Identification of genes governing resistance to PCN (Globodera rostochiensis) through transcriptome analysis in Solanum tuberosum.

ABSTRACT

Potato cyst nematodes (PCNs) are major pests worldwide that affect potato production. The molecular changes happening in the roots upon PCN infection are still unknown. Identification of transcripts and genes governing PCN resistance will help in the development of resistant varieties. Hence, differential gene expression of compatible (Kufri Jyoti) and incompatible (JEX/A-267) potato genotypes was studied before (0 DAI) and after (10 DAI) inoculation of Globodera rostochiensis J2s through RNA sequencing (RNA-Seq). Total sequencing reads generated ranged between 33 and 37 million per sample, with a read mapping of 48-84% to the potato reference genome. In the infected roots of the resistant genotype JEX/A-267, 516 genes were downregulated, and 566 were upregulated. In comparison, in the susceptible genotype Kufri Jyoti, 316 and 554 genes were downregulated and upregulated, respectively. Genes encoding cell wall proteins, zinc finger protein, WRKY transcription factors, MYB transcription factors, disease resistance proteins, and pathogenesis-related proteins were found to be majorly involved in the incompatible reaction after PCN infection in the resistant genotype, JEX/A-267. Furthermore, RNA-Seq results were validated through quantitative real-time PCR (qRT-PCR), and it was observed that ATP, FLAVO, CYTO, and GP genes were upregulated at 5 DAI, which was subsequently downregulated at 10 DAI. The genes encoding ATP, FLAVO, LBR, and GP were present in > 1.5 fold before infection in JEX-A/267 and upregulated 7.9- to 27.6-fold after 5 DAI; subsequently, most of these genes were downregulated to 0.9- to 2.8-fold, except LBR, which was again upregulated to 44.4-fold at 10 DAI.