BACKGROUND: Fig fruit are highly perishable at the tree-ripe (TR) stage. Commercial-ripe (CR) fruit, which are harvested before the TR stage for their postharvest transportability and shelf-life advantage, are inferior to TR fruit in size, color and sugar content. The succulent urn-shaped receptacle, serving as the protective structure and edible part of the fruit, determines fruit quality. Quantitative iTRAQ and RNA-Seq were performed to reveal the differential proteomic and transcriptomic traits of the receptacle at the two harvest stages. RESULTS: We identified 1226 proteins, of which 84 differentially abundant proteins (DAPs) were recruited by criteria of abundance fold-change (FC) ≥1.3 and p < 0.05 in the TR/CR receptacle proteomic analysis. In addition, 2087 differentially expressed genes (DEGs) were screened by ≥2-fold expression change: 1274 were upregulated and 813 were downregulated in the TR vs. CR transcriptomic analysis. Ficin was the most abundant soluble protein in the fig receptacle. Sucrose synthase, sucrose-phosphate synthase and hexokinase were all actively upregulated at both the protein and transcriptional levels. Endoglucanase, expansin, beta-galactosidase, pectin esterase and aquaporins were upregulated from the CR to TR stage at the protein level. In hormonal synthesis and signaling pathways, high protein and transcriptional levels of aminocyclopropane-1-carboxylate oxidase were identified, together with a few diversely expressed ethylene-response factors, indicating the potential leading role of ethylene in the ripening process of fig receptacle, which has been recently reported as a non-climacteric tissue. CONCLUSIONS: We present the first delineation of intra- and inter-omic changes in the expression of specific proteins and genes of TR vs. CR fig receptacle, providing valuable candidates for further study of fruit-quality formation control and fig cultivar innovation to accommodate market demand.

The whitefly Bemisia tabaci is a major pest to agriculture. Adults are able to fly for long distances and to colonize staple crops, herbs and ornamentals, and to vector viruses belonging to several important taxonomic groups. During their early development, whiteflies mature from eggs through several nymphal stages (instars I to IV) until adults emerge from pupae. We aim at reducing whitefly populations by inhibiting the emergence of adults from nymphs. Here we targeted dystrophin, a conserved protein essential for the development of the muscle system in humans, other animals and insects. We have exploited the fact that whitefly nymphs developing on tomato leaves feed from the plant phloem via their stylets. Thus, we delivered dystrophin-silencing double-stranded RNA to nymphs developing on leaves of tomato plantlets with their roots bathing in the silencing solution. Downregulation of dystrophin expression occurred mainly in pupae. Dystrophin silencing induced also the downregulation of the dystrophin-associated protein genes actin and tropomyosin, and disrupted F-actin. Most significantly, the treatment inhibited the emergence of adults from pupae, suggesting that targeting dystrophin may help to restrain whitefly populations. This study demonstrates for the first time the important role of dystrophin in the development of a major insect pest to agriculture.

Abscisic acid (ABA) levels increase significantly in plants under stress conditions and ABA is thought to serve as a key stress-response regulator. However, the direct effect of ABA on photosynthesis and the effect of mesophyll ABA on yield under both well-watered and drought conditions are still the subject of debate. Here, we examined this issue using transgenic Arabidopsis thaliana plants carrying a dominant ABA-signaling inhibitor under the control of a mesophyll-specific promoter (FBPase::abi1-1, abbreviated to fa). Under normal conditions, fa plants displayed slightly higher stomatal conductance and carbon assimilation than wild-type (WT) plants; however, these parameters were comparable following ABA treatment. These observations suggest that ABA does not directly inhibit photosynthesis in the short term. fa plants also exhibited a variety of altered phenotypes under optimal conditions, including more vigorous initial growth, earlier flowering, smaller flowers and delayed chlorophyll degradation. Furthermore, under optimal conditions, fa plant seed production was less than a third of that observed for the WT. However, under drought conditions, WT and fa seed yields were similar due to a significant reduction in WT seed and no reduction in fa seed. These findings suggest that endogenous basal ABA inhibits a stress-escape response under non-stress conditions, allowing plants to accumulate biomass and maximize yield. The lack of a correlation between flowering time and plant biomass combined with delayed chlorophyll degradation suggests that this stress-escape behavior is regulated independently and upstream of other ABA-induced effects such as rapid growth and flowering.

Abscisic acid (ABA) is known to be involved in stomatal closure. However, its role in stomatal response to rapid increases in the vapor pressure deficit (VPD) is unclear. To study this issue, we generated guard cell-specific ABA-insensitive Arabidopsis plants (guard-cell specific abi1-1; GCabi). Under non-stressed conditions, the stomatal conductance (g) and apertures of GCabi plants were greater than those of control plants. This supports guard-cell ABA role as limiting steady-state stomatal aperture under non-stressful conditions. When there was a rapid increase in VPD (0.15 to 1 kPa), the g and stomatal apertures of GCabi decreased in a manner similar that observed in the WT control, but different from that observed in WT plants treated with fusicoccin. Low VPD increased the size of the stomatal apertures of the WT, but not of GCabi. We conclude that guard-cell ABA does not play a significant role in the initial, rapid stomatal closure that occurs in response to an increase in VPD, but is important for stomatal adaptation to ambient VPD. We propose a biphasic angiosperm VPD-sensing model that includes an initial ABA-independent phase and a subsequent ABA-dependent steady-state phase in which stomatal behavior is optimized for ambient VPD conditions.

This study is aimed to explore the properties of cellulose nanocrystals (CNC)/polyvinyl alcohol (PVA) composite films with and without 1,2,3,4-butane tetracarboxylic acid (BTCA), a nontoxic crosslinker. CNC and CNC-PVA nanocomposite films are prepared using solution-casting technique. Differential scanning calorimetry (DSC) analyses show that crosslinking increased the glass transition temperature but reduced the melting temperature and crystallinity. Furthermore, high CNC concentrations in the PVA matrix interfere with PVA crystallinity, whereas in specific ratio between CNC and PVA, two different crystalline structures are observed within the PVA matrix. Film surfaces and fracture topographies characterized using scanning electron microscope indicate that at certain CNC-PVA ratios, micron-sized needle-like crystals have formed. These crystalline structures correlate with the remarkable improvement in mechanical properties of the CNC-PVA nanocomposite films, that is, enhanced tensile strain and toughness to 570% and 202 MJ m , respectively, as compared to pristine PVA. BTCA enhances the tensile strain, ultimate tensile stress, toughness, and modulus of CNC films compared to pristine CNC films. Water absorption of crosslinked CNC and CNC-PVA nanocomposite films is significantly reduced, while film transparency is significantly improved as a function of PVA and crosslinker content. The presented results indicate that CNC-PVA nanocomposite films may find applications in packaging, and though materials applications.