Physiology And Transcriptome Of Mustard Responsive To Cadmium Stress

As a kind of cruciferous Brassica plant, Mustard(Brassica juncea) is an important vegetable. Recent studies show that mustard is an ideal plants to phytoremediate Cd contaminated soil. Therefore, the mechanism of resistance to cadmium has important implications for applying mustard to remedy soil and foster low enriched genus Brassica plant. In this study, mustard was used for investigating the effects of different Cd trearments on their growth characteristics, the capacity of uptake and accumulation, nutrient uptake, photosynthetic characteristics and the changes antioxidant enzyme systems, analysing transcriptome of mustard by high-throughput sequencing technology. The preliminary mechanism of mustard for response to the stress by Cd was discussed.20mg/kg-100mg/kg Cd Stress suppresses the growth of mustard, and significantly reduces its biomass and elongation of root. The Cd contents in same organs of different Cd concentrations were significantly different. The content of Mn and Mg decreased in the mustard by Cd stress, and the transport of Ca and Zn was inhibited. Fe content in leaves was reduced as well. Cadmium stress affected photosynthesis of mustard that the Pn、Gs、Tr、Fm and ΦPSII significantly decreased.Mustard chlorophyll a and b decreased, but chlorophyll a was affected more. Plants can produce oxygen free radicals by Cd stress, while anti oxidative enzyme system can clear them to a certain extent. The content of MDA in plants increased significantly, and the activity of SOD, POD, GR and APX was promoted, but the activity of CAT was decreased. Mustard transcriptome sequencing obtained a total of115 228 sequences, and the average length is 986 bp. Go functional classification results are presented to show the Uni Gene mainly involved in metabolic processes、cellular processes and a single organismin of biological process, cells、organelle, and cell part of cellular component, binding and catalytic activity of biological process.Under Cd stress, 23 genes were up-regulated and 57 were down regulated both in root and leaf. The main function of these genes as follow:chlorophyll A/B binding protein, Serine/threonine phosphatases, C2H2-type zinc finger, Triose-phosphate Transporter family, Phosphate-induced protein 1 conserved region, Glutathione S-transferase, Glycerophosphoryl diester phosphodiesterase family, DNA-binding domain found in transcription regulators, Plant transposon protein, Strictosidine synthase, Glycosyl hydrolases family 17, ATP sulfurylase.