Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Chongqing, China.
Academy of Agricultural Sciences of Southwest University, State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Chongqing, China.
Physiol Plant. 2020 Apr;168(4):893-908. doi: 10.1111/ppl.13029. Epub 2019 Nov 25.
Double-flower loquat (Eriobotrya japonica) is a new germplasm with homeotic transformation of stamen into petal in whorl 3. However, little information is available on the molecular mechanism of this transformation. Herein, we analyzed the transcriptome, candidate genes and endogenous hormones to investigate the mechanisms underlying this homeotic transformation. Some transcription factors, such as MADS-box, TCP and MYB, were significantly differentially expressed. Importantly, we confirmed that one of these (DN39625_c0_g1), which encoded a C-class floral homeotic protein referred to as AGAMOUS ortholog (EjAG), was significantly downregulated. Subcellular localization of EjAG was found to be in the nucleus. Ectopic expression of EjAG rescued the development of stamens and carpels from the double-flower phenotype in an Arabidopsis ag mutant, suggesting that EjAG expression is associated with double-flower formation. Meanwhile, enrichment analyses showed that the differentially expressed genes (DEGs) were mainly involved in the metabolic pathways of hormone signal transduction. The DEGs of auxin, gibberellin A (GA) and cytokinin signaling pathways were mainly upregulated. However, the DEGs of abscisic acid (ABA) and the ethylene signaling pathway were mainly downregulated. Accordingly, the concentrations of indoleacetic acid, kinetin and GA were high at the petaloid stamen stage, but the ABA concentration remained low. The identified genes and pathways provide abundant sequence resources for studying the mechanisms underlying the homeotic transformation in loquat and other Rosaceae species.
双色海棠（Eriobotrya japonica）是一种新的种质资源，具有第 3 轮雄蕊同源转化为花瓣的特性。然而，对于这种转化的分子机制知之甚少。在此，我们分析了转录组、候选基因和内源性激素，以研究这种同源转化的机制。一些转录因子，如 MADS-box、TCP 和 MYB，表达水平显著差异。重要的是，我们证实其中一个（DN39625_c0_g1），编码一个 C 类花同源异型蛋白，称为 AGAMOUS 同源物（EjAG），表达水平显著下调。EjAG 的亚细胞定位发现位于细胞核中。在拟南芥 ag 突变体中异位表达 EjAG 可挽救双花瓣表型的雄蕊和心皮发育，表明 EjAG 表达与双花瓣形成有关。同时，富集分析表明差异表达基因（DEGs）主要参与激素信号转导的代谢途径。生长素、赤霉素 A（GA）和细胞分裂素信号通路的 DEGs 主要上调。然而，脱落酸（ABA）和乙烯信号通路的 DEGs 主要下调。因此，在瓣状雄蕊阶段，吲哚乙酸、激动素和 GA 的浓度较高，而 ABA 的浓度保持较低。鉴定的基因和途径为研究海棠及其他蔷薇科物种同源转化的机制提供了丰富的序列资源。
