Acquisition of a New Regulatory System by a Ds Transposon in Maize

9507612在玉米蜡质（Wx）基因的三个相关等位基因中。每一个都是由一个2个Ds插入到精确相同的位点引起的，一个等位基因wx-m5：CS 7（（Ds）（CS 7））在萌发中的回复比另外两个小90倍，即使所有三个等位基因在胚乳中显示出相同的频率的体细胞回复。CS 7 germinal逆转的抑制与Wx基因相关，独立于转座酶来源，并且不抑制在其他位点插入Ds的切除，这表明CS 7 Ds受到一种新型发育控制的顺式作用突变。在该提议中测试的总体假设是，由于CS 7 Ds中的突变，宿主植物现在可以通过发育限制其与适当的转座酶结合的可接近性来抑制该转座子。具体而言：1.将对SD 7、CS 8和CS 8311 B中的Ds元件进行测序和比较，2.在植物发育的不同阶段，比较DNA甲基化并定量切除率。DS元件的相互作用将通过测定CS 7/CS 8杂合子中CS 7 germ回复的抑制来测试。控制CS 7切除的顺式和反式作用因子将被鉴定，5.将鉴定出不同地结合CS 7 Ds和CS 8Ds的玉米蛋白。 本研究的目的是通过研究植物调节转座因子活性的机制以及它们之间的相互作用来了解植物的遗传控制机制。插入到玉米基因组上相同位置的玉米的三个转座子具有不同的胚芽切除频率，尽管这些频率在体细胞中是相同的。将开始研究以确定控制玉米植物中这种差异的机制。这些研究将有助于更全面地了解调控基因表达的因素，以及允许更多的洞察植物宿主因子参与转座。 ***

9507612 Weil Among three related alleles of the maize waxy (Wx) gene. each caused by a 2 kilobase Ds insertion into precisely the same site, one allele, wx-m5:CS7 ((Ds) (CS7), reverts germinally as much as 90 fold less than the other two even though all three alleles show the same frequent, somatic reversion in the endosperm. The suppression of CS7 germinal reversion is genetically linked to Wx, independent of the transposase source and does not suppress excision by Ds insertions at other loci, suggesting a cis-acting mutation subjecting the CS7 Ds to a novel type of developmental control. The overall hypothesis tested in this proposal is that, because of a mutation in the CS7 Ds, the host plant can now suppress this transposon by developmentally restricting how accessible it is to proper transposase binding. Specifically: 1. The Ds elements in SD7, CS8, and CS8311B will be sequenced and compared, 2. DNA methylation will be compared and the excision rate quantitated at different stages during plant development, 3. The interaction of the DS elements will be tested by assaying the suppressiol of CS7 germinal reversion in CS7/CS8 heterozygotes, 4. cis- and trans-acting factors controlling CS7 excision will be identified and 5. maize proteins that bind the CS7 Ds and the CS8 Ds differently will be identified. %%% The goal of this research is to understand genetic control mechanisms in plants by examining mechanisms whereby plants regulate transposable element activity and how they interact with each other. Three transposons of corn which have inserted into identical positions on the corn genome have different germinal excision frequencies although such frequencies are identical in somatic cells. Studies will be initiated to determine the mechanisms controlling such differences in the corn plant. These studies will contribute to a more general understanding of factors regulating gene expression as well as allowing more insight into the participation of plant host factors in transposition. ***