RNA-Seq Profiling Identifies Temperature-Responsive Genes in Germinating Urediniospores of Puccinia striiformis f. sp. tritici Race CYR34-8

Wheat stripe rust (yellow rust), a devastating disease caused by the phytopathogen Puccinia striiformis f. sp. tritici (Pst), poses a major threat to global wheat (Triticum aestivum L.) production. Under ongoing climate warming, the highly virulent Pst race CYR34 has become predominant in China and exhibits increased tolerance to elevated temperatures. Although temperature is known to influence Pst urediniospore germination, the molecular mechanisms underlying temperature sensitivity during this process remain poorly understood. In this study, we combined histological examinations with transcriptome sequencing across multiple temperature regimes to identify temperature-responsive genes and characterize the predicted protein association networks in Pst. Urediniospore germination of three Pst races was tested; stronger heat tolerance was observed in CYR34-8 with 67.40–77.40% germination at 9–16 °C. RNA-Seq analysis identified 89 differentially expressed genes (DEGs) associated with temperature sensitivity, and their expression patterns were validated by qRT-PCR. The DEGs were significantly enriched in ubiquinone and other terpenoid-quinone biosynthesis, glycan degradation, and longevity-regulating pathways. Among these DEGs, genes annotated as encoding an ABC transporter, malate dehydrogenase, Hsp70, and a class 3 lipase were identified as putative hub genes in the predicted protein association network and may be associated with the coordination of temperature responses and metabolic processes.