Effect of a rye B chromosome and its segments on homoeologous pairing in hybrids between common wheat and Aegilops variabilis
Effect of a rye B chromosome and its segments on homoeologous pairing in hybrids between common wheat and Aegilops variabilis
复制标题
DOI：
10.1266/ggs.87.1
复制
发表时间：
2012-02-01
影响因子：
1.1
通讯作者：
Endo, Takashi R.
中科院分区：
文献类型：
--
作者：
Kousaka, Ryota;Endo, Takashi R.
黑麦B染色体对寄主来说是多余的，但在减数分裂后通过不分离而增加，已有报道影响小麦-黑麦杂种的减数分裂同源配对。以小麦5B染色体上的phi基因为参照，研究了黑麦B染色体(B)及其片段(B-9和B-10)对普通小麦(2n=42)与变异山羊草(2n=28)杂交后代同源配对的影响。B-9和B-10染色体是小麦与B染色体相互易位的产物，B-9和B-10染色体有B着丝粒周段，B-10染色体有B远端染色体。当5B染色体缺失时，B和B-9染色体均抑制同源配对。另一方面，当5B存在时，B-9和B-10染色体促进同源配对。在配对抑制方面，B-9一剂比两剂强，B-9一剂比B-10一剂强。这些结果表明，B染色体对同源配对的影响不仅限于特定的区域，而且这种影响的强度取决于5B的存在与否以及B染色体的片段和剂量。含有5B和1个B-9的杂交种(2n=36)的平均交叉频率(10.23)显著高于仅含有5B的杂交种(2n=35)的平均交叉频率(2.78)，与缺乏5B的杂交种(2n=34)的平均交叉频率(14.09)相当。这一事实表明，B染色体或其片段可用于通过诱导小麦与外源染色体之间的同源配对而将外源基因导入小麦。
Rye B chromosomes, which are supernumerary chromosomes dispensable for the host but increase in number by non-disjunction after meiosis, have been reported to affect meiotic homoeologous pairing in wheat-rye hybrids. The effect of a rye B chromosome (B) and its segments (B-9 and B-10) on homoeologous pairing was studied in hybrids between common wheat (2n = 42) and Aegilops variabilis (2n = 28), with reference to the Phi gene located on wheat chromosome 5B. The B-9 and B-10 chromosomes are derived from reciprocal translocations between a wheat and the B chromosomes, and the former had the B pericentromeric segment and the latter had the B distal segment. Both the B and B-9 chromosomes suppressed homoeologous pairing when chromosome 5B was absent. On the other hand, the B-9 and B-10 chromosomes promoted homoeologous pairing when 5B was present. On pairing suppression, B-9 had a greater effect in one dose than in two doses, and B-9 had a greater effect than B-10 had in one dose. These results suggested that the effect of the B chromosomes on homoeologous pairing was not confined to a specific region and that the intensity of the effect varied depending on the presence or absence of 5B and also on the segment and dose of the B chromosome. The mean chiasma frequency (10.23) in a hybrid (2n = 36) possessing 5B and one B-9 was considerably higher than that (2.78) of a hybrid (2n = 35) possessing 5B alone, and was comparable with that (14.09) of a hybrid (2n = 34) lacking 5B. This fact suggested that the B chromosome or its segment can be used in introducing alien genes into wheat by inducing homoeologous pairing between wheat and alien chromosome.