Splicing Factor SR45 Enhances Cold Tolerance in Cassava by Recruiting Nu4A Complex and Transcription Factors to Activate WRKY30

Cassava is highly susceptible to cold stress, which disrupts mRNA alternative splicing; however, the role of splicing factor genes in modulating cold tolerance remains elusive. This research explores the multifaceted roles of the splicing factors, MeSR45-2 and MeSR34b, in regulating development and cold stress tolerance in cassava. Gain-of-function of MeSR45-2 and MeSR34b markedly enhanced cold tolerance, with minimal effects on pre-mRNA alternative splicing, and upregulated cold-responsive DREB, NAC, and WRKY genes. IP-MS analysis demonstrated that MeSR45-2 interacted with the Nucleosome Acetyltransferase of Histone H4 (NuA4) complex subunit MeEPL1a and transcription factors MeSPL13a and MeTCP15b, activating the expression of MeDREB2a, MeNAC26, and MeWRKY30. Overexpression of MeWRKY30 enhanced cold resistance, as evidenced by higher levels of Fv/Fm and improved root elongation. Overall, these findings reveal a novel role for MeSR45-2 in recruiting RNA transcription activators for cold tolerance, providing valuable insights for breeding cold-resistant cassava varieties.