Physiological and molecular mechanism studies on the conferred clubroot resistance of PbBa8.1 enriched in Brassica napus

• 1、Longping Branch, College of Biology, Hunan University, Changsha 410125, China
• 2、College of Life Science and Chemistry, Hunan University of Technology, Zhuzhou 412007, China
• 3、Crop Research Institute, Changsha 410125, China

Abstract：Clubroot is a soil-borne disease that affects cruciferous crops globally. Recently discovered in turnip in China, PbBa8.1 is a clubroot resistance gene that has been successfully transgenic to oilseed rape and widely used to genetically improve clubroot resistance in varieties. The experimental materials for this study were susceptible rapeseed varieties Fengyou 737 and its male parent SC4, as well as transgenic resistant varieties Fengyou 737R and its male parent SC4R. The transgenic varieties contained the introduced clubroot resistance gene PbBa8.1. The test materials were inoculated with Plasmodiophora brassicae spores via an artificial method, and physiological and biochemical indices, transcriptome and metabolome measurements were carried out at 1, 4 and 7 days to analyse the differential performances between susceptible and resistant materials. After artificial inoculation, the incidence and disease index of Fengyou 737 and SC4 were significantly higher than those of Fengyou 737R and SC4R. Additionally, the superoxide dismutase (SOD) and catalase (CAT) activities of SC4R were significantly higher than those of SC4. Furthermore, the malondialdehyde (MDA) content of SC4R was lower than that of SC4. Furthermore, the malondialdehyde (MDA) content of SC4R was lower than that of SC4. After inoculation and infestation, the transcriptome and metabolome analyses of SC4 and SC4R, Fengyou 737 and Fengyou 737R identified 6,065 differentially expressed genes (DEGs). Enrichment analyses indicated that genes related to plant immunity and defence responses against other organisms were significantly up-regulated in the genomes of SC4R and Fengyou 737R. Meanwhile, 1320 differentially expressed metabolites (DEMs) were screened, and the results of transcriptional and metabolic correlation analyses indicated that phenylalanine metabolism, nicotinic acid and nicotinamide metabolism, aminosugar and nucleotide sugar metabolism, carbon fixation in photosynthetic organisms, and interconversion of pentoses and gluconates were enriched in SC4 and SC4R, and the comparison of Fengyou 737 and Fengyou 737R simultaneously. This study used transcriptomic and metabolomic techniques to analyze the physiological, biochemical, transcriptional, and metabolic changes in resistant and susceptible materials under different genetic backgrounds. The analysis aimed to provide technical support for understanding the physiological, biochemical, and molecular mechanisms underlying clubroot resistance mediated by PbBa8.1 in rapeseed.

Keywords： Brassica napus Clubroot PbBa8.1 transcriptome metabolome mechanism study