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Fusarium wilt of banana caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) is one of the most disastrous fungal diseases. Biological control is a promising strategy for controlling Fusarium wilt of banana. To explore endophytic actinomycetes as biocontrol resources against Foc TR4, antagonistic strains were isolated from different tissues of medicinal plants. Here, a total of 144 actinomycetes were isolated and belonged to Nonomuraea, Kitasatospora, and Streptomyces. Forty-three isolates exhibited antifungal activities against Foc TR4. The strain labeled with 5-4 isolated from roots of Piper austrosinense had a broad-spectrum antifungal activity by the production of chitinase and β-1,3-glucanase and was identified as Streptomyces hygroscopicus subsp. hygroscopicus 5-4. Furthermore, disease index of banana wilt was significantly reduced by application of strain 5-4 in comparison with application of Foc TR4 alone. Exogenous application of strain 5-4 increased the expression levels of defense genes such as (PAL), peroxidase (POD), pathogenesis-related protein 1 (PR-1), hydrolytic enzymes (β-1,3-glucanase), lysin motif receptor kinase 1 (LYK-1), and mitogen-activated protein kinase 1 (MPK-1). The antifungal mechanism assay demonstrated that extracts of strain 5-4 inhibited spore gemination and hyphal growth of Foc TR4, and caused abnormally swollen, deformity, and rupture of Foc TR4 hypha. Thus, S. hygroscopicus subsp. hygroscopicus 5-4 could be used as a potential biological agent for controlling Fusarium wilt of banana.

Fatty acids in avocado fruit are crucial components influencing taste as well as fruit quality and nutritional value. Changes to fatty acid contents and concentrations in avocado fruit are important because of the associated effects on sensory properties. Hence, plant physiologists and molecular biologists interested in elucidating the influence of transcription factors on fatty acid accumulation in avocado fruit. In this study, APETALA2/ethylene-responsive factor (AP2/ERF) family members in avocado (Persea americana Mill.) were systematically and comprehensively analyze to identify potential PaAP2/ERF genes related to fatty acid accumulation. The results of bioinformatics analysis and the expression profiles of the AP2/ERF members suggested that 10 highly expressed PaAP2/ERF genes may encode transcription factors with functions related to the fatty acid accumulation in the avocado mesocarp. Furthermore, PaWRI1 and PaWRI2, two AP2/ERF transcription factor genes in avocado, were functionally characterized regarding their effects on fatty acid accumulation. The transcriptome and biochemical analyses of PaWRI1-2-overexpressing transgenic tomato plants revealed the up-regulated expression of 17 unigenes related to fatty acid synthesis and triacylglycerol assembly as well as increased fatty acid contents relative to the corresponding levels in the wild-type plants. In contrast, the overexpression of PaWRI2 in transgenic tomato plants up-regulated the expression of only six unigenes associated with fatty acid synthesis and triacylglycerol assembly and negligibly affected fatty acid accumulation when compared with wild-type plants. This systematic analysis provides a foundation for future studies regarding AP2/ERF functions associated with fatty acid accumulation.

The huge amount of metabolites in avocado mesocarp influences the commercial production of specific avocado fruits for consumption and for industrial applications. Additionally, the diversity in the metabolite content may be used as biomarker for differentiating among various avocado ecotypes. However, the differences in metabolites in avocado remain unclear among various avocado ecotypes. In this study, we first compared the lipid droplets, fatty acid compositions, and gene expression profiles of the mature avocado mesocarps of three ecotypes, and confirmed the differences in the mesocarp oil contents. Furthermore, the lipidomics and metabolomics based on the ultra-high-performance liquid chromatography-triple and time-of-flight mass spectrometry and ultra-high performance liquid chromatography-Q exactive-mass spectrometry were completed, respectively, which revealed considerable differences in the relative amounts of lipids from 10 classes and other metabolites from seven super-classes among the examined avocado ecotypes. The profiles of 65 lipids and 15 other metabolites could be potential candidate biomarkers useful for identifying diverse avocado ecotypes. This is the first comprehensive metabolomics-based comparative investigation of lipid and other metabolites among three avocado ecotypes.

Banana is a key staple food and fruit in countries all over the world. However, the development of the global banana industry is seriously threatened by Fusarium wilt disease, which is caused by Fusarium oxysporum f. sp. cubense (Foc). In particular, Foc tropical race 4 (Foc TR4) could infect more than 80% of global banana and plantain crops. Until now, there were no commercial chemicals or resistant cultivars available to control the disease. Biological control using actinomycetes is considered a promising strategy. In this study, 88 actinomycetes were isolated from a banana orchard without symptoms of Fusarium wilt disease for more than 10 years. An actinobacterial strain labeled as JBS5-6 has exhibited strong antifungal activities against Foc TR4 and other selected 10 phytopathogenic fungi. Based on phenotypic and biochemical traits as well as complete genome analysis, strain JBS5-6 was assigned to Streptomyces violaceusniger. Extracts of the strain inhibited the mycelial growth and spore germination of Foc TR4 by destroying membrane integrity and the ultrastructure of cells. The complete genome of strain JBS5-6 was sequenced and revealed a number of key function gene clusters that contribute to the biosynthesis of active secondary metabolites. Sixteen chemical compounds were further identified by gas chromatography-mass spectrometry (GC-MS). 5-hydroxymethyl-2-furancarboxaldehyde was one of the dominant components in strain JBS5-6 extracts. Moreover, fermentation broth of strain JBS5-6 significantly reduced the disease index of banana seedlings by inhibiting the infection of Foc TR4 in a pot experiment. Hence, strain JBS5-6 is a potential biocontrol agent for the management of disease and the exploitation of biofertilizer.

Banana residues are an important energy resource after fruit harvesting. The optionally dumping and burning causes severely environmental problems. Traditional compost efficiency was limited by lignocellulosic composition of banana residues. Inoculation with cellulase-producing microbes provides an efficient strategy for improving degradation of lignocellulosic materials. In our study, a newly isolated cellulolytic bacterium Acetobacter orientalis XJC-C with a salt and high temperature resistance was identified from a marine soft coral. By contrast, the strain can biodegrade different lignocellulosic agricultural residues, especially banana straw. The highest cellulolytic and ligninolytic enzyme activities were detected during composting at 40 days. Compared with the negative and positive control groups, the lignin degradation rate reached 76.24% in the A. orientalis XJC-C group, increased by 47.08% and 21.85%, respectively. Moreover, the strain improved significantly the metabolic activity and functional diversity of bacterial community. Hence, A. orientalis XJC-C will be a promising candidate for degrading lignocellulosic agricultural residues.

Fusarium wilt of banana caused by Fusarium oxysporum f. sp. cubense (Foc) is a disastrous soil-borne fungal disease. Foc tropical race 4 (Foc TR4) can infect almost all banana cultivars. Until now, there is a shortage of safety and effective control methods and commercial banana cultivars with a resistance against Foc TR4. Biocontrol using environmentally friendly microbes is a promising strategy for the management of Foc TR4. Here, a strain 5–10, newly isolated from a medicinal plant (Curculigo capitulata), exhibited a high antifungal activity against Foc TR4. Combing the morphological characteristics and molecular identification, strain 5–10 was classified as a Streptomyces genus. The sequenced genome revealed that more than 39 gene clusters were involved in the biosynthesis of secondary metabolites. Some multidrug resistance gene clusters were also identified such as mdtD, vatB, and vgaE. To improve the anti-Foc TR4 activity of the strain 5–10 extracts, an optimization method of fermentation broth was established. Antifungal activity increased by 72.13% under the fermentation system containing 2.86 g/L of NaCl and 11.57% of inoculation amount. After being treated with the strain 5–10 extracts, the Foc TR4 hyphae shrinked, deformed, and ruptured. The membrane integrity and cell ultrastructure incurred irreversible damage. Streptomyces sp. 5–10 extracts play a fungicidal role in Foc TR4. Hence, Streptomyces sp. 5–10 will be a potential biocontrol agent to manage fungal diseases by exploring the microbial fertilizer.

Fusarium wilt of banana caused by Fusarium oxysporum f. sp. cubense (Foc) is one of the most destructive diseases, severely limiting the development of banana industry. Especially, Foc tropical race 4 (Foc TR4) can infect and destroy almost all banana cultivars. Until now, there is still a lack of an effective method for controlling fusarium wilt. A biocontrol strategy using Actinobacteria is considered as a promising method for management of disease and pest. In this study, 229 Actinobacteria were isolated from rhizosphere soil samples of a primitive ecological mountain. An actinobacterium strain marked with YYS-7 exhibited a high antifungal activity against Foc TR4. Combining the physiological and biochemical characteristics as well as alignment of the 16S rRNA sequence, the strain YYS-7 was assigned to Streptomyces sp. The crude extracts of Streptomyces sp. YYS-7 obviously inhibited the mycelial growth of Foc TR4. The cell integrity and ultrastructure were seriously destroyed. In addition, Streptomyces sp. YYS-7 and crude extracts also showed a broad-spectrum antifungal activity against the selected seven phytopathogenic fungi. A gas chromatography-mass spectrometry (GC-MS) was used to predict the antifungal metabolites. A total of eleven different compounds were identified, including phenolic compounds, hydrocarbons, esters and acids. In the pot experiment, the crude extracts can significantly improve the banana plant's resistance to Foc TR4. Hence, Streptomyces sp. YYS-7 will be a potential biocontrol agent for the biofertilizer exploitation and the discovery of new bioactive substances.

Avocado is an economically important crop that is widely cultivated in the tropical and subtropical regions of China. However, there is a lack of sufficient information regarding the racial origins and genetic diversification of native avocado germplasm. On the basis of a race-specific kompetitive allele-specific PCR genotyping analysis, the 56 avocado accessions examined in this study were classified as complex hybrids, namely Guatemalan &times, Mexican &times, West Indian hybrids. The genetic relationships among the avocado accessions were assessed based on a quality trait evaluation and molecular characterization. The total flavonoid content was relatively useful for differentiating between native avocado accessions. A cluster analysis as well as principal component and coordinate analyses of quality traits and molecular characteristics differentiated the avocado accessions, but not according to geographical origins. Thus, the artificial flow of avocado germplasm or seed exchanges among farmers within specific regions may have contributed to the similar genetic backgrounds of avocado germplasm from different collections.

Avocado oil-based high internal phase emulsions (HIPEs) were formed and stabilized at by citrus nanofibers (CNFs) and tannic acid (TA) via a simple shear-induced emulsification technique. CNFs/TA colloidal complex (CTNFs) based on the hydrogen-bonding interaction between citrus nanofibers and TA was successfully generated. These complex colloidal nanofibers with enhanced interfacial reactivity can be utilized for the preparation of stable avocado oil-based HIPEs by one-step homogenization. A dense and orderly interfacial architecture via the combination of steric hindrance from fibers membrane and interfacial cargo of TA endowed the emulsions with favorable oxidative stability, evidenced by low lipid hydroperoxides, malondialdehyde and hexanal levels in the emulsions after thermally accelerated storage. The HIPEs are formed as a gel with a texture that can be modulated by adjusting TA concentration. Furthermore, a pH triggered responsible propertie was observed as a result of the pH-dependent bond of TA and citrus nanofibers. These results will likely extend the use of these surfactant-free, and potentially edible emulsions to new food, cosmetic, and pharmaceutical applications.

Avocado (Persea americana Mill.) is an economically important crop because of its high nutritional value. However, the absence of a sequenced avocado reference genome has hindered investigations of secondary metabolism. For next-generation high-throughput transcriptome sequencing, we obtained 365,615,152 and 348,623,402 clean reads as well as 109.13 and 104.10 Gb of sequencing data for avocado mesocarp and seed, respectively, during five developmental stages. High-quality reads were assembled into 100,837 unigenes with an average length of 847.40 bp (N50 = 1725 bp). Additionally, 16,903 differentially expressed genes (DEGs) were detected, 17 of which were related to carotenoid biosynthesis. The expression levels of most of these 17 DEGs were higher in the mesocarp than in the seed during five developmental stages. In this study, the avocado mesocarp and seed transcriptome were also sequenced using single-molecule long-read sequencing to acquired 25.79 and 17.67 Gb clean data, respectively. We identified 233,014 and 238,219 consensus isoforms in avocado mesocarp and seed, respectively. Furthermore, 104 and 59 isoforms were found to correspond to the putative 11 carotenoid biosynthetic-related genes in the avocado mesocarp and seed, respectively. The isoform numbers of 10 out of the putative 11 genes involved in the carotenoid biosynthetic pathway were higher in the mesocarp than those in the seed. Besides, alpha- and beta-carotene contents in the avocado mesocarp and seed during five developmental stages were also measured, and they were higher in the mesocarp than in the seed, which validated the results of transcriptome profiling. Gene expression changes and the associated variations in gene dosage could influence carotenoid biosynthesis. These results will help to further elucidate carotenoid biosynthesis in avocado.

Anthracnose is a fungal disease caused by Colletotrichum species, which is detrimental to numerous fruits, including strawberry. Use of fungicides to maintain fruit quality leads to potential environmental pollution and health risk. Biocontrol using beneficial microorganisms such as Streptomyces has been applied successfully for controlling postharvest diseases of fruit. In this study, strain H4 with a high antifungal activity against C. fragariae was isolated from Dichotella gemmacea in Xisha islands of South China Sea. Combining the morphological and biochemical characteristics with the 16S rRNA sequence analysis, this strain was assigned as Streptomyces sp. A preventive treatment using strain H4 extracts significantly reduced severity and incidence of anthracnose disease and maintained fruit hardness and color on harvested strawberry fruits. A minimum inhibitory concentration (MIC) and a minimum fungicidal concentration (MFC) were 1.563 × 10−3 g L-1 and 3.125 × 10−3 g L-1, respectively. Extracts could effectively inhibit mycelial growth and spore germination of C. fragariae in vitro. The mycelial structure of pathogenic fungi showed deformation, shrinkage, collapse and tortuosity. A significant decrease in sugar and protein contents was also observed in treated C. fragariae mycelia. Fourteen chemical compounds were identified by gas chromatography-mass spectrometer (GC–MS). Dibutyl phthalate was the major constituent. Notably, strain H4 and its extracts exhibited a broad-spectrum antifungal activity against seven selected plant pathogenic fungi. Hence, Streptomyces sp. H4 and its metabolites have a high efficiency of antagonistic roles against phytopathogenic fungi diseases. It provides a promising biological agent to control anthracnose of strawberry fruit.

Banana Fusarium wilt caused by Fusarium oxyspoum f. sp. cubense (Foc) is one of the most destructive diseases. Foc tropical race 4 (TR4) is threatening the global banana industry and can infect almost all banana cultivars. Until now, there is still a lack of an effective method for controlling fusarium wilt. Application of beneficial microbes is considered as an environmentally sound option to manage phytopathogenic fungi. We previously identified Streptomyces sp. H4 with a strong antifungal activity against Foc TR4. In this study, strain H4 extracts obviously inhibited mycelial growth, spore germination and tube elongation of Foc TR4. Spore germination was completely suppressed by 8 × EC50 of extracts. Cell membrane integrity and ultrastructure of Foc TR4 were destroyed, which was supported by the increase of extracellular conductivity and nucleic acid releasing. In a pot experiment, the fermentation broth of strain H4 significantly decreased the disease index of Foc TR4 and improved the growth of banana seedlings. Hence, Streptomyces sp. H4 will be a potential microbial resource for the biocontrol of banana Fusarium wilt and the promotion of plant growth.

Avocado (Persea americana Mill.) is an important fruit crop commercially grown in tropical and subtropical regions. Despite the importance of avocado, there is relatively little available genomic information regarding this fruit species. In this study, we functionally annotated the full-length avocado transcriptome sequence based on single-molecule real-time sequencing technology, and predicted the coding sequences (CDSs), transcription factors (TFs), and long non-coding RNA (lncRNA) sequences. Moreover, 76,777 simple sequence repeat (SSR) loci detected among the 42,096 SSR-containing transcript sequences were used to develop 149,733 expressed sequence tag (EST)-SSR markers. A subset of 100 EST-SSR markers was randomly chosen for an analysis that detected 15 polymorphicEST-SSR markers, with an average polymorphism information content of 0.45. These 15markers were able to clearly and effectively characterize46 avocado accessions based on geographical origin. In summary, our study is the first to generate a full-length transcriptome sequence and develop and analyze a set of EST-SSR markers in avocado. The application of third-generation sequencing techniques for developing SSR markers is a potentially powerful tool for genetic studies.

Fatty acids are important components of the avocado mesocarp, so a better understanding of how their change during fruit development will contribute to improving the quality of avocado fruits and their nutritional value. The changes in fatty acids, lipid droplets, and expression of some key genes and regulators participating in late glycolysis and fatty acid biosynthesis were analyzed at different stages of the development of avocado mesocarp. The total fatty acid contents of the avocado mesocarp increased during fruit development, with an increase by a factor of seven (from 1,628.04 to 11,116.30 mg/100 g dry weight) in the late stage of fruit maturation, this was confirmed by the changes observed in the lipid droplets. The composition of the main fatty acids varied at four developmental stages of fruit development. Palmitic, palmitoleic, oleic, and linoleic acid contents generally increased during fruit development, reaching maxima at Harvest, with percentages of total fatty acids of 50%, 9%, 31%, and 8%, respectively. Meanwhile, the amount of PaWRI1, PaACP4-2, and PapPK-β1 expressed consistently increased by up to 4-fold during fruit development. This comprehensive analysis has indicated that the changes in the expressions of PaWRI1, PaACP4-2, and PapPK-β1 were consistent with those in the total fatty acid contents, so they might have key roles in the accumulation of oil in the avocado mesocarp.

Mouse CT26 colorectal tumors are heavily infiltrated by tumor-specific CD8 T cells, but nevertheless grow rapidly in Balb/c mice. These tumors are partially responsive to anti-PD-1 (α-PD-1) monoclonal antibody therapy, which suggests that an active suppression of the tumor-specific cytotoxic T cells exists in the untreated tumor. As chemokine receptor 2 (CCR2) is expressed by a potentially suppressive leukocyte subset within these tumors (monocytic myeloid derived suppressor cells aka M-MDSCs), we aimed to test whether CCR2 blockade could enhance the anti-tumor effects of α-PD-1. We have found that the therapeutic effects of α-PD-1 therapy are appreciably enhanced by specific blockade of CCR2 via a small molecule antagonist. This combined α-PD-1/CCR2i approach significantly decreases overall tumor size and increases the proportion of long-term survivors, with more than 50% of the mice (up to 73%) showing complete regression of a previously established tumor. The effects of this combined therapy are dependent on the presence of CD8+ T cells, as tumors do not respond to the therapy in CD8-depleted mice. The anti-CT26 tumor response is specific: long term survivors are resistant to re-inoculation with the CT26 tumor (even without further dosing of either drug) but are not resistant to the 4T1 breast tumor. CCR2 antagonism alters the tumor microenvironment by reducing the number of M-MDSC per gram of tumor (a CCR2hi population phenotypically defined as CD11b+/Ly6G-/Ly6Chi). Reduction in tumor size is inversely proportional to the ratio of CD8 T cells to M-MDSC. These data are consistent with a hypothesis that CCR2 antagonism enhances α-PD-1 therapy by preventing M-MDSC from accumulating within the tumor, thus reducing their suppressive effects on cytotoxic T cells. Citation Format: James J. Campbell, Christine Janson, Linda Ertl, Chris Li, Zhenhua Miao, Antoni Krasinski, Rebecca Lui, Venkat Mali, Jeffrey McMahon, Yibin Zheng, Yu Wang, Xiaoping Zang, Vicky Chhina, Marta Vilalta, Alice Kumamoto, Ton Dang, Shirley Liu, Simon Yao, Penglie Zhang, Thomas J. Schall, Rajinder Singh. Inhibition of chemokine receptor 2 (CCR2) with a small molecule antagonist enhances the effectiveness of checkpoint inhibition by altering the tumor microenvironment in mouse colorectal tumors: Reducing tumor size and increasing long term survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1745.

Temporal and spatial changes in delta(13) C and delta 15 N of particulate organic matter (POM) and Hemiculter leucisculus were studied in the Yangtze River of China. Isotopic signatures of POM showed seasonal variations, which was assumed to be associated with allochthonous organic input and autochthonous phytoplankton growth. delta C-13 of H. leucisculus was 1.1 % higher than that of POM, which suggested that the food source of H. leucisculus was mostly from the POM. A mass balance model indicated the trophic position of H. leucisculus in the food web of Yangtze River was estimated to be 2.0 - 2.1, indicating that this fish mainly feeds on planktonic organic matter, which agreed with previous gut content analysis.