Figure 10.

Expression profiles of genes encoding proteins producing or detoxifying reactive oxygen species (ROS) in chickpea roots and nodules. A) In the very intricate ROS pathway in legume nodules, superoxide radicals (O2-) are generated by elevated mitochondrial respiration rates. In turn, leghemoglobin (LB2+), the enzyme keeping the nodules free of molecular oxygen (O2), can spontaneously be converted to ferric LB (LB3+), generating new O2-. These radicals can induce further conversions of LB2+ to LB3+. The generated superoxide radical can be directly dismutated by SOD to H2O2, which is immediately decomposed, as depicted in (B). On the other hand, H2O2 can generate hydroxyl radicals (OH-) in the presence of abundant free Fe+ ions, which are sequestered by metallothionein-like proteins. B) Hydrogen peroxide can be scavenged via the glutathione/ascorbate cycles or the action of catalases (CAT) NC: UniTag expression profiles indicating prevalence in nodules (with various intensities of blue):Organ-specific expression NS and RS: UniTag expression profiles of roots and nodules, and up- and down-regulation under salt stress (with various intensities of red and green, respectively): Stress-specific expression

Molina et al. BMC Plant Biology 2011 11:31   doi:10.1186/1471-2229-11-31
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