TaJUB1 is phosphorylated by TaMPK4 to enhance TaXIP3 transcription and reduce Cd accumulation

Cadmium (Cd) has been recognized as a prevalent toxic pollutant that poses a significant threat to human health through the food chain. To mitigate this risk, reducing Cd accumulation in crops is an effective strategy. In this work, we observed that the overexpression of TaXIP3 resulted in a substantial reduction in Cd accumulation in wheat. Further investigation revealed that TaJUB1 functions as an upstream regulator of TaXIP3, positively influencing its expression. Transgenic wheat lines overexpressing TaJUB1 were generated and these transgenic plants exhibited lower Cd concentrations compared to the WT. TaMPK4 was found to phosphorylate TaJUB1, thereby enhancing the transcription of TaXIP3. Moreover, five haplotypes for TaJUB1 were identified, with Hap4 and Hap5 demonstrating strong positive associations with reduced Cd absorption. The unique tyrosine residue present in Hap4 and Hap5 serves as a key phosphorylation site for TaMPK4, which exhibited a higher phosphorylation capacity towards these haplotypes. These findings illuminate the TaMPK4-TaJUB1-TaXIP3 pathway, elucidating its association with Cd absorption in wheat and providing a foundation for utilizing molecular technology in breeding low Cd varieties.