PEG胁迫对萌动苦豆子子叶抗旱生理及氧化苦参碱含量的影响

Influence of PEG stress on cotyledons physiology and oxymatrine content in germinating seeds of Sophora alopecuroides

以PEG-6000模拟干旱条件,测定苦豆子种子萌发、萌动种子子叶中质膜相对透性(PMP)、丙二醛(MDA)和脯氨酸(Pro)含量以及抗氧化物酶POD、CAT、SOD酶活性以及氧化苦参碱含量,探讨苦豆子种子的抗旱适应性。结果表明:10%PEG胁迫下,种子的发芽势、发芽率、发芽指数和活力指数均达到最高,依次为66.67%,78.67%,24.40和183.79,20%PEG胁迫种子仍有较高的发芽能力。随PEG胁迫程度加剧,萌动苦豆子种子子叶中质膜相对透性和Pro含量逐渐上升,MDA含量逐渐下降;POD、CAT和SOD 3种保护酶对干旱胁迫的保护作用不尽相同,中轻度胁迫(PEG≤20%)时POD酶起主要作用,重度胁迫(PEG>20%)时CAT和SOD酶起主要作用。PEG胁迫使子叶中OMA含量下降,OMA含量与抗旱生理指标间均存在负相关。适度干旱有助于苦豆子种子萌发,萌动种子对干旱有强的防御机制。

The drought resistance and physiological characteristic and oxymatrine（ OMA） content of Sophora alopecuroides germinating seed were investigated under the simulation drought stress by PEG- 6000. The results showed that germinating energy,germinating percentage,germinating index,and seeds vigor index of S. alopecuroides simultaneously reached maximum at 10% PEG,with maximum value of 66. 76%,78. 67%,24. 40,and183. 79 respectively. Meanwhile,at 20% PEG stress,significant germinating capability was still detected in germinating seed of S. alopecuroides. With increasing PEG stress,the relative permeability of plasma membrane and proline content increased gradually,while malonaldehyde（ MDA） content in cotyledon of S. alopecuroides germinating seed decreased. It was found that the protecting mechanisms of peroxidase（ POD）,catalase（ CAT） and superoxide dismutase（ SOD） for S. alopecuroides germinating seed under PEG stress varied,with POD playing major role under mild stress（ PEG≤20%） but CAT and SOD under severe stress（ PEG 20%）. OMA content in cotyledons of S. alopecuroides germinating seed decreased with higher PEG stress and OMA content was found to be negatively correlated with relative permeability of plasma membrane,proline and MDA content,and activities of SOD,POD and CAT. These results indicate that moderate drought stress is helpful to S. alopecuroides at seed germination stage.