**Signs of Silence: Small RNAs and Antifungal Responses in** *Arabidopsis thaliana* **and** *Zea mays* **in** *Arabidopsis thaliana* **and** *Zea mays*

**Signs of Silence: Small RNAs and Antifungal Responses** 

DOI: 10.5772/intechopen.69795

Andrea Balmer, Emanuele De Paoli, Azeddine Si‐Ammour, Brigitte Mauch‐Mani and Dirk Balmer Azeddine Si‐Ammour, Brigitte Mauch‐Mani and Dirk Balmer Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.69795

Andrea Balmer, Emanuele De Paoli,

#### **Abstract**

Plant small RNAs (sRNAs) are pivotal regulators of gene expression, which are crucial in maintaining genome integrity and flexibility during development, abiotic and biotic stress responses. Current evidence suggests that sRNAs might be inherent to the sophisticated plant innate immune system battling bacteria. However, the role of sRNAs during anti‐ fungal plant defences is less clear. Therefore, this chapter investigates the sRNA‐mediated plant antifungal responses against the hemibiotrophic fungi *Colletotrichum higginsianum* and *Colletotrichum graminicola* in their respective compatible hosts *Arabidopsis thaliana* and Zea mays. A phenotypic and metabolomic analysis of *A. thaliana* sRNA mutants in response to *C. higginsianum* infection was performed, showing a hormonal and meta‐ bolic imbalance during fungal infection in these plants. To find whether fungal-induced sRNA could directly regulate defence genes in an agricultural important plant model, the expression of maize miRNAs in response to *C. graminicola* leaf and root infections was investigated. The results revealed the tissue-specific local and systemic adaptation of the miRNA transcriptome, where only a few miRNAs were targeting defence pathways. The general picture presented here points towards a role of sRNAs as fine-tuners of genetic and metabolomic defence response layers. This chapter also further discusses the poten‐ tial of utilizing sRNA-based fungal control strategies.

**Keywords:** small RNA, antifungal plant defence, metabolomics, deep sequencing
