Comparative hormonal and transcriptomic analysis of heat stress responses in cassava and potato

Improving crop heat tolerance is essential under the increasingly frequent extreme temperature conditions worldwide. Cassava (Manihot esculenta Crantz) is a tropical crop with strong resistance to high temperature and high light, whereas potato (Solanum tuberosum L.) is a temperate crop highly sensitive to heat stress. To elucidate the differences in heat stress responses between cassava and potato, this study combined transcriptome sequencing with hormonal profiling. The results revealed that cassava exhibited significant changes in hormone signaling with relatively lower amplitude, whereas potato showed large fluctuations in both hormone levels and signaling pathways. Transcriptome analysis identified numerous differentially expressed genes (DEGs) in cassava cultivars KU50 and SC205 and in potato cultivars FAVORITA and Qingshu No. 9. Weighted gene co-expression network analysis (WGCNA) identified 13 regulatory modules in cassava and 11 in potato. In cassava, heat-responsive transcription factors and heat shock proteins (HSPs) were generally downregulated, while genes involved in photosynthetic electron transport and lignin biosynthesis were upregulated; the opposite trend was observed in potato. RT-qPCR validation confirmed the transcriptome data. These findings provide valuable gene resources for breeding heat-tolerant crop varieties and offer insights into the molecular mechanisms underlying heat tolerance in tropical vs temperate crops.