Effects of the oxygen exposure on plants were investigated in intact hypocotyl tissues of etiolated seedlings from mung bean (Vigna radiata L.). We report here that spin-lattice NMR relaxation time (Τ1) of water proton of intact tissues, which can be measured with a 180° - τ -90° pulse sequence at 20 MHz, is responsible to the oxygen exposure. When the tissues placed in the NMR tube were exposed to 95% oxygen for 5 s, a rapid decrease in the Τ1 values and a subsequent relaxation process were observed. The value was fully recovered to the initial one during a 40 min incubation. Heat-denatured tissues did not show such recovery response, suggesting that the Τ1 recovery requires heat-sensitive components contained in the tissues. To examine a possibility that scavenging activities of oxygen radicals is involved in the mechanism for the Τ1 response, effects of supplemental scavengers were tested. We have found that the shortening of Τ1 induced by oxygen exposure to membrane fractions was strongly suppressed by the radical scavenger superoxide dismutase (SOD), Tiron and ascorbate. These results suggest that activities of O2 production in the tissues are involved in the mechanism for abrupt shortening of Τ1.
|Number of pages||8|
|Journal||Journal of the Faculty of Agriculture, Kyushu University|
|Publication status||Published - Feb 2000|
All Science Journal Classification (ASJC) codes
- Agronomy and Crop Science