Phosphate‐induced resistance to pathogen infection in Arabidopsis

Abstract

In nature, plants are concurrently exposed to a number of abiotic and biotic stresses. Our understanding of convergence points between responses to combined biotic/abiotic stress pathways remains, however, rudimentary. Here we show that MIR399 overexpression, loss-of-function of PHOSPHATE2 (PHO2), or treatment with high phosphate (Pi) levels is accompanied by an increase in Pi content and accumulation of reactive oxygen species (ROS) in Arabidopsis thaliana. High Pi plants (e.g., miR399 overexpressors, pho2 mutants, and plants grown under high Pi supply) exhibited resistance to infection by necrotrophic and hemibiotrophic fungal pathogens. In the absence of pathogen infection, the expression levels of genes in the salicylic acid (SA)-and jasmonic acid (JA)-dependent signaling pathways were higher in high Pi plants compared to wild-type plants grown under control conditions, which is consistent with increased levels of SA and JA in non-infected high Pi plants. During infection, an opposite regulation in the two branches of the JA pathway (ERF1/PDF1.2 and MYC2/VSP2) occurs in high Pi plants. Thus, while pathogen infection induces PDF1.2 expression in miR399 OE and pho2 plants, VSP2 expression is downregulated by pathogen infection in these plants. This study supports the notion that Pi accumulation promotes resistance to infection by fungal pathogens in Arabidopsis, while providing a basis to better understand interactions between Pi signaling and hormonal signaling pathways for modulation of plant immune responses.

Regulation of plant biotic interactions and abiotic stress responses by inositol polyphosphates

“…In rice, miR399 overexpression resulted in P i accumulation in leaves and higher susceptibility to the fungal pathogen Magnaporthe oryzae, which was also observed upon high P i fertilization (Campos-Soriano et al, 2020). In contrast, Val-Torregrosa et al (2022) demonstrated an enhanced resistance to necrotrophic and hemibiotrophic fungal pathogens in Arabidopsis lines overexpressing miR399, as well as in pho2 loss-of-function lines. The high P i accumulation in Arabidopsis leaves caused by miR399 overexpression and lack of functional PHO2 was linked to an elevated ROS production.…”

“…Recent studies have pointed to a connection between plant’s P i status and immune responses ( Campos-Soriano et al, 2020 ; Val-Torregrosa et al, 2022 ). These findings are based on the involvement of a miRNA species (miR399) in the regulation of P i homeostasis in Arabidopsis ( Chiou et al, 2006 ; Paul et al, 2015 ).…”

“…This was assumed to be related to an increased HR in these plants during pathogen infection. Besides the changes in ROS levels, the mutant lines showed elevated SA and JA levels, combined with the upregulation of SA- and JA-dependent defense genes ( Val-Torregrosa et al, 2022 ). Intriguingly, pho2 mutants were also shown to accumulate high levels of InsP 8 ( Riemer et al, 2021 ).…”

In silico Genome-Wide Computational Profiling of Non-Coding RNA in Oil Palm Elaeis guineensis and its Pathogen Ganoderma boninense

“…Lastly, overexpression of the predicted miR399 could be potentially exploited by resulting in lossof-function of PHOSPHATE2 (PHO2), coupled with an increase in inorganic phosphate (Pi) content and accumulation of ROS to promote resistance toward infection in A. thaliana., as observed by Val-Torregrosa et al (2022) Downregulation of miRNAs has previously been shown to confer resistance towards its pathogen in several plant species. This means, there could be a similar exploitation of the 6 predicted miRNAs (miR156, miR169, miR396, miR397, miR398, and miR2118) found in E. guineensis genome for disease resistance.…”

Phosphorus availability drives mycorrhiza induced resistance in tomato

“…P levels also impact plant interactions with other organisms by altering plant tissues’ nutritional value for organisms feeding on them (pathogens and herbivores) and by modulating plant defenses ( Breuillin et al, 2010 ; Castrillo et al, 2017 ; Chan et al., 2021 ). The role of P in plant immunity is currently under intense scrutiny, and the data reveal a very complex scenario ( Chan et al., 2021 ; Qu et al., 2021 ; Val-Torregrosa et al, 2022 ). The phosphate starvation response in plants has been suggested to increase plant resistance to necrotrophic pathogens and leaf chewing herbivores in several plant species (Arabidopsis, tomato, tobacco) pointing to a positive cross-talk between the JA- and P- starvation signaling pathways that activates plant immunity ( Khan et al., 2016 ).…”