Overexpression of heat stress-responsive AtPLC9 confers heat tolerance in transgenic rice

As global warming becomes increasingly severe, it is urgent that we enhance the heat tolerance of crops. Understanding the mechanisms of heat tolerance will help breeders develop heat-resistant lines and protect yield. In a previous study, we showed that Arabidopsis thaliana phosphoinositide-specific phospholipase C9 (AtPLC9) promotes heat tolerance. Mutations in AtPLC9 reduce heat tolerance, while overexpression lines exhibit high heat tolerance. In this study, we ectopically overexpressed AtPLC9 in rice to examine its regulation of heat tolerance in this crop. Transgenic rice exhibited greater heat tolerance than the wild type. However, AtPLC9 did not improve the resistance to salt, drought or cold in transgenic lines. High-throughput RNA-seq revealed that extensive and dynamic transcriptome reprofiling occurred in transgenic plants after heat stress. Moreover, the expression of some transcription factors and calcium ion-related genes showed specific upregulation in transgenic rice after heat stress, which might contribute to enhanced heat resistance. In conclusion, this study provides preliminary guidance for using AtPLC9 to improve heat tolerance in cereal crops and, more broadly, highlights that heterologous transformation can assist with molecular breeding.