Transcript Analysis and Regulative Events during Flower Development in Olive (<i>Olea europaea</i> L.)

The identification and characterization of transcripts involved in flower organ development, plant reproduction and metabolism represent key steps in plant phenotypic and physiological pathways, and may generate high-quality transcript variants useful for the development of functional markers. This study was aimed at obtaining an extensive characterization of the olive flower transcripts, by providing sound information on the candidate MADS-box genes related to the ABC model of flower development and on the putative genetic and molecular determinants of ovary abortion and pollen-pistil interaction. The overall sequence data, obtained by pyrosequencing of four cDNA libraries from flowers at different developmental stages of three olive varieties with distinct reproductive features (Leccino, Frantoio and Dolce Agogia), included approximately 465,000 ESTs, which gave rise to more than 14,600 contigs and approximately 92,000 singletons. As many as 56,700 unigenes were successfully annotated and provided gene ontology insights into the structural organization and putative molecular function of sequenced transcripts and deduced proteins in the context of their corresponding biological processes. Differentially expressed genes with potential regulatory roles in biosynthetic pathways and metabolic networks during flower development were identified. The gene expression studies allowed us to select the candidate genes that play well-known molecular functions in a number of biosynthetic pathways and specific biological processes that affect olive reproduction. A sound understanding of gene functions and regulatory networks that characterize the olive flower is provided.参与花器官发育、植物生殖与代谢过程的转录本的鉴定与表征，是解析植物表型与生理通路的关键环节，同时可获取可用于开发功能标记的优质转录本变异体。本研究旨在全面表征油桃花转录本，一方面提供与花发育ABC模型相关的候选MADS-box基因（MADS-box genes）的可靠信息，另一方面解析子房败育与花粉-雌蕊互作的潜在遗传与分子决定因子。本研究通过对三个具有差异化生殖特性的油橄榄品种（Leccino、Frantoio与Dolce Agogia）不同发育阶段花组织的四个cDNA文库开展焦磷酸测序，共获得约465,000条表达序列标签（Expressed Sequence Tags, EST），经组装得到14,600余个重叠群（contigs）与约92,000条单序列（singletons）。其中56,700个单基因簇（unigenes）成功获得注释，并通过基因本体论（Gene Ontology, GO）分析，阐明了测序转录本及其推导蛋白在对应生物学过程中的结构组织与潜在分子功能。研究鉴定出了在花发育阶段的生物合成通路与代谢网络中发挥潜在调控作用的差异表达基因。通过基因表达分析，本研究筛选出了在多条影响油橄榄生殖的生物合成通路与特定生物学过程中发挥已知分子功能的候选基因。本研究为阐明油桃花特征相关的基因功能与调控网络提供了扎实的认知基础。