水稻BCAT 4基因突变株幼苗对PEG模拟干旱胁迫的响应

Response of BCAT 4 Mutant Seedlings to PEG Simulated Drought Stress in Rice

以水稻野生型‘日本晴’(NIP)及其BCAT 4基因突变体bcat 4-1为材料,在苗期进行PEG-6000模拟干旱处理,分析其对幼苗形态、生长和抗逆生理指标的影响,以探究BCAT 4基因在水稻响应干旱胁迫中的作用。结果表明:(1)20%PEG处理后野生型NIP幼苗叶片中BCAT4表达量显著高于对照(处理0 d),复水后幼苗存活率显著高于突变体bcat 4-1。(2)20%PEG处理后,两水稻材料幼苗叶片的相对叶绿素含量下降,脯氨酸和可溶性糖含量上升,抗氧化酶活性先上升后下降,且突变体bcat 4-1中上述各指标均显著低于同期NIP。(3)两材料幼苗叶片中丙二醛和过氧化氢含量及相对电导率随胁迫处理天数增加而上升,且bcat 4-1均显著高于同期NIP。(4)在20%PEG处理后,两水稻材料间根系各形态、生长和生理指标的差异均小于相应叶片。研究发现,BCAT 4基因突变加剧了干旱胁迫下水稻幼苗叶片叶绿素含量的下降,抑制了地上部渗透调节物质的积累及抗氧化酶活性上升的幅度,促进了丙二醛和过氧化氢积累以及相对电导率增加,从而降低了水稻的耐旱性。

We analyzed the morphology,growth and stress resistance traits of rice seedlings under PEG-6000 treatment to explore the effect of BCAT4 on the response to drought stress,using the wild-type‘Nipponbare’(NIP)and mutant bcat4-1 as materials.The results showed that:(1)after 20%PEG treatment,the expression level of BCAT4 in wild-type NIP seedling leaves was significantly higher than that of the control,and the survival rate after rehydration was significantly higher than that of mutant bcat4-1.(2)After 20%PEG treatment,the relative contents of chlorophyll were decreased,the contents of proline and soluble sugar were increased,while the activities of antioxidant enzymes were increased first and then decreased in the leaves of both rice seedlings and the values of above traits in mutant bcat4-1 were significantly lower than those in NIP.(3)The contents of malondialdehyde and hydrogen peroxide,and relative conductance increased with the increase of treatment days in the leaves of both rice seedlings and were significantly higher in bcat4-1 than in NIP.(4)The differences of the morphological,growth and physiological traits between the two rices in roots were less than those in leaves.It was found that BCAT4 mutation aggravated the decrease of chlorophyll content in rice seedling leaves,inhibited the accumulation of osmotic substances and the increase of antioxidant enzyme activities in the shoots,and promoted the accumulation of malondialdehyde and hydrogen peroxide and the increase of relative conductivity under drought stress,which resulting in reduced tolerance of rice seedlings to drought.