Table of Contents

This work uses functional genomics to delineate the role of the inositol synthesis genes in regulating growth, development, and cell death and reveals a connection between inositol, phosphatidylinositol, and sphingolipids.

Arabidopsis mutants defective in MAPK signaling were found to have aberrant microtubule organization and cell growth. This study shows that two mitogen-activated protein kinase kinase kinase isoforms, mitogen-activated protein kinase 4 and microtubule-associated protein 65, play a role in the organization of cortical microtubules.

This work demonstrates that three closely related Arabidopsis transcription factors are involved in activating the specific modifications to cell walls that are required for a fully functional root cap. These transcription factors share a generic transcriptional activity with other closely related proteins, which are involved in different aspects of cell wall modification.

The NADH dehydrogenase complex (complex I) represents the largest functional module of the respiratory chain and at the same time is the least known. Based on a novel biochemical strategy, a model on its internal structure is presented. In plants, complex I comprises several extra protein subunits that partially integrate side activities into the complex and contribute to its special shape.

This work demonstrates that three closely related Arabidopsis transcription factors are involved in activating the specific modifications to cell walls that are required for a fully functional root cap. These transcription factors share a generic transcriptional activity with other closely related proteins, which are involved in different aspects of cell wall modification.

This study describes Arabidopsis root innate immune responses to various microbial elicitors and their salicylic acid signaling-independent suppression by coronatine, a phytotoxin produced by Pseudomonas syringae. These experiments have revealed new features of the root response to pathogen attack and the mechanisms that pathogens in turn may employ to block the host innate immune response.

Alkylresorcinol synthases (ARSs) are thought to participate in the biosynthesis of a diversity of defense-related plant phenolic lipids. This work presents the functional characterization of two ARS enzymes involved in the biosynthesis of allelochemicals produced in sorghum root hair cells as well as three enzymes likely dedicated to the biosynthesis of alkylresorcinolic phytoanticipins in rice.

It is difficult for a purely mutational model to explain the evolution of asexuality in plants and animals. This work finds that expression patterns of many reproduction genes, including an overabundance of regulatory factors, differ during sexual and asexual ovule development, thus providing a possible mechanism for inducing the complex reproductive changes required to generate clonal offspring.

Alkylresorcinol synthases (ARSs) are thought to participate in the biosynthesis of a diversity of defense-related plant phenolic lipids. This work presents the functional characterization of two ARS enzymes involved in the biosynthesis of allelochemicals produced in sorghum root hair cells as well as three enzymes likely dedicated to the biosynthesis of alkylresorcinolic phytoanticipins in rice.

This study sought to identify genes involved in the biosynthesis of the triterpene skeleton in Medicago truncatula using a comprehensive gene expression clustering analysis. The UGT73F3 gene was shown to function as a uridine diphosphate glycosyltransferase in the biosynthesis of triterpene saponins.

This work uses functional genomics to delineate the role of the inositol synthesis genes in regulating growth, development, and cell death and reveals a connection between inositol, phosphatidylinositol, and sphingolipids.

This study describes fungal infection–related development of Magnaporthe oryzae induced on rice roots and on hydrophilic polystyrene. A fungal mutant with abnormal preinfection hyphae and lacking the ortholog of the karyopherin exportin-5 had defects in full disease symptom production on leaves and roots, showing that this fungal karyopherin plays an important role during plant colonisation.

This study describes fungal infection–related development of Magnaporthe oryzae induced on rice roots and on hydrophilic polystyrene. A fungal mutant with abnormal preinfection hyphae and lacking the ortholog of the karyopherin exportin-5 had defects in full disease symptom production on leaves and roots, showing that this fungal karyopherin plays an important role during plant colonisation.

This work uses functional genomics to delineate the role of the inositol synthesis genes in regulating growth, development, and cell death and reveals a connection between inositol, phosphatidylinositol, and sphingolipids.

This study describes fungal infection–related development of Magnaporthe oryzae induced on rice roots and on hydrophilic polystyrene. A fungal mutant with abnormal preinfection hyphae and lacking the ortholog of the karyopherin exportin-5 had defects in full disease symptom production on leaves and roots, showing that this fungal karyopherin plays an important role during plant colonisation.

The GER4 transcript encoding a germin-like protein of barley is derived from a dense cluster of tandemly duplicated, pathogen-induced genes that are subject to purifying selection. The GER4c promoter was found to regulate strong and pathogen-specific expression of the GUS reporter in barley, and multiple redundant WRKY factor binding sites were required for promoter activation.

The GER4 transcript encoding a germin-like protein of barley is derived from a dense cluster of tandemly duplicated, pathogen-induced genes that are subject to purifying selection. The GER4c promoter was found to regulate strong and pathogen-specific expression of the GUS reporter in barley, and multiple redundant WRKY factor binding sites were required for promoter activation.

The GER4 transcript encoding a germin-like protein of barley is derived from a dense cluster of tandemly duplicated, pathogen-induced genes that are subject to purifying selection. The GER4c promoter was found to regulate strong and pathogen-specific expression of the GUS reporter in barley, and multiple redundant WRKY factor binding sites were required for promoter activation.

This work provides evidence that both bZIP28 and NF-Y subunits are recruited under stress to form a transcriptional complex that upregulates the expression of endoplasmic reticulum stress-induced genes. The bZIP28/NF-Y complex specifically binds to an element common to the promoters of the targeted stress genes.

This work uses functional genomics to delineate the role of the inositol synthesis genes in regulating growth, development, and cell death and reveals a connection between inositol, phosphatidylinositol, and sphingolipids.

This work provides evidence that APETALA3 and PISTILLATA influence petal morphogenesis in part through the negative regulation of a family of proteins that in turn modulate the activity of a number of other signaling pathways, providing a mechanistic link between developmental and physiological responses.

The authors identified a rice R2R3 MYB transcription factor, Carbon Starved Anther (CSA), that regulates sugar partitioning from leaves to anthers and is required for the production of functional pollen. CSA directly regulates the expression of the monosaccharide transporter gene MST8, which encodes a key component of the anther sugar unloading pathway.

This work shows that the Arabidopsis CRT1 (for compromised for recognition of turnip crinkle virus) protein, a general resistance (R) protein-interacting protein, functions early in R gene–mediated defense responses. Moreover, reduction of the CRT1 family's activity compromises resistance to bacterial and oomycete pathogens and programmed cell death in Arabidopsis and Nicotiana benthamiana.

In Arabidopsis thaliana, the F-box protein ZTL affects the period length of the circadian clock by regulating the stability of the core clock proteins TOC1 and PRR5. This study shows that, together with ZTL, the ZTL homologs FKF1 and LKP2 are also involved in the same protein stability regulation to determine the pace and robustness of the plant circadian clock.

The NADH dehydrogenase complex (complex I) represents the largest functional module of the respiratory chain and at the same time is the least known. Based on a novel biochemical strategy, a model on its internal structure is presented. In plants, complex I comprises several extra protein subunits that partially integrate side activities into the complex and contribute to its special shape.

This work describes a novel method for imaging cell anatomy and cell wall features by scanning electron microscopy. The method was used to image sieve plates and sieve element geometry at high resolution to correlate sieve tube–specific conductivity with phloem flow measurements.

ANKYRIN REPEAT-CONTAINING PROTEIN 2A (AKR2A) is known to be involved in targeting proteins to the chloroplast outer envelope membrane. This work provides evidence that AKR2A binds specifically to several single-membrane spanning proteins that are targeted to various cellular compartments, suggesting that AKR2A may serve as a molecular chaperone for a set of membrane proteins.

This work examines the function of MGOUN1 (MGO1) in Arabidopsis stem cell maintenance, showing that mgo1 mutations enhance the specific stem cell defects in hypomorphic wuschel alleles. Positional cloning reveals that MGO1 encodes topoisomerase IB, thereby linking topoisomerase function to the propagation of developmentally regulated gene function.

The authors identified a rice R2R3 MYB transcription factor, Carbon Starved Anther (CSA), that regulates sugar partitioning from leaves to anthers and is required for the production of functional pollen. CSA directly regulates the expression of the monosaccharide transporter gene MST8, which encodes a key component of the anther sugar unloading pathway.

The GER4 transcript encoding a germin-like protein of barley is derived from a dense cluster of tandemly duplicated, pathogen-induced genes that are subject to purifying selection. The GER4c promoter was found to regulate strong and pathogen-specific expression of the GUS reporter in barley, and multiple redundant WRKY factor binding sites were required for promoter activation.

The authors identified a rice R2R3 MYB transcription factor, Carbon Starved Anther (CSA), that regulates sugar partitioning from leaves to anthers and is required for the production of functional pollen. CSA directly regulates the expression of the monosaccharide transporter gene MST8, which encodes a key component of the anther sugar unloading pathway.

This work provides evidence that APETALA3 and PISTILLATA influence petal morphogenesis in part through the negative regulation of a family of proteins that in turn modulate the activity of a number of other signaling pathways, providing a mechanistic link between developmental and physiological responses.

This work shows that the Arabidopsis CRT1 (for compromised for recognition of turnip crinkle virus) protein, a general resistance (R) protein-interacting protein, functions early in R gene–mediated defense responses. Moreover, reduction of the CRT1 family's activity compromises resistance to bacterial and oomycete pathogens and programmed cell death in Arabidopsis and Nicotiana benthamiana.

Arabidopsis mutants defective in MAPK signaling were found to have aberrant microtubule organization and cell growth. This study shows that two mitogen-activated protein kinase kinase kinase isoforms, mitogen-activated protein kinase 4 and microtubule-associated protein 65, play a role in the organization of cortical microtubules.

The mechanism of vacuole inheritance is poorly understood. This work makes use of the model organism C. merolae, which has a minimum set of organelles that are systematically inherited, and identifies vig1 as being essential for vacuole inheritance.

This study sought to identify genes involved in the biosynthesis of the triterpene skeleton in Medicago truncatula using a comprehensive gene expression clustering analysis. The UGT73F3 gene was shown to function as a uridine diphosphate glycosyltransferase in the biosynthesis of triterpene saponins.

The GER4 transcript encoding a germin-like protein of barley is derived from a dense cluster of tandemly duplicated, pathogen-induced genes that are subject to purifying selection. The GER4c promoter was found to regulate strong and pathogen-specific expression of the GUS reporter in barley, and multiple redundant WRKY factor binding sites were required for promoter activation.

Alkylresorcinol synthases (ARSs) are thought to participate in the biosynthesis of a diversity of defense-related plant phenolic lipids. This work presents the functional characterization of two ARS enzymes involved in the biosynthesis of allelochemicals produced in sorghum root hair cells as well as three enzymes likely dedicated to the biosynthesis of alkylresorcinolic phytoanticipins in rice.

Arabidopsis SHB1 contains two signature domains homologous to the SYG1 protein family from a variety of organisms and plant species, and the function of the two domains remains largely unknown. We report the function of the two signature domains of SHB1 in light signaling and the identification of an SHB1-containing light signaling complex in the nucleus.

The mechanism of vacuole inheritance is poorly understood. This work makes use of the model organism C. merolae, which has a minimum set of organelles that are systematically inherited, and identifies vig1 as being essential for vacuole inheritance.

The mechanism of vacuole inheritance is poorly understood. This work makes use of the model organism C. merolae, which has a minimum set of organelles that are systematically inherited, and identifies vig1 as being essential for vacuole inheritance.

Chromosome breakage was the first property of transposable elements identified by McClintock. Evidence is presented to show that chromosome breakage can be attributed to alternative transposition reactions that involve the termini of multiple closely linked elements.

This study analyzed the l-Phe biosynthetic pathways in Petunia hybrida flowers, which emit high levels of Phe-derived volatiles. RNA interference suppression of petunia arogenate dehydratase1 provides in planta evidence that l-Phe is synthesized via arogenate and uncovers a novel posttranscriptional regulation of the shikimate pathway.

This study analyzed the l-Phe biosynthetic pathways in Petunia hybrida flowers, which emit high levels of Phe-derived volatiles. RNA interference suppression of petunia arogenate dehydratase1 provides in planta evidence that l-Phe is synthesized via arogenate and uncovers a novel posttranscriptional regulation of the shikimate pathway.

This work demonstrates that three closely related Arabidopsis transcription factors are involved in activating the specific modifications to cell walls that are required for a fully functional root cap. These transcription factors share a generic transcriptional activity with other closely related proteins, which are involved in different aspects of cell wall modification.