盐胁迫对红叶石楠花青素含量及抗氧化系统的影响

采用盆栽实验研究不同NaCl添加量(质量分数分别为0、0.1%、0.2%、0.3%和0.4%)对红叶石楠地上部鲜重、株高、叶片Na含量、K⁺/Na⁺、细胞膜透性、叶片含水量、脯氨酸含量、抗氧化酶活性,以及花青素含量的影响。结果表明,在0.2%及更高浓度的NaCl处理下,红叶石楠生长受到抑制,叶片Na含量、细胞膜透性、脯氨酸含量显著(P<0.05)增加,K⁺/Na⁺、叶片相对含水量显著(P<0.05)下降。盐胁迫造成红叶石楠叶片的H₂O₂及丙二醛(MDA)含量显著(P<0.05)增加,0.4%NaCl处理下,H₂O₂及MDA含量在新叶上的增幅分别为162%和128%,在老叶上的增幅分别为114%和33%。随着盐胁迫加剧,新叶氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性显著(P<0.05)升高,过氧化物酶(POD)活性和花青素含量显著(P<0.05)下降。与之相反,老叶的SOD和CAT酶活显著(P<0.05)下降,而POD活性和花青素含量显著(P<0.05)上升。由此可见,花青素在抵御盐胁迫诱导的氧化伤害中具有重要作用,其在叶片中的含量与CAT酶活性呈现此消彼长的关系。

Effects of salt stress on anthocyanin content and activities of antioxidant enzymes in leaves of Photinia frasery

In the present study, a pot experiment with Photinia frasery was conducted to examine NaCl addition (0, 0.1%, 0.2% 0.3%, 0.4%) on fresh weight of aboveground parts, plant height increase, plant growth, Na and K concentration, electrolyte leakage, relative water content, contents of proline, H₂O₂, malondialdehyde (MDA), anthocyanin and activities of the enzymes related to antioxidant system of plant leaves. It was shown that the growth of Photinia frasery was inhibited when NaCl addition amount was 0.2% or higher. Na and proline content, electrolyte leakage were significantly (P<0.05) increased, while K⁺/Na⁺ and relative water content were significantly (P<0.05) decreased. Salt stress induced oxidative stress of leaves. The H₂O₂ and MDA contents were significantly (P<0.05) increased by 162% and 128% in new leaves, and by 114% and 33% in old leaves, respectively. For new leaves, activities of SOD and CAT were significantly (P<0.05) enhanced, while POD activity and anthocyanin contents were significantly (P<0.05) decreased as the salt stress increased. However, activities of SOD and CAT were significantly (P<0.05) decreased, while POD activity and anthocyanin contents were significantly (P<0.05) increased as the salt stress increased in old leaves. Thus, it could be concluded that anthocyanin was an important antioxidant molecular of Photinia frasery, which partially replaced the antioxidant roles of CAT under salt stress.