Stone formation in peach fruit exhibits spatial coordination of the lignin and flavonoid pathways and similarity to Arabidopsis dehiscence

<p>Abstract</p> <p>Background</p> <p>Lignification of the fruit endocarp layer occurs in many angiosperms and plays a critical role in seed protection and dispersal. This process has been extensively studied with relationship to pod shatter or dehiscence in <it>Arabidopsis</it>. Dehiscence is controlled by a set of transcription factors that define the fruit tissue layers and whether or not they lignify. In contrast, relatively little is known about similar processes in other plants such as stone fruits which contain an extremely hard lignified endocarp or stone surrounding a single seed.</p> <p>Results</p> <p>Here we show that lignin deposition in peach initiates near the blossom end within the endocarp layer and proceeds in a distinct spatial-temporal pattern. Microarray studies using a developmental series from young fruits identified a sharp and transient induction of phenylpropanoid, lignin and flavonoid pathway genes concurrent with lignification and subsequent stone hardening. Quantitative polymerase chain reaction studies revealed that specific phenylpropanoid (phenylalanine ammonia-lyase and cinnamate 4-hydroxylase) and lignin (caffeoyl-CoA O-methyltransferase, peroxidase and laccase) pathway genes were induced in the endocarp layer over a 10 day time period, while two lignin genes (<it>p-</it>coumarate 3-hydroxylase and cinnamoyl CoA reductase) were co-regulated with flavonoid pathway genes (chalcone synthase, dihydroflavanol 4-reductase, leucoanthocyanidin dioxygen-ase and flavanone-3-hydrosylase) which were mesocarp and exocarp specific. Analysis of other fruit development expression studies revealed that flavonoid pathway induction is conserved in the related Rosaceae species apple while lignin pathway induction is not. The transcription factor expression of peach genes homologous to known endocarp determinant genes in <it>Arabidopsis </it>including <it>SHATTERPROOF</it>, <it>SEEDSTCK </it>and <it>NAC SECONDARY WALL THICENING PROMOTING FACTOR 1 </it>were found to be specifically expressed in the endocarp while the negative regulator <it>FRUITFU</it>L predominated in exocarp and mesocarp.</p> <p>Conclusions</p> <p>Collectively, the data suggests, first, that the process of endocarp determination and differentiation in peach and <it>Arabidopsis </it>share common regulators and, secondly, reveals a previously unknown coordination of competing lignin and flavonoid biosynthetic pathways during early fruit development.</p

Development of an HRMA-Based Marker Assisted Selection (MAS) Approach for Cost-Effective Genotyping of <i>S</i> and <i>M</i> Loci Controlling Self-Compatibility in Apricot (<i>Prunus armeniaca</i> L.)

The apricot species is characterized by a gametophytic self-incompatibility (GSI) system. While GSI is one of the most efficient mechanisms to prevent self-fertilization and increase genetic variability, it represents a limiting factor for fruit production in the orchards. Compatibility among apricot cultivars was usually assessed by either field pollination experiments or by histochemical evaluation of in vitro pollen tube growth. In apricots, self-compatibility is controlled by two unlinked loci, S and M, and associated to transposable element insertion within the coding sequence of SFB and ParM-7 genes, respectively. Self-compatibility has become a primary breeding goal in apricot breeding programmes, stimulating the development of a rapid and cost-effective marker assisted selection (MAS) approach to accelerate screening of self-compatible genotypes. In this work, we demonstrated the feasibility of a novel High Resolution Melting Analysis (HRMA) approach for the massive screening of self-compatible and self-incompatible genotypes for both S and M loci. The different genotypes were unambiguously recognized by HRMA, showing clearly distinguishable melting profiles. The assay was developed and tested in a panel of accessions and breeding selections with known self-compatibility reaction, demonstrating the potential usefulness of this approach to optimize and accelerate apricot breeding programmes

Characterization of the Symbiotic Nitrogen-Fixing Common Bean Low Phytic Acid (lpa1) Mutant Response to Water Stress

The common bean (Phaseolus vulgaris L.) low phytic acid (lpa1) biofortified genotype produces seeds with improved nutritional characteristics and does not display negative pleiotropic effects. Here we demonstrated that lpa1 plants establish an efficient nitrogen-fixing symbiosis with Rhizobium etli CE3. The lpa1 nodules showed a higher expression of nodule-function related genes than the nodules of the parental wild type genotype (BAT 93). We analyzed the response to water stress of lpa1 vs. BAT 93 plants grown under fertilized or under symbiotic N2-fixation conditions. Water stress was induced by water withholding (up to 14% soil moisture) to fertilized or R. etli nodulated plants previously grown with normal irrigation. The fertilized lpa1 plants showed milder water stress symptoms during the water deployment period and after the rehydration recovery period when lpa1 plants showed less biomass reduction. The symbiotic water-stressed lpa1 plants showed decreased nitrogenase activity that coincides with decreased sucrose synthase gene expression in nodules; lower turgor weight to dry weight (DW) ratio, which has been associated with higher drought resistance index; downregulation of carbon/nitrogen (C/N)-related and upregulation of stress-related genes. Higher expression of stress-related genes was also observed in bacteroids of stressed lpa1 plants that also displayed very high expression of the symbiotic cbb3 oxidase (fixNd)

Transcriptional basis of drought-induced susceptibility to the rice blast fungus Magnaporthe oryzae

BGPI : équipe 4Plants are often facing several stresses simultaneously. Understanding how they reactand the way pathogens adapt to such combinational stresses is poorly documented.Here, we developed an experimental system mimicking field intermittent drought onrice followed by inoculation by the pathogenic fungus Magnaporthe oryzae. Thisexperimental system triggers an enhancement of susceptibility that could be correlatedwith the dampening of several aspects of plant immunity, namely the oxidative burst andthe transcription of several pathogenesis-related genes. Quite strikingly, the analysisof fungal transcription by RNASeq analysis under drought reveals that the fungus isgreatly modifying its virulence program: genes coding for small secreted proteins weremassively repressed in droughted plants compared to unstressed ones whereas genescoding for enzymes involved in degradation of cell-wall were induced. We also showthat drought can lead to the partial breakdown of several major resistance genes byaffecting R plant gene and/or pathogen effector expression.We propose a model wherea yet unknown plant signal can trigger a change in the virulence program of the pathogento adapt to a plant host that was affected by drought prior to infection

Additional file 9: of Integrative genomics approaches validate PpYUC11-like as candidate gene for the stony hard trait in peach (P. persica L. Batsch)

Table S5. Phenotypic evaluation for SH trait and allelic status at YUC11 TC microsatellites of the two F2 segregating progenies BO10040 and BO10039 (issued from the SH parent ‘D4162’). (DOCX 16 kb

Additional file 2: of Integrative genomics approaches validate PpYUC11-like as candidate gene for the stony hard trait in peach (P. persica L. Batsch)

Figure S1. Evolution of flesh firmness during ripening of four peach accessions with a stony hard (‘BO05030081’ and ‘IFF331’) or non-SH/MF (‘Bolero’, ‘Redhaven’) texture, as measured through a penetration-based test. (BMP 4181 kb

Additional file 3: of Integrative genomics approaches validate PpYUC11-like as candidate gene for the stony hard trait in peach (P. persica L. Batsch)

Table S2. List of primers used for quantitative PCR analyses. (DOCX 12 kb