Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706.
Genetics. 1974 Oct;78(2):691-701. doi: 10.1093/genetics/78.2.691.
The R(r):standard allele in maize, which conditions anthocyanin pigmentation in plant and seed tissues in the presence of appropriate complementary factors, is associated with a tandem duplication. The proximal member of the duplication carries P, the plant pigmenting determiner and the distal member member carries S, the seed pigmenting determiner. Derivatives from R(r) that have lost S function are designated r(r). They represent either losses of the distal member of the duplication (P derivatives) or mutations of S to s (P s). Derivatives that have lost P function are designated R(g), and represent either losses of the proximal member of the duplication (S derivatives) or mutations of P to p (p S).-All four possible types of r(r)/R(g) heterozygotes were tested for their capacity to yield R(r) reconstitution by crossing over. No R(r) derivatives were obtained from P/S heterozygotes, a result consistent with the view that P and S occupy corresponding positions in homologous chromosome segments. R(r) reconstitution was detected in both tandem duplication heterozygotes P s/S and P/p S, and was found to be about ten times more frequent in the latter. The ratio of R(r) reconstitution in the two heterozygotes is a function of position of the anthocyanin marker within the duplicated segment. The data from these heterozygotes allow one to measure the distance between P and S, that is to say, the genetic length of the duplicated segment. This distance was found to be 0.16 map units. The highest frequency of R(r) reconstitution was obtained from P s/p S heterozygotes, since direct pairing (see PDF) as well as the p//s type of displaced pairing have the potential to produce R(r) derivatives. One of the R(g) derivatives used in this study, R(g) (6), was found to back-mutate in some sublines to R(r). The basis for this instability remains unknown.
玉米中的 R(r)：标准等位基因，在适当的互补因子存在下，可使植物和种子组织中的花色素沉着，与串联重复有关。重复的近端成员携带 P，是植物色素决定因素，而远端成员携带 S，是种子色素决定因素。失去 S 功能的 R(r)衍生物被指定为 r(r)。它们要么代表重复的远端成员的丢失（P 衍生物），要么代表 S 突变为 s（P s）。失去 P 功能的衍生物被指定为 R(g)，代表重复的近端成员的丢失（S 衍生物）或 P 突变为 p（p S）。四种可能类型的 r(r)/R(g)杂合体都进行了交叉重组产生 R(r)重组的能力测试。从 P/S 杂合体中未获得 R(r)衍生物，这一结果与 P 和 S 占据同源染色体片段相应位置的观点一致。在串联重复杂合体 P s/S 和 P/p S 中均检测到 R(r)重组，且在后一种杂合体中更为常见，约为前者的 10 倍。两种杂合体中 R(r)重组的比例是花青素标记在重复片段内位置的函数。来自这些杂合体的数据允许人们测量 P 和 S 之间的距离，即重复片段的遗传长度。该距离为 0.16 个图谱单位。从 P s/p S 杂合体中获得了最高频率的 R(r)重组，因为直接配对（参见 PDF）以及 p//s 类型的易位配对都有可能产生 R(r)衍生物。在这项研究中使用的一个 R(g)衍生物，R(g)（6），在一些亚系中发现会回突变为 R(r)。这种不稳定性的基础尚不清楚。
