Abstract
The late blight caused by Phytophthora infestans (P. infestans) has been a major constraint for worldwide sustainable potato production. Chinese potato cultivar Qingshu 9 has shown excellent field performance against late blight. To understand the mechanism underlying its resistance, the transcriptomic dynamics of Qingshu 9 infected with P. infestans was systematically investigated to identify the resistance-related genes. In total, 2027 shared differentially expressed genes (DEGs) were identified when infected with P. infestans at 24, 48 and 72 h post-inoculation. Based on k-mean cluster analysis, the DEGs showed four types of expression patterns, suggesting their divergent functions in response to P. infestans infection. KEGG enrichment analysis showed that the significantly enriched DEGs were involved in the biosynthesis of secondary metabolites, plant–pathogen interaction, and photosynthesis. Furthermore, 980 transcription factor genes belonging to 68 families were found in the DEGs, of which AP2-EREBP and MYB genes were the most abundant. Moreover, many genes related to disease resistance showed differential expression during infection. Finally, the expression of nine DEGs was validated by quantitative real-time PCR. These results provide valuable information for understanding late resistance in potato cultivar Qingshu 9.
Highlights
The late blight, caused by P. infestans, is regarded as the most severe disease affecting potato production worldwide
Different Transcription Factor (TF) genes were found to display differential expression during P. infestans infection in Qingshu 9, and these genes may positively or negatively regulate the response to P. infestans and co-regulate the resistance of Qingshu 9. These results provide a resource for future research into resistance genes, and the cloning of disease-resistant TF genes is of great significance for genetic engineering to improve disease resistance in potato
differentially expressed genes (DEGs) were significantly enriched in the categories of biosynthesis of secondary metabolites, plant–pathogen interaction pathways, and transcriptional regulation, etc., which are considered to play important roles in Qingshu 9’s resistance to late blight and is similar to the results found for plant-pathogen interaction in previous reports [63,64,65,66,67]
Summary
The late blight, caused by P. infestans, is regarded as the most severe disease affecting potato production worldwide. A qualitative resistance trait to P. infestans has been identified in Mexican hexaploid wild species Solanum demissum (S. demissum), and numerous resistance genes (R1~R11) have been defined and even isolated [5,6]. It is obviously inefficient to use a few single-disease-resistant R genes to improve P. infestans resistance in potato breeding [7]. Quantitative traits with broad-spectrum resistance have the potential to significantly improve the durability of potato resistance to P. infestans. The application of quantitative resistance genes with broad-spectrum and durable resistance to P. infestans in potato breeding is one of the effective ways to prevent disease in potato [10]
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