Kelch-type F-box protein TaFBK34 improves wheat seedling tolerance to heat stress

Based on the climate change and more extreme temperature events in the past 30 years, heat stress (HS) has become one of the most detrimental abiotic stresses that affect crop growth and development, limit their geographical distribution, and reduce yield. As a typical chimonophilous crop, wheat is very sensitive to high temperature. Deciphering the molecular mechanism of the wheat response to high temperature will help in the development of cultivars that perform better under HS.

In this study, we identified a wheat Kelch-type F-box gene, TaFBK34. Overexpression of TaFBK34 wheat plants (TaFBK34-OE) showed stronger heat tolerance compared to the wild type, while plants with attenuated TaFBK34 (TaFBK34-RNAi) exhibited the phenotype of heat sensitivity. Increased expression of antioxidant-related genes and a heat-shock protein gene was observed in TaFBK34-OE plants compared with the wild type, coinciding with higher activities of the antioxidant enzymes, accumulation of proline and soluble sugar, reduced malondialdehyde and reactive oxygen species content. The opposite trends were observed in TaFBK34-RNAi lines. TaFBK34 interacts with the ADP-ribosylation factor, TaARL2. Compared to the wild type, more TaARL2 protein accumulated in TaFBK34-RNAi lines after HS treatment; moreover, TaARL2 continued to increase after MG132 (a proteasome inhibitor) injection for 12 h + 37 °C for 12 h, indicating that TaARL2 is involved in the response to HS and is degraded by the 26S proteasome.

These findings show that TaFBK34 improves wheat tolerance to HS, at least in part through an interaction with the TaARL2 protein, and provides potential applications of these genes for the improvement of wheat.