Technical Abstract: A receptor-like protein kinase (Ppsrkl1) was isolated from a peach bark cDNA library prepared with RNAs isolated from bark collected in December (cold acclimated). Sequence analysis indicates that this gene is related to the S-locus family of receptor protein kinases (SRKs) and that it shares greatest homology with ZMPK1 from maize and At4g32300 from Arabidopsis, both of which are intron-less genes. In bark tissues Ppsrkl1 is induced by water deficit treatment, repressed by short-day (SD) photoperiods and shows no response at all to cold treatment. Ppsrkl1 mRNA also increases in abundance in roots in response to water deficit. In fruit, Ppsrkl1 shows no response up to 6 h after wounding, but at 12 and 24 h after wounding Ppsrkl1 mRNA shows an abrupt decline in abundance. This decline is prevented by the addition of salicylic acid to the wound site. Ppsrkl1 mRNA rapidly decreases in abundance in fruit after 10 min exposure to UV-C radiation, followed by a return to normal levels within 3 h. Interestingly, Ppsrkl1 mRNA shows a second decline in abundance 12 h after treatement. These experiments suggest that Ppsrkl1 is negatively regulated by both phytochrome and cryptochrome signaling pathways, and is positively influenced by water stress, particularly in bark and roots.