光对不同叶龄花生叶片糖酵解代谢的影响

EfFect of Light on Glycolysis During Leaf Development in Arachis hypogaea L.

光对花生不同叶龄的磷酸丙糖、3-磷酸甘油醛脱氢酶、丙酮酸激酶和丙酮酸含量的影响不同。成长叶片光合速率大于暗呼吸,在光下,TP增高,细胞质G3PDh活性受抑制,PK活性和Pyr含量下降;DCMU处理则消除光的影响,TP下降,细胞质G3PDh和PK活性升高。花生成长叶在光下糖酵解(EMP)途径受抑制,抑制位点是G3PDh和PK。幼叶光合微弱,呼吸作用强,TP和Pyr及细胞质酶活均不受光、暗条件和DCMU处理影响,其EMP途径和在暗中同样速率运转。老叶光合和暗呼吸均较弱,TP和两种酶活不论在光和暗中均无差异,Pyr少,EMP途径运转也慢。

Effect of light on the glycolysis of green tissues of peanut (Arachis hypogaea) leaves with different ages was studied. Apparent photosynthetic rate gradually increased with the increase of leaf age and reached its maximum on the 7th day and remained relatively constant for four days when the leaves became mature, then decreased gradually to the 21st day when the leaves became old. It was shown that young leaves had the highest respiration rate, which decreased gradually with leaf development (Fig. 1). Triose phosphate content increased in both chloroplastic and nonchloroplastic fractions of illuminated mature (7～10 days) leaves as compared with that in dark-treated leaves, while those in young (0～1 day) and old (21 days) leaves remained unchanged under illumination (Fig. 2). Chloroplastic glyceraldehyde- 3 -phosphate dehydrogenase activity was enhanced by illumination in all (young, mature and old) leaves, with the greatest enhancement in mature leaves, while that in nonchloroplastic fraction was not affected or even slightly decreased in mature leaves (Fig. 3). Under illumination, pyruvate kinase activity in young leaves increased, while that in mature leaves decreased; light had no effect on the activity of pyruvate kinase in old leaves (Fig. 4). It was found that pyruvate content in chloroplastie fraction, increased in young leaves and decreased in mature leaves, but no change was found in old leaves. Pyruvate content in non-chloroplastic fractions decreased only in mature leaves, no change was found in either young or old leaves under illumination (Fig.5). When peanut leaves were treated with DCMU (100 μmol/L), an inhibitor of photosynthetic: electron transport, no effect of light on triose phosphate and pyruvate ontents as well as on the activities of glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase was found; the results were similar to those of dark treatment (Table 1). It was concluded that light had significant effect on glycolysis of green tissues of mature leaves, but no effect was found in young and old leaves. This effect may be mediated by photosynthesis.