Phytophthora capsici is an oomycete plant pathogen that causes blight and fruit rot of peppers and other important vegetable crops,and results in multi-billion dollar losses in crop production annually.In this study,we employed A.thaliana-P.capsici pathosystem to investigate the pathogenic mechanism of oomycete pathogens.Total RNA was isolated from stems,flowers and infected leaves at 6 and 12 h after inoculation with P.capsici strain LT263.An Arabidopsis thaliana cDNA library was constructed at an early stage of P.capsici infection.The unamplified cDNA library was consisted of 4.0×106 independent colonies,and the length of inserted fragments was ranged from 0.5 kb to 3.0 kb with an average size of 1.5 kb.The cDNA library was then applied to screen for PINP1 interacting proteins,and 157 putative nuclear proteins were obtained by analyzing protein sequence and subcellular localization.Functional analysis in term of Gene Ontology showed that these candidate proteins were involved in 7 biological processes and 6 molecular functions.These data suggest that this is a high quality library and suitable for identifying the interacting proteins of an interested protein in the A.thaliana and P.capsici pathosystem.