Genetic programs controlling life history of annual-biennial weeds

加拿大小飞蓬是一年生-二年生杂草，具有一年生和二年生两种表型。当种子在冬季暴露于低温下时，所得到的植物对开花刺激（未发芽种子春化）产生反应，表现出一年生表型。用放线菌酮代替未萌发种子的春化处理。用差减筛选法从低温下培养的未萌发种子中分离出遗传克隆。19个克隆中有9个是未知基因。来自松本地区的一株加拿大假丝酵母表现为专性一年生表型。这些结果表明，未萌发种子春化是一个关键的生态因子，通过改变一些遗传和生化过程，建立一年生表型的一年生植物。

Conyza canadensis is an annual-biennial weed, which exhibits both annual and biennial phenotype. When the seeds of C.canadensis had been exposed to low temperatures during winter, the resultant plants became responsive to flowering stimuli (ungerminated-seed vernalization), showing annual phenotype. Cycloheximide substituted for the ungerminated-seed vernalization. Genetic clones were isolated from the ungerminated seeds incubated in low temperatures using a subtractive differential screening. Nine out of the 19 clones were unknown genes. A strain of C.canadensis originated from Matsumoto district showed obligate annual phenotype. These findings indicate that the ungerminated-seed vernalization is a key ecological factor for establishing the annual phenotype in annual-biennial plants by modifying some genetical and biochemical processes.