镉胁迫下三种藓类植物的细胞伤害及光合色素含量的变化

Leaf cell damage and changes in photosynthetic pigment contents of three moss species under cadmium stress

采用水培试验研究了不同浓度Cd胁迫下3种藓类植物的细胞伤害、光合色素含量和Cd含量的变化,以探讨其对Cd胁迫的反应敏感性和耐性.结果表明:低浓度Cd(1 mg.L-1)胁迫显著损伤尖叶拟船叶藓和匍枝青藓叶细胞,3种藓的叶细胞伤害率随Cd浓度的升高而显著增加,高浓度Cd(100 mg.L-1)胁迫下的细胞伤害率大小为匍枝青藓>湿地匍灯藓>尖叶拟船叶藓.低浓度Cd胁迫(1 mg.L-1)对3种藓类植物的总叶绿素含量无显著影响,随着Cd胁迫浓度的增加(≥10 mg.L-1),3种藓类植物总叶绿素含量显著下降,降幅顺序为匍枝青藓>湿地匍灯藓>尖叶拟船叶藓;1和10 mg.L-1 Cd胁迫对3种藓类植物叶绿素a/b值无显著影响,100 mg.L-1 Cd胁迫下湿地匍灯藓和匍枝青藓叶绿素a/b值显著下降;Cd胁迫对匍枝青藓类胡萝卜素含量的影响最大,1 mg.L-1 Cd下其类胡萝卜素含量显著降低.3种藓类植物均能显著地富集Cd,其体内Cd累积量以尖叶拟船叶藓最高,湿地匍灯藓次之,匍枝青藓最少.细胞伤害率、叶绿素和类胡萝卜素含量的变化可用来指示3种藓类植物对Cd胁迫的敏感性差异.尖叶拟船叶藓对Cd胁迫的耐受性最强,湿地葡灯藓和匍枝青藓相对较弱.3种藓类植物对Cd胁迫的耐受性与其体内Cd累积量呈明显的正相关关系.

A hydroponic experiment was conducted to study the leaf cell damage and the changes in photosynthetic pigment contents of three moss species under Cd stress,aimed to reveal the Cd sensibility and tolerance of the species.Even though the Cd stress was relatively low （ 1 mg Cd·L^-1） ,the leaf cells of Dolichomitriopsis diversiformis and Plagiomnium acutum were damaged.With the increasing level of Cd stress,the leaf cell damage of the three moss species aggravated significantly,and the resulted damage under high level （ 100 mg·L^-1） Cd stress was in the order Brachythecium procumbens 〉P.acutum 〉D.diversiformis.Relatively low （ 1 mg·L^-1） Cd stress had no significant effects on the total chlorophyll content of the three species.However,with the increase of Cd stress （ ≥ 10 mg·L^-1） ,the total chlorophyll content decreased significantly,with the order of B.procumbens 〉P.acutum 〉D.diversiformis.The Cd stress at 1 and 10 mg·L^-1 had no significant effects on the chlorophyll a /b,but the Cd stress at 100 mg·L^-1 led to a significant decrease of chlorophyll a /b in 〉P.acutum and〉 B.procumbens.The maximal decline of carotenoid content in B.procumbens was observed at 1 mg·L^-1 of Cd.The three moss species could significantly enrich Cd,and the Cd enrichment was D.diversiformis P.acutum B.procumbens.The leaf cell damage rate and the changes of chlorophyll and carotenoid contents could be used to indicate the differences in the sensitivity of D.diversiformis,P.acutum,and B.procumbens to Cd stress.D.diversiformis had the strongest tolerance to Cd stress,while P.acutum and B.procumbens had weaker tolerance.The tolerance of the three moss species to Cd stress was positively correlated to the capability of their Cd enrichment.