Water deficit mechanisms in perennial shrubs Cerasus humilis leaves revealed by physiological and proteomic analyses

Integrated Analysis of the Metabolome and Transcriptome on Anthocyanin Biosynthesis in Four Developmental Stages of Cerasus humilis Peel Coloration

Cerasus humilis is a unique dwarf shrub and fruit color is an important trait in the species. In this study, we evaluated the transcriptomic and metabolomic profiles of the plant at different developmental stages to elucidate the mechanism underlying color formation. In a metabolomics analysis, 16 anthocyanin components were identified at four developmental stages, and high levels of cyanidin O-syringic acid and pelargonidin 3-O-beta-d-glucoside (callitephin chloride) were correlated with the reddening of the fruit peel. A co-expression analysis revealed that ANS and UFGT play key roles in pigmentation (PCC > 0.82). Additionally, transcriptome data showed that most anthocyanin biosynthetic genes and two MYB transcription factors were significantly up-regulated. QRT-PCR results for these differentially expressed genes were generally consistent with the high-throughput sequencing. Moreover, the overexpression of ChMYB1 (TRINITY_DN21536_c0_g1) in apple calli could contribute to the accumulation of anthocyanin. It was also found that UFGT (TRINITY_DN19893_c1_g5) and ChMYB1 (TRINITY_DN21536_c0_g1) have similar expression patterns. These findings provide insight into the mechanisms underlying anthocyanin accumulation and coloration during fruit peel development, providing a basis for the breeding of anthocyanin-rich C. humilis cultivars.

Identification of LecRLK gene family in Cerasus humilis through genomic-transcriptomic data mining and expression analyses

Lectin receptor-like protein kinases (LecRLKs) have been shown to be involved in plants’ responses to various biotic and abiotic stresse factors. Cerasus humilis is an important fruit species widely planted for soil and water conservation in northern China due to its strong tolerance to drought and salinity stresses. In this study, a total of 170 LecRLK family genes (125 G-types, 43 L-types and 2 C-types) were identified in the newly released whole-genome sequences of C. humilis. Furthermore, nine representative LecRLK genes in young plants of C. humilis under varying drought and salinity stresses were selected for qRT-PCR analysis. Our systematic comparative analyses revealed the active participation of these nine LecRLK genes in the salt and drought stress responses of C. humilis. The results from our study have provided a solid foundation for future functional verification of these LecRLK family genes and will likely help facilitate the more rapid and effective development of new stress resistant Cerasus humilis cultivars.

Fruit quality and antioxidant potential of Prunus humilis Bunge accessions

In this study, we aimed to evaluate the fruit quality of Prunus humilis and identify cultivars that could provide superior human health benefits. We measured the basic characteristics, bioactive compounds, and antioxidant capacities of 137 P. humilis accessions. Flavonoid and phenol content were determined via colorimetry and ultrahigh performance liquid chromatography. Single fruit and stone weights varied widely and were genetically diverse among accessions. The variation in soluble solid content was comparatively narrow. Total flavonoid content (TFC) ranged from 3.90 to 28.37 mg/g FW, with an average of 10.58 mg/g FW in 2019. Significant differences between accessions in terms of TFC, total phenol content, and antioxidant capacity were found. TFC in the accessions was normally distributed and predominantly in the medium range (9.57-15.23 mg/g FW). Red was the predominant peel color over all other phenotypes (i.e., dark red, red, light red, red-orange, and yellow). There was no obvious correlation between peel color and TFC. Catechin was the major flavonoid component in the fruit. Principal component analysis showed that TFC, ABTS, single fruit weight, and vertical and horizontal diameter contributed to the first two principal components for each accession. Accessions 10-02, 3-17-2, 3-17-4, and JD1-6-7-37 were characterized by high TFC, ABTS, and large fruit. We believe that our results will aid in the breeding and functional food processing of Prunus humilis.

Differential Regulation of Anthocyanins in Cerasus humilis Fruit Color Revealed by Combined Transcriptome and Metabolome Analysis

Coloring is an important appearance quality of fruit. In order to evaluate the relationship between metabolites and fruit color, we analyzed the metabolites and transcriptional profiles of two different Cerasus humilis cultivars: “RF” (cv. Zhangwu, red fruit) and “YF” (cv. Nongda No.5, yellow fruit). The results of identification and quantification of metabolites showed that there were significant differences in the contents of 11 metabolites between RF and YF. Transcriptomics was used to analyze the expression patterns of genes related to the anthocyanin biosynthesis pathway, and subsequently, the regulation network of anthocyanin biosynthesis was established to explore their relationship with color formation. QRT-PCR, performed for 12 key genes, showed that the expression profiles of the differentially expressed genes were consistent with the results of the transcriptome data. A co-expression analysis revealed that the late genes were significantly positively correlated with most of the different metabolites. The results of the study provide a new reference for improving the fruit color of Cerasus humilis in the future.

Physiological and iTRAQ-based proteomic analyses reveal that melatonin alleviates oxidative damage in maize leaves exposed to drought stress

To explain the underlying mechanism of melatonin-mediated drought stress responses in maize, maize pre-treated with or without melatonin was subjected to 20% PEG nutrient solution to induce drought stress. We found that exogenous melatonin significantly improved drought tolerance, demonstrated by improved photosynthesis, reduced ROS accumulation, enhanced activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and increased content of glutathione (GSH). Comparative iTRAQ proteomic analyses revealed a higher abundance of differentially expressed proteins (DEPs) in melatonin-treated maize under drought stress for carbon fixation in photosynthetic organisms, photosynthesis, biosynthesis of amino acids, and biosynthesis of secondary metabolites, compared to untreated plants. Changes in the above molecular mechanisms could explain the melatonin-induced physiological effects associated with drought tolerance. In summary, this study provides a more integrated picture about the effects of melatonin on the physiological and molecular mechanisms in maize seedlings responding to drought stress.

Analysis of Polyphenols Composition and Antioxidant Activity Assessment of Chinese Dwarf Cherry (Cerasus humilis (Bge.) Sok.)

The fruits of Chinese dwarf cherry ( Cerasus humilis (Bge.) Sok.), which is unique to China, can be canned and used to make products such as jam and wine. They also contain abundant bioactive compounds, including cinnamoylquinic acids and flavonoids. However, there has been no systematic study on the functional compounds in these fruits. In this study, the polyphenol compounds of 28 different genotypes of Chinese dwarf cherry in Liaoning province were systematically characterized using high-performance liquid chromatography with photodiode array detection and HPLC coupled with quadrupole time-of-flight mass spectrometry. A total of 31 polyphenols, including 6 anthocyanins, 7 cinnamoylquinic acids, 1 flavone, and 17 flavonols, were identified, and 23 of these compounds were detected in Chinese dwarf cherry for the first time. In addition, 4 genotypes showed higher total polyphenol content and antioxidant activities. It may be advantageous to use these 4 genotypes for commercial processing of Chinese dwarf cherry fruits into healthcare products. The results of this study will improve understanding of the chemical mechanism of polyphenols formation and lay the foundation for selective functional composition breeding in Chinese dwarf cherry.

Overexpression of the ChVDE gene, encoding a violaxanthin de-epoxidase, improves tolerance to drought and salt stress in transgenic Arabidopsis

To investigate the protective mechanism of violaxanthin de-epoxidase (VDE) zeaxanthin in Cerasus humilis under drought and salt-stress conditions, we cloned the entire cDNA sequence of ChVDE from C. humilis and generated ChVDE-overexpression (OE) and ChVDE-complementation (CE) Arabidopsis plants. The open reading frame of ChVDE contained 1,446 bp nucleotides and encoded 481 amino acids. The ChVDE showed the highest similarity with those of Camellia sinensis and Citrus sinensis. Subcellular localization analysis showed that ChVDE was located in the chloroplasts. OE plants showed stronger root growth and higher levels of total chlorophyll as compared to WT and VDE mutant (npq1-2) plants. Moreover, the relative de-epoxidation state of the xanthophyll cycle pigments (A + Z)/(V + A+Z) was higher in OE plants than in the controls. OE plants had enhanced photosynthetic rates, respiration rates, and transpiration rates compared with the WT or npq1-2 plants after drought or salt treatment. Collectively, our results demonstrate that ChVDE plays a positive role in both drought and salt tolerance.

Carbenoxolone ameliorates insulin sensitivity in obese mice induced by high fat diet via regulating the IκB-α/NF-κB pathway and NLRP3 inflammasome

The characteristic feature of obesity and insulin resistance is chronic low-grade inflammation. Nod-Like Receptor Pyrin 3 (NLRP3) inflammasome plays a central role in obesity-induced insulin resistance. However, how does Carbenoxolone (CBX) play its role in ameliorating insulin resistance in peripheral tissues of obese mice induced by high-fat diet (HFD) remains unknown. In our study, we explored the molecular mechanism of CBX in improving insulin resistance in liver and skeletal muscle in mice induced by the HFD. Our results revealed that in the CBX group, a significant decrease in fasting blood glucose, insulin and HOMA-IR score were observed. CBX could attenuate intracellular lipid accumulation and inflammation aggravation in liver and skeletal muscle. Besides, treatment with CBX could significantly reduce expressions of p-IκB-α, p-NF-κB, p-IRS-1, NLRP3 and inflammatory factors, increase expressions of p-PI3K and p-AKT. Therefore, CBX could dramatically improve insulin resistance in liver and skeletal muscle in mice induced by the high-fat diet. In conclusions, we demonstrate that CBX has a significant protective effect on diet-induced obesity in mice. The potential mechanisms include inhibiting IκB-α/NF-κB pathway, restricting the production of NLRP3 inflammasome and other inflammatory factors, reducing the expression of p-IRS-1, increasing the expressions of p-PI3K and p-AKT, thus ameliorating insulin resistance in liver and skeletal muscle of high-fat diet mice. Therefore CBX is an active agent against diet-induced obesity and is given the opportunity for the treatment of obesity related diseases.