瓠瓜与黄瓜的性别表现和内源乙烯与氧化酶活性的关系

瓠瓜（Lagenaria leucantha Rusby）及黄瓜（Cucumis sativus L.)的性别表现与植株组织中乙烯释放量及氧化酶活性有一定关系。在瓠瓜上，乙烯剂处理在诱导植株雌性化的同时，增加了植株茎尖的乙烯释放量，提高了过氧化物酶、过氧化氢酶、多酚氧化酶和抗坏血酸氧化酶的活性。同样经低夜温处理的黄瓜植株，其茎尖和叶片组织中这四种氧化酶的活性越高，越有利于雌花的分化。此外，在不同性别类型的黄瓜品种中，发现雌性越强的品种，其植株茎尖组织的乙烯释放量和ACC含量越多，过氧化物酶和过氧化氢酶的活性也越高。从总的方面来看，在所测定的四种氧化酶中，以过氧化物酶的活性与雌/雄花比值的关系最为密切，并且总是呈正相关，在黄瓜上其相关系数(r）为0.843。但是，对雌/雄花比值与乙烯释放量和过氧化物酶活性之间的相互关系进行通径分析，结果表明，过氧化物酶主要不是直接作用于瓜类的性别分化（直接通径系数Pd=0.179），而是通过乙烯（间接通径系数Pi=0.665）的作用来影响瓜类的性别表现。

RELATION OF SEX EXPRESSION TO ETHYLENE EVOLUTION AND OXIDASE ACTIVITY IN LAGENARIA LEUCANTHA AND CUCUMIS SATIVUS

In the present study,two cultivars of Chinese white-flowered gourd ( Lagenaria leucantha Rusby ) and four cultivars of cucumber ( Cucumis sativus L.) were used,in order to find out the relation of sex expression to internal ethylene evolution and activity of some oxidases. The results of the experiment showed that sex expression was found to be related not only to internal ethylene evolution but also seemingly to some oxidase activity. Plants of Lagenaria leucantha femalized by ethephon increased ethylene evolution and activity of peroxidase , catalase, polyphenol oxidase and ascorbic acid oxidase. Similarly, the higher is activity of the four oxidases in the tips and leaves of cucumber plants treated with different night-temperature, the stronger is their female-ness. In addition, the stronger femaleness in various types of sex expression in cucumber,the more ethylene evolution and ACC. content in their tip tissues, and the higher activity of peroxidase and catalase. The activity of peroxidase was found to be more closely correlated with the ratio of female to male(r = 0.843 in cucumber) . By the use of path coefficient analysis, it was indicated that peroxidase did not mainly play a direct role in the sex differentiation(direct path coefficient as 0.179), but indirectly affected the sex expression through ethylene action within the shoot tips ( indirect path coefficient as 0.665) .