Transcriptomic analysis identifies the key genes involved in stamen petaloid in lotus (Nelumbo nucifera)

Abstract

BackgroundFlower morphology, a phenomenon regulated by a complex network, is one of the vital ornamental features in Nelumbo nucifera. Stamen petaloid is very prevalent in lotus flowers. However, the mechanism underlying this phenomenon is still obscure.ResultsHere, the comparative transcriptomic analysis was performed among petal, stamen petaloid and stamen through RNA-seq. Using pairwise comparison analysis, a large number of genes involved in hormonal signal transduction pathways and transcription factors, especially the MADS-box genes, were identified as candidate genes for stamen petaloid in lotus.ConclusionsTaken together, these results provide an insight into the molecular networks underlying lotus floral organ development and stamen petaloid.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-4950-0) contains supplementary material, which is available to authorized users.

Comparative transcriptomic analysis provides an insight into floral organ petaloid in lotus (Nelumbo nucifera)

“…It has been declared that stamen petaloid is more similar to petal than to stamen. This is consistent with stamen petaloid having the petal morphology as previously reported [15]. The number of DEGs between C vs Cp and P vs Cp did not show any significant difference, suggesting that the abnormal flower organ (carpel petaloid) remained more of the carpel trait with petal-like features.…”

“…These candidate genes were reported that they involved in stamen petaloid [15]. These indicate that GH3 and GATA are essential in petal formation and promote to alteration other floral organs to petal-like feature.…”

“…This result suggested that these DEGs might share some conserved gene expression in stamen petaloid and carpel petaloid. After filtering out the genes with a low expression (FPKM <5), the several numbers of DEGs were assigned to transcription factors and plant hormone signal transduction out of 41 common DEGs (Table S2) Three DEGs (NNU_10192, NNU_12600 and 17837) were reported in our recent and previously study suggesting that they are associated with stamen petaloid [15]. This is more so for NNU_10192 being an AG homologue gene, a member of MADS-box family belonged to classical ABC model.…”

“…These results show that a declined expression of AG in inner whorl results in carpel petaloid formation and breaks down the gene expression boundary. In the previously study, we performed transcriptome analysis for stamen petaloid showing that several MADS-box genes, including AG were found to be possibly involved in floral organ specification [15].…”

“…Previously, it has been shown that the obscure expression of several candidate genes in boundaries of petal and stamen could result in the stamen petaloid formation [15], which might also be influenced by DNA methylation [16]. Additionally, the latest studies on lotus were comprehensively reviewed which revealed the absence of a detailed study on petaloid formation in N. nucifera [17].…”