十个八倍体小偃麦的细胞学鉴定和染色体构成分析

Cytological Identification and Chromosome Constitution Analyses of Ten Octoploid Trititrigia Accessions

培育新的八倍体小偃麦,对于利用偃麦草遗传物质进行小麦的遗传改良具有重要意义。本研究利用细胞学和基因组原位杂交技术,对从中间偃麦草与小麦品种烟农15杂交后代选育出的10个八倍体小偃麦山农TE256、山农TE259、山农TE261、山农TE262、山农TE263、山农TE265、山农TE266、山农TE267-1、山农TE270和山农TE274进行了细胞学鉴定和染色体构成分析。结果表明,10个八倍体小偃麦绝大多数单株根尖细胞的染色体数目为2n=56,个别单株含有54或55条染色体;大多数2n=56单株的花粉母细胞在减数分裂中期I的染色体构型为2n=28II,少数花粉母细胞存在单价体、三价体或四价体,后期I染色体可均等分向两极,仅有极少数细胞出现染色单体提前分离等现象;10个八倍体小偃麦均含有普通小麦的全套染色体和中间偃麦草的1个混合染色体基组,其中间偃麦草染色体是由来自中间偃麦草3个不同染色体基组的染色体构成的混合染色体基组,其染色体构成分别为2St+8J^S+2J+2J-St、2St+8J^S+4J、2St+8J^S+2J+2J-St、2St+8J^S+2J+2J-St、2St+8J^S+2J+2J-St、6St+4J^S+2J+2J-St、4St+6J^S+2J+2J-St、2St+8J^S+4J、2St+8J^S+4J和4St+6J^S+4J,与目前已报道的八倍体小偃麦均有所不同。研究结果可为这些新型八倍体小偃麦的研究和有效利用提供参考依据。

Developing new octoploid Trititrigia is of great significance for using Thinopyrum intermedium to the genetic improvement of common wheat. Tenoctoploid Trititrigia accessions, i.e., Shannong TE256, Shannong TE259, Shannong TE261, Shannong TE262, Shannong TE263, Shannong TE265, ShannongTE266, Shannong TE267-1, Shannong TE270, and Shannong TE274, were developed from the progenies of the cross between Thinopyrum intermedium andcommon wheat variety ‘Yannong 15’. In this study, cytological methods and genomic in situ hybridization （GISH） were employed to determine cytologicalstability and chromosome constitutions of the 10 octoploid Trititrigia accessions. Mitotic observation indicated that most plants of octoploid Trititrigia had 56chromosomes and a few had 54 or 55 chromosomes. Chromosomes in most pollen mother cells of plants with 2n = 56 formed 28 bivalents, showing a high degreeof cytogenetic stability, simultaneously, univalents, trivalents and tetravalents appeared occasionally at meiotic metaphase I. At meiosis anaphase I （PMC AI）,most chromosomes segregated equally to the two poles except for several univalent chromosomes moving ahead in very few cells. Fourteen Th. intermediumchromosomes were observed to be added to the whole set of common wheat chromosomes in each octoploid Trititrigia, and the alien chromosome constitutions of the 10 octoploidTrititrigia accessions were 2St＋8J^S＋2J＋2J-St, 2St＋8J^S＋4J, 2St＋8J^S＋2J＋2J-St, 2St＋8J^S＋2J＋2J-St, 2St＋8J^S＋2J＋2J-St, 6St＋4J^S＋2J＋2J-St, 4St＋6J^S＋2J＋2J-St, 2St＋8J^S＋4J, 2St＋8JS＋4J, and 4St＋6JS＋4J. These alien chromosome constitutions were different from those reported in octoploid Trititrigia, suggesting that the 10 octoploidTrititrigia accessions are novel materials and might be valuable in wheat breeding programs.