Physiological and genetic analyzes of population differentiation in plants in relation to life cycle regulation mechanisms.

(1)在发育和遗传分析的基础上，阐明了日本不同生境小豆蔻（Cardamine flexuosa，十字花科）的种群分化机制。研究计划分为三个部分：(i)仙台（38.16 N.140.54E）日长自然变化条件下开花的光周期需求；（ii）在完全调控的环境下，光周期组合和低温处理对生命周期调控的生理分析；（iii）通过所测各同工酶酶谱的相似性对群体进行遗传分析。位于高纬度地区的种群表现出较长的开花时间，这意味着在冬季为干旱和寒冷的条件准备高耐受性的个体是有用的。相反，在低纬度地区，由于相对温和的环境选择压力，开花表现为大小依赖。最低纬度为24.98 N的龙葵种群在较高的温度条件下萌发受到抑制。然而，在高纬度地区，没有温度控制对种子萌发的影响。在同工酶分析中发现了与纬度生境相关的遗传相似性，特别是位于北纬38°以北的群体，对开花表现出强烈的光周期依赖性。但在远离该纬度的其他种群中也观察到相同的基因型。综上所述，在高纬度种群中，由营养生长阶段向生殖生长阶段转变的生命周期受光周期响应的调控，而萌发过程则不受光周期响应的调控。另一方面，在低纬度种群中，温度调节萌发过程的开启或关闭，但在发育开关中完全不受控制。

(1). We clarified the mechanisms of population differentiation in Cardamine flexuosa (Cruciferae) collected from various habitats in Japan in relation to these characters of life cycle regulation based on developmental and genetic analyzes.(2). The research was planned on three parts as follow : (i) Photoperiodic requirement for flowering under natural alteration of daylength at Sendai (38.16 N.140.54E), (ii) Physiological analyzes of the life cycle regulation depending on combinations with photoperiods and chilling treatments under completely regulated environments, (iii) Genetic analysis of the populations appeared from similarities of zymograms in various isozymes tested.(3). Populations located at higher latitude showed tightly a long-day required flowering, meaning to be useful preparing high tolerant individuals for dry and cold conditions in winter. Populations at lower latitude, inversely, showed a size dependent flowering because of relatively mild environmental selective pressure.(4). Yonakuni population located 24.98 N being the lowest latitude showed very severe regulation whick suppressed the germination with higher temperature refimes. However, no temperature control for germination observed for population located at higher latitude.(5). Genetic similarities in relation to latitudinal habitats were found in isozyme analysis, especially among populations located beyond 38 N to north which showed strong photoperiodic dependency to flowering. But the same genotypes were also observed in other populations far from the latitude.(6). In conclusion, the life cycle was regulated in switching growth phase from vegetative to reproductive by photoperiodic response in higher latitude populations, but no control in germination process. On the other hand, it was regulated in switching on or off germinating procedure by temperature in lower latitude populations, but completely no control in developmental switching.