Plant U-box E3 ubiquitin ligase (PUB) is involved in various environmental stress conditions. However, the molecular mechanism of U-box proteins in response to abiotic stress in wheat remains unknown. In this study, two U-box E3 ligase genes (TaPUB2 and TaPUB3), which are highly expressed in response to adverse abiotic stresses, were isolated from common wheat, and their cellular functions were characterized under drought stress. Transient expression assay revealed that TaPUB2 was localized in the cytoplasm and Golgi apparatus, whereas TaPUB3 was expressed only in the Golgi apparatus in wheat protoplasts. Additionally, TaPUB2 and TaPUB3 underwent self-ubiquitination. Moreover, TaPUB2/TaPUB3 heterodimer was identified in yeast and the cytoplasm of wheat protoplasts using a pull-down assay and bimolecular fluorescence complementation analysis. Heterogeneous overexpression of TaPUB2 and TaPUB3 conferred tolerance to drought stress. Taken together, these results implied that the heterodimeric form of U-box E3 ubiquitin ligases (TaPUB2/TaPUB3) responded to abiotic stress and roles as a positive regulator of drought stress tolerance.

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Functional characterization of wheat histone H2B monoubiquitination enzyme TaHUB2 in response to vernalization in Keumkang (Triticum aestivum L.

Plant U‐box E3 ligases (PUBs) are important regulators of responses to various abiotic stress conditions. In this study, we found that wheat (Triticum aestivum. L) PUBs TaPUB2 and TaPUB3 enhanced abscisic acid (ABA) responses and salt tolerance in Arabidopsis. We generated transgenic Arabidopsis lines overexpressing TaPUB2 and TaPUB3 and performed various plant physiological experiments. Overexpression of TaPUB2 and TaPUB3 increased tolerance to salinity stress in an ABA‐dependent manner in transgenic plants, as evidenced by germination and survival rates, root length, stomatal aperture regulation, membrane peroxidation, photosynthetic activities, reactive oxygen species scavenging activities and expression of various ABA and salinity stress‐related genes. These results demonstrate the functions of PUBs under ABA and salinity stress conditions and provide valuable information for the development of salinity stress‐tolerant crop species.

Grain yield in wheat is mostly governed prior to flowering during primordia development. Mature primordia development, floret fertility, and maximum grain number per spikelet are the three most important characteristics of spike development. The genes involved in primordia formation, on the other hand, have remained unclear. Here, we demonstrate molecular characterization of Triticum aestivum MARCH9 (TraesCS7A01G283700) which encodes RING domain, might play a positively regulating primordium and floret development until anthesis stages. TaMARCH9 expression level was highly induced at differentiation stages (WS 3-6) in Yeongkwang cultivar. TaMARCH9 exhibited ubiquitination activities and was localized to the plasma membrane using a transient expression system in tobacco. Moreover, overexpression of TaMARCH9 in Arabidopsis plant displayed early flowering phenotypes compared to wild-type. Some of flowering related genes such as FLC, MAF, FT and SOC were highly induced in TaMARCH9overexpressing Arabidopsis plants. Our finding suggested that TaMARCH9 may act a key role in the formation of floret primordium development and/or flowering time in wheat.