Marfil Carlos F, Camadro Elsa L, Masuelli Ricardo W
Laboratorio de Biología Molecular, EEA La Consulta INTA, Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo and CONICET, Chacras de Coria Mendoza, Argentina.
BMC Plant Biol. 2009 Feb 20;9:21. doi: 10.1186/1471-2229-9-21.
The wild potato Solanum ruiz-lealii Brüch. (2n = 2x = 24), a species of hybrid origin, is endemic to Mendoza province, Argentina. Recurrent flower malformations, which varied among inflorescences of the same plant, were observed in a natural population. These abnormalities could be the result of genomic instabilities, nucleus-cytoplasmic incompatibility or epigenetic changes. To shed some light on their origin, nuclear and mitochondrial DNA of plants with normal and plants with both normal and malformed flowers (from here on designated as plants with normal and plants with abnormal flower phenotypes, respectively) were analyzed by AFLP and restriction analyses, respectively. Also, the wide genome methylation status and the level of methylation of a repetitive sequence were studied by MSAP and Southern blots analyses, respectively.
AFLP markers and restriction patterns of mitochondrial DNA did not allow the differentiation of normal from abnormal flower phenotypes. However, methylation patterns of nuclear DNA discriminated normal and abnormal flower phenotypes into two different groups, indicating that abnormal phenotypes have a similar methylation status which, in turn, was different from the methylation patterns of normal phenotypes. The abnormal flower phenotype was obtained by treating a normal plant with 5-Azacytidine, a demethylating agent, giving support to the idea of the role of DNA methylation in the origin of flower abnormalities. In addition, the variability detected for DNA methylation was greater than the detected for nucleotide sequence.
The epigenetic nature of the observed flower abnormalities is consistent with the results and indicates that in the diploid hybrid studied, natural variation in methylation profiles of anonymous DNA sequences could be of biological significance.
野生马铃薯鲁氏茄（Solanum ruiz - lealii Brüch.，2n = 2x = 24）是一种杂交起源的物种，原产于阿根廷门多萨省。在一个自然种群中观察到反复出现的花畸形现象，同一植株的不同花序上的畸形情况各不相同。这些异常可能是基因组不稳定、核质不相容或表观遗传变化的结果。为了探究其起源，分别通过扩增片段长度多态性（AFLP）分析和限制性分析，对具有正常花的植株以及同时具有正常花和畸形花的植株（以下分别称为具有正常花表型的植株和具有异常花表型的植株）的核DNA和线粒体DNA进行了分析。此外，还分别通过甲基化敏感扩增多态性（MSAP）分析和Southern杂交分析，研究了全基因组甲基化状态以及一个重复序列的甲基化水平。
AFLP标记和线粒体DNA的限制性图谱无法区分正常花表型和异常花表型。然而，核DNA的甲基化模式将正常花表型和异常花表型分为两个不同的组，表明异常表型具有相似的甲基化状态，而这又与正常表型的甲基化模式不同。用脱甲基剂5 - 氮杂胞苷处理正常植株可得到异常花表型，这支持了DNA甲基化在花异常起源中起作用的观点。此外，检测到的DNA甲基化变异性大于核苷酸序列的变异性。
观察到的花异常的表观遗传性质与结果一致，表明在所研究的二倍体杂种中，匿名DNA序列甲基化谱的自然变异可能具有生物学意义。
