Synthesis of dehydrin-like proteins in Quercus ilex L. and Quercus cerris L. seedlings subjected to water stress and infection with Phytophthora cinnamomi.

The synthesis of dehydrin-like proteins in 24-month-old Quercus cerris and Q. ilex seedlings subjected to water stress and/or infection with Phytophthora cinnamomi, was investigated. An estimated 50 kDa dehydrin-like protein was observed in leaves of symptomless Q. ilex (drought tolerant) in control, as well as in seedlings infected with P. cinnamomi, throughout the experiment. Water stress, with a midday stem water potential value lower than -2.7 MPa (up to 8 weeks), increased band intensity. Two new polypeptides with a molecular weight of about 60 and 63 kDa, respectively, were detected in Q. ilex, under enhanced water stress conditions (=-4.0 MPa). No dehydrin-like proteins were observed in leaves of symptomless Q. cerris (drought susceptible) neither in control nor in infected treatments. With a midday stem water potential lower than -3.8 MPa (up to 7 weeks), water stress induced the synthesis of a protein with an approx. molecular weight of 43 kDa, while a band of about 36.5 kDa was detected for both water stress and infection treatments. These results suggest the involvement of dehydrin-like proteins in the response of Q. ilex and Q. cerris seedlings to different stresses.