Plasmodesmata-localized proteins and reactive oxygen species orchestrate light-induced rapid systemic signaling in Arabidopsis

Abstract

Systemic signaling and systemic acquired acclimation (SAA) are key to the survival of plants during episodes of abiotic stress. These processes depend on a continuous chain of cell-to-cell signaling events that extends from the initial tissue that senses the stress (local tissue) to the entire plant (systemic tissues). Among the different systemic signaling molecules and processes thought to be involved in this cell-to-cell signaling mechanism are reactive oxygen species (ROS), calcium, electric and hydraulic signals. How these different signals and processes are interlinked, and how they transmit the systemic signal all the way from the local tissue to the entire plant, remain however largely unknown. Here, studying the systemic response of Arabidopsis thaliana to a local treatment of excess light stress, we report that respiratory burst oxidase homolog D (RBOHD)-generated ROS enhance cell-to-cell transport and plasmodesmata (PD) pore size in a process that depends on the function of PD-localized proteins (PDLPs) 1 and 5, promoting the cell-to-cell transport of systemic signals during responses to light stress. We further identify aquaporins, and several different calcium-permeable channels, belonging to the glutamate receptor-like, mechanosensitive small conductance-like, and cyclic nucleotide-gated families, as involved in this process, but determine that their function is primarily required for the maintenance of the signal in each cell along the path of the systemic signal, as well as for the establishment of acclimation at the local and systemic tissues. PD and RBOHD-generated ROS orchestrate therefore light stress-induced rapid cell-to-cell spread of systemic signals in Arabidopsis.One-sentence summaryRespiratory burst oxidase homolog D-generated reactive oxygen species enhance cell-to-cell transport and plasmodesmata (PD) pore size in a process that depends on the function of the PD-localized proteins (PDLPs) 1 and 5, promoting the cell-to-cell transport of rapid systemic signals during the response of Arabidopsis to excess light stress.

Integration of electric, calcium, reactive oxygen species and hydraulic signals during rapid systemic signaling in plants

“…5A). This finding was in agreement with our previous findings that in response to a local HL stress treatment, expression of Zat10 and MYB30 was only suppressed, but not abolished, at 2 and 8 min in the glr3.3;glr3.6 double mutant (44). In response to a local treatment of wounding, the systemic expression of JAZ5 and JAZ7 was high in wild type plants (Fig.…”

“…The whole-plant live ROS imaging method we developed (26) has been validated in different studies using different mutants (27,44,55), omics tools (27,29,41), and more recently whole-plant imaging of transgenic plants with stable expression of cytosolic reduction-oxidation sensitive green fluorescent protein 1 (roGFP1; 40). Although the whole-plant live imaging methods, presented in our current study to record systemic changes in calcium levels and membrane potentials (Figs.…”

“…Quantified total RNA was used for cDNA synthesis (PrimeScript RT Reagent Kit; Takara Bio, Kusatsu, Japan). Transcript expression was quantified by real-time qPCR using iQ SYBR Green supermix (Bio-Rad Laboratories, Hercules, CA, USA), as described in (44), with specific primers for HL: ZAT10 (AT1G27730) 5'-ACTAGCCACG TTAGCAGTAGC-3' and 5'-GTTGAAGTTTGACCGGAAGTC-3' and MYB30…”

“…In addition, the calcium channels glutamate receptorlike (GLR) 3.3 and 3.6 were found to play a key role in regulating systemic electric and calcium signals during wounding (16)(17)(18)21), and the respiratory burst oxidase homolog D and F (RBOHD and RBOHF) proteins were found to play a key role in the regulation of systemic ROS signals during high light (HL) stress (25)(26)(27)(28)(29). Systemic ROS signals were further shown to be regulated by cyclic nucleotide-gated calcium channel 2 (CGNC2), mechanosensitive small conductance-like (MSL) channels 2 and 3, and plasmodesmata (PD)-localized proteins (PDLP) 1 and 5, during systemic responses to HL stress (44).…”

“…(A) Real-time quantitative PCR (qPCR) analysis of transcript expression in local and systemic leaves of wild type and rbohD, glr3.3;glr3.6 and pdlp5 plants subjected to a local high light (HL) stress treatment applied to a single local leaf. Transcripts tested (Zat10 and MYB30) were previously found to respond to HL stress at the local and systemic leaves of wild-type plants(29,44,55). (B) Same as (A) but plants were subjected to a local wounding treatment applied to of a single local leaf.…”