AUTHOR=Sang Wen , Huang Zeng-Rong , Yang Lin-Tong , Guo Peng , Ye Xin , Chen Li-Song 

TITLE=Effects of High Toxic Boron Concentration on Protein Profiles in Roots of Two Citrus Species Differing in Boron-Tolerance Revealed by a 2-DE Based MS Approach

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00180

DOI=10.3389/fpls.2017.00180

ISSN=1664-462X

ABSTRACT=<p>Citrus are sensitive to boron (B)-toxicity. In China, B-toxicity occurs in some citrus orchards. So far, limited data are available on B-toxicity-responsive proteins in higher plants. Thirteen-week-old seedlings of “Sour pummelo” (<italic>Citrus grandis</italic>) and “Xuegan” (<italic>Citrus sinensis</italic>) was fertilized every other day until dripping with nutrient solution containing 10 μM (control) or 400 μM (B-toxicity) H<sub>3</sub>BO<sub>3</sub> for 15 weeks. The typical B-toxic symptom only occurred in 400 μM B-treated <italic>C. grandis</italic> leaves, and that B-toxicity decreased root dry weight more in <italic>C. grandis</italic> seedlings than in <italic>C. sinensis</italic> ones, demonstrating that <italic>C. sinensis</italic> was more tolerant to B-toxicity than <italic>C. grandis</italic>. Using a 2-dimensional electrophoresis (2-DE) based MS approach, we identified 27 up- and four down-accumulated, and 28 up- and 13 down-accumulated proteins in B-toxic <italic>C. sinensis</italic> and <italic>C. grandis</italic> roots, respectively. Most of these proteins were isolated only from B-toxic <italic>C. sinensis</italic> or <italic>C. grandis</italic> roots, only nine B-toxicity-responsive proteins were shared by the two citrus species. Great differences existed in B-toxicity-induced alterations of protein profiles between <italic>C. sinensis</italic> and <italic>C. grandis</italic> roots. More proteins related to detoxification were up-accumulated in B-toxic <italic>C. grandis</italic> roots than in B-toxic <italic>C. sinensis</italic> roots to meet the increased requirement for the detoxification of the more reactive oxygen species and other toxic compounds such as aldehydes in the former. For the first time, we demonstrated that the active methyl cycle was induced and repressed in B-toxic <italic>C. sinensis</italic> and <italic>C. grandis</italic> roots, respectively, and that <italic>C. sinensis</italic> roots had a better capacity to keep cell wall and cytoskeleton integrity than <italic>C. grandis</italic> roots in response to B-toxicity, which might be responsible for the higher B-tolerance of <italic>C. sinensis</italic>. In addition, proteins involved in nucleic acid metabolism, biological regulation and signal transduction might play a role in the higher B-tolerance of <italic>C. sinensis</italic>.</p>