Flower development and sufficient fruit set are important parameters with respect to walnut yield. Knowledge about flowering genes of fruit trees can help to conduct better molecular breeding programs. Therefore, this study was carried out to investigate the expression pattern of some flowering genes (FT, SOC1, CAL, LFY and TFL1) in Persian walnut (cv. Chandler) during the growing season and winter dormancy. The results showed that walnut flower induction and initiation in Shahmirzad, Iran occurred in early June and late September, respectively. After meeting chilling and heat requirement, flower differentiation and anthesis occurred in late-March and mid-April to early-May, respectively. Study of flowering gene expression showed that the expression of the FT gene increased in three stages including before breaking of bud dormancy, from late March to late April (coincided with flower differentiation and anthesis) and from late May to mid-June (coincided with flower induction). Like FT, the expression of SOC1 gene increased during flower induction and initiation (mid-May to early-August) as well as flower anthesis (mid-April to early-May). LFY and CAL genes as floral meristem identity genes are activated by FT and SOC1 genes. In contrast with flowering stimulus genes, TFL1 showed overexpression during winter dormancy which prevented flowering. The expression of FT gene activated downstream floral meristem identity genes including SOC1, CAL and LFY which consequently led to release bud dormancy as well as flower anthesis and induction. Also, TFL1 as a flowering inhibitor gene in walnut showed overexpression during the bud dormancy. Chilling accumulation reduced TFL1 gene expression and increased the expression of flowering genes which ultimately led to overcome dormancy.

中文翻译：

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波斯核桃开花：花卉发育过程中的基因表达模式

花的发育和充足的坐果是关于核桃产量的重要参数。有关果树开花基因的知识可以帮助开展更好的分子育种计划。因此，本研究旨在研究波斯核桃（cv。Chandler）在生长季节和冬季休眠期间某些开花基因（FT，SOC1，CAL，LFY和TFL1）的表达模式。结果表明，伊朗Shahmirzad核桃花的诱导和萌发分别发生在6月初和9月下旬。满足冷热要求后，分别在3月下旬和4月中旬至5月上旬发生了花的分化和开花。对开花基因表达的研究表明，FT基因的表达在三个阶段都增加了，包括打破芽休眠之前，从3月下旬至4月下旬（与花的分化和花粉同时发生）和从5月下旬至6月中旬（与花的诱导同时发生）。与FT一样，SOC1基因的表达在花的诱导和萌发（5月中旬至8月上旬）以及花期（4月中旬至5月上旬）期间均增加。作为花分生组织同一性基因的LFY和CAL基因被FT和SOC1基因激活。与开花刺激基因相反，TFL1在冬季休眠期间表现出过度表达，阻止了开花。FT基因的表达激活了下游花分生组织同一性基因，包括SOC1，CAL和LFY，从而导致释放芽休眠以及开花和诱导花期。另外，TFL1作为核桃中的开花抑制剂基因在芽休眠期间显示出过表达。