小麦幼苗中过氧化物歧化酶活性与幼苗脱水忍耐力相关性的研究

本文着重探讨当前国际上提出的一种植物抗旱机制的新理论——即生物自由基与植物保护酶系统间相互作用的理论。在水分逆境情况下,植物细胞内自由基产生和清除的平衡遭到破坏,过剩的自由基会伤害细胞膜系统。过氢化物歧化酶是氧自由基的清除剂,因此它的活性的高低应与植物的抗旱能力密切相关。以小麦幼苗为材料,采用光化学方法测定了过氧化物歧化酶活性,同时测定幼苗的脱水耐受力,发现在不同组织和器官中,在不同发育阶段的幼苗中,二者均存在有正相关性。此外,还测定了幼苗脱水前后过氧化物歧化酶活性的变化,发现酶活性在脱水处理时升高。我们推测小麦幼苗经受干旱的过程中,细胞内可能包含生物自由基的有害作用。

THE POSITIVE CORRELATIONS BETWEEN THE ACTIVITY OF SUPEROXIDE DISMUTASE AND DEHYDRATION TOLERANCE IN WHEAT SEEDLINGS

Damage to crops by drought is still a serious problem in large areas of the world.Considerable research has been undertaken to discover the mechanisms of dro- ught injury and drought resistance of plants.However,the critical features of drought injury have not yet been identified.In the past ten years a free radical hypothesis has been suggested to account for subcellular damage caused by severe environments.Su- peroxide (oxygen radical) is normally produced in hydrated tissues.It is controlled by free radical scavenging reactions.One such scavenger is the enzyme superoxide dismu- tase (SOD).Under water stress,production of excess free radicals may occur in dehy- drated plant tissues and this probably damages the membranes by causing peroxidation of the lipid components.So far few studies have been done to determine if drought in- jury is correlated with the free radical mechanism.In the present study,the SOD ac- tivities in wheat seedlings under water stress have been investigated by measuring the photoreduction of nitro blue tetrazolium using a spectrometric method.Meanwhile,the viabilities of wheat seedlings during drying were followed by tetrazolium test.These results provided information on the relationship between SOD activity and the dehydra- tion tolerance of the plant.