Ribonucleases during cold acclimation in winter and spring wheats

Triticum durum Desf. cv. Cappelli and x Haynaldoticum sardoum Meletti et Onnis, a recently formed spontaneous hybrid derived from Cappelli, were studied in order to test their response to hardening. x H. sardoum segregates into two natural lines: Culmo Vuoto (hollow stem-CV), a typical winter wheat, and Culmo Pieno (solid stem-CP), a typical spring wheat. T. durum cv. Cappelli is a typical spring wheat. Freezing test and measurements of electrolytical conductivity have shown that CV, the only winter wheat, is able to acclimate more quickly and to a larger extent than spring wheats. SDS-PAGE with activity staining specific for RNases highlighted an increase in WL B (neutral salt-stimulated RNases) with a higher mobility in the leaves of seedlings which have been hardened (2 °C) for 2, 7 and 14 days, but not in leaves of ABA treated seedlings. This increase is more precocious in hardened CV, and the enzyme is more active in acclimated leaves than in unhardened ones. Unlike RNases, COR14 is equally present in winter and spring acclimated plants.