Switchgrass (Panicum virgatum L.) polyubiquitin gene (PvUbi1 and PvUbi2) promoters for use in plant transformation

<p>Abstract</p> <p>Background</p> <p>The ubiquitin protein is present in all eukaryotic cells and promoters from ubiquitin genes are good candidates to regulate the constitutive expression of transgenes in plants. Therefore, two switchgrass (<it>Panicum virgatum </it>L.) ubiquitin genes (<it>PvUbi1 </it>and <it>PvUbi2</it>) were cloned and characterized. Reporter constructs were produced containing the isolated 5' upstream regulatory regions of the coding sequences (i.e. <it>PvUbi1 </it>and <it>PvUbi2 </it>promoters) fused to the <it>uidA </it>coding region (<it>GUS</it>) and tested for transient and stable expression in a variety of plant species and tissues.</p> <p>Results</p> <p><it>PvUbi1 </it>consists of 607 bp containing <it>cis</it>-acting regulatory elements, a 5' untranslated region (UTR) containing a 93 bp non-coding exon and a 1291 bp intron, and a 918 bp open reading frame (ORF) that encodes four tandem, head -to-tail ubiquitin monomer repeats followed by a 191 bp 3' UTR. <it>PvUbi2 </it>consists of 692 bp containing <it>cis</it>-acting regulatory elements, a 5' UTR containing a 97 bp non-coding exon and a 1072 bp intron, a 1146 bp ORF that encodes five tandem ubiquitin monomer repeats and a 183 bp 3' UTR. <it>PvUbi1 </it>and <it>PvUbi2 </it>were expressed in all examined switchgrass tissues as measured by qRT-PCR. Using biolistic bombardment, <it>PvUbi1 </it>and <it>PvUbi2 </it>promoters showed strong expression in switchgrass and rice callus, equaling or surpassing the expression levels of the CaMV <it>35S, 2x35S, ZmUbi1</it>, and <it>OsAct1 </it>promoters. GUS staining following stable transformation in rice demonstrated that the <it>PvUbi1 </it>and <it>PvUbi2 </it>promoters drove expression in all examined tissues. When stably transformed into tobacco (<it>Nicotiana tabacum</it>), the <it>PvUbi2+3 </it>and <it>PvUbi2+9 </it>promoter fusion variants showed expression in vascular and reproductive tissues.</p> <p>Conclusions</p> <p>The <it>PvUbi1 </it>and <it>PvUbi2 </it>promoters drive expression in switchgrass, rice and tobacco and are strong constitutive promoter candidates that will be useful in genetic transformation of monocots and dicots.</p

Spectral responses in near-infrared of the mixed compounds III-V, ternary and quaternary, based on GaSb

From the simulation of the spectral response of the different photodetector devices elaborated in our laboratory (C.E.M.), we determine the influence of geometrical and physical parameters in order to achieve the best photodetector operating at the wavelength 2.55 $\mu$m. In this paper we present: Gao$_{0.6}$In$_{0.4}$Sb$_{\rm n}$/Ga$_{0.6}$In$_{0.4}$Sb$_{\rm p}$ homojunctions matched on GaSb$_{\rm p}$ substrate, Ga$_{0.75}$In$_{0.25}$As$_{0.23}$Sb$_{\rm p}$/GaSb$_{\rm n}$ ternary heterojunction and GaSb$_{\rm p}$/Ga$_{0.74}$In$_{0.26}$As$_{0.23}$Sb$_{\rm 0.77p}$/GaSb$_{\rm n}$ quaternary heterojunction. The GaSb$_{\rm p}$ layer with an energy band gap greater than Ga$_{0.74}$In$_{0.26}$As$_{0.23}$Sb$_{\rm 0.77p}$ optical gap will act as a window, reducing the effect of surface recombinaison. Results of the simulation are compared to experimental curves to determine the values of photoelectrical parameters (diffusion length, recombination velocity at the surface ...).Les mesures de réponse spectrale dans la gamme [0,4 eV à 2 eV] ont été effectuées sur des homojonctions, Ga$_{0,6}$In$_{0,4}$Sb$_{\rm n}$/Ga$_{0,6}$In$_{0,4}$Sb$_{\rm p}$ déposées sur un substrat de GaSb et des hétérostructures ternaires Ga$_{0,75}$In$_{0,25}$Sb$_{\rm p}$/GaSb$_{\rm n}$ et quaternaires GaSb$_{\rm p}$/Ga$_{0,74}$In$_{0,26}$As$_{0,23}$Sb$_{\rm 0,77p}$/GaSb$_{\rm n}$. La couche de GaSbp avec un gap plus grand que celui de Ga$_{0,74}$In$_{0,26}$As$_{0,23}$Sb$_{\rm 0,77p}$ joue le rôle d'effet fenêtre. En s'appuyant sur les résultats de la simulation et en accordant les spectres expérimentaux aux spectres théoriques, on détermine les valeurs des paramètres photoélectriques (longueurs de diffusion, les vitesses de recombinaison en surface ... ) intervenant dans le rendement quantique

Development of an efficient transient transformation protocol for avocado (Persea americana Mill.) embryogenic callus

En este trabajo se presenta el estudio de la eficiencia de diferentes marcadores de fluorescencia con la técnica de biobalística para la transformación transitoria de callo embriogénico de aguacate y su uso para el estudio comparativo de diferentes promotores.This research was funded byMinisterio de Ciencia e Innovación of Spain and Feder European Union Funds (grant no. AGL2011-30354-C02-01)