Cloning and expression analysis of alanine aminotransferase gene TaAlaAT1 in wheat infected with stripe rust fungus.

There is increasing evidence that some genes encoding aminotransferase associated with plant carbon and nitrogen metabolism also play critical roles in the induction of plant defense against pathogens. An EST, homologous to the rice alanine aminotransferase gene, was isolated from an incompatible suppression subtractive hybridization (SSH) cDNA library of wheat leaves infected with Puccinia striiformis f. sp. tritici. Using in silicon cloning and RT-PCR, a 1 563 bp cDNA sequence was obtained from wheat and designated TaAlaAT1. Sequence analysis showed that TaAlaAT1 included a complete 1 440 bp ORF and encoded a putative protein composed of 479 amino acids. The deduced amino acid sequence was revealed the presence of the conserved aminotransferase signature and highly homologous to alanine aminotransferase in Oryza sativa, Vitis vinifera, Glycine max, Arabidopsis thaliana and Medicago truncatula. The expression pattern of TaAlaAT1 at transcription level was investigated by semi-quantitative RT-PCR and real-time PCR, respectively, which revealed that TaAlaAT1 transcripts were up-regulated in incompatible interaction of wheat and stripe rust, whereas down-regulated in compatible interaction, and apparently different between incompatible and compatible interaction. It was speculated that TaAlaAT1 was involved in wheat defense response to P. striiformis.