CALMODULIN-LIKE-38 and PEP1 RECEPTOR 2 integrate nitrate and brassinosteroid signals to regulate root growth

Yuan

Proc. Natl. Acad. Sci. U.S.A.

et al. 2023

As a crucial nitrogen source, nitrate (NO 3 − ) is a key nutrient for plants. Accordingly, root systems adapt to maximize NO 3 − availability, a developmental regulation also involving the phytohormone auxin. Nonetheless, the molecular mechanisms underlying this regulation remain poorly understood. Here, we identify low-nitrate-resistant mutant ( lonr ) in Arabidopsis ( Arabidopsis thaliana ), whose root growth fails to adapt to low-NO 3 − conditions. lonr2 is defective in the high-affinity NO 3 − transporter NRT2.1. lonr2 ( nrt2.1 ) mutants exhibit defects in polar auxin transport, and their low-NO 3 − -induced root phenotype depends on the PIN7 auxin exporter activity. NRT2.1 directly associates with PIN7 and antagonizes PIN7-mediated auxin efflux depending on NO 3 − levels. These results reveal a mechanism by which NRT2.1 in response to NO 3 − limitation directly regulates auxin transport activity and, thus, root growth. This adaptive mechanism contributes to the root developmental plasticity to help plants cope with changes in NO 3 − availability.

Section: Resultsmentioning

confidence: 99%

The nitrate transporter NRT2.1 directly antagonizes PIN7-mediated auxin transport for root growth adaptation

Yuan

Proc. Natl. Acad. Sci. U.S.A.

et al. 2023

“…CML37 is a positive regulator of herbivory-induced defense, and mutation of CML37 decreases the JA level in Arabidopsis ( Scholz et al 2014 ). CML38 can interact with the PEP1 RECEPTOR 2, a receptor for the DAMP plant elicitor peptide (Pep) 1 and Pep2, to regulate root development in Arabidopsis ( Song et al 2021 ). Therefore, it is possible that esDNA regulates calcium signaling to modulate JA levels.…”

Section: Discussionmentioning

confidence: 99%

Plant extracellular self-DNA inhibits growth and induces immunity via the jasmonate signaling pathway

et al. 2023

Plants have evolved sophisticated mechanisms to detect various forms of danger. Damage-associated molecular patterns (DAMPs) are endogenous danger molecules that are released from damaged cells and activate the innate immunity. Recent evidence suggests that plant extracellular self-DNA (esDNA) can serve as a DAMP molecule. However, the mechanisms by which esDNA functions are largely unknown. In this study, we confirmed that esDNA inhibits root growth and triggers reactive oxygen species (ROS) production in a concentration- and species-specific manner in Arabidopsis (Arabidopsis thaliana) and tomato (Solanum lycopersicum L.). Furthermore, by combining RNA sequencing, hormone measurement and genetic analysis, we found that esDNA-mediated growth inhibition and ROS production are achieved through the jasmonic acid (JA) signaling pathway. Specifically, esDNA induces JA production and the expression of JA responsive genes. The esDNA-mediated growth inhibition, ROS production and gene expression are impaired in the JA-related mutants. Finally, we found that the JA signaling pathway is required for the esDNA-elicited resistance against the pathogens Botrytis cinerea and Pseudomonas syringae pv. tomato DC3000. This finding highlights the importance of JA signaling in esDNA-mediated biological effects, thereby providing insight into how esDNA functions as a DAMP.

“…Moreover, treatment of proscoop12 mutant roots with synthesized PROSCOOP12 peptide inhibited the elongation of roots by reducing the number of meristematic cells and cell length (Guillou et al., 2022). Recently, it has been reported that CALMODULIN‐LIKE‐38 (CML38) was induced by low nitrate conditions, and the cml38 mutant shows longer root length in A. thaliana (Song et al., 2021). Unlike DEFL202 and DEFL203, CML38 negatively regulates nitrate uptake.…”

Section: Discussionmentioning

confidence: 99%

Zinc deficiency‐induced defensin‐like proteins are involved in the inhibition of root growth in Arabidopsis

et al. 2023

SUMMARYThe depletion of cellular zinc (Zn) adversely affects plant growth. Plants have adaptation mechanisms for Zn‐deficient conditions, inhibiting growth through the action of transcription factors and metal transporters. We previously identified three defensin‐like (DEFL) proteins (DEFL203, DEFL206 and DEFL208) that were induced in Arabidopsis thaliana roots under Zn‐depleted conditions. DEFLs are small cysteine‐rich peptides involved in defense responses, development and excess metal stress in plants. However, the functions of DEFLs in the Zn‐deficiency response are largely unknown. Here, phylogenetic tree analysis revealed that seven DEFLs (DEFL202–DEFL208) were categorized into one subgroup. Among the seven DEFLs, the transcripts of five (not DEFL204 and DEFL205) were upregulated by Zn deficiency, consistent with the presence of cis‐elements for basic‐region leucine‐zipper 19 (bZIP19) or bZIP23 in their promoter regions. Microscopic observation of GFP‐tagged DEFL203 showed that DEFL203‐sGFP was localized to the apoplast and plasma membrane. Whereas a single mutation of the DEFL202 or DEFL203 genes only slightly affected root growth, defl202 defl203 double mutants showed enhanced root growth under all growth conditions. We also showed that the size of the root meristem was increased in the double mutants compared with the wild type. Our results suggest that DEFL202 and DEFL203 are redundantly involved in the inhibition of root growth under Zn‐deficient conditions through a reduction in root meristem length and cell number.