海岸黑松和紫穗槐对间歇强净风和风沙流吹袭的生理响应机制

Abstract

以海岸防风固沙优势树种紫穗槐（Amorpha fruticosa Linn）和黑松（Pinus thunbergii Parl）为研究对象，利用野外便携式沙风洞用间歇风吹模拟自然阵风，通过分析间歇强净风（18m/s）和强风沙流（172.93g cm^-1 min^-1）吹袭过程中和风后恢复中，两树种叶片膜脂过氧化产物含量、抗氧化酶活力、渗透调节物含量的变化，以探讨其对自然阵风吹袭响应机制及自愈修复生理机制。结果表明，自然状况下，紫穗槐和黑松叶片相对含水量（RWC）相近，但抗氧化酶活力及种类和渗透调节物含量及种类上存在差异。紫穗槐叶片丙二醛含量（MDA）、脯氨酸含量及过氧化氢酶（CAT）和过氧化物酶（POD）活力分别较黑松高93.3%、78.6%、118.8%、6.5倍。而黑松可溶糖含量和超氧化物歧化酶（SOD）活力较紫穗槐高111.5%和28.2%。在间歇净风和风沙流处理中，随着风吹袭次数增多，黑松叶片RWC趋于小幅降低，可溶性糖含量及POD、SOD、CAT活力呈小幅波动式变化；紫穗槐叶片RWC大幅下降，伴随着脯氨酸含量，POD、CAT、SOD活力大幅增高和MDA含量下降。在风吹袭中，叶片抗氧化酶活力和渗透调节含量的变化与叶片含水量变化密切相关。在风吹袭处理后的恢复期，黑松叶片MDA、可溶性糖、脯氨酸含量和CAT活力下降，但叶片一直维持较高可溶性糖含量和SOD活力；而紫穗槐伴随叶片RWC回升，而MDA、可溶性糖、脯氨酸含量下降和POD、CAT、SOD活力的增高。研究表明，风吹袭引发叶片水分亏缺成为启动植物对缺水补偿机制的诱导因子（自愈修复）。在风吹袭中增高的渗透调节物通过提高细胞吸水力为自愈修复提供物质基础，而抗氧化酶通过抑制膜脂过氧化、维护膜的完整性和弹性为自愈修复提供生理保护。因此，渗透调节和抗氧化酶通过维护水分平衡和氧自由基代谢平衡而在抗风生长和自愈修复中起重要生理保护作用。;In this study, the coastal area wind and sand blowing resistant Amorpha fruticosa Linn and Pinus thunbergii Parl were used as materials to learn how they responded physiologically to intervals of strong wind and wind-drift blowing, and what mechanisms of physiological adaptation and self-repairing were involved in their resistance to wind-drift blowing and self-repairing after wind blowing. The plants were subjected to 18 m/s wind speed and wind-drift blowing (172.93g cm^-1 min^-1) for 20 min and allowed to repair for 24h after the blowing treatment (repair period); these treatments were repeated three times using an outdoor portable wind tunnel. Relative water content (RWC), malondialdehyde (MDA), proline, soluble sugar, and the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were measured in the leaves of the plants. The results showed that in the natural environment, there were no difference in RWC in the two species, but there were differences in the kinds of antioxidant enzyme and osmotic regulators between A. fruticosa and P. thunbergii, with the MDA content, proline content, and the activities of CAT and POD in leaves of A. fruticosa higher by 93.3%, 78.6%, 118.8%, and 650% than those in leaves of P. thunbergii. The soluble sugar content and SOD activity in leaves of P. thunbergii were higher by 111.5% and 28.2% than those in leaves of A. fruticosa. With increasing repetitions of blowing, RWC tended to decrease to a lower level, while the soluble sugar content and the activities of POD, SOD, CAT exhibited slight fluctuations in the leaves of P. thunbergii, but in A. fruticosa leaves, RWC dramatically dropped, and proline content and the activities of POD, CAT, and SOD significantly increased. Furthermore, during the repairing period, the contents of MDA, soluble sugar, and proline and CAT activity decreased in the leaves of P. thunbergii but the contents of MDA, soluble sugar, and proline decreased, and the activities of POD, CAT, and SOD increased, accompanied by an increase of RWC, in the leaves of A. fruticosa. These results indicate that water shortage induced by wind blowing was a direct factor causing physiological regulation and activating the compensation mechanism for water shortage (self-healing repair) in both trees. Although the two tree species belonged to different families and used different kinds of osmotic regulator and antioxidant enzymes in the physiological regulation of wind resistance, they both had the same strong ability to regulate physiological mechanisms during strong wind blows and post-wind repairing periods. It suggests that water shortage might activate the self-healing physiological mechanism. Under wind blowing, the increased content of soluble sugar and proline might provide materials for self-healing by improving cell water absorption, while antioxidases played an important physiological protective role in inhibition of membrane lipid peroxidation, thus maintaining membrane integrity and elasticity for self-healing. Therefore, self-healing is the key physiological adaptative mechanism for the two trees to adjust to the intervals of strong sea wind blowing on the coast.