白刺花幼苗抗旱与耐寒协同响应的生理生化评价

Physiological and Biochemical Evaluation of Synergistic Responses in Drought and Cold Tolerance of Sophora davidii seedlings

为探讨白刺花幼苗抗旱与耐寒协同响应的生理生化适应机制,以白刺花实生苗为材料,采用盆栽自然干旱及人工控温方法,分析幼苗抗旱生理,再以人工低温处理对白刺花抗氧化酶系、细胞膜损伤以及渗透调节的影响。结果表明:自然干旱胁迫下,白刺花叶片相对含水量随着干旱时间的增长显著减小,复水后2 d又能恢复生长;适度的干旱有利于光合色素的积累,严重时光合色素含量反而降低;超氧化物歧化酶(superoxide dismutase,SOD)、过氧化物酶(peroxidase,POD)、过氧化氢酶(catalase,CAT)3种保护酶随着干旱时间的延长呈先升后降变化,SOD和POD活性8 d时达到峰值,分别为458.85、5.30 U/g,比对照增加142.53%、68.25%。丙二醛(malondialdehyde,MDA)含量随干旱增强呈缓慢上升的趋势,15 d达到高峰,峰值为6.20 mmol/g,比对照增加108.75%;渗透调节物质脯氨酸(proline,Pro)含量呈先增后降趋势,10 d高达459.67 mg/g,比对照增加226.45%;干旱胁迫与低温交叉处理,白刺花叶片光合色素含量明显减小,3种保护酶变化与干旱胁迫相似,呈先升后降变化;MDA含量随低温胁迫延长呈缓慢上升的趋势,Pro含量的变化呈上升趋势。不同胁迫时期3种保护酶对白刺花抗旱性与耐寒性主导作用不同,表现为相互协调的作用方式。逆境胁迫下白刺花通过提高抗氧化酶并积累渗透调节物质Pro以减轻活性氧对膜伤害;干旱胁迫可提高白刺花对低温的适应能力,这种交叉适应性可能与保护酶系和渗透调节能力的增强有关。

The purpose of the paper is to investigate the physiological and biochemical mechanism of drought and low temperature stress in Sophora davidii seedlings.S.davidii seedlings were used as the experimental materials to evaluate the changes of anti-oxidant protective enzyme activities,membrane injury indexes,osmotic adjustment substances in leaves under increasingly severe drought in natural conditions,and late artificial low temperature treated,with pot ex-periments.The results showed that the relative water content of leaves decreased significantly with the increase of drought time,and the growth could be restored 2 days after rehydration.Moderate drought was beneficial to the accu-mulation of photosynthetic pigments,but the content of synchromes decreased in severe drought.Superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)activities first increased and then decreased with prolonged drought stress.The peak activity of SOD and POD was 458.85 U/g and 5.30 U/g,respectively on the 8th day,which was 142.53%and 68.25%more than CK respectively.Malondialdehyde(MDA)showed a slow increase with the prolonged drought stress,the peak value was 6.20 mmol/g FW on the 15th day,which was 108.75%higher than that of CK.Osmotic adjustment substances such as proline increased first and then decreased with prolonged drought stress,the peak value was 459.67 mg/g on the 10th day,which was 226.45%higher than that that of CK.Under drought stress and low temperature,photosynthetic pigment content of S.davidii leaves decreased significantly,and the changes of three protective enzymes activities(SOD,POD and CAT)increased first and then decreased,which were similar to those under drought stress.Malondialdehyde(MDA)and proline(Pro)showed increase gradually when cold stress continued.Three protective enzymes could play inter-coordinating roles at different stress stages for drought resistance and cold tolerance of S.davidii.The study revealed that S.davidii positively responded to stress through improved antioxidant enzyme activity and the accumulation of osmotic adjustment substances as proline,which could help to reduce reactive oxygen to the membrane damage.Drought stress could improve the adaptability to low temperature,which may be related to the en-hancement of protective enzyme system and osmotic regulation ability.