Table of Contents

An apparently simple trade-off in plant defense against bacterial pathogens and insect herbivores shows unexpected mechanistic complexity.

Rumex palustris and Rumex acetosa are two closely related species that survive flooding using distinct strategies. Using a genomics approach, this study identifies novel molecular components and processes that contribute to the survival of these plant species that normally complete their life cycle in flood-prone environments.

This work characterizes transgenic lines with altered expression of calmodulin (CaM) N-methyltransferase to demonstrate that the methylation status of CaM plays a role in CaM-mediated signaling pathways. The findings add a new level of complexity to our understanding of CaM signaling mechanisms in plants.

Transcriptomics of N-deprived Chlamydomonas sta6, CC-4349 (a wild-type strain), and three complemented STA6 strains showed upregulation of glyoxylate and gluconeogenesis pathways, validated by enzyme and metabolite analyses. Resequencing of all strains revealed that sta6 and CC-4349 are distantly related, highlighting the importance of using complemented strains for relating phenotype to genotype.

This work shows that HOS1, previously characterized as a nuclear pore–associated E3 ubiquitin ligase, is required for nucleo-cytoplasmic mRNA export. This study demonstrates that this reduction in nucleo-cytoplasmic export by hos1, or mutations to other previously characterized nuclear pore–associated proteins, leads to altered RNA levels and rhythms, circadian clock function, and cold signaling.

Aldoximes are precursors of several classes of direct plant defense compounds. This study characterizes two cytochrome P450 monooxygenase enzymes, CYP79D6/7, which are involved in gypsy moth–induced aldoxime formation in western balsam poplar. Volatile formation mediated by CYP79s may be a general phenomenon in the plant kingdom.

Aldoximes are precursors of several classes of direct plant defense compounds. This study characterizes two cytochrome P450 monooxygenase enzymes, CYP79D6/7, which are involved in gypsy moth–induced aldoxime formation in western balsam poplar. Volatile formation mediated by CYP79s may be a general phenomenon in the plant kingdom.

This work characterizes two cytochrome P450s and two monoterpene synthases that are coexpressed in flowers and thus predicted to be involved in monoterpenoid metabolism. The results show that despite Arabidopsis thaliana being autogamous, its flowers exhibit extensive linalool metabolism.

Pathway engineering has been the predominant strategy used to enhance valuable natural products in plants. This study identifies sequestration mechanisms associated with pathway engineering outputs that enable the plastid organelle to adapt and accommodate newly synthesized precursors and products.

Catalase directly interacts with and detoxifies reactive oxygen species. This work identifies catalase-deficient mutants in a screen for suppression of cell death and finds that promotion of cell death associated with the plant hypersensitive response requires catalase, suggesting that catalase could act as a direct molecular link between reactive oxygen species and cell death signaling.

An apparently simple trade-off in plant defense against bacterial pathogens and insect herbivores shows unexpected mechanistic complexity.

Ser palmitoyltransfersase (SPT) regulation of sphingolipid homeostasis is critical for mediating plant growth and programmed cell death (PCD). As key components of this regulation, two 56–amino acid SPT-interacting proteins are shown to be essential for male gametophyte viability, and altered expression strongly affects SPT activity and sensitivity to the PCD-inducing mycotoxin fumonisin B₁.

Transcriptomics of N-deprived Chlamydomonas sta6, CC-4349 (a wild-type strain), and three complemented STA6 strains showed upregulation of glyoxylate and gluconeogenesis pathways, validated by enzyme and metabolite analyses. Resequencing of all strains revealed that sta6 and CC-4349 are distantly related, highlighting the importance of using complemented strains for relating phenotype to genotype.

Ser palmitoyltransfersase (SPT) regulation of sphingolipid homeostasis is critical for mediating plant growth and programmed cell death (PCD). As key components of this regulation, two 56–amino acid SPT-interacting proteins are shown to be essential for male gametophyte viability, and altered expression strongly affects SPT activity and sensitivity to the PCD-inducing mycotoxin fumonisin B₁.

This work identifies a stress-responsive histone demethylase that specifically demethylates the repressive epigenetic marks histone H3 Lysine 27 (H3K27me2/3) in rice. This enzyme preferentially targets stress-responsive genes and is involved in dynamic removal of H3K27me3 from defense-related genes and their basal and induced expression during biotic stress.

Novel methods were developed and demonstrated for the discovery of genetic regulatory networks in wood-forming tissues. Transfection of protoplasts from differentiating xylem with the transcription factor gene Ptr-SND1-B1 and novel computational analysis revealed a three-level hierarchical genetic regulatory network that was verified by ChIP and Ptr-SND1-B1 overexpression in transgenic plants.

This work characterizes two cytochrome P450s and two monoterpene synthases that are coexpressed in flowers and thus predicted to be involved in monoterpenoid metabolism. The results show that despite Arabidopsis thaliana being autogamous, its flowers exhibit extensive linalool metabolism.

This article identifies and characterizes an Arabidopsis protein, GGCT2;1, which has a cation transport regulator-like (ChaC-like) domain that functions as a γ-glutamyl cyclotransferase. In vivo studies in yeast and Arabidopsis establish that GGCT2;1 recycles Glu as part of the γ-glutamyl cycle and thus maintains GSH homeostasis to counteract heavy metal and metalloids toxicity.

This work shows that, similarly to its homolog in animals, the plant RETINOBLASTOMA-RELATED protein modulates cell differentiation by regulating the trans-activating activity of a key transcription factor involved in a particular developmental process, suggesting that some developmental mechanisms may be conserved between the plant and animal kingdoms.

This work characterizes transgenic lines with altered expression of calmodulin (CaM) N-methyltransferase to demonstrate that the methylation status of CaM plays a role in CaM-mediated signaling pathways. The findings add a new level of complexity to our understanding of CaM signaling mechanisms in plants.

This work shows that, similarly to its homolog in animals, the plant RETINOBLASTOMA-RELATED protein modulates cell differentiation by regulating the trans-activating activity of a key transcription factor involved in a particular developmental process, suggesting that some developmental mechanisms may be conserved between the plant and animal kingdoms.

This work shows that, similarly to its homolog in animals, the plant RETINOBLASTOMA-RELATED protein modulates cell differentiation by regulating the trans-activating activity of a key transcription factor involved in a particular developmental process, suggesting that some developmental mechanisms may be conserved between the plant and animal kingdoms.

Plastid-localized glutathione reductase2 regulates root growth and root meristem maintenance through modulation of its GSH redox status, resulting in regulation of downstream effectors of the auxin/PLETHORA pathway, as well as of some auxin/ PLETHORA-independent pathways. This function differs from that of glutathione reductase1, which is not essential for plant development.

This work examines the role of the NAC transcription factor ANAC096, finding that ANAC096 interacts with specific bZIP transcription factors to globally affect abscisic acid–responsive transcription during osmotic and drought stresses.

Plastid-localized glutathione reductase2 regulates root growth and root meristem maintenance through modulation of its GSH redox status, resulting in regulation of downstream effectors of the auxin/PLETHORA pathway, as well as of some auxin/ PLETHORA-independent pathways. This function differs from that of glutathione reductase1, which is not essential for plant development.

Pathway engineering has been the predominant strategy used to enhance valuable natural products in plants. This study identifies sequestration mechanisms associated with pathway engineering outputs that enable the plastid organelle to adapt and accommodate newly synthesized precursors and products.

Some stages of the protein N-glycosylation pathway are required for corn smut (Ustilago maydis) to successfully infect its host plant. If fungal proteins are not properly glycosylated, the host plant can detect the infection and activate defense mechanisms to suppress it. Disruption of glycosylation pathways in Ustilago reduces its infectious capabilities but has few other phenotypes.

Transcriptomics of N-deprived Chlamydomonas sta6, CC-4349 (a wild-type strain), and three complemented STA6 strains showed upregulation of glyoxylate and gluconeogenesis pathways, validated by enzyme and metabolite analyses. Resequencing of all strains revealed that sta6 and CC-4349 are distantly related, highlighting the importance of using complemented strains for relating phenotype to genotype.

Pathway engineering has been the predominant strategy used to enhance valuable natural products in plants. This study identifies sequestration mechanisms associated with pathway engineering outputs that enable the plastid organelle to adapt and accommodate newly synthesized precursors and products.

This work identifies a Pooideae-specific microRNA that posttranscriptionally regulates the florigen gene FT under different daylength conditions in Brachypodium distachyon, revealing one mechanism in the complex but precise genetic regulatory pathways for flowering time control in plants.

This work identifies SH3P2 as a novel regulator of autophagy and provides a conserved model for autophagosome biogenesis in Arabidopsis. Autophagosome-related structures, such as isolation membranes and ER-derived omegasome-like structures, are characterized and SH3P2 is shown to bind to PI3P and regulate autophagosome formation via the association with the PI3K complex and ATG8.

The expression of calmodulin isoforms with unique Ca²⁺ binding affinities could confer on plant cells an additional ability to translate the distinct Ca²⁺ signals that accompany various stimuli. Using isoforms of conserved and divergent calmodulin sequences, this study finds that differences in affinity and the effect of competing Mg²⁺ tunes the responsiveness of the isoforms to the appropriate Ca²⁺ signature.

Transcriptomics of N-deprived Chlamydomonas sta6, CC-4349 (a wild-type strain), and three complemented STA6 strains showed upregulation of glyoxylate and gluconeogenesis pathways, validated by enzyme and metabolite analyses. Resequencing of all strains revealed that sta6 and CC-4349 are distantly related, highlighting the importance of using complemented strains for relating phenotype to genotype.

This work shows that HOS1, previously characterized as a nuclear pore–associated E3 ubiquitin ligase, is required for nucleo-cytoplasmic mRNA export. This study demonstrates that this reduction in nucleo-cytoplasmic export by hos1, or mutations to other previously characterized nuclear pore–associated proteins, leads to altered RNA levels and rhythms, circadian clock function, and cold signaling.

An apparently simple trade-off in plant defense against bacterial pathogens and insect herbivores shows unexpected mechanistic complexity.

Chloride and other anions are essential for cell volume regulation and other functions in plant cells. This study demonstrates the existence of an apical negative gradient of cytosolic chloride concentration in pollen tubes, and establishes a role for the SLAH3 homolog of SLOW ANION CHANNEL-ASSOCIATED 1, regulated by the calcium-dependent protein kinases CPK2 and CPK20, in regulating pollen tube apical growth.

This work shows that HOS1, previously characterized as a nuclear pore–associated E3 ubiquitin ligase, is required for nucleo-cytoplasmic mRNA export. This study demonstrates that this reduction in nucleo-cytoplasmic export by hos1, or mutations to other previously characterized nuclear pore–associated proteins, leads to altered RNA levels and rhythms, circadian clock function, and cold signaling.

Ser palmitoyltransfersase (SPT) regulation of sphingolipid homeostasis is critical for mediating plant growth and programmed cell death (PCD). As key components of this regulation, two 56–amino acid SPT-interacting proteins are shown to be essential for male gametophyte viability, and altered expression strongly affects SPT activity and sensitivity to the PCD-inducing mycotoxin fumonisin B₁.

This work identifies the Arabidopsis thaliana mutant maigo5 (mag5), which abnormally accumulates precursor forms of storage proteins. MAG5 is a plant ortholog of yeast Sec16 that is a key component for COPII vesicle formation. MAG5/SEC16A is required for protein export from the ER and functions at ERESs that are associated with mobile Golgi stacks where it regulates COPII coat turnover.

The lignin pathway is a favored target for improvement of lignocellulosic feedstocks because lignin affects enzymatic sugar release from cell walls. Using a combination of approaches, this article identifies candidate lignin pathway genes likely to be functionally involved in lignification in the dedicated energy crop switchgrass, as well as some expected candidates with questionable function.

This work characterizes two cytochrome P450s and two monoterpene synthases that are coexpressed in flowers and thus predicted to be involved in monoterpenoid metabolism. The results show that despite Arabidopsis thaliana being autogamous, its flowers exhibit extensive linalool metabolism.

This work characterizes transgenic lines with altered expression of calmodulin (CaM) N-methyltransferase to demonstrate that the methylation status of CaM plays a role in CaM-mediated signaling pathways. The findings add a new level of complexity to our understanding of CaM signaling mechanisms in plants.

This study demonstrates that salt stress–induced changes in actin microfilament dynamics regulate mitochondrial movement and activity, which in turn regulate a salt-induced calcium change and cell death.

This work examines the role of the NAC transcription factor ANAC096, finding that ANAC096 interacts with specific bZIP transcription factors to globally affect abscisic acid–responsive transcription during osmotic and drought stresses.

Aldoximes are precursors of several classes of direct plant defense compounds. This study characterizes two cytochrome P450 monooxygenase enzymes, CYP79D6/7, which are involved in gypsy moth–induced aldoxime formation in western balsam poplar. Volatile formation mediated by CYP79s may be a general phenomenon in the plant kingdom.

The lignin pathway is a favored target for improvement of lignocellulosic feedstocks because lignin affects enzymatic sugar release from cell walls. Using a combination of approaches, this article identifies candidate lignin pathway genes likely to be functionally involved in lignification in the dedicated energy crop switchgrass, as well as some expected candidates with questionable function.

MAP65s function as microtubule cross-linking proteins, and three of five P. patens MAP65s localize to the phragmoplast equator in protonemal cells. Simultaneous RNAi-mediated knockdown of those three MAP65s compromised microtubule bipolarity and affected accumulation and/or fusion of cell plate–destined vesicles at the equatorial plane.

This study demonstrates that salt stress–induced changes in actin microfilament dynamics regulate mitochondrial movement and activity, which in turn regulate a salt-induced calcium change and cell death.