Genome-wide identification of auxin response factor (ARF) family in kiwifruit (Actinidia chinensis) and analysis of their inducible involvements in abiotic stresses.

Auxin response factor (ARF) acts as a vital component of auxin signaling and participates in growth, development, and stress responses in plants. In the present study, we comprehensively analyzed kiwifruit's (Actinidia chinensis) ARF genes (AcARFs) and their involvement in abiotic stress response. We identified a total of 41 AcARFs encoding ARFs in the A. chinensis genome. AcARF genes were characterized by the classic ARF_resp and a B3 domain and primarily localized on the cytoplasm and nucleus. AcARFs were categorized into eight subgroups as per the phylogenetic analysis. Synteny analysis showed that 35 gene pairs in AcARF family underwent segmental and whole genome duplication events. Promoter cis-element prediction revealed that AcARFs might be involved in abiotic factors related to stress response, which was later assessed and validated by qRT-PCR based expression analysis. Additionally, AcARFs showed tissue-specific expression. These findings extend our understanding of the functional roles of AcARFs in stress responses. Taken together, the systematic annotation of the AcARF family genes provides a platform for the functional and evolutionary study, which might help in elucidating the precise roles of the AcARFs in stress responses. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-01011-4.

Optimization of strains for fermentation of kiwifruit juice and effects of mono- and mixed culture fermentation on its sensory and aroma profiles.

In this study, a quality evaluation model of fermented kiwifruit juice (KJ) based on strain growth characteristics, sensory quality and functional characteristics was established by PCA, and the effects of mono- and mixed culture fermentation on the sensory and aroma profiles of KJ were comparatively studied. Experiments determined that L. brevis (LB) was the optimal strain for monoculture fermentation, and L. plantarum (LP2):LB = 1:2 was the optimum ratio for mixed fermentation. The results showed that lactic acid bacteria (LAB) fermentation significantly reduced the pH, soluble solid content and lightness, and improved its functional characteristics and viscosity. Mixed culture fermentation was superior to monoculture fermentation in terms of colony counts, sensory quality and viscosity. In general, after LAB fermentation, the concentrations of esters, ketones, alcohols and terpenoids in KJ increased significantly, while the concentrations of aldehydes decreased significantly. The production of esters and terpenoids was more strongly promoted by monoculture fermentation, while mixed culture fermentation promoted the production of more ketones and alcohols. 2,5-octanedione and 1-octen-3-ol could be the characteristic aroma compounds of mixed fermented KJ.

Cysteine-Based Redox-Responsive Nanoparticles for Fibroblast-Targeted Drug Delivery in the Treatment of Myocardial Infarction.

Upon myocardial infarction (MI), activated cardiac fibroblasts (CFs) begin to remodel the myocardium, leading to cardiac fibrosis and even heart failure. No therapeutic approaches are currently available to prevent the development of MI-induced pathological fibrosis. Most pharmacological trials fail from poor local drug activity and side effects caused by systemic toxicity, largely due to the lack of a heart-targeted drug delivery system that is selective for activated CFs. Here, we developed a reduced glutathione (GSH)-responsive nanoparticle platform capable of targeted delivering of drugs to activated CFs within the infarct area of a post-MI heart. Compared with systemic drug administration, CF-targeted delivery of PF543, a sphingosine kinase 1 inhibitor identified in a high-throughput antifibrotic drug screening, had higher therapeutic efficacy and lower systemic toxicity in a MI mouse model. Our results provide a CF-targeted strategy to deliver therapeutic agents for pharmacological intervention of cardiac fibrosis.

Evaluation of the color and aroma characteristics of commercially available Chinese kiwi wines via intelligent sensory technologies and gas chromatography-mass spectrometry.

As a deeply processing product of kiwifruit, kiwifruit wine (KW) has also shown promising commercial development prospects. In this study, the color and aroma characteristics of 14 commercially available KW were evaluated using intelligent sensory technologies (electronic nose (E-nose) and colorimeter) and gas chromatography-mass spectrometry (GC-MS). Different types of KW had similar color trends, namely, yellow-green or yellow; however, individual samples showed a bright green color and had a high transparency. E-nose and GC-MS reached a relatively consistent conclusion that fermented wine and Lu Jiu were closer and significantly differed from those of distilled wine and beer. A total of 215 volatile organic compounds were identified in all KW. 50 key odor-active compounds were identified, of which ethyl caprylate, which had high OAVs in all samples (30-565.17), was considered the key odor-active compound of KW; likewise, damascenone also made a prominent aroma contribution in the different types of KW. Moreover, ß-ionone, ethyl undecanoate, ethyl 2-methylvalerate were outstanding in different fermented wines. Acids and terpenoids were prominent in beer. The study could provide a data support and market information for the quality control, research, production and development of KW.

Modification in structural, physicochemical, functional, and in vitro digestive properties of kiwi starch by high-power ultrasound treatment.

Kiwi starch (KS) is a fruit-derived starch; in order to improve its processing performance and increase its added value, it is necessary to modify KS to enhance the positive attributes and to enlarge its application. In this study, KS was modified by high-power ultrasound treatment (HUT) to reveal the relationship between the structure and function of KS with different treatment powers (0, 200, 400, and 600 W) and different treatment times (0, 10, 20, and 30 min). The results showed that HUT destroyed the granular morphology of KS, formed holes and cracks on the surface, and reduced the particle size and the short-range molecular order of KS. After different HUTs, the apparent amylose content (AAC), swelling power (SP), water solubility index (WSI), viscosity and setback value (SB) of KS were significantly increased, while the gelatinization temperature was significantly decreased. In addition, HUT significantly reduced the content of rapidly digestible starch (RDS) and slowly digestible starch (SDS), while it significantly enhanced the content of resistant starch (RS) (64.08-72.73%). In a word, HUT as a novel physical modification method for KS, enlarged its application, and fulfilled different demands of a starch-based product, which introduces another possibility for kiwi fruit further processing.

Optimization of ultrasonic-assisted enzymatic extraction of kiwi starch and evaluation of its structural, physicochemical, and functional characteristics.

A new ultrasound-assisted enzymatic extraction (UAEE) method of starch from kiwifruit was established and optimized using response surface methodology (RSM). Under optimal conditions (the pectinase-to-cellulase-to-papain ratio = 1:2:1 g/kg, solid/liquid ratio = 1:6.68, extraction pH = 5.23, ultrasound power = 300 W, and extraction temperature = 52 °C), the kiwi starch (KS) yield was about 4.25%, and the starch content of KS was 873.23 mg/g. Compared to other extraction methods, UAEE can obtain KS with high yield and purity with a shorter extraction time and less solvent and enzyme. The extracted KS has a low gelatinization enthalpy (8.02 J/g) and a high peak viscosity (7933 cP), with obvious particle properties and low adhesion. In addition, KS is rich in polyphenols, has strong antioxidant activity, and has higher contents of amylose starch (30.74%) and resistant starch (60.18%). This study established a novel and highly efficient method for KS extraction and suggest several possible applications for KS in the food industry.

Analysis of the Aroma Chemical Composition of Commonly Planted Kiwifruit Cultivars in China.

The aroma chemical composition of commonly planted kiwifruit cultivars in China was analyzed. The combination of 2-octanone with 3-octanone was the most suitable dual internal standard for quantitative analysis in GC-MS. A total of 172 aroma components in 23 kiwifruit cultivars were detected, and ethyl butanoate, (E)-2-hexen-1-ol, and (E)-2-hexenal could be considered the core aroma components in kiwifruit, but still need further confirmation using Sensomics. E-nose could effectively distinguish different cultivars of kiwifruit. Clustering based on GC-MS and E-nose results tends to be consistent and demonstrate a certain degree of similarity. Kiwifruit cultivars with different flesh colors cannot be effectively distinguished by their aroma chemical compositions. Different species of kiwifruit can be distinguished to some extent by their aroma chemical compositions, but the effect was not satisfactory. These results could prove valuable in the breeding, planting, and marketing of kiwifruits.

Nutrient compositions and antioxidant capacity of kiwifruit (Actinidia) and their relationship with flesh color and commercial value.

The nutritional quality and antioxidant capacity of China domestic kiwifruit and imported kiwifruit with different prices and the relationships of retail price among cultivars, nutritional qualities and flesh color were investigated. Results showed that cultivar was the main factor influencing nutritional quality, though the product region could also affect the cultivar characteristics to some extent. Additionally, nutritional quality and antioxidant capacity of kiwifruit had no relationship to the product region. What's more, there was no correlation among the nutrient compositions, antioxidant capacity and retail price of kiwifruit. At the same time, the flesh color was associated with greater commercial value but was not higher nutritional quality or antioxidant capacity. Thus indicates to consumers that imported kiwifruit were not all superior to local versions, and the priciest kiwifruit did not equal to the most nutritious kiwifruit, also the color kiwifruit. There still need more research to help consumers to choose kiwifruit.

Isolation and developmental expression analysis of L-myo-inositol-1-phosphate synthase in four Actinidia species.

Myo-inositol (MI) is an important polyol involved in cellular signal transduction, auxin storage, osmotic regulation, and membrane formation. It also serves as a precursor for the production of pinitol, ascorbic acid, and members of the raffinose family. The first committed step for MI formation is catalyzed by L-myo-inositol-1-phosphate synthase (MIPS). We isolated MIPS cDNA sequences from Actinidia eriantha, Actinidia rufa, and Actinidia arguta and compared them with that of Actinidia deliciosa. Each comprised 1533 bp, encoding 510 amino acids with a predicted molecular weight of 56.5 KDa. The MIPS protein was highly conserved in Actinidia, sharing 98.94% identity among species. The MIPS gene was expressed in the flowers, leaves, petioles, and carpopodia. Similarly high levels of expression were detected in the young fruit of all four species. Overall activity of the enzyme was also maximal in young fruit, indicating that this developmental stage is the key point for MI synthesis in Actinidia. Among the four species, A. arguta had the greatest concentration of MI as well as the highest ratios of MI:sucrose and MI:glucose+fructose. This suggests that conversion to MI from carbohydrates was most efficient in A. arguta during early fruit development.