镉胁迫对茎瘤芥种子萌发、生理特性及镉积累的影响

Effects of Cd Stress on Seed Germination,Physiological Characteristic and Cd Accumulation of Brassica juncea var.tumida Tsenet Lee

以茎瘤芥品种“永安小叶”为试材,采用水培方法研究不同浓度(0μmol/L、10μmol/L、25μmol/L、50μmol/L、100μmol/L、200μmol/L、500μmol/L)Cd胁迫对茎瘤芥种子萌发、生理特性及镉积累的影响。结果表明,10~25μmol/L的Cd胁迫对茎瘤芥种子萌发和幼苗生长无明显影响,50μmol/L及以上浓度的Cd胁迫不仅显著抑制了种子萌发和幼苗生长,还降低了叶绿素含量。随着Cd浓度增加,MDA、O_(2)·-和H_(2)O_(2)含量呈逐渐上升趋势。Cd胁迫下,茎瘤芥幼苗可通过提高抗氧化酶(SOD、CAT、APX和GR)的活性,以及抗氧化物质ASA和GSH的含量而抵御Cd胁迫,避免氧化伤害。但当Cd浓度超过200μmol/L时,抗氧化防御系统受到影响,抵御能力下降。随着Cd浓度升高,茎瘤芥幼苗对Cd的积累程度增大,且根系中的积累量大于幼芽中的积累量。研究表明,茎瘤芥可耐受25μmol/L及以下浓度的Cd胁迫,种子在此浓度范围内仍能正常萌发和生长,而随着Cd浓度继续增加,耐受能力逐渐下降。

The main Brassica juncea var.tumida Tsenet Lee cultivar'Yongan Xiaoye'was used as the test material,and the hydroponic method was adopted to investigate the effects of different concentrations(0μmol/L,10μmol/L,25μmol/L,50μmol/L,100μmol/L,200μmol/L,500μmol/L)of Cd stress on seed germination,physiological characteristic and Cd accumulation of Brassica juncea var.tumida Tsenet Lee.The results showed that 10-25μmol/L Cd stresses had no significant effects on seed germination and seedling growth of Brassica juncea var.tumida Tsenet Lee,while 50μmol/L and higher concentrations of Cd stresses not only significantly decreased the seed germination and seedling growth,but also reduced its chlorophyll content.With the increase of Cd concentration,MDA,O_(2)·-and H_(2)O_(2) contents showed gradually increasing trends.Under Cd stress,Brassica juncea var.tumida Tsenet Lee seedlings could resist Cd stress by means of increasing activities of the antioxidant enzymes SOD,CAT,APX and GR,as well as increasing the contents of the antioxidant substances ASA and GSH,so as to avoid oxidative damage.However,when the Cd concentration exceeded 200μmol/L,the antioxidant defense system could be affected and the resistance ability was reduced.With the increase of Cd concentration,Brassica juncea var.tumida Tsenet Lee seedlings accumulated more Cd,and the accumulation in the roots were greater than in the young shoots.Study showed that Brassica juncea var.tumida Tsenet Lee could tolerate Cd stress within 25μmol/L concentrations,in this concentration range,seeds could normally germinate and grow,while with the increase of Cd concentration,the tolerance would be gradually reduced.