Forward genetic screens have led to the isolation of several genes involved in secondary cell wall formation. A variety evidence, however, suggests that list identified is not exhaustive. To address this problem, microarray data been generated from tissue undergoing formation and used identify exhibit a similar expression pattern wall–specific cellulose synthase IRREGULAR XYLEM1 (IRX1) IRX3. Cross-referencing analysis with publicly available resulted selection 16 for reverse analysis. Lines...

In a screen to identify novel cellulose deficient mutants, three lines were shown be allelic and define complementation group, irregular xylem5 ( irx5 ). IRX5 was cloned encodes member of the CesA family synthase catalytic subunits (AtCesA4). plants have an identical phenotype previously described mutations in two other members this gene IRX1 IRX3 IRX5, IRX3, are coexpressed exactly same cells, all proteins interact detergent solubilized extracts, suggesting that required for synthesis...

Recessive mutations at three loci cause the collapse of mature xylem cells in inflorescence stems Arabidopsis. These irregular (irx) were identified by screening plants from a mutagenized population microscopic examination stem sections. The cell defect was associated with an up to eightfold reduction total amount cellulose stems. amounts wall-associated phenolics and polysaccharides unaffected mutations. Examination walls using electron microscopy demonstrated that decreases content irx...

The irregular xylem3 (irx3) mutant of Arabidopsis has a severe deficiency in secondary cell wall cellulose deposition that leads to collapsed xylem cells. irx3 mutation been mapped the top arm chromosome V near marker nga106. Expressed sequence tag clone 75G11, which exhibits similarity synthase, was found be tightly linked irx3, and genomic clones containing gene corresponding 75G11 complemented mutation. Thus, IRX3 encodes synthase component is specifically required for synthesis wall....

A severe lignin mutant, irx4, has been identified in Arabidopsis thaliana as a result of its collapsed xylem phenotype. In contrast to previously described irx mutants, irx4 plants have 50% less than wild-type plants, whilst the cellulose and hemicellulose content remained unchanged. These alterations composition secondary cell walls had dramatic effect on morphology architecture walls, which expand fill most cell, also physical properties stems. Further analysis indicated that mutation...

The irregular xylem 1 (irx1) mutant of Arabidopsis has a severe deficiency in the deposition cellulose secondary cell walls, which results collapsed cells. This mutation been mapped to 140-kb region chromosome 4. A synthase catalytic subunit was found be located this region, and genomic clones containing gene complemented irx1 mutation. IRX1 shows homology previously described (IRX3). Analysis irx3 phenotypes demonstrates that both IRX3 are essential for production same cell. Thus, define...

Summary Previous studies using co‐expression analysis have identified a large number of genes likely to be involved in secondary cell‐wall formation. However, the function very few these is known. We studied phenotype irx7 , irx8 and irx9 three previously described irregular xylem ( irx ) mutants, irx14 parvus‐3 which we now show also mutants. All five mutations encoding putative glycosyltransferases, exhibited decreases xylan. In addition, all mutants were found same specific defect xylan...

Controlling the orientation of cell division is fundamental to development complex body plans. This particularly apparent in plants, where determined by differential growth that results solely from changes expansion and plane. Despite importance plant development, mechanisms regulating this process remain almost completely unknown. During vascular meristematic cambial cells divide down their long axis a highly orientated manner generate clear files cells. The receptor kinase PXY has...

As one of the most abundant polysaccharides on Earth, xylan will provide more than a third sugars for lignocellulosic biofuel production when using grass or hardwood feedstocks. Xylan is characterized by linear β(1,4)-linked backbone xylosyl residues substituted glucuronic acid, 4- O -methylglucuronic acid arabinose, depending plant species and cell types. The biological role these decorations unclear, but they have major influence properties polysaccharide. Despite recent isolation several...

Summary Xylan, the major hemicellulosic polysaccharide in Arabidopsis secondary cell walls, requires a number of glycosyltransferases (GT) to catalyse formation various glycosidic linkages found polymer. In this study, we characterized IRX10 and IRX10‐like ( IRX10‐L ), two highly homologous genes encoding members glycosyltransferase family 47 (GT47). T‐DNA insertions gave mild irregular xylem (irx) phenotype consistent with minor defect cell‐wall synthesis, whereas plants containing...

In plants, the cambium and procambium are meristems from which vascular tissue is derived. contrast to most plant cells, stem cells within these tissues thin extremely long. They particularly unusual as they divide down their long axis in a highly ordered manner, parallel tangential of stem. CLAVATA3-LIKE/ESR-RELATED 41 (CLE41) PHLOEM INTERCALATED WITH XYLEM (PXY) multifunctional ligand-receptor pair that regulate cell division, organisation xylem differentiation tissue. A transcription...

Recent spectroscopic evidence implicating a binuclear iron site at the reaction center of fatty acyl desaturases suggested to us that certain hydroxylases may share significant amino acid sequence similarity with desaturases. To test this theory, we prepared cDNA library from developing endosperm castor-oil plant (Ricinus communis L.) and obtained partial nucleotide sequences for 468 anonymous clones were not expressed high levels in leaves, tissue deficient 12-hydroxyoleic acid. This...

Mutants at the BOTERO1 locus are affected in anisotropic growth all non-tip-growing cell types examined. Mutant cells shorter and broader than those of wild type. inflorescence stems show a dramatically reduced bending modulus maximum stress yield. Our observations root epidermis that expansion defect bot1 is correlated with orientation cortical microtubules. We found within apical portion root, which roughly corresponds to meristem, microtubules were loosely organized became much more...

Cellulose synthesis in the developing xylem vessels of Arabidopsis requires three members cellulose synthase (CesA) gene family. In young vessels, these proteins localize within cell, whereas older all CesA colocalize with bands cortical microtubules that mark sites secondary cell wall deposition. absence one subunit, however, remaining two subunits are retained demonstrating required to assemble a functional complex. altered catalytic activity normally, suggesting is not for this...

Understanding seed germination biology and the dynamics of dormancy is essential to developing reliable techniques. This paper presents some new data reviews recent findings from studies on Australian species, with respect role temperature moisture in control germination. A seed-burial experiment was conducted over a 1-year period (January–December) seeds Acanthocarpus preissii Lehm., Astroloma xerophyllum (DC.) Sond., Gahnia grandis (Labill.) S.T.Blake, Goodenia scaevolina F.Muell. Tersonia...

The procambium and cambium are meristematic tissues from which vascular tissue is derived. Vascular initials differentiate into phloem towards the outside of stem xylem inside. A small peptide derived CLV-3/ESR1-LIKE 41 (CLE41) thought to promote cell divisions in meristems by signalling through PHLOEM INTERCALLATED WITH XYLEM (PXY) receptor kinase. pxy mutants, however, display only reductions number, suggesting a mechanism exists that allows plants compensate for absence PXY. Consistent...

Summary The irregular xylem 2 ( irx2 ) mutant of Arabidopsis thaliana exhibits a cellulose deficiency in the secondary cell wall, which is brought about by point mutation KORRIGAN KOR β,1‐4 endoglucanase (β,1‐4 EGase) gene. Measurement total crystalline inflorescence stem indicates that contains approximately 30% level present wild type (WT). Fourier–Transform Infra Red (FTIR) analysis, however, there no decrease primary walls cortical and epidermal cells stem. expression correlated with...

Summary During secondary cell wall formation, developing xylem vessels deposit cellulose at specific sites on the plasma membrane. Bands of cortical microtubules mark these and are believed to somehow orientate synthase complexes. We have used live imaging intact roots Arabidopsis explore relationship between microtubules, actin complex during formation. The complexes seen form bands beneath synthesis. find that their maintenance is dependent upon underlying bundles which localize (CSC)...

There are 10 genes in the Arabidopsis genome that contain a domain described Pfam database as of unknown function 579 (DUF579). Although DUF579 is widely distributed eukaryotic species, there no direct experimental evidence to assign it. Five family members co-expressed with marker for secondary cell wall formation. Plants which two closely related have been disrupted by T-DNA insertions less xylose result decreased xylan content, and exhibit mildly distorted xylem vessels. Consequently we...

The woody tissue of trees is composed xylem cells that arise from divisions stem within the cambial meristem. rate cell formation dependent upon division cambium and controlled by both genetic environmental factors. In annual plant Arabidopsis, signaling between a peptide ligand CLE41 receptor kinase PXY controls divisions; however, pathway regulating secondary growth in has not been identified. Here, we show an aspen PttPXY its PttCLE41 are functional orthologs act to control...