Research on genetic variation and gene conservation of the tolerant poplar species for drought stress.

本研究建立了组织培养、愈伤组织培养和原生质体培养的无性系繁殖方法。研究了杨树无性系对低水势、低盐度和低pH胁迫的反应。首次建立了生长在中国干旱区的杨树无性系繁殖技术。这为保存在日本大田条件下不能生长的中国杨树的遗传资源提供了可能。这也使得温带杨树的遗传保护成为可能。以胡杨、毛白杨、白杨、大白杨为试材，采用试管苗方法测定了胡杨、毛白杨、大白杨和大白杨对低渗透压、低盐度和低pH胁迫的耐受性。在供试杨树无性系中，胡杨对这三种胁迫的耐受性最强。我认为胡杨具有较高的遗传潜力，可用于培育干旱地区的新栽培者。最后对这些杨树进行了原生质体培养试验。观察到了克隆的成功形成，证明了利用原生质体培养进行遗传操作的可能性。

Methods for clonal propagation by tissue culture, callus culture and protoplast culture were established in this research project. The reactions of poplar clones for the stresses of low water potential, salinity and low pH conditions were also investigated.At first clonal propagation techniques of the poplars growing at the arid district in China was established. This made possible to conserve genetic resources of Chinese poplars which cannot grow in the field condition in Japan in vitro. This made the genetic conservation of temperate poplars possible too. The tolerance abilities for the stresses of low osmotic pressure and salinity and low pH of Populus euphratica, Populus tomentosa, Populus alba cv.pyramidalis X Populus tomentosa and Populus maximowiczii X Populus plantierensis were tested by using in vitro cultured shoots. Populus euphratica showed the highest tolerant for these three types of stress among test poplar clones. I think Populus euphratica has high genetic potential for the breeding of new cultivers for arid region. Finally protoplast culture was tested for these poplars. Successful colony formation was observed and the possibility of the genetic manipulation using protoplast culture was shown.