胡瓜自交系間同功異構酶變異性及其遺傳

Isozyme Variation and Inheritance in Inbred Lines of Cucumber (Cucumis sativus L.)

利用澱粉膠體或聚丙烯醯氨膠體電泳分析胡瓜自交系的同功異構酵素變異性，結果有三種酵素具有多型性。蘋果酸去氫酶（MDH）顯示6-8個條帶區，其命名依酵素之移動性朝正極最快者為1，依此類推。帶區1及3各有兩條移動性不同之條帶（1a，1b；3a，3b）；帶區4在本試驗中顯示一個條帶；帶區2, 5, 及6各為單條帶型；所有自交系均具有不變的帶區2；另外在帶區3、4、5、6也發現有不具酵素活性的空白區，可能是由null allele所控制合成；帶區7及8含一至數個條帶，其解析度較低，無法判斷是否具有變異性；帶區3, 4, 5及6為子葉特異條帶，在本葉無法偵測到，屬於子葉特異同功異構酶。依各自交系所含不同MDH條帶區之種類，可以分為三種類型（A，B及C型）。磷酸葡萄糖酸去氫酶（PGD）帶區可分為PGD-1及PGD-2，快速移動條帶區（1）具有兩個條帶（1a及1b），因此不同自交系可依此將表現型分為PGD-A或-B型，慢速移動條帶區（2）之移動性在所有自交系均相同；在乾燥種子或幼苗子葉中均可染出PGD酵素活性。莽草酸去氫酶（SKDH）有兩型，每型均由一群移動較快且較淡色及一條較慢且深染的條帶群組成，兩型之間慢移動條帶的染色較深，且其移動性具有差異，不同自交系亦可分為SKDH-A或-B型，以各型之較慢一條帶可做遺傳分析。將具不同多型性自交系間雜交或回交，以進行遺傳分析，結果顯示Mdh-1，Pgd-1及Skdh-1均各為自一個基因座的兩個共顯性等位基因所控制；MDH-3,MDH-4條帶區若無null band，則其遺傳模式和上述相同；若具有空白的null band'則其遺傳模式較複雜，目前仍不清礎。具多型性之MDH，PGD及SKDH三種酵素可作為一代雜交種子純度或育種親本鑑定之標示因子。

Starch gel and polyacrylamide gel electrophoresis were used to analyse isozyme polymorphism in 15 inbred lines of cucumber (Cucumis sativus L.) and C. hardwickii inbred. Three enzyme systems were found to be polymorphic, including malate dehydrogenase (MDH), 6-phosphogluconate dehydrogenase (PGD), and shikimate dehydrogenase (SKDH). A null allele in the MDH-3, MDH-4, and MDH-5 activity zones, which belong to cotyledon specific isozymes, were detected in some inbred lines. Its mode of inheritance still needs to be elucidated. Genetic analyses of backcross and F2 generations showed that Mdh-1、Pgd-1 and Skdh-1 were all inherited as a single locus with two alleles, respectively. Mdh-3 locus, when in non-null state, was also controlled by two alleles.