Tuesday October 20 2009
CEA
In Vivo Cell Wall Loosening by Hydroxyl Radicals during Cress Seed Germination and Elongation Growth.
Plant Physiol. (2009) 209, 150, 1855-1865.
CEA
Loosening of cell walls is an important developmental processin key stages of the plant life cycle, including seed germination,elongation growth, and fruit ripening. Here, we report directin vivo evidence for hydroxyl radical (·OH)-mediatedcell wall loosening during plant seed germination and seedlinggrowth. We used electron paramagnetic resonance spectroscopyto show that ·OH is generated in the cell wall duringradicle elongation and weakening of the endosperm of cress (Lepidiumsativum; Brassicaceae) seeds. Endosperm weakening precedes radicleemergence, as demonstrated by direct biomechanical measurements.By 3H fingerprinting, we showed that wall polysaccharides areoxidized in vivo by the developmentally regulated action ofapoplastic ·OH in radicles and endosperm caps: the productionand action of ·OH increased during endosperm weakeningand radicle elongation and were inhibited by the germination-inhibitinghormone abscisic acid. Both effects were reversed by gibberellin.Distinct and tissue-specific target sites of ·OH attackon polysaccharides were evident. In vivo ·OH attack oncell wall polysaccharides were evident not only in germinatingseeds but also in elongating maize (Zea mays; Poaceae) seedlingcoleoptiles. We conclude that plant cell wall loosening by ·OHis a controlled action of this type of reactive oxygen species.
Muller K, Linkies A, Vreeburg R A M, Fry S C, Krieger-Liszkay A, Leubner-Metzger G. (2009). In Vivo Cell Wall Loosening by Hydroxyl Radicals during Cress Seed Germination and Elongation Growth. Plant Physiol. 150, 1855-1865.