In Vitro Haustorium Development in Roots and Root Cultures of the Hemiparasitic Plant Triphysaria Versicolor

Parasitic plants in the Orobanchaceae invade host plant roots through root organs called haustoria. Parasite roots initiate haustorium development when exposed to specific secondary metabolites that are released into the rhizosphere by host plant roots. While molecular approaches are increasingly being taken to understand the genetic mechanism underlying these events, a limitation has been the lack of a transformation system for parasitic plants. Since the haustorium development occurs in roots of Orobanchaceae, root cultures may be suitable material for transient or stable transformation experiments. To this end, root cultures were obtained from explants, and subsequently calluses, from the hemiparasitic plant Triphysaria versicolor. The cultured roots retained their competence to form haustoria when exposed to host roots, host root exudates, or purified haustorium-inducing factors. The root culture haustoria invaded host roots and initiated a vascular continuity between the parasite and host roots. The ontogeny of haustoria development on root cultures was indistinguishable from that on seedlings roots. Root cultures should provide useful material for molecular studies of haustorium development.     

Identification of mutant gene responsible for cotyledons necrosis in developing seedlings of Arabidopsis thaliana]

Genetic and molecular analyses of an Arabidopsis thaliana mutant with necrotic cotyledons from the collection of insertion mutants obtained earlier were conducted. The mutation under study showed incomplete dominance and represented a single insertion of the T region of pLD3 vector used for transformation of germinating seeds to the plant genome during the creation of the collection. Using TAIL-PCR, a fragment of the mutant DNA adjacent to the left border of the T-DNA insertion was isolated and sequenced. Computer r-aided analysis showed that the insertion was located on the left arm of chromosome 1. The open reading frame containing the insertion has one exon and encodes a protein of 446 amino acids, whose functions are unknown.     

Identification of a gene, included in control of root system development in Arabidopsis thaliana

Genetic and molecular genetic analysis of a lethal root mutant of Arabidopsis thaliana was carried out. The mutant was obtained from a collection created earlier by means of insertion mutagenesis. The mutation was found to be recessive. It was caused by an insertion of the T region of vector pLD3 used for transformation of germinating seeds when creating the collection of insertion mutants. A 118-bp DNA fragment flanking the left border of the insertion was isolated using the TAIL PCR technique, and its nucleotide sequence was determined. Computer analysis of this DNA region demonstrated that it was located in exon 32 of the YUP8HI2R.44 gene in chromosome 1.     

Genes targets identification of 5-amino-<Emphasis Type="Italic">exo</Emphasis>-3-azatricyclo[5.2.1.0<Superscript>2,6</Superscript>]decane-4-one in an in vivo model of arrhythmia

The molecular mechanisms of action of 5-amino-exo-3-azatricyclo[5.2.1.0^2,6]decane-4-one (P11), a compound possessing strong antiarrhythmic, nootropic, anti-inflammatory and analgesic activity, have been studied. Cardiac rhythm disturbances were modeled by administering the arrhythmogenic compound aconitin in a dose of 50 μg/kg to the animals from the control group. P-11 in a dose of 0.3 mg/kg was injected intravenously in the experimental group of animals 2 min before aconitin administration. P-11 target genes were identified using the Atlas™ Rat cDNA Expression macroarray (#7738-1, BD Biosciences, United States). Reproducible changes in the expression levels of 16 genes in the heart of rats treated with P-11 concommitantly to arrhythmia modeling in vivo were detected. The genes regulated by the substance coded for proteins of the extracellular matrix are (glypican 1, Gpc1; tissue inhibitor of metalloproteinase 2, 3, Timp2, Timp3), intracellular signaling proteins (rho GTPase activating protein 7, Dlc1; protein tyrosine phosphatase 4a1, Ptp4a1; phosphodiesterase 4D, PDE4D; PI3-kinase regulatory subunit alpha, PIK3R1; guanine nucleotide binding protein alpha 12, Gna12), proteins involved in glycolysis (phosphofructokinase 1, Pfk1), intercellular interactions (junction plakoglobin, Jup), and hemostasis (tissue plasminogen activator, Plat), membranebound pumps and transporters (solute carrier family 16, member 1, Slc16a1; ATPase, Na⁺/K⁺ transporting, Atp1a), and others (c-fos proto-oncogene, c-fos; telomerase protein component 1, tlp; Annexin 1, anxa1). Therefore, the data concerning the selective effect of P-11 on genes coding for proteins involved in arrhythmogenesis allow for considering this compound as a promising medication for pathogenetically oriented therapy of arrhythmias.     

Identification of the gene whose mutation leads to hypocotyl tropism in Arabidopsis thaliana

Genetic and molecular analysis of a mutant of Arabidopsis thaliana with bended hypocotyl from a previously obtained collection of insertion mutants is presented. The examined mutation was shown to be recessive and based on a single insertion of pLD3 vector T-region into the A. thaliana genome. Computer-aided analysis of a DNA region adjacent to the left border of the insertion revealed a putative site of T-DNA insertion, the At1g15760 gene from 609-bp chromosome 1 represented by a single exon.     

Creation of a collection of morphological insertional mutants of Arabidopsis thaliana

A collection of transgenic Arabidopsis thaliana plants has been obtained by Agrobacterium-mediated transformation. The genomes of the transgenic plants contain insertions of T-DNA of the vector plasmids pLD3 or pPCVRN4. Genes bearing T-DNA insertions were shown to constitute 12-18% of the total number of A. thaliana genes. Seventy-five lines have been chosen from the collection and subjected to genetic and molecular-genetic analysis. Of these, 5 were dominant mutants, and 70, recessive insertion mutants with various morphological defects. Identification of mutant phenotypes and genetic characterization of the transgenic lines have been performed with the use of nutrient media supplemented with exogenous hormones, which revealed five recessive lethal mutants and one dominant sterile mutant.     

Identification of the gene whose mutation leads to hypocoptyl tropism in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

Genetic and molecular analysis of a mutant of Arabidopsis thaliana with bended hypocoptyl from a previously obtained collection of insertion mutants is presented. The examined mutation was shown to be recessive and based on a single insertion of pLD3 vector T-region into the A. thaliana genome. Computer-aided TAIL-PCR analysis of a DNA region adjacent to the left border of the insertion revealed a putative site of T-DNA insertion, the 609-bp At1g15760 gene from chromosome 1 represented by a single exon.Translated from Genetika, Vol. 41, No. 3, 2005, pp. 427–429.Original Russian Text Copyright © 2005 by Ogarkova, Tomilov, Tomilova, Tarasov.