Comparative transcriptomics reveals defense acquisition in Brassica rapa by synchronizing brassinosteroids metabolism with PR1 expression

• Published in: European journal of plant pathology 2022-04, Vol.162 (4), p.869-884
• Main Authors: Ahmad, Aqeel, Wang, Rui, Mubeen, Samavia, Akram, Waheed, Hu, Du, Yasin, Nasim Ahmad, Khan, Moman, Wu, Tingquan
• Format: Article
• Language: English
• Subjects: Agriculture; Biomedical and Life Sciences; Biosynthesis; Brassica; Brassica rapa; Brassinosteroids; Calcium ions; Delayed response; Ecology; Food plants; Food security; Gene expression; Gene regulation; Gene sequencing; Genes; Inoculation; Life Sciences; Metabolism; Pathogens; Plant Pathology; Plant protection; Plant Sciences; Protein metabolism; Protein turnover; Synchronism; Transcriptomics; Zinc finger proteins
• ISSN: 0929-1873; 1573-8469
• DOI: 10.1007/s10658-021-02443-0

The current investigation reveals the molecular basis of Brassica rapa resistance against Hyaloperonospora brassicae based on RNA sequencing. The resistant line RB5 remained symptomless even after three days of post-inoculation. There was the maximum number of down-regulated genes (5156) in S1 after 96 h post-inoculation. Resistant line RB5 had 392 upregulated genes related to metabolic processes at 0 h post-inoculation. The comparison of both the lines after 96 h showed a slower but steady upregulation in the gene expression in RB5 (less than 3000 genes). The brassinosteroid (BR) biosynthesis pathway showed a down-regulation of its genes with the maximum down-regulation of BSK. Studying the calcium ions chain revealed 72% upregulated genes. However, the concluding physiological response resulted from the upregulation of PR genes (usually more than 2 times upregulation in most cases). Among PR genes, the loci Bra003774 and Bra025730 depicted an upregulation of more than two times, consequently supporting the elevated expression of WRKY22 and PR1. However, due to the end position of PR1 in defense responses, it was annotated as a delayed response factor to the attacking pathogen. MKS1 pathway was proved less sensitive toward the pathogenic attack; however, MEKK2 metabolism was proved more sensitive. After PR1, Zinc finger protein metabolism was the second highly activated process in the Brassica cells with the elevated expression of 42% genes. The study adds precious information about the host–pathogen relationship and could assist plant protection and food security programs.