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Leaf cDNA-AFLP analysis of two citrus species differing in manganese tolerance in response to long-term manganese-toxicity

Chen-Ping Zhou12, Yi-Ping Qi3, Xiang You14, Lin-Tong Yang15, Peng Guo1, Xin Ye15, Xin-Xing Zhou15, Feng-Jiao Ke15 and Li-Song Chen125*

Author Affiliations

1 Institute of Horticultural Plant Physiology, Biochemistry and Molecular Biology, Fujian Agriculture and Forestry University, 350002 Fuzhou, China

2 College of Horticulture, Fujian Agriculture and Forestry University, 350002 Fuzhou,, China

3 Institute of Materia Medica, Fujian Academy of Medical Sciences, 350001 Fuzhou, China

4 College of Life Science, Fujian Agriculture and Forestry University, 350002 Fuzhou, China

5 College of Resources and Environmental Sciences, Fujian Agriculture and Forestry University, 350002 Fuzhou, China

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BMC Genomics 2013, 14:621  doi:10.1186/1471-2164-14-621

Published: 14 September 2013



Very little is known about manganese (Mn)-toxicity-responsive genes in citrus plants. Seedlings of ‘Xuegan’ (Citrus sinensis) and ‘Sour pummelo’ (Citrus grandis) were irrigated for 17 weeks with nutrient solution containing 2 μM (control) or 600 μM (Mn-toxicity) MnSO4. The objectives of this study were to understand the mechanisms of citrus Mn-tolerance and to identify differentially expressed genes, which might be involved in Mn-tolerance.


Under Mn-toxicity, the majority of Mn in seedlings was retained in the roots; C. sinensis seedlings accumulated more Mn in roots and less Mn in shoots (leaves) than C. grandis ones and Mn concentration was lower in Mn-toxicity C. sinensis leaves compared to Mn-toxicity C. grandis ones. Mn-toxicity affected C. grandis seedling growth, leaf CO2 assimilation, total soluble concentration, phosphorus (P) and magenisum (Mg) more than C. sinensis. Using cDNA-AFLP, we isolated 42 up-regulated and 80 down-regulated genes in Mn-toxicity C. grandis leaves. They were grouped into the following functional categories: biological regulation and signal transduction, carbohydrate and energy metabolism, nucleic acid metabolism, protein metabolism, lipid metabolism, cell wall metabolism, stress responses and cell transport. However, only 7 up-regulated and 8 down-regulated genes were identified in Mn-toxicity C. sinensis ones. The responses of C. grandis leaves to Mn-toxicity might include following several aspects: (1) accelerating leaf senescence; (2) activating the metabolic pathway related to ATPase synthesis and reducing power production; (3) decreasing cell transport; (4) inhibiting protein and nucleic acid metabolisms; (5) impairing the formation of cell wall; and (6) triggering multiple signal transduction pathways. We also identified many new Mn-toxicity-responsive genes involved in biological and signal transduction, carbohydrate and protein metabolisms, stress responses and cell transport.


Our results demonstrated that C. sinensis was more tolerant to Mn-toxicity than C. grandis, and that Mn-toxicity affected gene expression far less in C. sinensis leaves. This might be associated with more Mn accumulation in roots and less Mn accumulation in leaves of Mn-toxicity C. sinensis seedlings than those of C. grandis seedlings. Our findings increase our understanding of the molecular mechanisms involved in the responses of plants to Mn-toxicity.

cDNA-AFLP; Citrus grandis; Citrus sinensis; Leaves; Manganese