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

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 antifungal 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 metabolic 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 potential of utilizing sRNA-based fungal control strategies.

Metabolomics in Plant Priming Research: The Way Forward?

“…Learning from nature, plant biologists have observed that the interaction of plants with necrotising pathogens, beneficial microbes or agrochemicals can cause a sensitisation of the plant immune system, resulting in a faster and stronger induction of resistance mechanisms upon subsequent infections [ 18 , 19 , 20 , 21 ]. Memory of a past event may determine the response to future environmental stimuli, thus resulting in phenotypic and stimulus-dependent plasticity of response traits [ 22 ].…”

Characterization of microRNAs and Target Genes in Musa acuminata subsp. burmannicoides, var. Calcutta 4 during Interaction with Pseudocercospora musae

“…In silico differential expression analysis during interaction with P. musae, although not significant, nevertheless, indicated evidence for modulation, with increased expression in relation to controls at 12DAI, as well as down-regulation of members at both time points. Such down-regulation has also been described in the defence response to the hemibiotroph Colletotrichum graminicola in Zea mays [ 81 ].…”

“…The miRNA169 family contains four loci in Arabidopsis , with target host genes involved in a number of different processes related to plant defence and development [ 96 ]. Also responsive to PAMPs such as flg22 [ 60 ], down-regulation in Z. mays during interaction with C. graminicola has also been described, associated with increased JA signalling [ 81 ]. Here, a total of six members were expressed across the treatments, with non-significant in silico data revealing positive expression modulation during interaction with P. musae at 3DAI.…”