Sheridan William F, Auger Donald L
Department of Biology and Microbiology, South Dakota State University, Brookings, South Dakota 57007-2142, USA.
Genetics. 2008 Oct;180(2):755-69. doi: 10.1534/genetics.108.091843. Epub 2008 Sep 9.
The B-A-A translocations have enabled us to simultaneously assess the possible dosage-sensitive interactions of two nonhomologous chromosome segments in affecting maize plant development. Maize B-A-A translocations contain segments of two nonhomologous essential A chromosomes in tandem arrangement attached to a segment of the long arm of a supernumerary B chromosome. By utilizing the frequent nondisjunction of the B centromere at the second pollen mitosis we produced plants containing an extra copy of the two A chromosome segments. We compared these hyperploid plants with nonhyperploid plants by measuring leaf width, plant height, ear height, internode length, stalk circumference, leaf length, and tassel-branch number in 20 paired families that involved one of the chromosome arms 1S, 1L, 4L, 5S, and 10L. One or more of the seven measured traits displayed dosage sensitivity among 17 of the 20 B-A-A translocations, which included the involvement of chromosome arms 2L, 3L, 5L, 6L, and 7L. The most obvious effect of an increased dosage of the B-A-A translocation was a significant decrease in the traits in the hyperploid plants. These effects may be either the additive effects of hyperploidy for the two chromosome segments or a result of gene interaction between them.
B-A-A易位使我们能够同时评估两个非同源染色体片段在影响玉米植株发育方面可能存在的剂量敏感相互作用。玉米B-A-A易位包含两个非同源必需A染色体的片段，它们串联排列并连接到一个额外B染色体长臂的一段上。通过利用B着丝粒在第二次花粉有丝分裂时频繁的不分离现象，我们培育出了含有两份A染色体片段的植株。我们在涉及1S、1L、4L、5S和10L这五条染色体臂之一的20对家族中，通过测量叶宽、株高、穗位高、节间长度、茎粗、叶长和雄穗分枝数，将这些超倍体植株与非超倍体植株进行了比较。在20个B-A-A易位中的17个中，七个测量性状中的一个或多个表现出剂量敏感性，其中涉及2L、3L、5L、6L和7L染色体臂。B-A-A易位剂量增加最明显的影响是超倍体植株的性状显著降低。这些影响可能是两个染色体片段超倍体的累加效应，也可能是它们之间基因相互作用的结果。
