Maddison Joanna, Lyons Tom, Plöchl Matthias, Barnes Jeremy
Department of Agricultural and Environmental Science, Newcastle University, Newcastle upon Tyne, UK.
Planta. 2002 Jan;214(3):383-91. doi: 10.1007/s004250100625.
Leaf L-ascorbate content of an ozone (O3)-sensitive radish genotype (Raphanus sativus L. cv. Cherry Belle) was increased 2-fold by feeding hydroponically cultivated plants L-galactono- 1,4-lactone (GalL). Plants were grown in controlled-environment chambers ventilated with charcoal/Purafil-filtered air, and administered one of two O3 fumigation regimes: chronic exposure (75 nmol O3 mol(-1) for 7 h day(-1) for 21 days) and acute exposure (180 nmol O3 mol(-1) for 9 h). Chronic O3 exposure decreased root growth by 11% in plants maintained in pure nutrient solution (-GalL), but resulted in no change in root growth in GalL-fed plants (+GalL). Similarly, GalL-feeding counteracted the negative effects of O3 on CO2 assimilation rate observed in control plants (-GalL). Under acute O3 exposure, GalL-fed plants showed none of the visible symptoms of injury, which were extensive in plants not fed GalL. Leaf CO2 assimilation rate was decreased by acute 03 exposure in both GalL treatments, but the extent of the decline was less marked in GalL-fed plants. No significant changes in stomatal conductance resulted from GalL treatment, so O3 Uptake into leaves was equivalent in + GalL and -GalL plants. Feeding GalL, on the other hand, enhanced the level of ascorbate, and resulted in the maintenance of the redox state of ascorbate under acute O3 fumigation, in both the leaf apoplast and symplast. The effect of GalL treatment on ascorbate pools was consistent with the reduction in O3 damage observed in GalL-fed plants. Attempts to model O3 interception by the ascorbate pool in the leaf apoplast suggested a greater capacity for O3 detoxification in GalL-fed plants, which corresponded with the increase in O3 tolerance observed. However, modelled data for GalL-fed plants suggested that additional constituents of the leaf apoplast may play an important role in the attenuation of environmentally-relevant O3 fluxes.
通过水培法给臭氧（O₃）敏感型萝卜基因型（萝卜品种樱桃贝儿）植株投喂L-半乳糖-1,4-内酯（GalL），其叶片L-抗坏血酸含量增加了两倍。植株在配备有木炭/普瑞菲尔过滤空气通风设备的可控环境培养箱中生长，并接受两种O₃熏蒸处理方式之一：长期暴露（75 nmol O₃ mol⁻¹，每天7小时，共21天）和急性暴露（180 nmol O₃ mol⁻¹，9小时）。在纯营养液（-GalL）中培养的植株，长期O₃暴露使根系生长降低了11%，但在投喂GalL的植株（+GalL）中根系生长没有变化。同样，投喂GalL抵消了O₃对对照植株（-GalL）中二氧化碳同化率的负面影响。在急性O₃暴露下，投喂GalL的植株未表现出任何可见的损伤症状，而未投喂GalL的植株损伤广泛。两种GalL处理方式下，急性O₃暴露均使叶片二氧化碳同化率降低，但投喂GalL的植株下降程度较小。GalL处理未导致气孔导度发生显著变化，因此+GalL和-GalL植株叶片对O₃的吸收量相当。另一方面，投喂GalL提高了抗坏血酸水平，并在急性O₃熏蒸下使叶片质外体和共质体中抗坏血酸的氧化还原状态得以维持。GalL处理对抗坏血酸库的影响与在投喂GalL的植株中观察到的O₃损伤减少一致。对叶片质外体中抗坏血酸库拦截O₃的尝试建模表明，投喂GalL的植株具有更强的O₃解毒能力，这与观察到的O₃耐受性增加相对应。然而，投喂GalL植株的建模数据表明，叶片质外体的其他成分可能在减弱与环境相关的O₃通量方面发挥重要作用。
