Identification of differentially expressed genes in a pistillody common wheat mutant using an annealing control primer system.

ABSTRACT

HTS-1 is a new kind of pistillody wheat. All or parts of its stamen are transformed into pistils or pistil-like structures, and it has more seed sets per floret than normal wheat under normal cultivation conditions. To investigate the expression divergence in this mutant, an annealing control primer system was used to identify differentially expressed genes (DEGs) in the young spikelets. As a result, three DEGs, including HDB2, HGF2, and HCG4, were detected, with variable expression in HTS-1 and the control. After further confirmation using real-time reverse transcription polymerase chain reaction analysis, these genes were overexpressed in HTS-1 wheat. NGF2 was identified in the double ridge to floret differentiation stages; HDB2 and HCG4 were identified in the stage of pistil and stamen-differentiating. Therefore, we inferred that the homeotic transformation of stamens into pistil-like structures occurred during the early stage of stamen development. Sequence alignment analysis revealed that HDB2 encodes a putative protein of 189 amino acids, with high homology to the DEAD-box ATP-dependent RNA helicase, and HCG4 was identical to the Chinese spring wheat cDNA clone predicted protein according to GenBank. However, NGF2 was not found to have significant similarity to any reported proteins, suggesting it is a new functional gene in wheat. The results suggest that HDB2, HCG4, and HGF2 are minor genes contributing to pistillody trait formation in HTS-1.