脱落酸与水分胁迫下棉花幼苗水分关系及保护酶活性的影响

Effects of Abscisic Acid on Water Relationship and Defensive Enzymes Activities in Cotton Seedling under Water Stress

以晋棉21和抗虫棉99B为材料,研究了脱落酸处理的棉花幼苗,在聚乙二醇(PEG)6000不同渗透胁迫(0.5MPa,0.8MPa,1.1MPa)下,叶片相对含水量、渗透势、质膜透性以及超氧歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)变化。结果表明,脱落酸能减缓水分胁迫时期棉花叶片含水量的降低,提高叶片渗透势;两个品种的SOD、POD、CAT的活性都比未处理的高;且品种之间表现出明显的差异,晋棉21比抗虫棉99B膜脂过氧化程度低,减少了膜脂过氧化产物丙二醛(MDA)在叶片中的积累。表明脱落酸能增加棉花体内保护酶活性,降低膜脂过氧化作用,保护膜结构的完整性,减少水分胁迫的伤害,且晋棉21比抗虫棉抗水分胁迫能力强;同时表明抗虫棉与抗旱性没有相同的生理基础。

The variations of relative water content (RWC), osmotic potential, activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) of Jin-mian 21 and 99 B cotton seedling were studied under the condition of PEG6000 osmotic stress and abscisic acid (ABA). The content of malondiadehyde (MDA), metabolite of membrane lipid peroxidation, and the drought resistance under water stress of two cotton cultivars were also tested and compared.Cotton seeds sterilized with 0.1%HgCl_2 for 5 min, rinsed with tap water, were germinated under 28℃ in culture chamber. After germinated, the seeds were sown in plastic pots containing sands and incubated in room. After emergence, seedlings were irrigated with 1/2 Hoagland nutrition solution, incubated with 14h/d, 5000 Lx, and a day/night temperature of 28℃/20℃. After the third leaf fully elongated, the seedlings were separated to two groups, one irrigated with 1/2 Hoagland nutrition solution and the other with the same solution containing 0.2×10^(-5) mol·L^(-1) ABA for one week. Each treatment consisting of ten plants was duplicated three times. Then seedlings were treated with three different polyethylene glycol (PEG) water potential solutions of Hoagland(-0.5 MPa, -0.8 MPa,( -1.1MPa).) After 24 hours, physiological indexes of the third leaf of two cultivars were tested. The results showed that ABA could slow down the reduction of RWC and increased osmotic potential under PEG different osmotic stress (-0.5 MPa,-0.8 MPa,-1.1 MPa) in cotton seedlings. When PEG osmotic potential was -1.1 MPa, RWC of Jin-mian 21 and 99B were 86% and 74%, separately; osmotic potential of two cultivars were separately -1.28 Mpa and -1.69 Mpa, the result showed that ABA could increase water content of cotton leaves, therefore Jin-mai 21 was higher drought resistant than 99B. After treated with ABA, the defensive enzyme activities of SOD, CAT and POD were higher than the untreated, and there were significant difference between the two cultivars. Function of membrane lipid peroxidation in Jin-mian 21 was lower than that in 99B. In addition, the accumulation of MDA of Jin-mian 21 decreased in comparison with 99B. Our results demonstrated that ABA could protect the intactness of membrane structure and decreased the hurt of water stress. The experimental results also indicated that the anti-insect ability of 99B and the drought resistance of Jin-mian 21 had no common physiological foundations. poten