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

(1)。在发育分析和遗传分析的基础上，阐明了日本不同生境豆蔻种群分化的机制与生活史调控特征的关系。本研究分三个部分进行：(I)仙台(38.16 N.140.54E)自然日长变化条件下开花的光周期需求；(Ii)完全调控环境下光周期和低温处理组合对生活史调节的生理分析；(Iii)从各种同工酶图谱的相似性进行群体遗传分析。位于较高纬度的种群表现出较长的开花日数，这意味着有助于为冬季干旱和寒冷条件下的高耐受性个体做准备。相反，较低纬度的种群由于相对较小的环境选择压力而表现出大小依赖的开花。Yonakuni种群位于最低纬度24.98N处，表现出很强的调节作用，随着温度的升高，萌发受到抑制。而高纬度种群的萌发没有观察到温度控制。(5)同工酶分析表明，不同纬度生境间的遗传相似性较大，尤其是北纬38 N以上对开花表现出较强光周期依赖性的居群。但在远离纬度的其他种群中也观察到了相同的基因型别。综上所述，在较高纬度种群中，光周期反应可以调控植物从营养生长期向生殖生长期的转换生长，但对萌发过程没有控制作用。另一方面，低纬度种群的萌发过程受温度的调控，而发育转换则完全不受控制。

(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.