Enhanced Activity of Genes Associated With Photosynthesis, Phytohormone Metabolism and Cell Wall Synthesis Is Involved in Gibberellin-Mediated Sugarcane Internode Growth.

Rongfa Chen,Huiwen Zhou,Haifeng Yan,Yegeng Fan,Xing Huang,Jianming Wu,Zhongfeng Zhou,Lihang Qiu,Prakash Lakshmanan,Mengling Weng,Yangrui Li

doi:10.3389/fgene.2020.570094

Abstract

Internode elongation is an important trait in sugarcane as it affects the sugarcane yield. Gibberellin (GA) is a key modulator of internode elongation in sugarcane. Understanding the gene expression features of GA-mediated internode elongation has both scientific and practical significance. This study aimed to examine the transcriptomic changes in the internode elongation of sugarcane following GA treatment. Eighteen cDNA libraries from the internode tissues on days of 0, 3, and 6 in control and GA treatment groups were sequenced and their gene expression were studied. RNA-seq analysis revealed 1,338,723,248 reads and 70,821 unigenes from elongating internodes of sugarcane. Comparative studies discovered a large number of transcripts that were differentially expressed in GA-treated samples compared to the control. Further analysis revealed that the differentially expressed genes were enriched in the metabolic process, one-carbon compound transport, and single-organism process. Kyoto Encyclopedia of Genes and Genomes pathway annotation showed significant enrichment in photosynthesis and plant hormone signal transduction, indicating its involvement in internode elongation. The function analysis suggested that metabolic pathways and biosynthesis of secondary metabolites, plant hormones, and cell wall components were enriched in the internodes of the GA-treated plants. The hub genes were identified, with the function of cellulose synthesis. The results of this study provide a global view of mRNA changes during sugarcane internode elongation and extend our knowledge of the GA-mediated cellular processes involved in sugarcane stem growth.

Highlights

Sugarcane is a major agricultural crop in China, which as a country provides ∼80% of sugar produced globally (Chen et al, 2019), the second largest bioenergy crop in the world (Tomes et al, 2011)
To understand the growth effect and the molecular changes caused by GA treatment in sugarcane, 18 cDNA libraries constructed from both GA-treated and control plant internodes were sequenced and the data were analyzed
We found that the “Inositol metabolic process” was enriched in the differentially expressed genes (DEGs) when compared to G1 vs G2 and G1 vs G3

Summary

Introduction

Sugarcane is a major agricultural crop in China, which as a country provides ∼80% of sugar produced globally (Chen et al, 2019), the second largest bioenergy crop in the world (Tomes et al, 2011). Shoot length in graminaceous plants is largely determined by internode elongation, which is controlled the genetic make-up (Qi et al, 2011; Li et al, 2012), environmental factors (Mazzella et al, 2000; Peralta et al, 2002), and hormonal interactions (Buck-Sorlin et al, 2005; Liu et al, 2016). Plant growth regulators, such as auxin, gibberellins (GAs), ethylene, and abscisic acid (ABA) are the key regulators of internode elongation (Santner et al, 2009). Strategies to promote internode elongation are important for improving the sugarcane yield

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