Deciphering the transcriptomic response of Fusarium verticillioides in relation to nitrogen availability and the development of sugarcane pokkah boeng disease.

Zhenyue Lin,Muqing Zhang,Jihua Wang,Qiang Guo,Shiqiang Xu,Baoshan Chen,Charles A Powell,Yixue Bao

doi:10.1038/srep29692

Abstract

Pokkah boeng, caused by Fusarium verticillioides, is a serious disease in sugarcane industry. The disease severity is related to the sugarcane genotype as well as environmental considerations, such as nitrogen application. The impact of the nitrogen source (ammonium sulfate, urea, or sodium nitrate) on sugarcane pokkah boeng disease and its pathogen was investigated in planta and fungal growth and sporulation production was measured in vitro. The results showed that ammonium and nitrate were beneficial to fungal mycelium growth, cell densities, and sporulation, which enhanced the disease symptoms of sugarcane pokkah boeng compared to urea fertilization. A total of 1,779 transcripts out of 13,999 annotated genes identified from global transcriptomic analysis were differentially expressed in F. verticillioides CNO-1 grown in the different sources of nitrogen. These were found to be involved in nitrogen metabolism, transport, and assimilation. Many of these genes were also associated with pathogenicity based on the PHI-base database. Several transcription factors were found to be associated with specific biological processes related to nitrogen utilization. Our results further demonstrated that nitrogen availability might play an important role in disease development by increasing fungal cell growth as well as influencing the expression of genes required for successful pathogenesis.

Highlights

Analyses revealed that the secondary metabolism (SM) gene[6] expression profiles in F. fujikuroi depended on the quantity and quality of the nitrogen source, including the expression of the polyketide synthase (PKS) gene cluster[7]
The disease severity index (DSI) of sugarcane pokkah boeng was significantly lower in the urea-treated plants compared to the control (CK) and the ammonium and nitrate treatment groups (Fig. 1C)
CNO-1 showed sparse colony edges when cultured in the urea and nitrate, but colonies were less dense and compact when cultured in the ammonium

Summary

Introduction

Analyses revealed that the secondary metabolism (SM) gene[6] expression profiles in F. fujikuroi depended on the quantity and quality of the nitrogen source, including the expression of the polyketide synthase (PKS) gene cluster[7]. Major GATA transcription factors (AreA and AreB) and their co-repressor Nmr play a central role in the nitrogen regulatory network[8]. Despite the progress made in studying nitrogen regulation of secondary metabolism, the molecular action modes as well as possible interactions between the regulators are not well understood. We characterized disease development in F. verticillioides-inoculated sugarcane plants exposed to different forms of nitrogen, including sodium nitrate, urea, or ammonium sulfate. We examined the morphology and growth of F. verticillioides CNO-1 and elucidated transcriptome profiles under different nitrogen availability

Methods

Results

Conclusion