Identification of the domains of cauliflower mosaic virus protein P6 responsible for suppression of RNA silencing and salicylic acid signalling.

Cauliflower mosaic virus (CaMV) encodes a 520 aa polypeptide, P6, which participates in several essential activities in the virus life cycle including suppressing RNA silencing and salicylic acid-responsive defence signalling. We infected Arabidopsis with CaMV mutants containing short in-frame deletions within the P6 ORF. A deletion in the distal end of domain D-I (the N-terminal 112 aa) of P6 did not affect virus replication but compromised symptom development and curtailed the ability to restore GFP fluorescence in a GFP-silenced transgenic Arabidopsis line.

Cauliflower mosaic virus protein P6 inhibits signaling responses to salicylic acid and regulates innate immunity.

Cauliflower mosaic virus (CaMV) encodes a multifunctional protein P6 that is required for translation of the 35S RNA and also acts as a suppressor of RNA silencing. Here we demonstrate that P6 additionally acts as a pathogenicity effector of an unique and novel type, modifying NPR1 (a key regulator of salicylic acid (SA)- and jasmonic acid (JA)-dependent signaling) and inhibiting SA-dependent defence responses We find that that transgene-mediated expression of P6 in Arabidopsis and transient expression in Nicotiana benthamiana has profound effects on defence signaling, suppressing expression of representative SA-responsive genes and increasing expression of representative JA-responsive genes. Relative to wild-type Arabidopsis P6-expressing transgenics had greatly reduced expression of PR-1 following SA-treatment, infection by CaMV or inoculation with an avirulent bacterial pathogen Pseudomonas syringae pv tomato (Pst).

Genotoxicity evaluation of effluents from textile industries of the region Fez-Boulmane, Morocco: a case study.

In order to investigate the biological hazard of effluents from textile industries of Fez-Boulmane region in Morocco, mutagenicity and phytotoxicity tests were performed on different biological systems. Moreover, the efficiency of a Sequencing Batch Reactor (SBR) system, working by activated sludge on a laboratory scale, was estimated by comparing the ecotoxicity results observed before and after wastewater treatment. Evaluation of the genotoxic potential was investigated by means of classic mutagenicity tests on D7 strain of Saccharomyces cerevisiae and by phytotoxicity tests on Allium sativum L.

Components of Arabidopsis defense- and ethylene-signaling pathways regulate susceptibility to Cauliflower mosaic virus by restricting long-distance movement.

We analyzed the susceptibility of Arabidopsis mutants with defects in salicylic acid (SA) and jasmonic acid (JA)/ethylene (ET) signaling to infection by Cauliflower mosaic virus (CaMV). Mutants cpr1-1 and cpr5-2, in which SA-dependent defense signaling is activated constitutively, were substantially more resistant than the wild type to systemic infection, implicating SA signaling in defense against CaMV. However, SA-deficient NahG, sid2-2, eds5-1, and pad4-1 did not show enhanced susceptibility.

Characterization of LEAFY COTYLEDON1-LIKE gene in Helianthus annuus and its relationship with zygotic and somatic embryogenesis.

The Helianthus annuus LEAFY COTYLEDON1-LIKE (HaL1L) gene encodes a heme-activated protein 3 subunit of the CCAAT box-binding factor. The phylogenetic analysis indicates that HaL1L is closely related to LEAFY COTYLEDON1 (LEC1)-type of Arabidopsis thaliana. In particular, the peptide results homologous to the LEC1-LIKE gene of A.

Expression of two genes encoding gibberellin 2- and 3-oxidases in developing seeds of Phaseolus coccineus.

We have isolated PcGA3ox1, a cDNA clone from developing runner bean (Phaseolus coccineus) seeds that shows significant amino acid homology with the gibberellin (GA) 3-oxidases. A recombinant fusion protein of PcGA3ox1 converted GA20 and GA9 to GA1 and GA4, respectively. In situ hybridization results showed that transcripts of this gene accumulate specifically within the suspensor of globular-stage embryos.

Arabidopsis mutants that suppress the phenotype induced by transgene-mediated expression of cauliflower mosaic virus (CaMV) gene VI are less susceptible to CaMV-infection and show reduced ethylene sensitivity.

Protein P6 is the main symptom determinant of cauliflower mosaic virus (CaMV), and transgene-mediated expression in Arabidopsis induces a symptom-like phenotype in the absence of infection. Seeds of a P6-transgenic line, A7, were mutagenized by gamma-irradiation and M2 seedlings were screened for mutants that suppressed the phenotype of chlorosis and stunting. We identified four mutants that were larger and less chlorotic than the A7 parent but which contained an intact and transcriptionally active transgene.

Mutations that delay flowering in Arabidopsis de-couple symptom response from cauliflower mosaic virus accumulation during infection.

summary The development of disease symptoms in plants infected with a compatible virus involves complex signalling interactions between host and viral gene products. Photoperiod is an important influence on the transition from vegetative growth to flowering. Symptoms in wild-type Arabidopsis plants grown under long days were much less severe than in plants grown under short days, although under long days, the levels of replicating virus were 1.