NaCl胁迫对扭果花旗杆幼苗生理特性和染色体行为的影响

Effects of NaCl Stress on Physiological Characteristics and Chromosomal Behavior of Dontostemon elegans Maxim.Seedlings

扭果花旗杆(Dontostemon elegans Maxim.)是新疆达坂城荒漠植被组成的重要物种,具有耐旱抗风、耐贫瘠等特性,在维持荒漠生态系统稳定性中具有重要作用。为了探讨扭果花旗杆幼苗对盐胁迫的应答机制,本研究以30 d扭果花旗杆幼苗为研究材料,设置了四组不同浓度梯度的NaCl胁迫处理(0 mmol/L,50 mmol/L,100 mmol/L,150 mmol/L),分析了不同浓度NaCl对扭果花旗杆幼苗生理特性及根尖细胞染色体行为的影响。结果表明:(1)随NaCl胁迫浓度的增加,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均先升高后降低;且活性变化趋势一致,均在150 mmol/L达到最大值。(2)随NaCl胁迫浓度的增加,脯氨酸(Pro)、可溶性蛋白(SP)、丙二醛(MDA)含量均呈现先上升后下降趋势。(3)低浓度的NaCl胁迫(50 mmol/L)胁迫促进扭果花旗杆种子根尖细胞的有丝分裂,较高浓度胁迫(NaCl>50 mmol/L)胁迫则表现出抑制种子根尖细胞的有丝分裂,且随盐浓度的增大,抑制作用更加明显;同时,研究发现种子根尖细胞染色体畸变率、微核率与NaCl浓度呈正相关。因此,扭果花旗杆通过提高抗氧化酶的活力及小分子物质的积累来抵御NaCl胁迫,另外低浓度NaCl胁迫对扭果花旗杆种子根尖细胞有丝分裂还有促进作用。本研究结果将为干旱区抗逆野生植物资源的筛选提供理论依据。

Dontostemon elegans Maxim.is an important species of desert vegetation at Dabancheng,Xinjiang.It has the characteristics of drought-resistant,wind-resistant and saline-tolerant,and plays an important role in maintaining the stability of desert ecosystem.In order to explore the response mechanism of Dontostemon elegans Maxim.seedlings to salt stress,this study used 30 d Dontostemon elegans Maxim.seedlings as the material and set four groups of NaCl stress treatments with different concentration gradient(0 mmol/L,50 mmol/L,100 mmol/L,150 mmol/L)to analyze the influence of different concentration of NaCl on the physiological characteristics of Dontostemon elegans Maxim.seedlings and the chromosome behavior of root tip cells.The results showed that:(1)With the increase of salt stress concentration,SOD activity,CAT activity and POD activity all increased first and then decreased.The activity trend was consistent,reaching the maximum at 150 mmol/L.(2)With the increase of NaCl stress concentration,the contents of proline,soluble protein and malondialdehyde all showed a trend of increasing first and then decreasing.(3)Low concentration of NaCl(50 mmol/L)promoted the mitosis of root tip cells in Dontostemon elegans Maxim.seeds,and high concentration of NaCl(50 mmol/L)inhibited the mitosis of root tip cells.With the increase of salt concentration,the inhibition was more obvious.Mean while,the chromosome aberration rate and micronucleus rate of seed root tip cells were positively correlated with the increase of NaCl concentration.It can be seen that the Dontostemon elegans Maxim.can resist NaCl stress by improving the activity of antioxidant enzymes and the accumulation of small molecules.Low concentration NaCl stress can also promote the root tip mitosis of Dontostemon elegans Maxim.seeds.The results of this study will provide a theoretical basis for the screening of stress resistant wild plant resources in arid areas.