海水胁迫对菠菜叶绿素代谢的影响

Chlorophyll Metabolism of Spinach Leaves under Seawater Stress

以耐海水品种‘荷兰3号’和海水敏感品种‘圆叶菠菜’为试验材料,采用营养液栽培,研究海水胁迫对菠菜叶绿素代谢的影响。结果表明,海水胁迫下,2个菠菜品种叶片的叶绿素a(Chl a)、叶绿素b(Chl b)和总叶绿素含量以及叶绿素合成前体———原叶绿素酸(Pchl)、镁原卟啉IX(Mg-proto IX)、原卟啉IX(Proto IX)和尿卟啉原III(UroIII)含量均明显降低,而胆色素原(PBG)和δ-氨基酮戊酸(ALA)积累,‘圆叶菠菜’的变化幅度大于‘荷兰3号’。海水胁迫下,‘荷兰3号’叶片的叶绿素酶(Chlase)活性无显著变化,胆色素原脱氨酶(PBGD)和尿卟啉原III合酶(UROS)活性在胁迫第3天显著下降,而‘圆叶菠菜’Chlase活性显著上升,PBGD和UROS活性显著下降。研究发现,在海水胁迫条件下,菠菜叶片的叶绿素合成代谢受阻,受阻位点位于PBG→UroIII的转化过程,其中‘圆叶菠菜’的受阻程度大于‘荷兰3号’;耐海水品种‘荷兰3号’叶片叶绿素含量降低主要由叶绿素合成代谢受阻引起,而海水敏感品种‘圆叶菠菜’叶绿素含量的降低则是由叶绿素合成受阻和叶绿素降解共同作用的结果。

The effects of seawater stress on chlorophyll metabolism of two spinach cultivars,Helan No.3（seawater tolerant cultivar） and Yuanye spinach（seawater sensitive cultivar） were investigated by hydroponics.The results showed that the contents of chlorophyll b（Chl b）,chlorophyll a（Chl a）,Chl（a＋b） and precursor of Chl such as protochlorophyll（Pchl）,Mg-protoporphyrin IX（Mg-proto IX）,protoporphyrin IX（Proto IX） and uroorphyrinogen III（UroIII） in two spinach cultivars were decreased significantly,whereas porphobilinogen（PBG） and δ-aminolevulinic acid（ALA） were increased significantly under seawater stress.The change range is greater in cv.Yuanye than that in cv.Helan No.3.The activity of chlorophyllase（Chlase） was not influenced in the leaves of Helan No.3 under seawater stress,whereas activities of porphobilinogen deaminase（PBGD） and uroporphyrinogen III synthase（UROS） were decreased significantly on the third day of treatment.As to cv.Yuanye,PBGD and UROS were decreased significantly with the chlase activity increasing significantly.The results showed that chlorophyll biosynthesis in leaves of two spinach cultivars was blocked by seawater stress at the step from PBG to UroIII,and cv.Yuanye was more susceptible to seawater than Helan No.3.The decrease of Chl in cv.Helan No.3 was caused by block of chlorophyll synthesis,whereas the reasons of the decrease of Chl in cv.Yuanye were block of chlorophyll synthesis and accelerating degradation of chlorophyll.