title: Comparative Transcriptome and iTRAQ Proteome Analyses of Citrus Root Responses to Candidatus Liberibacter asiaticus Infection.
abstract: Root samples of 'Sanhu' red tangerine trees infected with and without Candidatus Liberibacter asiaticus (CLas) were collected at 50 days post inoculation and subjected to RNA-sequencing and isobaric tags for relative and absolute quantification (iTRAQ) to profile the differentially expressed genes (DEGs) and proteins (DEPs), respectively. Quantitative real-time PCR was subsequently used to confirm the expression of 16 selected DEGs. Results showed that a total of 3956 genes and 78 proteins were differentially regulated by HLB-infection. Among the most highly up-regulated DEPs were sperm specific protein 411, copper ion binding protein, germin-like proteins, subtilisin-like proteins and serine carboxypeptidase-like 40 proteins whose transcript levels were concomitantly up-regulated as shown by RNA-seq data. Comparison between our results and those of the previously reported showed that known HLB-modulated biological pathways including cell-wall modification, protease-involved protein degradation, carbohydrate metabolism, hormone synthesis and signaling, transcription activities, and stress responses were similarly regulated by HLB infection but different or root-specific changes did exist. The root unique changes included the down-regulation in genes of ubiquitin-dependent protein degradation pathway, secondary metabolism, cytochrome P450s, UDP-glucosyl transferases and pentatricopeptide repeat containing proteins. Notably, nutrient absorption was impaired by HLB-infection as the expression of the genes involved in Fe, Zn, N and P adsorption and transportation were significantly changed. HLB-infection induced some cellular defense responses but simultaneously reduced the biosynthesis of the three major classes of secondary metabolites, many of which are known to have anti-pathogen activities. Genes involved in callose deposition were up-regulated whereas those involved in callose degradation were also up-regulated, indicating that the sieve tube elements in roots were hanging on the balance of life and death at this stage. In addition, signs of carbohydrate starvation were already eminent in roots at this stage. Other interesting genes and pathways that were changed by HLB-infection were also discussed based on our findings.
authors.affiliation: Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, P.R.China; Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture, Guangzhou, 510640, P.R.China; Key Laboratory of Tropical and Subtropical Fruit Tree Researches, Guangdong Province, Guangzhou, 510640, P.R.China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhong
authors.affiliation: Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, P.R.China; Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture, Guangzhou, 510640, P.R.China; Key Laboratory of Tropical and Subtropical Fruit Tree Researches, Guangdong Province, Guangzhou, 510640, P.R.China.
authors.forename: Chun-Zhen
authors.initials: CZ
authors.lastname: Cheng
authors.affiliation: Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, P.R.China; Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture, Guangzhou, 510640, P.R.China; Key Laboratory of Tropical and Subtropical Fruit Tree Researches, Guangdong Province, Guangzhou, 510640, P.R.China.
authors.forename: Nong-Hui
authors.initials: NH
authors.lastname: Jiang
authors.affiliation: Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, P.R.China; Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture, Guangzhou, 510640, P.R.China; Key Laboratory of Tropical and Subtropical Fruit Tree Researches, Guangdong Province, Guangzhou, 510640, P.R.China.
authors.forename: Bo
authors.initials: B
authors.lastname: Jiang
authors.affiliation: Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, P.R.China; Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture, Guangzhou, 510640, P.R.China; Key Laboratory of Tropical and Subtropical Fruit Tree Researches, Guangdong Province, Guangzhou, 510640, P.R.China.
authors.forename: Yong-Yan
authors.initials: YY
authors.lastname: Zhang
authors.affiliation: Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, P.R.China; Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture, Guangzhou, 510640, P.R.China; Key Laboratory of Tropical and Subtropical Fruit Tree Researches, Guangdong Province, Guangzhou, 510640, P.R.China.
authors.forename: Bo
authors.initials: B
authors.lastname: Wu
authors.affiliation: Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, P.R.China; Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture, Guangzhou, 510640, P.R.China; Key Laboratory of Tropical and Subtropical Fruit Tree Researches, Guangdong Province, Guangzhou, 510640, P.R.China.
authors.forename: Min-Lun
authors.initials: ML
authors.lastname: Hu
authors.affiliation: Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, P.R.China; Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture, Guangzhou, 510640, P.R.China; Key Laboratory of Tropical and Subtropical Fruit Tree Researches, Guangdong Province, Guangzhou, 510640, P.R.China.
authors.forename: Ji-Wu
authors.initials: JW
authors.lastname: Zeng
authors.affiliation: Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, P.R.China; Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture, Guangzhou, 510640, P.R.China; Key Laboratory of Tropical and Subtropical Fruit Tree Researches, Guangdong Province, Guangzhou, 510640, P.R.China.
authors.forename: Hua-Xue
authors.initials: HX
authors.lastname: Yan
authors.affiliation: Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture, Guangzhou, 510640, P.R.China; Key Laboratory of Tropical and Subtropical Fruit Tree Researches, Guangdong Province, Guangzhou, 510640, P.R.China.
authors.forename: Gan-Jun
authors.initials: GJ
authors.lastname: Yi
authors.affiliation: Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, P.R.China; Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture, Guangzhou, 510640, P.R.China; Key Laboratory of Tropical and Subtropical Fruit Tree Researches, Guangdong Province, Guangzhou, 510640, P.R.China.
authors.forename: Guang-Yan
authors.initials: GY
authors.lastname: Zhong
mesh_terms: D050260:Carbohydrate Metabolism; D002851:Chromatography, High Pressure Liquid; D002957:Citrus / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D054884:Host-Pathogen Interactions; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology*; D020543:Proteome / Q000032:analysis*; D040901:Proteomics; D060888:Real-Time Polymerase Chain Reaction; D012230:Rhizobiaceae / Q000502:physiology*; D017423:Sequence Analysis, RNA; D021241:Spectrometry, Mass, Electrospray Ionization; D059467:Transcriptome; D015854:Up-Regulation
chemical_list: D020543:Proteome