Shi, H., Wang, Y., Zhang, D., Chen, L. and Zhang, Y. 2015. Pear PIP1 gene is regulated during fruit development and is invovled in response to salicylic acid and ethylene. Can. J. Plant Sci. 95: 77-85. Plasma membrane intrinsic proteins (PIPs), a subfamily of aquaporins, are widely implicated in plant growth and development. A gene encoding a plasma membrane intrinsic protein and designated PpPIP1 was isolated from pear (Pyrus pyrifolia). Using PCR amplification techniques, the genomic clone corresponding to PpPIP1 was isolated and shown to contain three introns with typical GT/AG boundaries defining the splice junctions. The deduced PpPIP1 protein contains the conserved features of PIPs: six transmembrane a-helices, a major intrinsic protein domain, and a conserved asparagine-proline-alanine (NPA) signature sequence. Phylogenetic analyses clearly demonstrated that PpPIP1 has the highest homology with apple (Malus×domestica) MdPIP1a and Malus hupehensis MhPIP1-1. PpPIP1 transcripts were mainly detected in young leaves, shoots, petals and mesocarp of fruit, but a relatively low expression signal was detected in anthers. In particular, expression of PpPIP1 was developmentally regulated in fruit. Further study demonstrated that PpPIP1 expression in pear fruit was down-regulated by salicylic acid (SA) and up-regulated by ethylene. These data suggest that PpPIP1 may be involved in the response to SA and ethylene during fruit development, which would provide valuable information for water permeability studies in pear.