De novo assembly and transcriptome analysis of two contrary tillering mutants to learn the mechanisms of tillers outgrowth in switchgrass (Panicum virgatum L.).

Kaijie Xu,Lili Shi,Yongfeng Wang,Guaiqiang Chai,Yajun Xi,Shudong Liu,Fengli Sun

doi:10.3389/fpls.2015.00749

Kaijie Xu, Lili Shi + Show 5 more

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https://doi.org/10.3389/fpls.2015.00749

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Abstract

Tillering is an important trait in monocotyledon plants. The switchgrass (Panicum virgatum), studied usually as a source of biomass for energy production, can produce hundreds of tillers in its lifetime. Studying the tillering of switchgrass also provides information for other monocot crops. High-tillering and low-tillering mutants were produced by ethyl methanesulfonate mutagenesis. Alteration of tillering ability resulted from different tiller buds outgrowth in the two mutants. We sequenced the tiller buds transcriptomes of high-tillering and low-tillering plants using next-generation sequencing technology, and generated 34 G data in total. In the de novo assembly results, 133,828 unigenes were detected with an average length of 1,238 bp, and 5,290 unigenes were differentially expressed between the two mutants, including 3,225 up-regulated genes and 2,065 down-regulated genes. Differentially expressed gene analysis with functional annotations was performed to identify candidate genes involved in tiller bud outgrowth processes using Gene Ontology classification, Cluster of Orthologous Groups of proteins, and Kyoto Encyclopedia of Genes and Genomes pathway analysis. This is the first study to explore the tillering transcriptome in two types of tillering mutants by de novo sequencing.

Highlights

Tillering is well known to play an important role in determining direct yields of monocotyledons
These results suggest that the change in tiller number in the two mutants was caused by alteration of tiller bud outgrowth and tiller elongation
Two tillering mutants that displayed high and low tillering were generated by ethyl methanesulfonate (EMS) mutagenesis

Summary

Introduction

Tillering is well known to play an important role in determining direct yields of monocotyledons. Tillering generally comprises two steps: the initiation of tiller buds and their outgrowth. At present, tillering studies are restricted to minority grains, especially rice. MONOCULM1 (MOC1), mutation for this gene leads to rice have only one main culm without tillers, play important roles in tiller meristems initiation in rice (Li et al, 2003; Sun et al, 2010b; Lin et al, 2012; Xu et al, 2012). OsTB1 was confirmed as a negative regulator of lateral branching in rice, presumably through expression in axillary buds (Takeda et al, 2003; Choi et al, 2012; Guo et al, 2013).

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