Metabolome and Transcriptome Joint Analysis Reveals That Different Sucrose Levels Regulate the Production of Flavonoids and Stilbenes in Grape Callus Culture.

To reveal the effect of sucrose concentration on the production of secondary metabolites, a metabolome and transcriptome joint analysis was carried out using callus induced from grape variety Mio Red cambial meristematic cells. We identified 559 metabolites-mainly flavonoids, phenolic acids, and stilbenoids-as differential content metabolites (fold change ≥2 or ≤0.5) in at least one pairwise comparison of treatments with 7.5, 15, or 30 g/L sucrose in the growing media for 15 or 30 days (d). Resveratrol, viniferin, and amurensin contents were highest at 15 d of subculture; piceid, ampelopsin, and pterostilbene had higher contents at 30 d. A transcriptome analysis identified 1310 and 498 (at 15 d) and 1696 and 2211 (at 30 d) differentially expressed genes (DEGs; log2(fold change) ≥ 1, p < 0.05) in 7.5 vs. 15 g/L and 15 vs. 30 g/L sucrose treatments, respectively. In phenylpropane and isoflavone pathways, DEGs encoding cinnamic acid 4-hydroxylase, chalcone synthase, chalcone isomerase, and flavanone 3-hydroxylase were more highly expressed at 15 d than at 30 d, while other DEGs showed different regulation patterns corresponding to sucrose concentrations and cultivation times. For all three sucrose concentrations, the stilbene synthase (STS) gene exhibited significantly higher expression at 15 vs. 30 d, while two resveratrol O-methyltransferase (ROMT) genes related to pterostilbene synthesis showed significantly higher expression at 30 vs. 15 d. In addition, a total of 481 DEGs were annotated as transcription factors in pairwise comparisons; an integrative analysis suggested MYB59, WRKY20, and MADS8 as potential regulators responding to sucrose levels in flavonoid and stilbene biosynthesis in grape callus. Our results provide valuable information for high-efficiency production of flavonoids and stilbenes using grape callus.

Polygalacturonase gene family analysis identifies FcPG12 as a key player in fig (Ficus carica L.) fruit softening.

BACKGROUND: The fig (Ficus carica L.) tree has high economic value. However, its fruit have a short shelf life due to rapid softening. Polygalacturonases (PGs) are essential hydrolases, responsible for the pectin degradation that plays a key role in fruit softening. However, fig PG genes and their regulators have not yet been characterized. RESULTS: In this study, 43 FcPGs were identified in the fig genome. They were non-uniformly distributed on 13 chromosomes, and tandem repeat PG gene clusters were found on chromosomes 4 and 5. Ka/Ks calculation and collinear analysis indicated negative selection as the main driver of FcPG family expansion. Fourteen FcPGs were found expressed in fig fruit with FPKM values > 10, of which seven were positively correlated, and three, negatively correlated with fruit softening. Eleven FcPGs were upregulated and two downregulated in response to ethephon treatment. FcPG12, a member of the tandem repeat cluster on chromosome 4, was selected for further analyses due to its sharp increment in transcript abundance during fruit softening and its response to ethephon treatment. Transient overexpression of FcPG12 led to decreased fig fruit firmness and increased PG enzyme activity in the tissue. Two ethylene response factor (ERF)-binding GCC-box sites were found on the FcPG12 promoter. Yeast one-hybrid and dual luciferase assays showed that FcERF5 binds directly to the FcPG12 promoter and upregulates its expression. Transient overexpression of FcERF5 upregulated FcPG12 expression, thereby increasing PG activity and fruit softening. CONCLUSIONS: Our study identified FcPG12 as a key PG gene in fig fruit softening, and its direct positive regulation by FcERF5. The results provide new information on the molecular regulation of fig fruit softening.

Independent flavonoid and anthocyanin biosynthesis in the flesh of a red-fleshed table grape revealed by metabolome and transcriptome co-analysis.

BACKGROUND: Red flesh is a desired fruit trait, but the regulation of red flesh formation in grape is not well understood. 'Mio Red' is a seedless table grape variety with light-red flesh and blue-purple skin. The skin color develops at veraison whereas the flesh color develops at a later stage of berry development. The flesh and skin flavonoid metabolomes and transcriptomes were analyzed. RESULTS: A total of 161 flavonoids were identified, including 16 anthocyanins. A total of 66 flavonoids were found at significantly different levels in the flesh and skin (fold change ≥ 2 or ≤ 0.5, variable importance in projection (VIP) ≥ 1). The main anthocyanins in the flesh were pelargonidin and peonidin, and in the skin were peonidin, delphinidin, and petunidin. Transcriptome comparison revealed 57 differentially expressed structural genes of the flavonoid-metabolism pathway (log2fold change ≥ 1, FDR < 0.05, FPKM ≥ 1). Two differentially expressed anthocyanin synthase (ANS) genes were annotated, ANS2 (Vitvi02g00435) with high expression in flesh and ANS1 (Vitvi11g00565) in skin, respectively. One dihydro flavonol 4-reductase (DFR, Vitvi18g00988) gene was differentially expressed although high in both skin and flesh. Screened and correlation analysis of 12 ERF, 9 MYB and 3 bHLH genes. The Y1H and dual luciferase assays showed that MYBA1 highly activates the ANS2 promoter in flesh and that ERFCBF6 was an inhibitory, EFR23 and bHLH93 may activate the DFR gene. These genes may be involved in the regulation of berry flesh color. CONCLUSIONS: Our study revealed that anthocyanin biosynthesis in grape flesh is independent of that in the skin. Differentially expressed ANS, MYB and ERF transcription factors provide new clues for the future breeding of table grapes that will provide the health benefits as red wine.

Genome-wide analysis of JAZ family genes expression patterns during fig (Ficus carica L.) fruit development and in response to hormone treatment.

BACKGROUND: Jasmonate-ZIM domain (JAZ) repressors negatively regulate signal transduction of jasmonates, which regulate plant development and immunity. However, no comprehensive analysis of the JAZ gene family members has been done in the common fig (Ficus carica L.) during fruit development and hormonal treatment. RESULTS: In this study, 10 non-redundant fig JAZ family genes (FcJAZs) distributed on 7 chromosomes were identified in the fig genome. Phylogenetic and structural analysis showed that FcJAZ genes can be grouped into 5 classes. All the classes contained relatively complete TIFY and Jas domains. Yeast two hybrid (Y2H) results showed that all FcJAZs proteins may interact with the identified transcription factor, FcMYC2. Tissue-specific expression analysis showed that FcJAZs were highly expressed in the female flowers and roots. Expression patterns of FcJAZs during the fruit development were analyzed by RNA-Seq and qRT-PCR. The findings showed that, most FcJAZs were significantly downregulated from stage 3 to 5 in the female flower, whereas downregulation of these genes was observed in the fruit peel from stage 4 to 5. Weighted-gene co-expression network analysis (WGCNA) showed the expression pattern of FcJAZs was correlated with hormone signal transduction and plant-pathogen interaction. Putative cis-elements analysis of FcJAZs and expression patterns of FcJAZs which respond to hormone treatments revealed that FcJAZs may regulate fig fruit development by modulating the effect of ethylene or gibberellin. CONCLUSIONS: This study provides a comprehensive analysis of the FcJAZ family members and provides information on FcJAZs contributions and their role in regulating the common fig fruit development.

Proteome Analysis of Vacuoles Isolated from Fig (Ficus carica L.) Flesh during Fruit Development.

Fruit flesh cell vacuoles play a pivotal role in fruit growth and quality formation. In the present study, intact vacuoles were carefully released and collected from protoplasts isolated from flesh cells at five sampling times along fig fruit development. Label-free quantification and vacuole proteomic analysis identified 1,251 proteins, 1,137 of which were recruited as differentially abundant proteins (DAPs) by fold change ≥ 1.5, P < 0.05. DAPs were assigned to 10 functional categories; among them, 238, 186, 109, 93 and 90 were annotated as metabolism, transport proteins, membrane fusion or vesicle trafficking, protein fate and stress response proteins, respectively. Decreased numbers of DAPs were uncovered along fruit development. The overall changing pattern of DAPs revealed two major proteome landscape conversions in fig flesh cell vacuoles: the first occurred when fruit developed from late-stage I to mid-stage II, and the second occurred when the fruit started ripening. Metabolic proteins related to glycosidase, lipid and extracellular proteins contributing to carbohydrate storage and vacuole expansion, and protein-degrading proteins determining vacuolar lytic function were revealed. Key tonoplast proteins contributing to vacuole expansion, cell growth and fruit quality formation were also identified. The revealed comprehensive changes in the vacuole proteome during flesh development were compared with our previously published vacuole proteome of grape berry. The information expands our knowledge of the vacuolar proteome and the protein basis of vacuole functional evolution during fruit development and quality formation.

Extreme sugar accumulation in late fig ripening is accompanied by global changes in sugar metabolism and transporter gene expression.

Female fig (Ficus carica L.) fruit are characterized by a major increase in volume and sugar content during the final week of development. A detailed developmental analysis of water and dry matter accumulation during these final days indicated a temporal separation between the increase in volume due to increasing water content and a subsequent sharp increase in sugar content during a few days. The results present fig as an extreme example of sugar import and accumulation, with calculated import rates that are one order of magnitude higher than those of other sugar-accumulating sweet fruit species. To shed light on the metabolic changes occurring during this period, we followed the expression pattern of 80 genes encoding sugar metabolism enzymes and sugar transporter proteins identified in fig fruit. A parallel comparison with male fig fruits, which do not accumulate sugar during ripening, highlighted the genes specifically related to sugar accumulation. Tissue-specific analysis indicated that the expression of genes involved in sugar metabolism and transport undergoes a global transition.

Ethephon induces coordinated ripening acceleration and divergent coloration responses in fig (Ficus carica L.) flowers and receptacles.

KEY MESSAGE: The regulatory landscape of ethephon-accelerated fig ripening is revealed; flowers and receptacles exhibit opposite responses in anthocyanin accumulation; PG, PL and EXP are suggested key genes in fig softening. Ethephon is used to accelerate fig-fruit ripening for improvement of harvesting efficiency, but the underlying molecular mechanism is still unclear. To elucidate the detailed biological mechanism of ethylene-accelerated fig ripening, fruit in phase II (the lag phase on the double sigmoid growth curve) were treated with ethephon, and reached commercial ripeness 6 days earlier than the nontreated controls. Transcriptomes of flowers and the surrounding receptacles-which together make up the pseudocarp in fig fruit-were analyzed. There were 5189, 5818 and 2563 differentially expressed genes (DEGs) 2, 4 and 6 days after treatment (DAT) in treated compared to control fruit, screened by p-adjust < 0.05 and |log2(fold change) |≥ 2. The DEGs were significantly enriched in plant hormone metabolism and signal transduction, cell-wall modification, sugar accumulation and anthocyanin accumulation pathways. DEGs in the first three pathway categories demonstrated an overall similar expression change in flowers and receptacles, whereas DEGs in anthocyanin pigmentation revealed divergent transcript abundance. Specifically, in both flowers and receptacles, ethephon significantly upregulated 1-aminocyclopropane-1-carboxylate oxidase and downregulated most of the ethylene-response factor genes; polygalacturonase, pectate lyase and expansin were mainly upregulated; two acid beta-fructofuranosidases were upregulated. However, structural genes in the anthocyanin-synthesis pathway were mainly downregulated in female flowers 2 and 4 DAT, whereas they were upregulated in the receptacles. Our study reveals the regulatory landscape of the two tissues of fig fruit in ethylene-induced ripening; the differentially expressed pathways and genes provide valuable resources for the mining of target genes for crucial biological and commercial trait improvement.

Metabolome and transcriptome analysis of flavor components and flavonoid biosynthesis in fig female flower tissues (Ficus carica L.) after bagging.

BACKGROUND: Bagging can improve the appearance of fruits and increase the food safety and commodification, it also has effects on intrinsic quality of the fruits, which was commonly reported negative changes. Fig can be regarded as a new model fruit with its relatively small genome size and long fruit season. RESULTS: In this study, widely targeted metabolomics based on HPLC MS/MS and RNA-seq of the fruit tissue of the 'Zibao' fig before and after bagging were analyzed to reveal the metabolites changes of the edible part of figs and the underneath gene expression network changes. A total of 771 metabolites were identified in the metabolome analysis using fig female flower tissue. Of these, 88 metabolites (including one carbohydrate, eight organic acids, seven amino acids, and two vitamins) showed significant differences in fruit tissue before and after bagging. Changes in 16 structural genes, 13 MYB transcription factors, and endogenous hormone (ABA, IAA, and GA) metabolism and signal transduction-related genes in the biosynthesis pathway of flavonoids after bagging were analyzed by transcriptome analysis. KEGG enrichment analysis also determined significant differences in flavonoid biosynthesis pathways in female flower tissue before and after bagging. CONCLUSIONS: This work provided comprehensive information on the composition and abundance of metabolites in the female flower tissue of fig. The results showed that the differences in flavor components of the fruit before and after bagging could be explained by changes in the composition and abundance of carbohydrates, organic acids, amino acids, and phenolic compounds. This study provides new insights into the effects of bagging on changes in the intrinsic and appearance quality of fruits.

First report of Geotrichum candidum causing sour rot of peach in China.

Peach (Prunus persica L. Batsch) is one of the most important fruit crops in China (Wang et al. 2011). Yangshan Town of Jiangsu Province is one of the four major peach producing areas in China, with a growing area of 2,000 ha (Tian et al. 2018). During June 2020, a postharvest disease presenting with brown necrosis and rot occurred on peaches in Yangshan Town. The estimated damage was more than 10% of the total harvest. The symptoms included soft rot, and the lesion appeared sunken, accompanied with sour odor and white mycelia. Twelve peaches with representative symptom were sampled for pathogen isolation. Pieces (about 5 mm × 5 mm) from the lesion edge of symptomatic fruits were dissected and surface disinfected (3% NaClO for 10 s and 75% ethanol for 30 s), then rinsed three times with distilled water, dried on sterile filter paper and transferred to Potato Dextrose Agar (PDA) media plates supplemented with 150 ng/mL streptomycin sulfate. The plates were incubated at 28 ℃ for 3 days. Forty-eight isolations were obtained from the plates and isolates were single-spored. All isolates presented white, flat, milky yeast-like colonies with radial mycelia. Hyphae under microscope were septate, branched, disarticulating into arthroconidia measuring 3.39 to 9.27 × 2.05 to 7.71 µm. The morphological characteristics are consistent with Geotrichum candidum (De Hoog et al. 1986). Internal transcribed spacer (ITS) and 18s nuclear ribosomal small subunit (SSU) of the 48 isolates were amplified and sequenced using the primers ITS5/ITS4, and NS1/NS4 for molecular identification (Schoch et al. 2012). The resulted sequences showed no difference among all the isolates. Alignment by blastn showed the sequence of ITS and SSU were 100% (accession number. GQ376093) and 99.7% identical (accession number. KY977411.1) to Geotrichum candidum, respectively. The sequences of ITS (accession number MW493646) and SSU (accession number MW493648) were submitted to the GenBank. Commercial ripe peaches with the size of about 15 cm × 15 cm × 10 cm was used for pathogenicity test. Peaches were surface disinfected with 75% ethanol, then a wound with 4 mm in diameter and 5 mm in depth was made on the surface of each fruit. Ten peaches were inoculated with 10 µL (1×105 spores /mL) of the isolate suspension. Another ten peaches were inoculated with 10 µL sterile water as the control. Peaches were incubated individually at 28 ℃and a relative humidity of about 85%. After three days, large scale of pits and necrosis appeared on every peach inoculated, and the symptoms were consistent with the diseased peaches in Yangshan Town, while no symptoms non-inoculated on the control peaches were observed. The pathogen was re-isolated from the diseased fruit and was identified again by sequencing of ITS and SSU. All the tests were conducted three times. Considering the evidence, we identified the pathogen as G. candidum. This pathogen has been reported to cause sour rot was reported in kiwifruit, strawberry, melon and other fruits (Alonzo et al. 2020; Cheng et al. 2020; Halfeld-Vieira et al. 2020). To our knowledge, this is the first report of G. candidum causing sour rot of peach in China, which may cause a great loss to peach industry of China.

Cytokinin-induced parthenocarpy of San Pedro type fig (Ficus carica L.) main crop: explained by phytohormone assay and transcriptomic network comparison.

KEY MESSAGE: CPPU-induced San Pedro type fig main crop parthenocarpy exhibited constantly increasing IAA content and more significantly enriched KEGG pathways in the receptacle than in female flowers. N-(2-chloro-4-pyridyl)-N-phenylurea (CPPU) was applied to San Pedro fig (Ficus carica L.) main crop to induce parthenocarpy; the optimal effect was obtained with 25 mg L-1 application to syconia when female flowers were at anthesis. To elucidate the key expression changes in parthenocarpy conversion, significant changes in phytohormone level and transcriptome of fig female flowers and receptacles were monitored. HPLC-MS revealed increased IAA content in female flowers and receptacle 2, 4 and 10 days after treatment (DAT), decreased zeatin level in the receptacle 2, 4 and 10 DAT, decreased GA3 content 2 and 4 DAT, and increased GA3 content 10 DAT. ABA level increased 2 and 4 DAT, and decreased 10 DAT. CPPU-treated syconia released more ethylene than the control except 2 DAT. RNA-Seq and bioinformatics analysis revealed notably more differentially expressed KEGG pathways in the receptacle than in female flowers. In the phytohormone gene network, GA-biosynthesis genes GA20ox and GA3ox were upregulated, along with GA signal-transduction genes GID1 and GID2, and IAA-signaling genes AUX/IAA and GH3. ABA-biosynthesis gene NCED and signaling genes PP2C and ABF were downregulated 10 DAT. One ACO gene showed consistent upregulation in both female flowers and receptacle after CPPU treatment, and more than a dozen of ERFs demonstrated opposing changes in expression. Our results revealed early-stage spatiotemporal phytohormone and transcriptomic responses in CPPU-induced San Pedro fig main crop parthenocarpy, which could be valuable for further understanding the nature of the parthenocarpy of different fig types.

Differential color development and response to light deprivation of fig (Ficus carica L.) syconia peel and female flower tissues: transcriptome elucidation.

BACKGROUND: Color directly affects fruit quality and consumer preference. In fig syconia, the female flower tissue is contained in a receptacle. Anthocyanin pigmentation of this tissue and the peel differs temporally and spatially. A transcriptome study was carried out to elucidate key genes and transcription factors regulating differences in fig coloring. RESULTS: Anthocyanins in the female flower tissue were identified mainly as pelargonidin-3-glucoside and cyanidin-3-rutinoside; in the peel, the major anthocyanins were cyanidin 3-O-glucoside and cyanidin-3-rutinoside. Anthocyanin content was significantly higher in the female flower tissue vs. peel before fig ripening, whereas at ripening, the anthocyanin content in the peel was 5.39 times higher than that in the female flower tissue. Light-deprivation treatment strongly inhibited peel, but not female flower tissue, anthocyanin pigmentation. RNA-Seq revealed 522 differentially expressed genes (recruited with criteria log2 ≥ 2 and P < 0.05) at fig ripening, with 50 upregulated and 472 downregulated genes in the female flower tissue. Light deprivation upregulated 1180 and downregulated 856 genes in the peel, and upregulated 909 and downregulated 817 genes in the female flower tissue. KEGG enrichment revealed significantly changed expression in the phenylpropanoid-biosynthesis and flavonoid-biosynthesis pathways in the peel, but not in the female flower tissue, with significant repression of FcCHS, FcCHI, FcF3H, FcF3'H, FcDFR and FcUFGT transcripts. Light deprivation led to differential expression of 71 and 80 transcription factor genes in the peel and female flower tissue, respectively. Yeast one-hybrid screen revealed that FcHY5 and FcMYB114 bind the promoter regions of FcCHS and FcDFR, respectively in the flavonoid-biosynthesis pathway. CONCLUSIONS: Phenylpropanoid- and flavonoid-biosynthesis pathways were differentially expressed spatially and temporally in the peel and female flower tissue of fig syconia; pathway expression in the peel was strongly regulated by light signal. Differentially expressed transcription factors were recruited as candidates to screen important expression regulators in the light-dependent and light-independent anthocyanin-synthesis pathway. Our study lays the groundwork for further elucidation of crucial players in fig pigmentation.

Proteome and transcriptome analyses reveal key molecular differences between quality parameters of commercial-ripe and tree-ripe fig (Ficus carica L.).

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.

Identification of Fusarium Head Blight in Winter Wheat Ears Using Continuous Wavelet Analysis.

Fusarium head blight in winter wheat ears produces the highly toxic mycotoxin deoxynivalenol (DON), which is a serious problem affecting human and animal health. Disease identification directly on ears is important for selective harvesting. This study aimed to investigate the spectroscopic identification of Fusarium head blight by applying continuous wavelet analysis (CWA) to the reflectance spectra (350 to 2500 nm) of wheat ears. First, continuous wavelet transform was used on each of the reflectance spectra and a wavelet power scalogram as a function of wavelength location and the scale of decomposition was generated. The coefficient of determination R2 between wavelet powers and the disease infestation ratio were calculated by using linear regression. The intersections of the top 5% regions ranking in descending order based on the R2 values and the statistically significant (p-value of t-test < 0.001) wavelet regions were retained as the sensitive wavelet feature regions. The wavelet powers with the highest R2 values of each sensitive region were retained as the initial wavelet features. A threshold was set for selecting the optimal wavelet features based on the coefficient of correlation R obtained via the correlation analysis among the initial wavelet features. The results identified six wavelet features which include (471 nm, scale 4), (696 nm, scale 1), (841 nm, scale 4), (963 nm, scale 3), (1069 nm, scale 3), and (2272 nm, scale 4). A model for identifying Fusarium head blight based on the six wavelet features was then established using Fisher linear discriminant analysis. The model performed well, providing an overall accuracy of 88.7% and a kappa coefficient of 0.775, suggesting that the spectral features obtained using CWA can potentially reflect the infestation of Fusarium head blight in winter wheat ears.

Transcriptome analysis unravels spatiotemporal modulation of phytohormone-pathway expression underlying gibberellin-induced parthenocarpic fruit set in San Pedro-type fig (Ficus carica L.).

BACKGROUND: Gibberellin (GA) treatments can induce parthenocarpy in the main crop of San Pedro-type figs, the native non-parthenocarpic fruit, however, the underlying mechanism is still largely unclear. RESULTS: In our study, GA3 was applied to San Pedro-type fig main crop at anthesis. Sharply increased GA3 content was detected in both female flowers and receptacle, along with significantly decreased indole-3-acetic acid (IAA), zeatin and abscisic acid (ABA) levels in female flowers, and increased zeatin peak intensity and earlier ABA peak in receptacles. Transcriptome comparison between control and treatment groups identified more differentially expressed genes (DEGs) in receptacles than in female flowers 2 and 4 days after treatment (DAT); 10 DAT, the number of DEGs became similar in the two tissues. Synchronized changing trends of phytohormone-associated DEGs were observed in female flowers and receptacles with fruit development. Modulation of ethylene and GA signaling and auxin metabolism by exogenous GA3 occurred mainly 2 DAT, whereas changes in auxin, cytokinin and ABA signaling occurred mainly 10 DAT. Auxin-, ethylene- and ABA-metabolism and response pathways were largely regulated in the two tissues, mostly 2 and 10 DAT. The major components altering fig phytohormone metabolic and response patterns included downregulated GA2ox, BAS1, NCED and ACO, and upregulated ABA 8'-h and AUX/IAA. CONCLUSIONS: Thus GA-induced parthenocarpy in fig is co-modulated by the female flowers and receptacle, and repression of ABA and ethylene biosynthesis and GA catabolism might be the main forces deflecting abscission and producing fig parthenocarpy.

Identification of Wheat Yellow Rust Using Optimal Three-Band Spectral Indices in Different Growth Stages.

Yellow rust, a widely known destructive wheat disease, affects wheat quality and causes large economic losses in wheat production. Hyperspectral remote sensing has shown potential for the detection of plant disease. This study aimed to analyze the spectral reflectance of the wheat canopy in the range of 350⁻1000 nm and to develop optimal spectral indices to detect yellow rust disease in wheat at different growth stages. The sensitive wavebands of healthy and infected wheat were located in the range 460⁻720 nm in the early-mid growth stage (from booting to anthesis), and in the ranges 568⁻709 nm and 725⁻1000 nm in the mid-late growth stage (from filling to milky ripeness), respectively. All possible three-band combinations over these sensitive wavebands were calculated as the forms of PRI (Photochemical Reflectance Index) and ARI (Anthocyanin Reflectance Index) at different growth stages and assessed to determine whether they could be used for estimating the severity of yellow rust disease. The optimal spectral index for estimating wheat infected by yellow rust disease was PRI (570, 525, 705) during the early-mid growth stage with R² of 0.669, and ARI (860, 790, 750) during the mid-late growth stage with R² of 0.888. Comparison of the proposed spectral indices with previously reported vegetation indices were able to satisfactorily discriminate wheat yellow rust. The classification accuracy for PRI (570, 525, 705) was 80.6% and the kappa coefficient was 0.61 in early-mid growth stage, and the classification accuracy for ARI (860, 790, 750) was 91.9% and the kappa coefficient was 0.75 in mid-late growth stage. The classification accuracy of the two indices reached 84.1% and 93.2% in the early-mid and mid-late growth stages in the validated dataset, respectively. We conclude that the three-band spectral indices PRI (570, 525, 705) and ARI (860, 790, 750) are optimal for monitoring yellow rust infection in these two growth stages, respectively. Our method is expected to provide a technical basis for wheat disease detection and prevention in the early-mid growth stage, and the estimation of yield losses in the mid-late growth stage.

Integrating Early Growth Information to Monitor Winter Wheat Powdery Mildew Using Multi-Temporal Landsat-8 Imagery.

Powdery mildew is one of the dominant diseases in winter wheat. The accurate monitoring of powdery mildew is important for crop management and production. Satellite-based remote sensing monitoring has been proven as an efficient tool for regional disease detection and monitoring. However, the information provided by single-date satellite scene is hard to achieve acceptable accuracy for powdery mildew disease, and incorporation of early period contextual information of winter wheat can improve this situation. In this study, a multi-temporal satellite data based powdery mildew detecting approach had been developed for regional disease mapping. Firstly, the Lansat-8 scenes that covered six winter wheat growth periods (expressed in chronological order as periods 1 to 6) were collected to calculate typical vegetation indices (VIs), which include disease water stress index (DSWI), optimized soil adjusted vegetation index (OSAVI), shortwave infrared water stress index (SIWSI), and triangular vegetation index (TVI). A multi-temporal VIs-based k-nearest neighbors (KNN) approach was then developed to produce the regional disease distribution. Meanwhile, a backward stepwise elimination method was used to confirm the optimal multi-temporal combination for KNN monitoring model. A classification and regression tree (CART) and back propagation neural networks (BPNN) approaches were used for comparison and validation of initial results. VIs of all periods except 1 and 3 provided the best multi-temporal data set for winter wheat powdery mildew monitoring. Compared with the traditional single-date (period 6) image, the multi-temporal images based KNN approach provided more disease information during the disease development, and had an accuracy of 84.6%. Meanwhile, the accuracy of the proposed approach had 11.5% and 3.8% higher than the multi-temporal images-based CART and BPNN models', respectively. These results suggest that the use of satellite images for early critical disease infection periods is essential for improving the accuracy of monitoring models. Additionally, satellite imagery also assists in monitoring powdery mildew in late wheat growth periods.

Recombinant Lactococcus lactis expressing bioactive exendin-4 to promote insulin secretion and beta-cell proliferation in vitro.

In recent years, therapeutic peptides have garnered great interest in the pharmaceutical industry for the treatment of diabetes. Lactic acid bacteria (LAB) are an appealing vehicle for safe and convenient oral delivery of bioactive peptide and protein drugs. Exendin-4 (Exd4) is a glucagon-like protein-1 (GLP-1) receptor agonist that is considered an excellent therapeutic peptide drug for type 2 diabetes due to its longer-lasting bioactivity, resulting from resistance to dipeptidyl peptidase 4. We explored Lactococcus lactis with the nisin-controlled gene expression (NICE) system as an oral delivery system for recombinant (r) Exd4 peptide in situ. Heterologous expression and secretion of rExd4 by L. lactis NZ9000/pNZ8048-rExd4 were successful and efficient under the NICE system. In vitro treatment with rExd4 significantly enhanced insulin secretion of INS-1 cells and activated the PI3-K/AKT signal pathway with protein levels of AKT and p-AKT increasing 1.6- to 1.8-fold compared to negative controls, similar to the positive GLP-1 controls. INS-1 cells treated with rExd4 also showed enhanced proliferation and inhibited apoptosis, corresponding with the effects of the standard Exd4 and GLP-1 treatments. Our data suggest that the rExd4 secreted by L. lactis is a bioactive insulinotropic peptide and functional GLP-1 receptor agonist that enhances glucose-dependent insulin secretion and activates the PI3-K/AKT signal pathway; furthermore, it may be involved in improving proliferation and inhibiting apoptosis of INS-1 cells in in vitro treatments. Therefore, L. lactis producing rExd4 may potentially serve as a novel strategy for oral treatment of diabetes.

Recombinant Lactococcus lactis NZ9000 secretes a bioactive kisspeptin that inhibits proliferation and migration of human colon carcinoma HT-29 cells.

BACKGROUND: Proteinaceous bioactive substances and pharmaceuticals are most conveniently administered orally. However, the facing problems are the side effects of proteolytic degradation and denaturation in the gastrointestinal tract. In recent years, lactic acid bacteria (LAB) have been verified to be a promising delivery vector for susceptible functional proteins and drugs. KiSS-1 peptide, a cancer suppressor, plays a critical role in inhibiting cancer metastasis and its activity has been confirmed by direct administration. However, whether this peptide can be functionally expressed in LAB and exert activity on cancer cells, thus providing a potential alternative administration manner in the future, has not been demonstrated. RESULTS: A recombinant Lactococcus lactis strain NZ9000-401-kiss1 harboring a plasmid containing the gene of the tumor metastasis-inhibiting peptide KiSS1 was constructed. After optimization of the nisin induction conditions, the recombinant strain efficiently secreted KiSS1 with a maximum detectable amount of 27.9 µg/ml in Dulbecco's Modified Eagle medium. The 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide and would healing assays, respectively, indicated that the secreted KiSS1 peptide remarkably inhibited HT-29 cell proliferation and migration. Furthermore, the expressed KiSS1 was shown to induce HT-29 cell morphological changes, apoptosis and reduce the expression of matrix metalloproteinase 9 (MMP-9) at both mRNA and protein levels. CONCLUSIONS: A recombinant L. lactis NZ9000-401-kiss1 successfully expressing the human kiss1 was constructed. The secreted KiSS1 peptide inhibited human HT-29 cells' proliferation and migration probably by invoking, or mediating the cell-apoptosis pathway and by down regulating MMP-9 expression, respectively. Our results suggest that L. lactis is an ideal cell factory for secretory expression of tumor metastasis-inhibiting peptide KiSS1, and the KiSS1-producing L. lactis strain may serve as a new tool for cancer therapy in the future.

Combination of heterogeneous catalase and superoxide dismutase protects Bifidobacterium longum strain NCC2705 from oxidative stress.

Bifidobacteria are generally sensitive to oxidative stress caused by reactive oxygen species (ROS). To improve oxidative-stress tolerance, the superoxide dismutase (SOD) gene from Streptococcus thermophilus (StSodA) and the heme-dependent catalase (KAT) gene from Lactobacillus plantarum (LpKatL) were heterologously expressed in Bifidobacterium longum strain NCC2705. Three types of strain NCC2705 transformants were obtained: with transgenic SOD expression, with transgenic KAT expression, and with coexpression of the two genes. Intracellular expression of the genes and their functional role in oxidative-stress resistance were evaluated. In response to oxidative stress, B. longum NCC2705/pDP401-LpKatL (expressing LpKatL) and NCC2705/pDP-Kat-Sod (coexpressing LpKatL and StSodA) rapidly degraded exogenous H2O2 and the peroxides generated as a byproduct of aerobic cultivation, preventing oxidative damage to DNA and RNA. Individual expression of StSodA or LpKatL both improved B. longum NCC2705 cell viability. Survival rate of strain NCC2705 was further improved by combining SOD and KAT expression. The two enzymes played complementary roles in ROS-scavenging pathways, and coexpression led to a synergistic beneficial effect under conditions of intensified oxidative stress. Our results illustrate that heterogeneous expression of heme-dependent KAT and Mn(2+)-dependent SOD is functional in the B. longum oxidative-stress response, and synergistic protection is achieved when their expressions are combined.

Monitoring yellow rust progression during spring critical wheat growth periods using multi-temporal Sentinel-2 imagery.

BACKGROUND: Yellow rust (Puccinia striiformis f. sp. tritici) is a devastating hazard to wheat production, which poses a serious threat to yield and food security in the main wheat-producing areas in eastern China. It is necessary to monitor yellow rust progression during spring critical wheat growth periods to support its prediction by providing timely calibrations for disease prediction models and timely green prevention and control. RESULTS: Three Sentinel-2 images for the disease during the three wheat growth periods (jointing, heading, and filling) were acquired. Spectral, texture, and color features were all extracted for each growth period disease. Then three period-specific feature sets were obtained. Given the differences in field disease epidemic status in the three periods, three period-targeted monitoring models were established to map yellow rust damage progression in spring and track its spatiotemporal change. The models' performance was then validated based on the disease field truth data during the three periods (87 for the jointing period, 183 for the heading period, and 155 for the filling period). The validation results revealed that the representation of the wheat yellow rust damage progression based on our monitoring model group was realistic and credible. The overall accuracy of the healthy and diseased pixel classification monitoring model at the jointing period reached 87.4%, and the coefficient of determination (R2) of the disease index regression monitoring models at the heading and filling periods was 0.77 (heading period) and 0.76 (filling period). The model-group-result-based spatiotemporal change detection of the yellow rust progression across the entire study area revealed that the area proportions conforming to the expected disease spatiotemporal development pattern during the jointing-to-heading period and the heading-to-filling period reached 98.2% and 84.4% respectively. CONCLUSIONS: Our jointing, heading, and filling period-targeted monitoring model group overcomes the limitations of most existing monitoring models only based on single-phase remote sensing information. It performs well in revealing the wheat yellow rust spatiotemporal epidemic in spring, can timely update disease trends to optimize disease management, and provide a basis for disease prediction to timely correct model. © 2024 Society of Chemical Industry.