High Ambient Temperature Regulated the Plant Systemic Response to the Beneficial Endophytic Fungus Serendipita indica

Abstract

Most plants in nature establish symbiotic associations with endophytic fungi in soil. Beneficial endophytic fungi induce a systemic response in the aboveground parts of the host plant, thus promoting the growth and fitness of host plants. Meanwhile, temperature elevation from climate change widely affects global plant biodiversity as well as crop quality and yield. Over the past decades, great progresses have been made in the response of plants to high ambient temperature and to symbiosis with endophytic fungi. However, little is known about their synergistic effect on host plants. The endophytic fungus Serendipita indica colonizes the roots of a wide range of plants, including Arabidopsis. Based on the Arabidopsis-S. indica symbiosis experimental system, we analyzed the synergistic effect of high ambient temperature and endophytic fungal symbiosis on host plants. By transcriptome analysis, we found that DNA replication-related genes were significantly upregulated during the systemic response of Arabidopsis aboveground parts to S. indica colonization. Plant hormones, such as jasmonic acid (JA) and ethylene (ET), play important roles in plant growth and systemic responses. We found that high ambient temperature repressed the JA and ET signaling pathways of Arabidopsis aboveground parts during the systemic response to S. indica colonization in roots. Meanwhile, PIF4 is the central hub transcription factor controlling plant thermosensory growth under high ambient temperature in Arabidopsis. PIF4 is also involving JA and/or ET signaling pathway. We found that PIF4 target genes overlapped with many differentially expressed genes (DEGs) during the systemic response, and further showed that the growth promotion efficiency of S. indica on the pif4 mutant was higher than that on the wild-type plants. In short, our data showed that high ambient temperature strengthened the growth promotion effect of S. indica fungi on the aboveground parts of the host plant Arabidopsis, and the growth promotion effect of the systemic response under high ambient temperature was regulated by PIF4.

Symbiont-host interactome mapping reveals effector-targeted modulation of hormone networks and activation of growth promotion

“…2g and Supplementary Data 3 , 4 ). While the significance of hormones in the establishment of Si symbioses is well known 17 , 25 , 42 , only recently have we begun to understand the relevance of hormone function in Si -mediated beneficial effects 19 , 43 – 45 . The strong enrichment of hormone-related GO terms for exclusive Si host targets suggests an important role for SIECs in operating beneficial host activities.…”

“…Given that Si -mediated benefits involve hormone signalling 19 , 43 – 45 , we wondered if individual SIECs supported Si mediated phenotypes, such as growth promotion in Arabidopsis. We phenotyped 20 35S::SIEC lines that previously showed altered hormone activity in protoplasts, using primary root and hypocotyl length as a proxy for growth promotion in below- and above-ground tissue.…”

Plant–Fungi Interactions: Where It Goes?

“…In addition to those, symbiosis helps plants to retaliate against the biotic (e.g., parasites) and abiotic (e.g., drought, salinity, toxic compounds, and flooding) [ 54 , 57 ] stresses. Noteworthy that in addition to those symbionts, endophytic fungi also offer the aforementioned same benefits, while entomopathogenic fungi protect plants from insect pest attacks and also stimulate the plant defense responses [ 60 , 61 , 62 ]. However, unfortunately, in some cases, symbionts can also increase the activity of other plant pathogens, such as viruses (e.g., Potato virus), thus increasing disease susceptibility and reducing plant height and root development [ 41 ].…”

Proteasome Dysfunction Leads to Suppression of the Hypoxic Response Pathway in Arabidopsis

“…Six-day-old Arabidopsis seedlings growing on 1 /2 MS solid medium were harvested for transcriptome and reverse quantitative transcription PCR (RT-qPCR) analysis. The methods for transcriptome and RT-qPCR were used and described previously [56]. Briefly, the extracted total RNA was used for sequencing with a NovaSeq 6000 sequencer by Majorbio (Shanghai, China).…”