CrMYC1, a Catharanthus roseus elicitor- and jasmonate-responsive bHLH transcription factor that binds the G-box element of the strictosidine synthase gene promoter.

A cDNA encoding a bHLH transcription factor was isolated by the yeast one-hybrid system from a Catharanthus roseus cDNA library using the G-box element of the Strictosidine synthase gene promoter as bait. The corresponding protein (named CrMYC1) was shown to bind specifically to the G-box in yeast. In C. roseus suspension cells CrMYC1 mRNA levels are induced by fungal elicitor and jasmonate suggesting that CrMYC1 may be involved in the regulation of gene expression in response to these signals.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

GhERF-IIb3 regulates the accumulation of jasmonate and leads to enhanced cotton resistance to blight disease.

International audienceThe phytohormone jasmonic acid (JA) and its derivatives, collectively referred to as jasmonates, regulate many developmental processes, but are also involved in response to numerous abiotic/biotic stresses. Thus far, powerful reverse genetic strategies employing perception, signaling or biosynthesis mutants have broadly contributed to our understanding of JA implication in plant stress response and development; so did the chemical gain-of-function approach based on exogenous application of the hormone. However, there is currently no method that allows for in planta tightly controlled JA production. Investigating the control of the JA synthesis pathway in bacteria-infected cotton (Gossypium hirsutum L.) plants, we identified a transcription factor (TF), namely GhERF-IIb3, that could act as positive regulator of the JA pathway. Expression of this well-conserved TF in cotton leaves was sufficient to bring about in situ JA accumulation at physiological concentrations associated with enhanced cotton defense response to bacterial infection

cDNA-AFLP-based genetical genomics in cotton fibers

Equipe AFEF ‘Architecture et Fonctionnement des Espèces fruitières’ ; Team AFFS ‘Architecture and Functioning of Fruit Species’ Contact: [email protected] audienceGenetical genomics, or genetic analysis applied to gene expression data, has not been widely used in plants. We used quantitative cDNA-AFLP to monitor the variation in the expression level of cotton fiber transcripts among a population of inter-specific Gossypium hirsutum 9 G. barbadense recombinant inbred lines (RILs). Two key fiber developmental stages, elongation (10 days post anthesis, dpa), and secondary cell wall thickening (22 dpa), were studied. Normalized intensity ratios of 3,263 and 1,201 transcript-derived fragments (TDFs) segregating over 88 RILs were analyzed for quantitative trait loci (QTL) mapping for the 10 and 22 dpa fibers, respectively. Two-thirds of all TDFs mapped between 1 and 6 eQTLs (LOD[3.5). Chromosome 21 had a higher density of eQTLs than other chromosomes in both data sets and, within chromosomes, hotspots of presumably trans-acting eQTLs were identified. The eQTL hotspots were compared to the location of phenotypic QTLs for fiber characteristics among the RILs, and several cases of co-localization were detected. Quantitative RT-PCR for 15 sequenced TDFs showed that 3 TDFs had at least one eQTL at a similar location to those identified by cDNA-AFLP, while 3 other TDFs mapped an eQTL at a similar location but with opposite additive effect. In conclusion, cDNA-AFLP proved to be a cost-effective and highly transferable platform for genome-wide and population-wide gene expression profiling. Because TDFs are anonymous, further validation and interpretation (in silico analysis, qPCR gene profiling) of the eQTL and eQTL hotspots will be facilitated by the increasing availability of cDNA and genomic sequence resources in cotton. (Résumé d'auteur) AD -; ; CIRAD-PERSYST-UPR SCA (FRA); CIRAD-PERSYST-UMR Qualisud (FRA); CIRAD-BIOS-UMR PVBMT (REU); UM2 (FRA); Bayer (BEL); CSIRO (AUS); CIRAD-BIOS-UMR AGAP (FRA

Quantitative cDNA-AFLP reveals the extent of transcriptional polymorphism in developing cotton fibres

International audienceGenetic variability in fibre quality among the two major cultivated cotton species, Gossypium hirsutum (Gh) and G. barbadense (Gb), shows a complex multigenic inheritance. We developed a quantitative 3 targeting cDNA-AFLP analysis strategy in order to dissect transcriptional regulation differences between the developing fibres of these 2 species. Two studies were undertaken. In the first study the expression profiles of over 3000 transcripts from the 2 parental species were analysed by quantitative cDNA-AFLP during the time-course of fibre development, between 6 and 28 days post anthesis (dpa). The 2nd study (4400 transcripts profiled) focused on two key developmental stages of fibre development (10 and 22 dpa, respectively) at a population-wide level using an inter-specific RIL population. Major achievements include: (1) the partitioning of genes among significant expression profiles and its comparison between Gh and Gb; and (2) the mapping of a large (>5000) number of expression QTLs on the RIL genetic map and a comparison of their distributions with QTL for fibre phenotypic traits. This research is part of a larger project aimed at the genetic and genomic dissection of cotton fibre quality. (Résumé d'auteur

Changes in expression of fiber genes for all possible pair-wise comparisons.

<p>Comparisons are contrasted between: A- fiber development dates (10 vs. 22 dpa), B-genotypes (<i>G. hirsutum</i> and <i>G. barbadense</i>, <i>Gh</i> vs. <i>Gb</i>), and C-sub-genomic origin of reads (A sub-genome vs. D sub-genome). Gene expression was assessed digitally according to the origins of reads within contigs. In each pair-wise comparison bar length is proportional to the number of contigs showing differential over-expression (number of contigs also indicated in parentheses). Symbol ‘*’ indicates a statistical difference (P0.05) for each pair-wise comparison using Fisher’s exact test. For example, within the A panel (all comparisons involving 10 vs. 22 dpa), the comparison Gh10_A vs. Gh22_A (164 vs. 102, significantly different) indicates that within <i>G. hirsutum</i>, there are 164 contigs for which the A-tagged reads are more abundant (≥2-fold) at 10 dpa than at 22 dpa; conversely 102 contigs have more abundant representation of A-tagged reads at 22 dpa than at 10 dpa.</p

Genes most differentially expressed between the 2 stages of fiber development.

*<p>Brill, et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0048855#pone.0048855-Brill1" target="_blank">[72]</a> reported 4 isoforms, A–D, ‘new ‘C isoform with highest level at SCW synthesis stage, which corresponded (best blast hits) to 2 of the contigs, Contig_19300_bb and Contig_56175_bb, which had the highest differential 22>10, with 67 and 103-fold.</p

GO enrichment analysis between fiber development stages.

<p>The Gossip package of Blast2GO was used. Over representation of functional classes are presented among contigs with significant DGE (over-expression) at 10 compared to 22 dpa (upper Figure) and at 22 compared to 10 dpa (lower Figure). Significantly enriched GO terms (P<0.05) are highlighted, and the degree of color saturation of each node positively correlates with the enrichment significance of the corresponding GO term. Box color represent significance ranging from white for least significant to dark orange for most significant enrichment, arrows indicate hierarchical relationships.</p

Schematic partitioning of the 39,099 variant positions between intra- and inter-genotypic SNPs.

<p>Variant positions are counted among contigs covered by the 2 genotypes and with at least 6 reads of both. The blue and brown bars symbolize the A_T and D_T sub-genome co-assembled homoeo-copies. Genotypes are symbolized in plain (<i>G. hirsutum</i>) and dotted (<i>G. barbadense</i>) lines.</p