21039565
not annotated - annotated - LINNAEUS only
Aerenchyma formation in the rice stem and its promotion by H2O2.
* Gas spaces (aerenchyma) form as an adaptation to submergence to facilitate gas exchange. In rice (Oryza sativa), aerenchyma develop by cell death and lysis, which are poorly understood at the cellular level. * Aerenchyma formation was studied in rice stems by light microscopy. It was analyzed in response to submergence, ethylene and hydrogen peroxide (H(2)O(2)) treatment, and in the MT2b::Tos17 mutant. O(2)*(-) was detected with nitroblue tetrazolium and an epinephrine assay. H(2)O(2) was detected with 3,3'-diaminobenzidine. * Aerenchyma develop constitutively in all internodes of the deep-water rice variety Pin Gaew 56, but are absent from the nodes. Constitutive aerenchyma formation was also observed in two lowland rice varieties, albeit to a lesser degree. A larger number of aerenchyma are present in older internodes, and at the top of each internode, revealing developmental gradients. Submergence or treatment with the ethylene-releasing compound ethephon promoted aerenchyma formation in all genotypes analyzed. Pre-aerenchymal cells contain less starch, no chloroplasts, thinner cell walls and produce elevated levels of O(2)*(-) and H(2)O(2) compared with other parenchymal cells. Ethephon promotes O(2)*(-) formation and H(2)O(2) promotes aerenchyma formation in a dose-dependent manner. Further-more, genetic downregulation of the H(2)O(2) scavenger MT2b enhances aerenchyma formation. * Aerenchyma formation is mediated by reactive oxygen species.
Ann file
T1 Species 28 32 rice
N1 Reference T1 Taxonomy:4530
T2 Species 160 164 rice
N2 Reference T2 Taxonomy:4530
T3 Species 166 178 Oryza sativa
N3 Reference T3 Taxonomy:4530
T4 Species 314 318 rice
N4 Reference T4 Taxonomy:4530
T5 Species 671 675 rice
N5 Reference T5 Taxonomy:4530
T6 Species 795 799 rice
N6 Reference T6 Taxonomy:4530