Transcriptomic analysis reveals the molecular mechanisms of wheat seedling resistance to Puccinia striiformis f. sp. tritici

Abstract Background: Stripe rust or yellow rust (Yr), caused by Puccinia striiformis f. sp. Tritici (Pst), is one of the most globally devastating fungal disease that significantly reduces yield and quality in wheat (Triticum aestivum). Although some Yr genes have been successfully used in wheat breeding and a little number of them have been cloned, large of the regulating networks and the molecular mechanisms of Pst resistance remains unknown. In this study, a pair of Yr-gene pyramiding line L58 and its background parent cv. Chuanyu12 (CY12) were used to study the transcriptome profiles after inoculated with Pst physiological race CYR34. Results: The results revealed that the different expression genes (DEGs) were significantly enriched in phenylpropanoid biosynthesis, phenylalanine metabolism, plant-pathogen interaction and MAPK signaling pathways after Pst-CYR34 inoculation. Compared with CY12, L58 showed greater up-regulated DEGs in those pathways by Pst infection at 24hpi. However, these DEGs became lower expression in L58 and opposite expression in CY12 at 7dpi. Besides, the activities of enzymes (PAL, POD) and products of phenylpropanoid pathway (lignin content) were significantly increased in both CY12 and L58, and the increase was greater and faster in the resistant line L58. Some candidate genes and transcription factors (TFs) associated with Pst resistance were identified, including LRR receptor-like serine/threonine protein kinase, disease resistance protein, MYB, NAC and WRKY transcription factors involved in the fine-tuning of Pst infection responses. Conclusions: Our results give insights into the regulating networks of Pst resistance and pave the way for durable resistant breeding in bread wheat.