Cloning and Analysis of Salt Stress-Related Gene TaMYB32 in Wheat

MYB transcriptional factors (TFs) are a multifunctional gene family in plant with partial number members involved in responses to abiotic stresses. A salt stress-related gene, TaMYB32, was screened out during the bulk sequencing of full length of cDNAs in wheat (Triticum aestivum L.) that were cloned in the authors' laboratory. TaMYB32 is 1250 bp in full length with a 732-bp open reading frame, encoding an R2R3-MYB TF with 244 amino acids. The sequences of TaMYB32 were cloned from either the hexaploid common wheat varieties Chinese Spring and Chadianhong or the diploid ancestors T. urartu UR206, Aegilops speltoides Y2006, and Ae. tauschii Y2282 using the primers that were designed based on the cDNA sequence of TaMYB32. Sequence analysis indicated that 2 types of sequences existed in the diploid ancestors and 4 in hexaploid wheat. One of the sequences was identical in both diploid and hexaploid wheat. This implied that TaMYB32 was conservative during the evolution of wheat. The genomic TaMYB32 sequences proved to be nonintron genes after comparing with their cDNA sequences. TaMYB32 was mapped onto the homoeologous group 6 of wheat using the electronic mapping strategy, and 2 copies of the gene were found in each genome of hexaploid wheat. This result was in agreement with that from sequencing. Homologous analysis found that TaMYB32 had a similarity with R2R3-MYB proteins from rice (Oryza sativa L.) and maize (Zea mays L.) as high as 72.4% and 73.7%, respectively. TaMYB32 expressed in roots, stems, leafs, pistils, and anthers in wheat, and the expression was induced by salt stress according to semiquantitative and real-time reverse transcript PCR.