【摘要】 Dotted/rDt是玉米遗传学中最早发现的双元转座子系统之一。为了揭示玉米中非自主性转座子rDt在其自主性转座子Dt调控下的转座遗传特性，选取了a1-rDt;Dt和a1-m1::rDt;Dt 2个rDt转座子插入突变等位基因，检测玉米籽粒紫色斑点表型差异的遗传基础，利用巢式PCR与特异性酶切相结合的方法检测并鉴定了这2种材料叶片组织中rDt体细胞转座的印迹序列类型。通过构建遗传杂交群体，统计分析各群体的后代籽粒表型以及A1野生型基因的回复突变频率。结果显示，在籽粒糊粉层紫色斑点大小均一但数目极低的a1-rDt;Dt材料中，仅检测到2种体细胞转座的印迹序列类型，其中1种是没有转座子插入前A1野生型。而在籽粒糊粉层紫色斑点大小不一、排列密集的a1-m1::rDt;Dt材料中可以检测到5种体细胞转座的印迹序列类型，其中3种类型均保持A1’回复突变基因的开放阅读框；同时，a1-m1::rDt;Dt材料中A1’的回复突变频率是a1-rDt;Dt材料的大约2.6倍。研究表明，rDt在a1插入位点体细胞转座后的修复产物序列组成相对简单，与Ac/Ds等hAT超家族转座子相似，且rDt体细胞转座产生的印迹序列类型及丰富度是两个a1基因插入突变体中A1’回复突变频率高低及玉米籽粒糊粉层表型差异的遗传基础。更多还原

【Abstract】 Dotted/rDt is one of the earliest two-element transposon systems discovered in maize genetic research. The a1-rDt;Dt and the a1-m1::rDt;Dt are two A1 mutations with distinguishable kernel spotting phenotype, few uniform spots vs many variedsize spots. To explore the genetic characteristics of the somatic and germinal transposition of the same non-autonomous transposon rDt in either mutant line under the regulation of autonomous transposon Dt, nest-PCR amplification and restriction endonuclease digestion were applied to reveal the genetic bases for the variation in the size and number of somatic reversion spots in the aleurone by sequence analysis on the footprints at the different insertion sites of two alleles. Furthermore, segregation populations were constructed for A1’ reversion frequency. The results showed that only two types of somatic footprint sequence were detected in a1-rDt;Dt line, including the exact wild-type sequence prior to any insertions. In contrast, five types of somatic footprint sequence were detected in a1-m1::rDt;Dt line with densely populated aleurone full of various purple spots, and three of them remained in the right open reading frame of possible A1’ reversion genes. Meanwhile, the reversion frequency to A1’ in a1-m1::r Dt;Dt lines was 2.6 times higher than that in a1-r Dt;Dt lines. These relatively simple composition of excision footprint upon somatic transpositions of r Dt at a1 locus was comparable with that of other family members from the h AT transposon superfamily such as Ac/Ds. Thus, the higher reversion frequency together with multiple reversion alleles may genetically contribute to the perceptible differences from spotting phenotype pattern in aleurone of the tow tested a1-rDt alleles.更多还原