Cloning a second form of adenine phosphoribosyl transferase gene (TaAPT2) from wheat and analysis of its association with thermo-sensitive genic male sterility (TGMS)

Adenine phosphoribosyl transferase (APRT) is the key enzyme that converts adenine to adenosine monophosphate (AMP) in the purine salvage pathway. A novel form of APRT gene from wheat (Triticum aestivum L.) was cloned through a combination of bioinformatic, RT-PCR and rapid amplification of cDNA ends (RACE) strategies. The total length of the cDNA sequence is 1097 nucleotides, in which an open reading frame (ORF) was found that encodes 221 amino acid residues. Alignment of the deduced amino acid sequence and that of the other plant APRT genes indicates that the novel cDNA in full-length is the form 2 of wheat APRT gene, which was named as TaAPT2. Twelve Single Nucleotide Polymorphism (SNP) sites were identified in the TaAPT2 gene from BNY-S, one wheat temperature-sensitive genic male sterile (TGMS) mutant line derived from the wild type of BNY-F, among which a single base substitution in the purine-binding domain resulted in the Asn to Thr transition. The protein secondary structure prediction revealed that this SNP mutation subsequently resulted in many changes in the quantity and the positions of the helix, extended strand and the loop, which perhaps affect the combining efficiency of the APRT. Northern analysis indicated that the abundance of TaAPT2 gene transcript in the young spikelets reduced obviously in BNY-S under low temperature stress (lower than 10 °C) at the early stage of pollen fertility alternation, however, the transcript of TaAPT2 gene in BNY-F was not affected, indicating that wheat TaAPT2 gene may be related to the fertility alternation and abortion of pollen development.