gena NAC041 i NAC084 između kontrolnog i stresnih tretmana. Global warming and climate change create an increased demand for the identification of drought and high temperature resistant plants in order to minimalize yield loss in crop plants. Kale (Brassica oleracea var. acephala) is a plant that has shown the ability to grow in high temperature environments and saline soils. In the first part of the experiments 33 varietes of kale from different parts of Croatia and Hercegovina were tested by exposing the seedlings to temperature stress (maximum 38 °C), drought (0,3 M mannitol) and the combination of the two stresses. Root growth, biomass, water and proline content were analyzed and two of the most and least resistant cultivars were chosen for further investigation and comparison. The four kale varieties were exposed to stresses previously described and chlorophyll a fluorescence was measured (OJIP method) as well as hydrogen peroxide content, lipid peroxidation and catalase activity. Levels of HSP70, HSP90 and Rubisco protein were estimated after immunodetection and expression analysis was performed for NAC041 and NAC084 genes. It was found that osmotic stress caused greater morphological changes, greater proline accumulation and more oxidative damage than high temperature stress. The comparison of sensitive and resistant varieties revealed that when exposed to osmotic and high temperature stress, the resistant varieties are able to maintain better photosystem II functionality and performance and had increased levels of HSP70, HSP90 and Rubisco protein. In the sensitive kale cultivar the expression of the NAC041 gene was reduced under osmotic stress and the NAC084 gene under combined high temperature and osmotic stress. The resistant kale cultivar did not show a statistically significant change in NAC041 and NAC084 gene expression between control and stress treatments. |
