海水胁迫对菠菜叶绿素代谢的影响

he 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(Chlb), chlorophyll a(Chla) ,Chl(a+b) and precursor of Chl such as protochlorophyll (Pchl), Mg-protoporphyrinIX(Mg-ProtoIX), protoporphyrinIX (Proto IX) and uroorphyrinogenIII (UroIII) in two spinach cultivars were decreased significantly, while Porphobilinogen (PBG) and δ-Aminolevulinic acid (ALA)were increased significantly by seawater with higher rate in cv. Yuanye. The activity of chlorophyllase (Chlase) activity was not influenced in the leaves of Helan No.3 under seawater stress, while 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. These results suggested that chlorophyll biosynthesis in leaves of wo 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.