Retraction Note: Cloning and characterization of TaPUB4, a U-box gene from common wheat (Triticum aestivum L.) involved in regulation of pollen development by influencing sucrose-starch pathway in anther

Development of functional pollen grains in plants is regulated through complex genetic networks and environmental clues. The ubiquitin-26S proteasome system is important in the post-translational modification of intracellular proteins, and the system includes the ubiquitin activating (E1), ubiquitin conjugating (E2), and ubiquitin ligase (E3) enzymes. Here, a novel plant U-box-containing cDNA was isolated in anther from common wheat (Triticum aestivum) and designed as TaPUB4. The cDNA encoding comprised 2598 bp, with an open reading frame of 865 amino acids. The deduced amino acid sequence of TaPUB4 showed 41.2–92.3% identity with other plant U-box homologous genes. Self-ubiquitination assay indicated that the bacterially expressed TaPUB4 protein had E3 ligase activity, and subcellular localization results showed that TaPUB4 was located in the nucleus and cytoplasm in onion epidermal cells. Overexpression of TaPUB4 gene in Arabidopsis atpub4 mutant restored partially the fertility of the mutant, increased the number of pollens in anthers, enhanced pollen viability, and displayed normal degradation of tapetum as anther development. The expression levels of genes related to starch deposition also changed greatly in the anthers of transgenic lines. These results support the notion that as a homolog of AtPUB4, TaPUB4 might control male fertility by regulating sucrose-starch metabolism in pollen grains, and this process may be accomplished through ubiquitin-proteasome system. The development and utilization of TaPUB4 as a functional molecular marker may be helpful for improving its fertility in wheat breeding programs in the future.