DA-6对草莓叶片叶绿素合成前体物质及关键酶酶活性的影响

为弄清DA-6提高草莓叶片叶绿素的作用效果,以温室栽培的‘甜查理’(Fragaria×ananassa Duch.cv.Sweet Charlie)草莓为试材,在结果前1个月用20mg/L DA-6对不同叶龄(幼叶和展开叶)进行叶面喷施。利用紫外分光光度计测定相关物质含量和酶活。结果表明:幼叶和展开叶叶绿素含量都有提高,但对幼叶效果明显好于展开叶,分别平均提高18%和5%。测定处理组降低了叶绿素的前体物质5-氨基酮戊酸(5-aminolevulinic acid,ALA)含量,但增加了后续中间产物胆色素原(porphobilinogen,PBG)含量,催化ALA向PBG转化的5-氨基酮戊酸脱水酶(5-aminolevulinate dehydratase,ALAD)的活性也有显著提高。因此,通过叶面喷施DA-6可提高ALA向PBG转化效率,使得后续产物有充足的底物合成叶绿素,从而使叶绿素含量增加。

Effects of DA-6 on key precursors and enzyme activity of chlorophyll biosynthesis in strawberry leaves

In order to understand the mechanism in enhancing the chlorophyll concentration in strawberry leaves,DA-6 was sprayed at 20mg/L on the young and expanded leaves of ’Sweet Charlie’(Fragaria×ananassa Duch.cv.Sweet Charlie)strawberry grown in greenhouse one month before fruit harvest.The concent of chlorophyll precursors and the relative enzyme activity were measured.The results showed that chlorophyll content in either young or expanded leaves increased after treatment.In particular,the chlorophyll content in young leaves increased by 18% but only 5% in the expanded leaves.DA-6 significantly increased the contents of chlorophyll intermediate products of porphobilinogen(PBG) and uroporphyrinoge(UrogenⅢ),but decreased the chlorophyll precursor of 5-aminolevulinic acid(ALA).The activity of the key enzyme of 5-aminolevulinate dehydratase(ALAD) catalyzing the conversion of ALA to PBG was also enhanced.Our study demonstrated that foliar spray of DA-6 increased the conversion efficiency of ALA to PBG,regulated the chlorophyll biosynthesis pathway and resulted in higher chlorophyll content in leaves.