Effects of ethephon on DNA methylation and gene expressions associated with shortened internodes in maize

Daxuan Yao,Xiuai Huo,Tinashe Zenda,Songtao Liu,Yunting Liu,Liang Dai,Huijun Duan

doi:10.1080/13102818.2017.1386591

Daxuan Yao, Xiuai Huo + Show 5 more

Open Access

https://doi.org/10.1080/13102818.2017.1386591

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Abstract

ABSTRACTIn this study, the molecular mechanism underlying ethephon-induced shortened internodes in maize was investigated using Zhengdan958 maize variety. The ethephon treatment was performed by spraying 225 mL/ha Ethephon 40% SL onto the foliage at the eight-expanded-leaves stage. The differentially expressed genes in the young internodes under ethephon treatment were identified through methylation-sensitive amplified fragment length polymorphism (MSAP), start codon targeted polymorphism (SCoT) and cDNA-amplified fragment length polymorphism (AFLP) analyses. MSAP results showed the methylation sites were widely distributed in both the ethephon-treated (at 27.8%) and control plants (30.1%). This suggested that ethephon treatment modified the methylation patterns; with 3.0% of the sites being hyper-methylated and 7.3% demethylated compared with the control. Based on SCoT analysis, 148 transcript derived fragments (TDFs) were obtained in the ethephon-treated plants. Among them, 38 were up-regulated (25.7%) and 47 down-regulated (31.8%). cDNA-AFLP analysis using 70 primer pairs identified 1635 TDFs in the ethephon-treated and the control plants. Of these, 600 and 564 TDFs were up- and down-regulated by the ethephon treatment, respectively. BLASTX analysis on 50 (randomly selected) differentially expressed TDFs divided them into several categories based on their putative biological functions: signal transduction (6%), resistance-related (14%), energy and metabolism (22%), transcription (4%), cell apoptosis (2%), unknown functional proteins (42%) and unknown genes (10%). Our results revealed that ethephon treatment could induce DNA methylation variation principally by increasing the demethylation tendency. This is suggested to play roles in stress-defence genes expression regulation and the differentially expressed genes could be associated with shortened internodes in maize.

Highlights

Maize (Zea mays L.) is one of the important food crops around the world [1,2,3]
Our results revealed that ethephon treatment could induce DNA methylation variation principally by increasing the demethylation tendency
High brightness without RNA contamination proved that the extracted genomic DNA (Figure 1(a)) used for methylation-sensitive amplified fragment length polymorphism (MSAP) analysis was of high integrity

Summary

Introduction

Its role has become increasingly prominent in the food, feed and industrial processing sectors as a result of continuously rising world food demands and development of global economy [4,5] This scenario calls for strategies to improve maize output. Several studies have noted that application of ethephon can thicken and shorten the internodes, subsequently reducing stalk lodging and enhancing maize yield [10,11]. These studies have largely centred on the physiological and biochemical mechanisms of how ethephon regulates the internode characterization [3,7,12]. Our results are a step towards an in-depth understanding of the internode shortening mechanism induced by ethephon and provide a theoretical basis for the control of stalk lodging in maize

Materials and methods

Results and discussion

Conclusions