Of all states represented at the conference,Missouri was the only one whose governor presented plans for enforcing the new regulations.
在会议上提到的所有的州当中,密苏里是唯一一个这样的州——州长提出了计划要强制执行新条例.
Of all states represented at the conference表示范围.
represented不是谓语动词,而是非谓语动词（过去分词）.分词短语represented at the conference作定语,修饰all states.因为all states与represented是被动关系,所以用过去分词.
这个分词短语可以改成一个定语从句：that were represented at the conference.
句子的主干是the governor of Missoouri was the only one.