不同植物叶片臭氧伤害症状及其生理响应机制的差异

快速发展的城市化和工业化引起近地层臭氧浓度不断升高,对城市绿化植物具有很大的毒性伤害。选择城市常见的景观植物万寿菊、矮牵牛及圆叶牵牛为供试植物,利用开顶式气室,研究了不同植物臭氧伤害症状及其生理响应机制的差异。结果表明:1)臭氧暴露后,供试植物叶片均出现了不同程度的臭氧伤害,或叶脉间黄化(万寿菊和矮牵牛),或出现白色斑点(圆叶牵牛),且随臭氧浓度升高其黄化程度加剧,白色斑点亦扩张形成白色斑块,最终叶片从症状形成的地方开始干枯。2)臭氧暴露加剧了供试植物叶片膜脂过氧化程度,但对可溶性蛋白含量没有显著影响,说明植物生长后期臭氧暴露并没有造成蛋白质退化进而引起植物抗臭氧胁迫能力的下降。3)臭氧暴露后万寿菊叶片茉莉酸含量降低,矮牵牛叶片水杨酸含量显著升高,而圆叶牵牛既有水杨酸含量的升高又有茉莉酸含量的降低,说明不同植物对臭氧伤害的激素响应是不一致的,茉莉酸保护能力减弱引起了臭氧对万寿菊叶片伤害,水杨酸过度累积造成了矮牵牛叶片的臭氧直接伤害,而圆叶牵牛的臭氧伤害则是2种原因都可能存在。因此,在大气臭氧浓度尚不能有效控制的情况下,明确不同植物臭氧伤害形成的激素响应,以采取针对性保护措施维持其最大生态效益。

Ozone Injury to Marigold (Tagetes erecta Linn.), Petunia (Petunia hybrida Vilm.) and Morning Glory (Pharbitis purpurea (L.) Voigt) and Their Different Physiological Responses

Elevated tropospheric ozone (O3) is detrimental to urban greening plants by degrading their aesthetic and social values. It is urgent to clarify the possible physiological mechanisms on different responses of plant species to O3 injury. In the present study, with open-top chamber method, marigold (Tagetes erecta Linn.), petunia (Petunia hybrida Vilm.) and morning glory (Pharbitis purpurea (L.) Voigt) were exposed to different O3 concentration treatments to investigate foliar injury and leaf plasmalemma, soluble protein and endogenous phytohormone responses to O3. The results showed that: 1) elevated O3 resulted in yellowing lesions between veins on the upper leaves surface of marigold and petunia, and white spotting on morning glory leaves. The lesions intensified with increasing O3 concentration and exposure duration; 2) O3 exposure exacerbated membrane lipid peroxidation, but did not significantly influence soluble protein content, indicating that O3 did not weaken plant defense ability brought about by protein in later growth stage; 3) elevated O3 significantly decreased jasmonic acid (JA) content of marigold and morning glory leaves, and enhanced salicylic acid content (SA) of petunia and morning glory leaves, indicating the distinct phytohormone responses to O3 among species. O3 injury was caused from weakened JA protection capability for marigold leaves, increased SA accumulation for petunia leaves, and both above changes for morning glory leaves. In order to maximize the ecological benefits, the different phytohormones response relating to O3 injury should be identified and the specific protective measures could be adopted in face of rising tropospheric O3 concentration.