Transcriptome Analysis of Pistillate Flowering in Pecan (Carya illinoinensis)

Pecan [Carya illinoinensis (Wangenh.) K. Koch] is a famous high grade dry fruit, oil tree species and excellent tree species for both timber and fruit. Pecan is a monoecious plant, and the formation and number of female flowers directly determine the pecan yield. In this work, to illuminate the molecular mechanism of floral formation in pecan, scanning electron microscopy was employed to distinguish the developmental stages of female flower. Three flower buds and two flowering stages were collected for high throughput RNA sequencing. 65,680 unigenes were generated with 41, 806 differentially expressed genes annotated. The plant hormones and sucrose metabolic pathways play important roles in flowering transition stage. 40 MADS-box genes were identified and differentially expressed during flower development.These findings are of great significance for further understanding of the molecular basis for reproductive development in Carya Nutt species.薄壳山核桃（Pecan，学名：Carya illinoinensis (Wangenh.) K. Koch）是享誉全球的高档干果、油料树种与材果兼用优良树种。该树种为雌雄同株植物，雌花的形成与数量直接决定薄壳山核桃的产量。本研究为阐明薄壳山核桃成花的分子机制，采用扫描电子显微镜（scanning electron microscopy）区分雌花发育时期；共采集3份花芽样本与2个开花时期样本开展高通量RNA测序（high throughput RNA sequencing），最终获得65680条单基因簇（unigenes），并注释得到41806个差异表达基因（differentially expressed genes）。研究发现，植物激素与蔗糖代谢通路在花转变阶段发挥关键作用；本研究共鉴定出40个MADS-box基因，且其在花发育过程中呈差异表达。上述研究结果对进一步解析山核桃属（Carya Nutt）植物生殖发育的分子基础具有重要意义。