Gottlieb Alexandra Marina, Poggio Lidia
Laboratorio de Citogenética y Evolución (LaCyE), Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes y Costanera Norte s/n, 4to. Piso, Pabellón II, Ciudad Universitaria, C1428EHA, Ciudad Autónoma de Buenos Aires, Argentina.
Genetica. 2010 Jun;138(6):567-78. doi: 10.1007/s10709-010-9449-9. Epub 2010 Mar 10.
The "yerba mate" tree, Ilex paraguariensis, is a functionally dioecious crop species with economic relevance in several South American countries. We report a genomic screening accomplished through representational difference analysis (RDA) in male and female I. paraguariensis trees. The aim of the present paper was to investigate the occurrence of sex-related genomic differences in order to develop an early gender detection molecular method that could help reducing energy inputs during the "yerba mate" processing and that could be suitable for breeding programs. An intra-experiment redundancy was detected via SSCP analysis and sequence characterization. Taking together both reciprocal RDA assays, fragments isolated can be discriminated into three main categories. The first category of fragments shows spurious affinities with available deposited sequences and could be considered as specific to I. paraguariensis. The second category comprises sequences identified as organellar or ribosomal plant DNA. Sequences grouped in the third category involve clones akin to conserved domains of retrotransposons (RNaseH, integrases and/or chromodomains) from at least two distinct lineages of Ty3/Gypsy retrotransposons and one from Ty1/Copia retroelements, which in addition are associated to sex determination regions of the Solanaceae, Caricaceae and Salicaceae. A contig sequence was assembled that codes for an integrase core domain and a chromodomain. The phylogenetic analysis of the so-called IPRE (for I. paraguariensis retroelement) integrase domain indicates that it belongs to the Del lineage of the Chromoviridae. This is the first report of mobile elements isolated and detected from the "yerba mate" tree. Although RDA derived fragments, so far tested, have been retrieved from both sexes with similar sequences, association to sex related regions cannot be completely discarded. Implications of present results are further discussed.
巴拉圭冬青树（Ilex paraguariensis），即“马黛茶”树，是一种功能上雌雄异株的作物品种，在几个南美国家具有经济价值。我们报告了一项通过代表性差异分析（RDA）对雄性和雌性巴拉圭冬青树进行的基因组筛选。本文的目的是研究性别相关的基因组差异的存在情况，以便开发一种早期性别检测分子方法，该方法有助于减少“马黛茶”加工过程中的能量投入，并且适用于育种计划。通过单链构象多态性（SSCP）分析和序列表征检测到实验内冗余。综合两个相互的RDA分析，分离出的片段可分为三大类。第一类片段与现有的已存入序列显示出虚假的亲和力，可被视为巴拉圭冬青树特有的片段。第二类包括被鉴定为细胞器或核糖体植物DNA的序列。归入第三类的序列涉及类似于反转录转座子（RNaseH、整合酶和/或染色质结构域）保守结构域的克隆，这些反转录转座子来自至少两个不同的Ty3/Gypsy反转录转座子谱系和一个Ty1/Copia反转录元件谱系，此外还与茄科、番木瓜科和杨柳科的性别决定区域相关。组装了一个编码整合酶核心结构域和染色质结构域的重叠群序列。对所谓的IPRE（巴拉圭冬青树反转录元件）整合酶结构域的系统发育分析表明，它属于嗜铬病毒科的Del谱系。这是首次从“马黛茶”树中分离和检测到移动元件的报告。尽管到目前为止测试的RDA衍生片段在两性中都以相似的序列被检索到，但与性别相关区域的关联不能完全排除。本文进一步讨论了当前结果的意义。
