Distinct function of SPL genes in age-related resistance inArabidopsis

Abstract

In plants, age-related resistance (ARR) refers to a gain of disease resistance during shoot or organ maturation. ARR associated with vegetative phase change, a transition from juvenile to adult stage, is a widespread agronomic trait affecting resistance against multiple pathogens. How innate immunity in a plant is differentially regulated during successive stages of shoot maturation is unclear. In this work, we found that Arabidopsis thaliana showed ARR against its bacterial pathogen Pseudomonas syringae pv. tomato DC3000 during vegetative phase change. The timing of the ARR activation was associated with a temporal drop of miR156 level. A systematic inspection of the loss- and gain-of-function mutants of 11 SPL genes revealed that a subset of SPL genes, notably SPL2, SPL10, and SPL11, activated ARR in adult stage. The immune function of SPL10 was independent of its role in morphogenesis. Furthermore, the SPL10 mediated an age-dependent augmentation of the salicylic acid (SA) pathway partially by direct activation of PAD4. Disrupting SA biosynthesis or signaling abolished the ARR against Pto DC3000. Our work demonstrated that the miR156-SPL10 module in Arabidopsis is deployed to operate immune outputs over developmental timing.

Shoot maturation strengthens FLS2-mediated resistance toPseudomonas syringae

“…We subsequently crossed 35S::MIM156 (Franco-Zorrilla et al, 2007;Wu et al, 2009;Wu & Poethig, 2006) into fls2-101 mutants to endow adult feature to the leaves 1&2 of fls2 (Figure 6C). Consistent with our previous observation (Hu et al, 2022) that knocking down miR156 function enhanced resistance against Pto DC3000, leaves 1&2 in MIM156 plants showed low bacterial multiplication. Loss of fls2 in the MIM156 background did not increase disease susceptibility in leaves 1&2 (which was not certified by peer review) is the author/funder.…”

“…The copyright holder for this preprint this version posted February 15, 2023. ; https://doi.org/10.1101/2023.02.14.528542 doi: bioRxiv preprint defense, the biosynthesis of wax and cuticle was upregulated in adult than that of juvenile Col-0 leaves (Hu et al, 2022). In maize and Arabidopsis, miR156 regulates cell wall composition during the vegetative phase change (li et al, 2019;Strable et al, 2008;Vega et al, 2002).…”

“…A decrease of papillae was observed in miR156-overexpressing rice plants (Xie et al, 2012), However, overexpression of miR156 in switchgrass increased lignin content and decreased susceptibility to fungal rust (Puccinia emaculata), while the plant became highly susceptible to Bipolaris species (Baxter et al, 2018). As a part of constitutive 1 defense, the biosynthesis of wax and cuticle was upregulated in adult than that of juvenile Col-0 leaves (Hu et al, 2022). In maize and Arabidopsis, miR156 regulates cell wall composition during the vegetative phase change (li et al, 2019;Strable et al, 2008;Vega et al, 2002).…”

“…The qPCR was performed using SYBR Green master mix (Applied Biosystems) in the QuantStudio 1 Real-Time PCR system (Applied Biosystems). qPCR conditions were the same as described in Hu et al, 2022. Reference genes were TUB2 (AT5G62690) and SAND (AT2G28390). Primers of qPCR were shown in supplementary Table . S2.…”

“…Planting and growing conditions (9 hours light/15 hours darkness) are the same as described in (Hu et al, 2022). All juvenile leaves of Col-0 and leaf 1 and 2 of mutants that were used in this work coming from 4-5 weeks old plants in soil.…”