不同倍性蝴蝶兰未减数雄配子的发生及其细胞学机理初探

采用压片法对不同倍性蝴蝶兰品种小孢子母细胞减数分裂及成熟花粉进行观测，并利用流式细胞仪测定了花粉中的DNA含量，发现除了单倍性配子外，均有少数未减数配子发生。不同倍性蝴蝶兰品种中单倍性、二倍性、三倍性和四倍性花粉平均直径分别为11.4、17.2、19.1和20.3 μm，花粉直径与倍性呈正相关关系（r = 0.935，P < 0.065）；二倍体、三倍体和四倍体蝴蝶兰品种未减数雄配子的平均发生率分别为0.59%、2.39%和0.67%，三倍体品种发生未减数雄配子的频率明显高于二倍体和四倍体品种；二倍体、三倍体和四倍体品种均通过二分体和三分体的方式形成未减数雄配子，其中二分体的形成是由于小孢子母细胞不进行减数分裂Ⅰ，而正常进行减数分裂Ⅱ所致，三分体的形成可能是由于纺锤体异常定位形成三极纺锤体所致。

Preliminarily Study on Formation and Cytological Mechanism of Unreduced Male Gametes in Different Ploidy Phalaenopsis

The microsporogenesis and mature pollens in different ploidy Phalaenopsis were observed using squash method，besides，DNA content of mature pollen was analyzed using flow cytometry. The results indicated that there were a few unreduced gametes including haploidy gametes in different ploidy Phalaenopsis. The mean diameter of haploidy，diploidy，triploidy and tetraploidy pollens was 11.4，17.2，19.1 and 20.3 μm，respectively，which was positively correlated with ploidy level（r = 0.935，P < 0.065）. The occurrence frequency of unreduced gamete in triploid（2.39%）was obviously higher than those in diploid（0.59%）and tetraploid（0.67%），suggesting that triploid was prone to producing more unreduced gametes. The unreduced male gametes in different ploidy Phalaenopsis were formed by way of dyad andtriad. The formation of dyads was due to the absence of meiosisⅠin a few microspore mother cells，while that of the triads was probably resulted from the formation of tripolar spindle at meiosisⅡ.