Table of Contents

Several recent reports suggest that gene-for-gene and basal resistance signaling pathways substantially share common regulatory components. This work shows that Os Pti1a, a rice homolog of tomato Pti1, negatively regulates both resistance signaling pathways in rice and that its function depends on RAR1, which is known to function as a molecular chaperone in disease resistance.

This work demonstrates that the CLASP ortholog in plant cells is a microtubule-associated protein that localizes along the full length of microtubules and shows enrichment at growing plus ends. clasp-1 mutants have defects in interphase and mitotic microtubule arrays and exhibit increased drug sensitivity. The data indicate a role for CLASP in stabilizing microtubules.

Strictosidine β-d-glucosidase (SG) functions in the biosynthesis of monoterpenoid indole alkaloids in plants. This work reports structural analysis and site-directed mutagenesis experiments describing native SG and the complex of an inactive mutant with the substrate strictosidine. The results reveal a unique conformation of the catalytic pocket specific to the SG enzyme.

N-myristoylation is a lipid modification ensuring the proper function and intracellular trafficking of proteins involved in signaling pathways. Comprehensive investigation of protein N-myristoylation in Arabidopsis shows that this function is critical for shoot apical meristem development and that the heterotrimeric SNF1-related kinase SnRK1 is a crucial primary target.

Arabidopsis siz1 mutants are smaller in stature and have lower tolerance to drought stress than the wild type. Gene expression analysis shows that SIZ1 mediates the expression of 300 drought-inducible genes independently of DREB2A and ABA. The authors conclude that the SIZ1 SUMO E3 ligase plays a role in the regulation of gene expression that influences plant growth and the drought stress response.

This study details the biological consequences and potential biochemical roles of amino acid substitutions in recessive resistance alleles at the Capsicum pvr1 locus encoding eIF4E. A Gly-to-Arg change at position 107 in the eIF4E protein encoded by multiple recessive resistance genes from diverse plants defines the most significant position for resistance to potyviruses.

Brassinosteroid is an essential phytohormone that regulates plant growth and development. The phosphorylation status of the transcription factor BZR1 tunes the intensity of BR signaling in various tissues and developmental stages of plants by modulating nucleocytoplasmic shuttling of BZR1 through interaction with 14-3-3 proteins.

Specialized functions of Arabidopsis DICER-LIKE genes (DCLs) are well characterized, but those in rice remain elusive. This work shows that DCL4 is the major DCL locus responsible for the processing of 21-nucleotide siRNAs in rice and suggests that processing of small interfering RNAs by Os DCL4 endonuclease has a broader role in rice development than the At DCL4 protein has in Arabidopsis.

Genetic analyses show that INCURVATA2 interacts with chromatin-remodeling genes TERMINAL FLOWER2 and CURLY LEAF, suggesting genetic and molecular interactions between chromatin remodeling factors and components of the DNA replication machinery.

One of the most important photoprotective mechanisms in plants and cyanobacteria is the selective replacement of photodamaged D1 during the repair of the photosystem II (PSII) complex. This work investigates the mechanism by which the damaged D1 subunit is removed from PSII complexes in cyanobacteria and shows that the exposed N-terminal region is required for degradation.

This study presents the three-dimensional structures of AvrL567-A and AvrL567-D, two avirulence proteins from the flax rust pathogen that interact with resistance proteins L5, L6, and L7 from flax. Amino acid residues conferring recognition differences were tested by site-directed mutagenesis and suggest that the specificity of interaction results from the cumulative effects of multiple amino acid contacts.

This study presents the three-dimensional structures of AvrL567-A and AvrL567-D, two avirulence proteins from the flax rust pathogen that interact with resistance proteins L5, L6, and L7 from flax. Amino acid residues conferring recognition differences were tested by site-directed mutagenesis and suggest that the specificity of interaction results from the cumulative effects of multiple amino acid contacts.

The genes SAWTOOTH1 and SAWTOOTH2 encode redundant regulatory proteins that are required to establish normal leaf shape. These genes likely act by promoting normal patterns of growth in the developing leaf, in part by suppressing the expression of other growth regulators that are normally found in the shoot apical meristem.

The genes SAWTOOTH1 and SAWTOOTH2 encode redundant regulatory proteins that are required to establish normal leaf shape. These genes likely act by promoting normal patterns of growth in the developing leaf, in part by suppressing the expression of other growth regulators that are normally found in the shoot apical meristem.

Arabidopsis siz1 mutants are smaller in stature and have lower tolerance to drought stress than the wild type. Gene expression analysis shows that SIZ1 mediates the expression of 300 drought-inducible genes independently of DREB2A and ABA. The authors conclude that the SIZ1 SUMO E3 ligase plays a role in the regulation of gene expression that influences plant growth and the drought stress response.

Rhizobium Nod factors (NFs) are key signaling molecules essential for the establishment of the nitrogen-fixing symbiosis in legumes. This work describes the characterization of novel cis-regulatory sequences required for NF-dependent root hair–specific gene expression in Medicago truncatula as well as both activator and repressor-type trans-interacting ERF factors.

Several recent reports suggest that gene-for-gene and basal resistance signaling pathways substantially share common regulatory components. This work shows that Os Pti1a, a rice homolog of tomato Pti1, negatively regulates both resistance signaling pathways in rice and that its function depends on RAR1, which is known to function as a molecular chaperone in disease resistance.

Agrobacterium tumefaciens protein 6b stimulates aberrant proliferation of plant cells. This work shows that 6b specifically binds histone H3, forms nucleosomes on DNA in the presence of core histones in vitro, and affects transcription patterns of a variety of genes in plants, suggesting a relationship between alterations in nucleosome structure and the expression of growth-regulating genes.

This study presents the three-dimensional structures of AvrL567-A and AvrL567-D, two avirulence proteins from the flax rust pathogen that interact with resistance proteins L5, L6, and L7 from flax. Amino acid residues conferring recognition differences were tested by site-directed mutagenesis and suggest that the specificity of interaction results from the cumulative effects of multiple amino acid contacts.

One of the most important photoprotective mechanisms in plants and cyanobacteria is the selective replacement of photodamaged D1 during the repair of the photosystem II (PSII) complex. This work investigates the mechanism by which the damaged D1 subunit is removed from PSII complexes in cyanobacteria and shows that the exposed N-terminal region is required for degradation.

The genes SAWTOOTH1 and SAWTOOTH2 encode redundant regulatory proteins that are required to establish normal leaf shape. These genes likely act by promoting normal patterns of growth in the developing leaf, in part by suppressing the expression of other growth regulators that are normally found in the shoot apical meristem.

Specialized functions of Arabidopsis DICER-LIKE genes (DCLs) are well characterized, but those in rice remain elusive. This work shows that DCL4 is the major DCL locus responsible for the processing of 21-nucleotide siRNAs in rice and suggests that processing of small interfering RNAs by Os DCL4 endonuclease has a broader role in rice development than the At DCL4 protein has in Arabidopsis.

Agrobacterium tumefaciens protein 6b stimulates aberrant proliferation of plant cells. This work shows that 6b specifically binds histone H3, forms nucleosomes on DNA in the presence of core histones in vitro, and affects transcription patterns of a variety of genes in plants, suggesting a relationship between alterations in nucleosome structure and the expression of growth-regulating genes.

N-myristoylation is a lipid modification ensuring the proper function and intracellular trafficking of proteins involved in signaling pathways. Comprehensive investigation of protein N-myristoylation in Arabidopsis shows that this function is critical for shoot apical meristem development and that the heterotrimeric SNF1-related kinase SnRK1 is a crucial primary target.

Agrobacterium tumefaciens protein 6b stimulates aberrant proliferation of plant cells. This work shows that 6b specifically binds histone H3, forms nucleosomes on DNA in the presence of core histones in vitro, and affects transcription patterns of a variety of genes in plants, suggesting a relationship between alterations in nucleosome structure and the expression of growth-regulating genes.

CONSTANS plays a central role in photoperiodic flowering. This work defines an additional flowering genetic pathway that regulates flowering initiation in response to daylength changes, in which microRNA172 promotes photoperiodic flowering independent of CONSTANS.

The genes SAWTOOTH1 and SAWTOOTH2 encode redundant regulatory proteins that are required to establish normal leaf shape. These genes likely act by promoting normal patterns of growth in the developing leaf, in part by suppressing the expression of other growth regulators that are normally found in the shoot apical meristem.

N-myristoylation is a lipid modification ensuring the proper function and intracellular trafficking of proteins involved in signaling pathways. Comprehensive investigation of protein N-myristoylation in Arabidopsis shows that this function is critical for shoot apical meristem development and that the heterotrimeric SNF1-related kinase SnRK1 is a crucial primary target.

Genetic analyses show that INCURVATA2 interacts with chromatin-remodeling genes TERMINAL FLOWER2 and CURLY LEAF, suggesting genetic and molecular interactions between chromatin remodeling factors and components of the DNA replication machinery.

This study details the biological consequences and potential biochemical roles of amino acid substitutions in recessive resistance alleles at the Capsicum pvr1 locus encoding eIF4E. A Gly-to-Arg change at position 107 in the eIF4E protein encoded by multiple recessive resistance genes from diverse plants defines the most significant position for resistance to potyviruses.

Strictosidine β-d-glucosidase (SG) functions in the biosynthesis of monoterpenoid indole alkaloids in plants. This work reports structural analysis and site-directed mutagenesis experiments describing native SG and the complex of an inactive mutant with the substrate strictosidine. The results reveal a unique conformation of the catalytic pocket specific to the SG enzyme.

This study presents the three-dimensional structures of AvrL567-A and AvrL567-D, two avirulence proteins from the flax rust pathogen that interact with resistance proteins L5, L6, and L7 from flax. Amino acid residues conferring recognition differences were tested by site-directed mutagenesis and suggest that the specificity of interaction results from the cumulative effects of multiple amino acid contacts.

CONSTANS plays a central role in photoperiodic flowering. This work defines an additional flowering genetic pathway that regulates flowering initiation in response to daylength changes, in which microRNA172 promotes photoperiodic flowering independent of CONSTANS.

Several recent reports suggest that gene-for-gene and basal resistance signaling pathways substantially share common regulatory components. This work shows that Os Pti1a, a rice homolog of tomato Pti1, negatively regulates both resistance signaling pathways in rice and that its function depends on RAR1, which is known to function as a molecular chaperone in disease resistance.

Specialized functions of Arabidopsis DICER-LIKE genes (DCLs) are well characterized, but those in rice remain elusive. This work shows that DCL4 is the major DCL locus responsible for the processing of 21-nucleotide siRNAs in rice and suggests that processing of small interfering RNAs by Os DCL4 endonuclease has a broader role in rice development than the At DCL4 protein has in Arabidopsis.

Strictosidine β-d-glucosidase (SG) functions in the biosynthesis of monoterpenoid indole alkaloids in plants. This work reports structural analysis and site-directed mutagenesis experiments describing native SG and the complex of an inactive mutant with the substrate strictosidine. The results reveal a unique conformation of the catalytic pocket specific to the SG enzyme.

Several recent reports suggest that gene-for-gene and basal resistance signaling pathways substantially share common regulatory components. This work shows that Os Pti1a, a rice homolog of tomato Pti1, negatively regulates both resistance signaling pathways in rice and that its function depends on RAR1, which is known to function as a molecular chaperone in disease resistance.

Agrobacterium tumefaciens protein 6b stimulates aberrant proliferation of plant cells. This work shows that 6b specifically binds histone H3, forms nucleosomes on DNA in the presence of core histones in vitro, and affects transcription patterns of a variety of genes in plants, suggesting a relationship between alterations in nucleosome structure and the expression of growth-regulating genes.

N-myristoylation is a lipid modification ensuring the proper function and intracellular trafficking of proteins involved in signaling pathways. Comprehensive investigation of protein N-myristoylation in Arabidopsis shows that this function is critical for shoot apical meristem development and that the heterotrimeric SNF1-related kinase SnRK1 is a crucial primary target.

This study presents the three-dimensional structures of AvrL567-A and AvrL567-D, two avirulence proteins from the flax rust pathogen that interact with resistance proteins L5, L6, and L7 from flax. Amino acid residues conferring recognition differences were tested by site-directed mutagenesis and suggest that the specificity of interaction results from the cumulative effects of multiple amino acid contacts.

Biosynthesis of secondary walls requires the coordinated expression of secondary wall biosynthetic genes. This article presents the discovery of a MYB transcription factor, MYB46, as a direct target of SND1 and demonstrates that MYB46 is another key regulator in activating the biosynthetic pathways for cellulose, xylan, and lignin.

In the flowering plant Arabidopsis, genes encoding pathogen defense proteins are often clustered in the genome. This study shows that the genes in one cluster are coordinately regulated by a positive feed-forward transcriptional signaling loop and negative regulation via RNA silencing. Plant pathogens that suppress RNA silencing might trigger expression of these defense genes.

Arabidopsis siz1 mutants are smaller in stature and have lower tolerance to drought stress than the wild type. Gene expression analysis shows that SIZ1 mediates the expression of 300 drought-inducible genes independently of DREB2A and ABA. The authors conclude that the SIZ1 SUMO E3 ligase plays a role in the regulation of gene expression that influences plant growth and the drought stress response.