美洲南瓜(Cucurbita pepo)种皮发育形态观察及其相关酶活性测定

Studies on morphology of seed coat development and its related enzyme activity assay in Cucurbita pepo

采用组织整体染色和石蜡切片相结合的方法对美洲南瓜有壳品种04LAg-26-2和无壳品种04LAg-26-28种皮发育形态结构比较观察。结果表明,有壳美洲南瓜种皮是由表皮层、下皮层、厚壁组织层、软组织层和绿色组织层构成,无壳裸仁南瓜的形成主要是授粉后18 d种皮发育过程中厚壁组织中的细胞变形、瓦解,缺少木质素的积累而导致了下皮层、厚壁组织层的缺失;对2个品种的种皮、叶片、叶柄和瓜囊不同组织中木质素合成相关酶活性测定结果表明,无壳品种04LAg-26-28在授粉18 d后,种皮中苯丙氨酸解氨酶(PAL)、肉桂酸-4-羟基化酶(C4H)、4-香豆酸-辅酶A连接酶(4CL)、肉桂醇脱氢酶(CAD)和过氧化物酶(POD)活性明显降低,而叶片、叶柄和瓜囊中这几种酶活性在授粉18 d后,呈逐渐增加的趋势。

The morphological structure of seed-coat development of two isogenic lines of Cucurbita pepo（normal,04LAg-26-2 and hull-less,04LAg-26-28） were comparatively studied through overall staining and paraffin section method.The results showed that the normal seed were composed of five tissue layers： The epidermis,hypodermis,sclerenchyma,parenchyma and chlorenchyma.The formation of hull-less seed was the cells of hypodermis tissues deformed,collapsed and lack of lignin accumulation among the development of seed-coat forming,so that the epidermis,parenchyma and chlorenchyma in the seed-coat were imperfect.The activity of ligin synthesis enzyme in different tissues including testa,leaf,petiole and capsule was tested,the results were as follows： The activity of phenylalanine ammonia-lyase（PAL）,cinnamic acid 4-hydroxylase（C4H）,4-coumarate CoA ligase（4CL）,cinnamyl alcohol dehydrogenase（CAD） and peroxidase（POD） in testa of 04LAg-26-28 reduced on 18 days after pollination,but the activity of all enzymes in leaf,petiole and capsule tissues increased significantly.