Dynamics of gene expression during development and expansion of vegetative stem internodes of bioenergy sorghumReportar como inadecuado




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Biotechnology for Biofuels

, 10:159

First Online: 21 June 2017Received: 21 December 2016Accepted: 14 June 2017DOI: 10.1186-s13068-017-0848-3

Cite this article as: Kebrom, T.H., McKinley, B. & Mullet, J.E. Biotechnol Biofuels 2017 10: 159. doi:10.1186-s13068-017-0848-3

Abstract

BackgroundBioenergy sorghum accumulates 75% of shoot biomass in stem internodes. Grass stem internodes are formed during vegetative growth and elongate in response to developmental and environmental signals. To identify genes and molecular mechanisms that modulate the extent of internode growth, we conducted microscopic and transcriptomic analyses of four successive sub-apical vegetative internodes representing different stages of internode development of the bioenergy sorghum genotype R.07020.

ResultsStem internodes of sorghum genotype R.07020 are formed during the vegetative phase and their length is enhanced by environmental signals such as shade and floral induction in short days. During vegetative growth, the first visible and youngest sub-apical internode was ~0.7 cm in length, whereas the fourth fully expanded internode was ~5 cm in length. Microscopic analyses revealed that all internode tissue types including pith parenchyma and vascular bundles are present in the four successive internodes. Growth in the first two sub-apical internodes occurred primarily through an increase in cell number consistent with expression of genes involved in the cell cycle and DNA replication. Growth of the 3rd internode was associated with an increase in cell length and growth cessation in the 4th internode was associated with up-regulation of genes involved in secondary cell wall deposition. The expression of genes involved in hormone metabolism and signaling indicates that GA, BR, and CK activity decreased while ethylene, ABA, and JA increased in the 3rd-4th internodes. While the level of auxin appears to be increasing as indicated by the up-regulation of ARFs, down-regulation of TIR during development indicates that auxin signaling is also modified. The expression patterns of transcription factors are closely associated with their role during the development of the vegetative internodes.

ConclusionsMicroscopic and transcriptome analyses of four successive sub-apical internodes characterized the developmental progression of vegetative stem internodes from initiation through full elongation in the sorghum genotype R.07020. Transcriptome profiling indicates that dynamic variation in the levels and action of GA, CK, IAA, BR, ethylene, ABA, and JA modulate gene expression and growth during internode growth and development. This study provides detailed microscopic and transcriptomic data useful for identifying genes and molecular pathways regulating internode elongation in response to various developmental and environmental signals.

KeywordsBioenergy Sorghum Internode Transcriptome Cell cycle Hormone AbbreviationsARFsauxin response factors

TIRtransport inhibitor response1

ABAabscisic acid

SLstrigolactones

CKcytokinin

GAgibberellic acid

BRbrassinosteroid

JAjasmonic acid

RPKMreads per kilobase of transcript per million mapped reads

PALphenylalanine ammonia-lyase

C4Hcinnamate-4-hydroxylase

4CL4-coumarate:CoA ligase

HCThydroxycinnamoyl-coenzyme A shikimate-quinate hydroxycinnamoyltransferase

C3Hcoumarate 3-hydroxylase

CCoAOMT1caffeoyl coenzyme A O-methyltransferase 1

CCR1cinnamoyl CoA reductase

COMTcaffeic acid-5-hydroxyferulic acid O-methyltransferase

CADcinnamyl alcohol dehydrogenase

Electronic supplementary materialThe online version of this article doi:10.1186-s13068-017-0848-3 contains supplementary material, which is available to authorized users.





Autor: Tesfamichael H. Kebrom - Brian McKinley - John E. Mullet

Fuente: https://link.springer.com/







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