de las Heras J I, King I P, Parker J S
School of Plant Sciences, University of Reading, Reading RG6 6AS, U.K.
Heredity (Edinb). 2001 Oct;87(Pt 4):474-9. doi: 10.1046/j.1365-2540.2001.00931.x.
The cuckoo chromosome 4S(L) from Aegilops sharonensis is preferentially transmitted when introduced by hybridization into common wheat, Triticum aestivum. Gametocidal (Gc) factors carried in 4S(L) induce chromosome breakage in meiospores not containing them, ensuring their transmission to the progeny. Chromosome breakage and break-fusion-bridge (BFB) cycles can also be observed during early embryo sac development of chromosome 4S(L) addition lines to wheat, often leading to the presence of dicentric chromosomes in the subsequent progeny. However, the process responsible for inducing the primary chromosomal breaks only appears to occur during the initial divisions of the embryo and endosperm. In the presence of chromosome 4S(L), treatment with the hypomethylating agent 5-azacytidine induces chromosome breakage in root tips. This suggests that the process of chromosome fragmentation, induced by the Gc factors during early seed development, is repressed at later stages by DNA methylation.
将沙伦山羊草的布谷鸟染色体4S(L)通过杂交导入普通小麦（小麦）时，它会被优先传递。4S(L)携带的配子致死（Gc）因子会在不包含它们的减数孢子中诱导染色体断裂，确保它们传递给后代。在小麦的4S(L)附加系的早期胚囊发育过程中也可以观察到染色体断裂和断裂-融合-桥（BFB）循环，这通常会导致后续后代中出现双着丝粒染色体。然而，负责诱导初级染色体断裂的过程似乎只在胚胎和胚乳的初始分裂期间发生。在存在染色体4S(L)的情况下，用去甲基化剂5-氮杂胞苷处理会在根尖诱导染色体断裂。这表明，在种子发育早期由Gc因子诱导的染色体片段化过程在后期被DNA甲基化抑制。
