An NAC Transcription Factor Controls Ethylene-Regulated Cell Expansion in Flower Petals

Abstract

Cell expansion is crucial for plant growth. It is well known that the phytohormone ethylene functions in plant development as a key modulator of cell expansion. However, the role of ethylene in the regulation of this process remains unclear. In this study, 2,189 ethylene-responsive transcripts were identified in rose (Rosa hybrida) petals using transcriptome sequencing and microarray analysis. Among these transcripts, an NAC (for no apical meristem [NAM], Arabidopsis transcription activation factor [ATAF], and cup-shaped cotyledon [CUC])-domain transcription factor gene, RhNAC100, was rapidly and dramatically induced by ethylene in the petals. Interestingly, accumulation of the RhNAC100 transcript was modulated by ethylene via microRNA164-dependent posttranscriptional regulation. Overexpression of RhNAC100 in Arabidopsis (Arabidopsis thaliana) substantially reduced the petal size by repressing petal cell expansion. By contrast, silencing of RhNAC100 in rose petals using virus-induced gene silencing significantly increased petal size and promoted cell expansion in the petal abaxial subepidermis (P , 0.05). Expression analysis showed that 22 out of the 29 cell expansion-related genes tested exhibited changes in expression in RhNAC100-silenced rose petals. Moreover, of those genes, one cellulose synthase and two aquaporin genes (Rosa hybrida Cellulose Synthase2 and R. hybrida Plasma Membrane Intrinsic Protein1;1/2;1) were identified as targets of RhNAC100. Our results suggest that ethylene regulates cell expansion by fine-tuning the microRNA164/RhNAC100 module and also provide new insights into the function of NAC transcription factors.

Genome-Wide Transcriptional Profiling to Elucidate Key Candidates Involved in Bud Burst and Rattling Growth in a Subtropical Bamboo (Dendrocalamus hamiltonii)

“…Ethylene, auxin, cytokinin, brassinosteroids, gibberellin related genes were up-regulated in growing tissues facilitating cell division (either directly or indirectly through cell cycle regulators). Phytohormone mediated cell wall acidification together with aquaporin, endoglucanase, XETs, and expansins facilitates cell expansion (Kretzschmar et al, 2011; Hayashi, 2012; Péret et al, 2012; Wolf et al, 2012; Pei et al, 2013; Sablowski and Carnier Dornelas, 2014). Expression profiles of most of the genes involved in maintenance of cell growth were broadly in accordance of previous report in temperate bamboo (He et al, 2013; Peng et al, 2013a).…”

An Ethylene-Induced Regulatory Module Delays Flower Senescence by Regulating Cytokinin Content

“…qRT-PCR reactions were performed using 1 mL cDNA as template and the Step One Plus real-time PCR system (Applied Biosystems) with the KAPA SYBR FAST quantitative PCR kit (Kapa Biosystems). RhACT5 was used as an internal control (Pei et al, 2013).…”

Temporal Petal Closure Benefits Reproductive Development of Magnolia denudata (Magnoliaceae) in Early Spring

“…During the anthesis, some flowers maintain open until petal withering, such as rose, while others show temporal closure and repeated opening of petals, such as lotus. From a physiological point of view, flower opening involves a high rate of cell expansion (Singh et al, 2011; Pei et al, 2013). It has attracted extensive attention of scientists by the complex regulation and also has inspired artists and common people by the impressive and emotional petal movements.…”