Cloning and Expression Analysis of Wheat Pheophorbide a Oxygenase Gene TaPaO

摘要

Pheophorbide a oxygenase (PaO) plays an important role in plant chlorophyll degradation. In this study, a novel gene, designated as TaPaO, was isolated from hexaploid wheat (Triticum aestivum). TaPaO was predicted to encode a protein with 523 amino acids. The encoded protein contained the typical Rieske (2Fe-2S) and mononuclear iron-binding domains as well as the C-terminus CxxC motif. Amino acid sequence alignment revealed that TaPaO shared a high degree of identity with other higher plant PaO proteins. The result of expression analysis indicated that TaPaO was expressed in roots, stems and leaves, and the expression level of TaPaO was obviously higher in leaves than in stems and roots. Quantitative real-time PCR showed that the expression of TaPaO was upregulated by abscisic acid (ABA) and methyl jasmonate (MeJA), but not by salicylic acid (SA) and gibberellic acid (GA(3)). Also, TaPaO could be induced by wounding, low temperature, and high salinity. Furthermore, the transcripts of TaPaO increased after infection with Puccinia recondita f. sp. tritici. However, the expression of TaPaO was not affected obviously after infection with Puccinia striiformis f. sp. tritici. These results suggest that TaPaO may be involved in plant defense responses to various stresses.