iTRAQ protein profile analysis of Citrus sinensis roots in response to long-term boron-deficiency

Abstract

Seedlings of Citrus sinensis were fertilized with boron (B)-deficient (0μM H3BO3) or -sufficient (10μM H3BO3) nutrient solution for 15weeks. Thereafter, iTRAQ analysis was employed to compare the abundances of proteins from B-deficient and -sufficient roots. In B-deficient roots, 164 up-regulated and 225 down-regulated proteins were identified. These proteins were grouped into the following functional categories: protein metabolism, nucleic acid metabolism, stress responses, carbohydrate and energy metabolism, cell transport, cell wall and cytoskeleton metabolism, biological regulation and signal transduction, and lipid metabolism. The adaptive responses of roots to B-deficiency might include following several aspects: (a) decreasing root respiration; (b) improving the total ability to scavenge reactive oxygen species (ROS); and (c) enhancing cell transport. The differentially expressed proteins identified by iTRAQ are much larger than those detected using 2D gel electrophoresis, and many novel B-deficiency-responsive proteins involved in cell transport, biological regulation and signal transduction, stress responses and other metabolic processes were identified in this work. Our results indicate remarkable metabolic flexibility of citrus roots, which may contribute to the survival of B-deficient plants. This represents the most comprehensive analysis of protein profiles in response to B-deficiency.

Biological significance: In this study, we identified many new proteins involved in cell transport, biological regulation and signal transduction, stress responses and other metabolic processes that were not previously known to be associated with root B-deficiency responses. Therefore, our manuscript represents the most comprehensive analysis of protein profiles in response to B-deficiency and provides new information about the plant response to B-deficiency. This article is part of a Special Issue entitled: Translational Plant Proteomics.

Keywords: 6-phosphogluconate dehydrogenase; 6PGDH; ABI3; ABI3-interacting protein 3; ACO; AIP3; ALDH; APX; B; BTF3; Boron-deficiency; CBS; CS; Citrus sinensis; DHN; G6PDH; GPx; GR; GRF; GS; K-homology; KH; LEA; MBF1; MDAR; MSR; NAC; NIP; PDI; PIP; PK; PM; POD; PPR; PR; Proteomics; ROS; Respiration; Root; S-formylglutathione hydrolase; SBP2; SFGH; SIP; SOD; TF; TIP; TPR; TRX; UDP-glucose pyrophosphorylase; UGPase; VDAC; abscisic acid insensitive 3; aconitase; aldehyde dehydrogenase; ascorbate peroxidase; basic transcription Factor 3; boron; citrate synthase; cystathionine-β-synthase; dehydrin; general regulatory factor; glucose-6-phosphate dehydrogenase; glutamine synthetase; glutathione peroxidase; glutathione reductase; iTRAQ; late embryogenesis abundant; methionine sulfoxide reductase; monodehydroascorbate reductase; multiprotein bridging factor 1; nascent polypeptide-associated complex; nodulin 26-like intrinsic protein; pathogen-related; pentatricopeptide repeat; peroxidase; plasma membrane; plasma membrane intrinsic protein; protein disulfide isomerase; pyruvate kinase; reactive oxygen species; selenium-binding protein 2; small basic intrinsic protein; superoxide dismutase; tetratricopeptide repeat; thioredoxin; tonoplast intrinsic protein; transcription factor; voltage-dependent anion channel.