The transcription factor Crz1-facilitated Phomopsis liquidambaris colonization boosting wheat against Fusarium...

Fusarium head blight (FHB), a devastating wheat disease worldwide caused by Fusarium graminearum, poses a serious threat to global wheat production and food security. The broad-spectrum endophytic fungus Phomopsis liquidambaris has application potential. Crz1, as a key transcription factor in the calcium signaling pathway, plays a pivotal role in regulating the fungal responses to environmental stress. Here, the overexpression and knockout mutants of Crz1 in P. liquidambaris were constructed and named OE-Crz1 and Ko-Crz1, respectively. The results demonstrated that Crz1 contributed to stress tolerance, cell wall integrity, and calcium homeostasis. Notably, the colonization level of the strain OE-Crz1 in wheat roots exhibited a 4.67-fold increase compared with the wild-type. The wheat pre-inoculated with OE-Crz1 significantly alleviated FHB severity. The grain infection rate was reduced from 68.67% to 37.33%, and the diseased spike rate from 68.04% to 38.65%. The expression of the genes involved in deoxynivalenol (DON) biosynthesis, Tri5 and Tri6, was downregulated to 6.86% and 2.97% of the control level, respectively, resulting in a 33.29% decrease in DON content in the grains. The findings indicate that Crz1 in P. liquidambaris is vital not only for fungal growth and development, but also for the root colonization of P. liquidambaris and its biocontrol capacity against F. graminearum. Thus, this study uncovers a novel function of Crz1 and provides a solid foundation for the practical application of this strain.