A thorough understanding of the biochemical and physiological basis of stress responses in plants is needed to rationally manipulate tolerance traits. Most studies have focused so far on the identification of stress-responsive genes in herbaceous plants. Forest trees, by contrast, have been largely ignored. Here we summarize our recent findings on the functional characterization of two chestnut seed proteins, the molecular chaperone CsHSP17.5 and the endochitinase CsCh3, which are produced when plants are affected by thermal stress and microbial infection.