title: Transcriptome Analysis of Brassica rapa Near-Isogenic Lines Carrying Clubroot-Resistant and -Susceptible Alleles in Response to Plasmodiophora brassicae during Early Infection.
abstract: Although Plasmodiophora brassicae is one of the most common pathogens worldwide, the causal agent of clubroot disease in Brassica crops, resistance mechanisms to it are still only poorly understood. To study the early defense response induced by P. brassicae infection, a global transcriptome profiling of the roots of two near-isogenic lines (NILs) of clubroot-resistant (CR BJN3-2) and clubroot-susceptible (BJN3-2) Chinese cabbage (Brassica rapa) was performed by RNA-seq. Among the 42,730 unique genes mapped to the reference genome of B. rapa, 1875, and 2103 genes were found to be up- and down-regulated between CR BJN3-2 and BJN3-2, respectively, at 0, 12, 72, and 96 h after inoculation (hai). Functional annotation showed that most of the differently expressed genes are involved in metabolism, transport, signal transduction, and defense. Of the genes assigned to plant-pathogen interactions, 151 showed different expression patterns between two NILs, including genes associated with pathogen-associated molecular patterns (PAMPs) and effectors recognition, calcium ion influx, hormone signaling, pathogenesis-related (PR) genes, transcription factors, and cell wall modification. In particular, the expression level of effector receptors (resistance proteins), PR genes involved in salicylic acid (SA) signaling pathway, were higher in clubroot-resistant NIL, while half of the PAMP receptors were suppressed in CR BJN3-2. This suggests that there was a more robust effector-triggered immunity (ETI) response in CR BJN3-2 and that SA signaling was important to clubroot resistance. The dataset generated by our transcriptome profiling may prove invaluable for further exploration of the different responses to P. brassicae between clubroot-resistant and clubroot-susceptible genotypes, and it will strongly contribute to a better understanding of the molecular mechanisms of resistance genes of B. rapa against P. brassicae infection.
authors.affiliation: Department of Horticulture, Shenyang Agricultural University Shenyang, China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Horticulture, Shenyang Agricultural University Shenyang, China.
authors.forename: Wenxing
authors.initials: W
authors.lastname: Pang
authors.affiliation: Department of Characteristic Horticulture, Taizhou Institute of Agricultural Sciences, Jiangsu Academy of Agricultural Sciences Taizhou, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Chen
authors.affiliation: National Key Laboratory of Crop Genetic Improvement and College of Plant Science and Technology, Huazhong Agricultural University Wuhan, China.
authors.forename: Chunyu
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Horticulture, Shenyang Agricultural University Shenyang, China.
authors.forename: Zhongyun
authors.initials: Z
authors.lastname: Piao
keywords: Brassica rapa; Plasmodiophora brassicae; RNA-seq; clubroot; disease resistance