Exogenous GA3 application altered morphology, anatomic and transcriptional regulatory networks of hormones in Eucalyptus grandis
Gibberellins (GAs) play a key role in plant growth and development including cell elongation, cell expansion, and xylem differentiation. Eucalyptus are the world’s most widely planted hardwood trees providing fiber and energy. However, the roles of GAs in Eucalyptus remain unclear and their effects on xylem development remain to be determined. In this study, E. grandis plants were treated with 0.10 mg L−1 GA3 and/or paclobutrazol (PAC, a GA inhibitor). The growth of shoot and root were recorded, transverse sections of roots and stems were stained using toluidine blue, and expression levels of genes related to hormone response and secondary cell wall biosynthesis were analyzed by quantitative real-time PCR. The results showed that GA3 dramatically promoted the length of shoot and root, but decreased the diameter of root and stem. Exogenous GA3 application also significantly promoted xylem development in both stem and root. Expression analysis revealed that exogenous GA3 application altered the transcript levels of genes related to the GA biosynthetic pathway and GA signaling, as well as genes related to auxin, cytokinin, and secondary cell wall. These findings suggest that GAs may interact with other hormones (such as auxin and cytokinin) to regulate the expression of secondary cell wall biosynthesis genes and trigger xylogenesis in Eucalyptus plants.
KeywordsGibberellin Eucalyptus grandis Root Xylem Anatomical Gene expression
We’d like to thank Dr. Zehong Ding for his critical reading of this manuscript.
CJF and BSZ designed the research. QYL, GSG, ZFQ, and XDL performed the experiments. CJF and QYL analyzed the data. CJF wrote the paper. CJF and BSZ revised the paper. All authors read and approved the final manuscript.
This work was supported by National Natural Science Foundation of China (Grant No. 31400554) and the Fundamental Research Funds for the Central Non-profit Research Institution of CAF (Grant No. CAFYBB2014QB040).
Compliance with ethical standards
Conflict of interests
The authors declare that they have no competing interests.
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