In vitro screening for low temperature tolerance of wheat genotypes

Abstract

Low temperature (LT) tolerance of 12 wheat (T. aestivum L.) genotypes was investigated in an in vitro zygotic embryo culture. Isolated embryos were grown on a modified MS medium for two months. Calluses were prepared by gradual decrease of temperatures (17°C-7 days, 5°C-7 days, -5°C-l day, -10°C-1 day) and then exposed to LT treatments (-15°C, 24 h and 48 h). After LT treatments, calluses were acclimated by gradual increase of temperatures and grown for another month. Based on the differences in callus fresh weight between the control group and calluses exposed to the LT treatments, levels of LT tolerance of wheat genotypes were determined. The results have shown that out of the 12 wheat cultivars, 6 had a high level of LT tolerance, 5 had a medium and only one spring cultivar (Venera) had a low level of LT tolerance. These results were compared with the results of the standard in situ test in a cold chamber. Only partial disagreement of results was determined in two cultivars with the medium level of LT tolerance (NSR-2 and Balkan). It can be concluded that the in vitro test can be successfully used for the separation of genotypes with high and low levels of LT tolerance, but for more precise separation within the medium level of LT tolerance, the test should be improved.

Ispitivana je tolerantnost 12 genotipova pšenice (T. aestivum L.) prema niskim temepraturama (NT) u in vitro kulturi zigotnog embriona. Izolovani embrioni gajeni su na modifikovanoj MS podlozi dva meseca. Proizvedeni kalusi izloženi su prvo dejstvu pripremnih temperatura (17°C-7 dana, 5°C-7 dana, -5°C-1 dan, -10°C-1 dan), a zatim i dejstvu NT (-15°C-24h i 48h). Nakon tretmana, kalusi su aklimatizovani postepenim povećavanjem temperature (obrnutim redosledom pripremnih temperatura) i gajeni još mesec dana. Na osnovu razlike u porastu sveže mase kalusa, između kontrolne grupe i kalusa izloženih dejstvu NT, utvrđen je stepen tolerantnosti pojedinih genotipova pšenice. Rezultati su pokazali da je od 12 ispitivanih sorti, 6 imalo visok stepen tolerantnosti prema NT, 5 je imalo srednji nivo tolerantnosti, dok je samo jedna jara sorta (Venera) imala veoma nizak nivo tolerantnosti. Ovi rezultati su poređeni sa rezultatima standardnog in situ testa u hladnim komorama. Utvrđeno je delimično nepoklapanje rezultata samo kod dve sorte srednjeg nivoa tolerantnosti (NSR-2 i Balkan). To nam ukazuje na činjenicu da se in vitro testom mogu pouzdano razdvojiti genotipovi visoke i niske tolerantnosti prema NT, dok je za razdvajanja u okviru srednjeg nivoa tolerantnosti potrebno doraditi ovaj test.