| Tomato (Solanum lycopersicum) is one of the major corps in greenhouse cultivation. Because of its wealth of nutrient, it’s popular with the majority of consumers. Tomato is not only one of the largest vegetable cultivated in greenhouse, but also an important representative species of Solanaceae plants. But the growth and development are susceptible to adverse environment conditions. Temperature stress is one of the most major factors that influence the growth and development, production and quality of tomato. Therefore, how to overcome and relieve these adversities, toensure the healthy growth of vegetables is very necessary.Brassinosteroids (BRs) are a group of plant steroid hormones that have been shown to play important roles in stress tolerance of plant, however, the mechanism is not very clear. In this paper, we use tomato as the experimental material, compared the low-temperature resistance with the BR biosynthetic mutant dim, wild type, DWARF-overexpressingtransgenic plants and RBOH-RNAi transgenic plants, studied by using the means of genetics, physiology, confirm BRs influence plant cold resistance, and RBOH play a key role in BRs regulation of plant resistance. we obtain GRXs gene silencing lines using virus induced gene silencing (VIGS) in tomato, research the biological functions of GRX from the genome analysis, photosynthetic electron transport and abiotic stress resistance. And discusses the GRX mediated BRs regulate low-temperature resistance and redox homeostasis of tomato.1. Genome-wide analysis of glutaredoxin family in tomato.44 tomato GRX genes were found from SGN, NCBI and other database by keyword search and sequence alignments in tomato genome. Phylogeneticanalysiswasperformed including tomatoandArabidopsis GRX wasconstructed.Consistent with theresultofArabidopsis, tomato GRX can be grouped into 3 types, including CPYC, CGFS, CC type. All of the GRX genes are distributed on 11 chromosomes throughout the tomato genome according to the chromosomal position on SGN database. Obtain ten GRX gene silencing lines using VIGS in tomato,SlGRX gene silence induce Y (NA) and Y (ND) increased obviouSly, have a significant impact the PSI electron transfer and protection ability, and SlGRX gene silence display enhanced sensitivity to heat and PQ stress. These show GRXs play important roles in photosynthetic electron transport and abiotic stress response.2. We have studied the role of GRX in heat stress tolerance. Virus-induced genesilencingof SlGRXS14, SlGRXS17, SlGRXC2, SlGRXS12, SlGRXS1 genes individually increasedmembrane lipid peroxidation and the accumulation of ROS and 2-Cys peroxiredoxin dimers, suppress the activities of antioxidant enzymes and decreased GSH/GSSG and ASA/DHA IN the leaves. Furthermore, silencing of SlGRXresulted in decreased expression of genes involved in the Calvin cycle and decreased activity of the associated enzymes. These results indicate that the GRXs involved in cellular redox homeostasis and heat stress response.3. We noticed that BRs could confer cold resistance in tomato. Using BR biosynthetic mutant dim, wild type, DWARF-overexpressing transgenic plants and exogenous spraying EBR, we found that the internal and external source BRs individually decreased the activities of antioxidant enzyme, the ratio of glutathione to oxidized glutathione (GSH/GSSG) and ASA/DHAin the leaves, reduced the accumulation of protein oxidation and 2-Cys peroxiredoxin dimers, resulted in enhanced the resistance to cold stress in the tomato. However, RBOH-RNAi inhibitedthe increase of the activity of antioxidant enzymes and the enhance of cold resistance regulated by BRs, so RBOH coding of NADPH oxidase may be involved in BRs regulation of tomato cold resistance. BRs induced increase expression of SIGRXS14 and SlGRXS12, while SIGRXS14 and SlGRXS12gene silencing suppression the EBR regulation function of the plant. All of these results suggest that SlGRXS14 and SlGRXS12 are involved in the BRs-inducedchanges incold resistance in tomato. |
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