Production of Leymus racemosus chromosome addition lines of common wheat and their evaluation as breeding materials

总状羊草（Leymus racemosus, 2n=28）是小麦科野生多年生植物，生长在海滨和旱地。其旺盛的生长和习性表明这种植物对生物和非生物胁迫具有耐受性。本研究选择携带总状羊草（Leymus racemosus）一条或一对染色体的普通小麦植株。在这项研究中，我们首先分离了重复的DNA序列，这些DNA序列可以作为总状伞染色体的标记。以这些DNA序列为探针，通过原位杂交，绘制了总状藓染色体的表意符号。我们现在已经得到了8条二体附加线和4条单体附加线。剩下的两条染色体没有遗传给后代。相比之下，染色体J2优先从雄性配子传递。附加品系表现出不同的形态变化，如尖穗变细、外稃有芒等。采用以下方法对采前发芽的耐受性进行了研究：在雨季中期收获一群含杂染色体的总形小麦植株，对穗和种子进行反复干燥和浸泡。在这项研究中获得的所有附加品系现在正在与其他机构的植物病理学家合作进行评估。在本研究中，我们意外地发现一个名为TaiI-family的重复序列在普通小麦的着丝粒区域显示了信号，尽管它最初被表征为l .总状体染色体的末端异染色质序列。taii家族是在普通小麦染色体的着丝粒区发现的第一个重复序列。

Leymus racemosus (2n=28) is a wild perennial species in Triticeae and grows in seashore and dry land. Its vigorous growth and habit suggest that this plant has tolerance to biological and abiological stresses. In this research, common wheat plants carrying one or a pair of chromosomes of Leymus racemosus were selected. For this study, we first isolated repetitive DNA sequences that could be used as the markers for each L.racemosus chromosome. By in situ hybridization using these DNA sequences as the probes, we drew an ideogram of the chromosomes of L.racemosus. We have now already obtained eight disomic addition lines and four monosomic addition lines. The remaining two chromosomes were not transmitted to the progeny. By contrast, chromosome 'J2' was transmitted preferentially from the male gametes. The addition lines showed various morphologic changes, such as tapered spikes and awned lemma. The tolerance for pre-harvest sprouting were examined by the following method : A population of wheat plants including miscellaneous chromosome(s) of L.racemosus was harvested in the middle of rainy season, and the spikes and seeds were repeatedly dried and soaked. All addition lines obtained in this research are now evaluated in cooperation with plant pathologists in the other institutions. In this study we unexpectedly found that one repetitive sequence, named TaiI-family, showed the signals on the centromeric regions of common wheat though it had been originally characterized as a terminal heterochromatin sequence in L.racemosus chromosomes. TaiI-family is the first repetitive sequence found in the centromeric regions of common wheat chromosomes.