Drought severely restricts plant production and global warming is further increasing drought stress for crops. Much information reveals the ability of individual microbes affecting plant stress ...tolerance. However, the effects of emergent bacterial community properties on plant drought tolerance remain largely unexplored. Here, we inoculated Arabidopsis plants in vivo with a four-species bacterial consortium (Stenotrophomonas rhizophila, Xanthomonas retroflexus, Microbacterium oxydans, and Paenibacillus amylolyticus, termed as SPMX), which is able to synergistically produce more biofilm biomass together than the sum of the four single-strain cultures, to investigate its effects on plant performance and rhizo-microbiota during drought. We found that SPMX remarkably improved Arabidopsis survival post 21-day drought whereas no drought-tolerant effect was observed when subjected to the individual strains, revealing emergent properties of the SPMX consortium as the underlying cause of the induced drought tolerance. The enhanced drought tolerance was associated with sustained chlorophyll content and endogenous abscisic acid (ABA) signaling. Furthermore, our data showed that the addition of SPMX helped to stabilize the diversity and structure of root-associated microbiomes, which potentially benefits plant health under drought. These SPMX-induced changes jointly confer an increased drought tolerance to plants. Our work may inform future efforts to engineer the emergent bacterial community properties to improve plant tolerance to drought.
Somatic cells acclimate to changes in the environment by temporary reprogramming. Much has been learned about transcription factors that induce these cell‐state switches in both plants and animals, ...but how cells rapidly modulate their proteome remains elusive. Here, we show rapid induction of autophagy during temporary reprogramming in plants triggered by phytohormones, immune, and danger signals. Quantitative proteomics following sequential reprogramming revealed that autophagy is required for timely decay of previous cellular states and for tweaking the proteome to acclimate to the new conditions. Signatures of previous cellular programs thus persist in autophagy‐deficient cells, affecting cellular decision‐making. Concordantly, autophagy‐deficient cells fail to acclimatize to dynamic climate changes. Similarly, they have defects in dedifferentiating into pluripotent stem cells, and redifferentiation during organogenesis. These observations indicate that autophagy mediates cell‐state switches that underlie somatic cell reprogramming in plants and possibly other organisms, and thereby promotes phenotypic plasticity.
Synopsis
Adjustment to new environmental signals requires temporary and rapid modulation of the cellular proteome. Proteome adjustments are found to require autophagy, which erases previous cellular states in plant somatic cells to allow new programs to unfold.
Multiple external stimuli rapidly activate autophagy in plant cells.
Proteome adjustments during cell‐state switching are disrupted in autophagy mutants.
Autophagy‐deficient plants exhibit decreased phenotypic plasticity.
Autophagy‐deficient somatic cells cannot de‐differentiate efficiently into pluripotent stem cells.
Exit from pluripotency and organ formation are dysregulated in autophagy‐deficient cells.
Autophagy facilitates cellular proteome adjustment to new stimuli and allows coordinated transition to a new cell state by erasing previous cellular programs.
MicroRNAs （miRNAs） are endogenous non-coding small RNAs that silence genes through mRNA degradation or translational inhibition. The phytohormone abscisic acid （ABA） is essential for plant ...development and adaptation to abiotic and biotic stresses. In Arabidopsis, miRNAs are implicated in ABA functions. However, ABA-responsive miRNAs have not been systematically studied in rice. Here high throughput sequencing of small RNAs revealed that 107 miRNAs were differentially expressed in the rice ABA deficient mutant, Osabal. Of these, 13 were confirmed by stem-loop RT-PCR. Among them, miR1425-5P, miR169a, miR169n, miR390-5P, miR397a and miR397b were up-regulated, but miR162b reduced in expression in Osabal. The targets of these 13 miRNAs were predicted and validated by gene expression profiling. Interestingly, the expression levels of these miRNAs and their targets were regulated by ABA. Cleavage sites were detected on 7 of the miRNA targets by 5＇-Rapid Amplification of cDNA Ends （5＇-RACE）. Finally, miR162b and its target OsTRE1 were shown to affect rice resistance to drought stress, suggesting that miR162b increases resistance to drought by targeting OsTRE1. Our work provides important information for further characterization and functional analysis of ABA-responsive miRNAs in rice.
Evolutionarily conserved protein associated with topoisomerase II (PAT1) proteins activate mRNA decay through binding mRNA and recruiting decapping factors to optimize posttranscriptional ...reprogramming. Here, we generated multiple mutants of pat1, pat1 homolog 1 (path1), and pat1 homolog 2 (path2) and discovered that pat triple mutants exhibit extremely stunted growth and all mutants with pat1 exhibit leaf serration while mutants with pat1 and path1 display short petioles. All three PATs can be found localized to processing bodies and all PATs can target ASYMMETRIC LEAVES 2‐LIKE 9 transcripts for decay to finely regulate apical hook and lateral root development. In conclusion, PATs exhibit both specific and redundant functions during different plant growth stages and our observations underpin the selective regulation of the mRNA decay machinery for proper development.
We investigated the role of the mRNA decay factor Protein Associated with Topoisomerase II (PAT1) by generating multiple mutants of pat1 and its homologs, path1 and path2. Through detailed analysis of their developmental phenotypes and RNA sequencing, we concluded that PAT1 plays a crucial role in leaf patterning. Moreover, it operates in conjunction with the other two PATs redundantly throughout plant development.
Evolutionarily conserved protein associated with topoisomerase II (PAT1) proteins activate mRNA decay through binding mRNA and recruiting decapping factors to optimize posttranscriptional ...reprogramming. Here, we generated multiple mutants of pat1 , pat1 homolog 1 ( path1 ), and pat1 homolog 2 ( path2 ) and discovered that pat triple mutants exhibit extremely stunted growth and all mutants with pat1 exhibit leaf serration while mutants with pat1 and path1 display short petioles. All three PATs can be found localized to processing bodies and all PATs can target ASYMMETRIC LEAVES 2‐LIKE 9 transcripts for decay to finely regulate apical hook and lateral root development. In conclusion, PATs exhibit both specific and redundant functions during different plant growth stages and our observations underpin the selective regulation of the mRNA decay machinery for proper development.
mRNA decapping plays essential roles in regulating gene expression during cellular reprogramming in response to developmental and environmental cues. The evolutionarily conserved PAT1 proteins ...activate decapping by binding mRNA, recruiting other decapping components, and promoting processing body (PB) assembly. Arabidopsis encodes 3 PAT proteins: PAT1, PATH1, and PATH2. Here, we report that only pat1 mutants exhibit hypersensitivity to ABA and that transcripts of ABA‐responsive genes, but not those of ABA biosynthesis genes, persist longer in these mutants. The pat1 mutants also exhibit increased resistance to drought stress and resistance to Pythium irregulare. This is supported by assays showing that PAT1 functions specifically in decapping of the canonical ABA‐responsive gene COR15A. In summary, PAT1 protein mediates decay of ABA‐responsive genes and, thus, regulates stress responses.
It is shown that AtCLCd negatively regulates Arabidopsis PTI, probably by interacting with the PRR signalling pathway. Its sequence indicates that AtCLCd encodes a chloride/proton exchanger.
Multicellular organisms perceive and transduce multiple cues to optimize development. Key transcription factors drive developmental changes, but RNA processing also contributes to tissue development. ...Here, we report that multiple decapping deficient mutants share developmental defects in apical hook, primary and lateral root growth. More specifically,
transcripts accumulate in decapping deficient plants and can be found in complexes with decapping components. Accumulation of
inhibits apical hook and lateral root formation. Interestingly, exogenous auxin application restores lateral roots formation in both
over-expressors and mRNA decay-deficient mutants. Likewise, mutations in the cytokinin transcription factors type-B ARABIDOPSIS RESPONSE REGULATORS (B-ARRs)
and
restore the developmental defects caused by over-accumulation of capped
transcript upon
overexpression. Most importantly, loss-of-function of
partially restores apical hook and lateral root formation in both
and
triple decapping deficient mutants. Thus, the mRNA decay machinery directly targets
transcripts for decay, possibly to interfere with cytokinin/auxin responses, during development.
Anion efflux is one of the most immediate responses of plant cells to pathogen attacks, suggesting that anion channels may play a role in plant defense. Recently we reported that the chloride channel ...AtCLCd negatively regulates Arabidopsis pathogen-associated molecular pattern-triggered immunity (PTI), probably by affecting trafficking of the pattern recognition receptors (PRRs). Since AtCLCd is localized to the trans-Golgi network, it is not likely to be directly involved in anion flux across the plasma membrane. Here, we used a pharmacological approach to explore further the function of plasma membrane-localized R-type and S-type anion channels in plant immunity. We found that the R-type and S-type anion channels play opposite roles in Arabidopsis innate immunity. Inhibition of the R-type anion channels enhances, whereas inhibition of the S-type channels inhibits PTI and effector-triggered immunity (ETI).
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