Pear IAA1 gene encoding an auxin-responsive Aux/IAA protein is involved in fruit development and response to salicylic acid

Abstract

Shi, H., Wang, Y., Li, Z., Zhang, D., Zhang, Y., Xiang, D., Li, Y. and Zhang, Y. 2014. Pear IAA1 gene encoding an auxin-responsive Aux/IAA protein is involved in fruit development and response to salicylic acid. Can. J. Plant Sci. 94: 263–271. Auxin-responsive Aux/IAA proteins are rapidly auxin-induced, short-lived proteins that act as repressors for the auxin response factor (ARF)-activated gene expression. A gene encoding an Aux/IAA protein and designated PpIAA1 was isolated from pear (Pyrus pyrifolia). Using PCR amplification techniques, the genomic clone corresponding to PpIAA1 was isolated and shown to contain three introns with typical GT/AG boundaries defining the splice junctions. The deduced PpIAA1 protein contains the conserved features of indole-3-acetic acids (IAA): four Aux/IAA conserved domains, Aux/IAA family domain, Aux/IAA-ARF dimerization domain profile, and conserved nuclear localization signal (NLS) motifs. Phylogenetic analyses clearly demonstrated PpIAA1 has the highest homology with grape VvIAA. PpIAA1 was preferentially expressed in fruit, and moderate expression was found in anthers. Relatively low expression signal was detected in other tissues including shoots, leaves, and petals. Moreover, expression of PpIAA1 was developmentally regulated in fruit. Further study demonstrated that PpIAA1 expression in pear fruit was remarkably regulated by salicylic acid and IAA. The data suggest that PpIAA1 might be involved in the interplay between IAA and salicylic acid signaling pathway during the fruit development of pear.