Functional characterization of two chalcone isomerase (CHI) revealing their responsibility for anthocyanins accumulation in mulberry

Transcriptomic and metabolomic analyses reveal the importance of ethylene networks in mulberry fruit ripening

Mulberry (Morus alba L.) is a climacteric and highly perishable fruit. Ethylene has been considered to be an important trigger of fruit ripening process. However, the role of ethylene in the mulberry fruit ripening process remains unclear. In this study, we performed a comprehensive analysis of metabolomic and transcriptomic data of mulberry fruit and the physiological changes accompanying the fruit ripening process. Our study revealed that changes in the accumulation of specific metabolites at different stages of fruit development and ripening were closely correlated to transcriptional changes as well as underlying physiological changes and the development of taste biomolecules. The ripening of mulberry fruits was highly associated with the production of endogenous ethylene, and further application of exogenous ethylene assisted the ripening process. Transcriptomic analysis revealed that differential expression of diverse ripening-related genes was involved in sugar metabolism, anthocyanin biosynthesis, and cell wall modification pathways. Network analysis of transcriptomics and metabolomics data revealed that many transcription factors and ripening-related genes were involved, among which ethylene-responsive transcription factor 3 (MaERF3) plays a crucial role in the ripening process. The role of MaERF3 in ripening was experimentally proven in a transient overexpression assay in apples. Our study indicates that ethylene plays a vital role in modulating mulberry fruit ripening. The results provide a basis for guiding the genetic manipulation of mulberry fruits towards sustainable agricultural practices and improve post-harvest management, potentially enhancing the quality and shelf life of mulberry fruits for sustainable agriculture and forestry.

Functional characterization of MaEXPA11 and its roles in response to biotic and abiotic stresses in mulberry

Mulberry is a traditional economic tree with various values in sericulture, ecology, food industry and medicine. Expansins (EXPs) are known as cell wall expansion related proteins and have been characterized to involve in plant development and responses to diverse stresses. In present study, twenty EXP and expansin-like (EXL) genes were identified in mulberry. RNA-seq results indicated that three EXP and EXL genes showed up-regulated expression level under sclerotiniose pathogen infection in three independent RNA-seq datasets. The most significant upregulated EXPA11 was selected as key EXP involving in response to sclerotiniose pathogen infection in mulberry. Furthermore, a comprehensive functional analysis was performed to reveal subcellular location, tissue expression profile of MaEXPA11 in mulberry. Down-regulation of MaEXPA11 using virus induced gene silence (VIGS) was performed to explore the function of MaEXPA11 in Morus alba. Results showed that MaEXPA11 can positively regulate mulberry resistance to Ciboria shiraiana infection and negatively regulate mulberry resistance to cold or drought stress.

Identification of Flavanone 3-Hydroxylase Gene Family in Strawberry and Expression Analysis of Fruit at Different Coloring Stages

The color of strawberry fruit is an important appearance quality index that affects the marketability of fruit, and the content and type of anthocyanin are two of the main reasons for the formation of fruit color. At present, the research on anthocyanin synthesis mainly focuses on the phenylpropane metabolic pathway, and the F3H gene family is an important member of this metabolic pathway. Therefore, in order to clarify the role of flavanone 3-hydroxylase (F3H) in regulating anthocyanin accumulation in strawberry, we identified F3H gene family members in strawberry and analyzed their bioinformatics and expression at different fruit color stages. The results showed that the strawberry F3H family contains 126 members, which are distributed on seven chromosomes and can be divided into six subgroups. The promoter region of strawberry F3H gene family contains light response elements, abiotic stress response elements and hormone response elements. Intraspecic collinearity analysis showed that there were six pairs of collinearity of the F3H gene. Interspecific collinearity analysis showed that there were more collinearity relationships between strawberry and apple, grape and Arabidopsis, but less collinearity between strawberry and rice. Via tissue-specific expression analysis, we found that the expression levels of FvF3H48, FvF3H120 and FvF3H74 were higher in the stages of germination, growth, flowering and fruit setting. The expression levels of FvF3H42 and FvF3H16 were higher in seeds. The expression levels of FvF3H16 and FvF3H11 were higher in the ovary wall of stage 1, stage 2, stage 3 and stage 5. FvF3H15 and FvF3H48 were highly expressed in the pericardium, anther, receptacle and anther. Real-time fluorescence quantitative PCR showed the expression changes in F3H in the fruit coloring process. The results indicate that the expression levels of most members were higher during the S3 stage, such as FvF3H7, FvF3H16, FvF3H32, FvF3H82, FvF3H89, FvF3H92 and FvF3H112. FvF3H63 and FvF3H104 exhibited particularly high expression levels during the S1 stage, with some genes also showing elevated expression during the S4 stage, including FvF3H13, FvF3H27, FvF3H66 and FvF3H103. FvF3H58, FvF3H69, FvF3H79 and FvF3H80 showed higher expression levels during the S2 stage. These findings lay the groundwork for elucidating the biological functions of the strawberry F3H gene family and the selection of related genes.

Cloning, Identification, and Functional Analysis of the Chalcone Isomerase Gene from Astragalus sinicus

Astragalus sinicus is an important winter-growing cover crop. It is widely utilized, not only as a cover crop for its benefits in fertilizing the soil but also as a landscape ground cover plant. Anthocyanins are involved in the pigmentation of plants in leaves and flowers, which is a crucial characteristic trait for A. sinicus. The formation of anthocyanins depends significantly on the enzyme chalcone isomerase (CHI). However, research on the CHI gene of A. sinicus remains unexplored. The rapid amplification of cDNA ends (RACE) approach was used in this research to clone the CHI sequence from A. sinicus (AsiCHI). The expression profiles of the AsiCHI gene in multiple tissues of A. sinicus were subsequently examined by qRT-PCR (Quantitative Real-Time PCR). Furthermore, the function of the AsiCHI was identified by the performance of ectopic expression in Arabidopsis (Arabidopsis thaliana). The outcomes revealed that the full-length cDNA of the AsiCHI gene (GeneBank: OQ870547) measured 972 bp in length and included an open reading frame of 660 bp. The encoded protein contains 219 amino acids with a molecular weight of 24.14 kDa and a theoretical isoelectric point of 5.11. In addition, the remarkable similarity between the AsiCHI protein and the CHI proteins of other Astragalus species was demonstrated by the sequence alignment and phylogenetic analysis. Moreover, the highest expression level of AsiCHI was observed in leaves and showed a positive correlation with anthocyanin content. The functional analysis further revealed that the overexpression of AsiCHI enhanced the anthocyanidin accumulation in the transgenic lines. This study provided a better understanding of AsiCHI and elucidated its role in anthocyanin production.

Full-length transcriptome analysis provides insights into flavonoid biosynthesis in Ranunculus japonicus

Ranunculus japonicus Thunb. is a traditional Chinese herb. Plants in the genus Ranunculus are generally rich in flavonoids, which have antibacterial, anti-infective, and other pharmacological effects. However, owing to the lack of reference genomes, little is known about the flavonoid biosynthetic pathway in R. japonicus. In this study, PacBio isoform sequencing (PacBio iso-seq) and DNA nanoball sequencing (DNB-seq) were combined to build a full-length transcriptome database for three different tissues of R. japonicus. A total of 395,402 full-length transcripts were obtained, of which 308,474 were successfully annotated. A Kyoto Encyclopedia of Genes and Genomes analysis identified 29 differentially expressed genes encoding nine key enzymes for flavonoid biosynthesis. Correlation analysis indicated that flavanone 3-hydroxylase and flavonol synthase genes might have key roles in the accumulation of flavonoid substances in the different tissues of R. japonicus. The structures of chalcone synthase and chalcone isomerase enzymes were spatially modeled. Reverse-transcription quantitative PCR was used to verify gene expression levels of key enzymes associated with flavonoid biosynthesis. In addition, 22 MYB transcription factors involved in flavonoid biosynthesis and phenylpropanoid biosynthesis were discovered. The reliable transcriptomic data from this study provide genetic information about R. japonicus as well as insights into the molecular mechanism of flavonoid biosynthesis. The results also provide a basis for developing the medicinal value R. japonicus.

Biological valorization of lignin to flavonoids

Lignin is the most affluent natural aromatic biopolymer on the earth, which is the promising renewable source for valuable products to promote the sustainability of biorefinery. Flavonoids are a class of plant polyphenolic secondary metabolites containing the benzene ring structure with various biological activities, which are largely applied in health food, pharmaceutical, and medical fields. Due to the aromatic similarity, microbial conversion of lignin derived aromatics to flavonoids could facilitate flavonoid biosynthesis and promote the lignin valorization. This review thereby prospects a novel valorization route of lignin to high-value natural products and demonstrates the potential advantages of microbial bioconversion of lignin to flavonoids. The biodegradation of lignin polymers is summarized to identify aromatic monomers as momentous precursors for flavonoid synthesis. The biosynthesis pathways of flavonoids in both plants and strains are introduced and compared. After that, the key branch points and important intermediates are clearly discussed in the biosynthesis pathways of flavonoids. Moreover, the most significant enzyme reactions including Claisen condensation, cyclization and hydroxylation are demonstrated in the biosynthesis pathways of flavonoids. Finally, current challenges and potential future strategies are also discussed for transforming lignin into various flavonoids. The holistic microbial conversion routes of lignin to flavonoids could make a sustainable production of flavonoids and improve the feasibility of lignin valorization.

Chromosomal-level genome and multi-omics dataset provides new insights into leaf pigmentation in Acer palmatum

Acer palmatum (A. palmatum), a deciduous shrub or small arbour which belongs to Acer of Aceraceae, is an excellent greening species as well as a beautiful ornamental plant. In this study, a high-quality chromosome-level reference genome for A. palmatum was constructed using Oxford Nanopore sequencing and Hi-C technology. The assembly genome was ∼745.78 Mb long with a contig N50 length of 3.20 Mb, and 95.30 % (710.71 Mb) of the assembly was anchored into 13 pseudochromosomes. A total of 28,559 protein-coding genes were obtained, ∼90.02 % (25,710) of which could be functionally annotated. The genomic evolutionary analysis revealed that A. palmatum is most closely related to A. yangbiense and A. truncatum, and underwent only an ancient gamma whole-genome duplication event. Despite lacking a recent independent WGD, 25,795 (90.32 %) genes of A. palmatum were duplicated, and the unique/expanded gene families were linked with genes involved in plant-pathogen interaction and several metabolic pathways, which might underpin adaptability. A combined genomic, transcriptomic, and metabolomic analysis related to the biosynthesis of anthocyanin in leaves during the different season were characterized. The results indicate that the dark-purple colouration of the leaves in spring was caused by a high amount of anthocyanins, especially delphinidin and its derivatives; and the red colouration of the leaves in autumn by a high amount of cyanidin 3-O-glucoside. In conclusion, these valuable multi-omic resources offer important foundations to explore the molecular regulation mechanism in leaf colouration and also provide a platform for the scientific and efficient utilization of A. palmatum.

Identification of Chalcone Isomerase Family Genes and Roles of CnCHI4 in Flavonoid Metabolism in Camellia nitidissima

Camellia nitidissima is a woody plant with high ornamental value, and its golden-yellow flowers are rich in a variety of bioactive substances, especially flavonoids, that are beneficial to human health. Chalcone isomerases (CHIs) are key enzymes in the flavonoid biosynthesis pathway; however, there is a scarcity of information regarding the CHI family genes of C. nitidissima. In this study, seven CHI genes of C. nitidissima were identified and divided into three subfamilies by phylogenetic analysis. The results of multiple sequence alignment revealed that, unlike CnCHI1/5/6/7, CnCHI2/3/4 are bona fide CHIs that contain all the active site and critical catalytic residues. Analysis of the expression patterns of CnCHIs and the total flavonoid content of the flowers at different developmental stages revealed that CnCHI4 might play an essential role in the flavonoid biosynthesis pathway of C. nitidissima. CnCHI4 overexpression significantly increased flavonoid production in Nicotiana tabacum and C. nitidissima. The results of the dual-luciferase reporter assay and yeast one-hybrid system revealed that CnMYB7 was the key transcription factor that governed the transcription of CnCHI4. The study provides a comprehensive understanding of the CHI family genes of C. nitidissima and performed a preliminary analysis of their functions and regulatory mechanisms.

Systematic functional characterization of cinnamyl alcohol dehydrogenase family members revealed their functional divergence in lignin biosynthesis and stress responses in mulberry

Mulberry (Morus) is used as a feed additive and biofuel materials. Cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.95) catalyzes the final step of monolignol biosynthesis and is responsible for various monolignols. Five MaCADs from Morus alba were cloned and functionally characterized in the present study. These MaCADs encoded proteins with 357-364 amino acids, and the putative protein sequences conservatively possessed two Zn²⁺ binding motifs and an NADP(H) cofactor binding motif. However, MaCAD1, 2, and 5 shared similar amino acids at substrate binding positions that differed from those possessed by bona fide CADs. MaCAD3 and 4 had conservative substrate binding sites, and both phylogenetic and expression profile analysis indicated they were bona fide CADs involved in lignin biosynthesis. The enzymatic assay showed that MaCAD1 and 5 had a high affinity to p-coumaryl aldehyde. MaCAD4 preferentially used coniferyl aldehyde and sinapyl aldehyde as substrates. His-72 and Tyr-124 in MaCAD1 stabilized p-coumaryl aldehyde, and may have resulted in the substrate preference for p-coumaryl aldehyde. Down-regulation of MaCADs in mulberry showed that MaCAD3/4 were dominant CADs that functioned in monolignol biosynthesis, and decreased MaCAD3/4 resulted in significant decreases of lignin content in both stems and leaves. MaCADs exhibited different expression patterns in response to various stresses, indicating their possible diverse roles. MaCAD2 and MaCAD5 may play positive roles in response to drought and cold stresses, respectively. These results provide a systematic functional analysis of MaCADs in mulberry and an important foundation for the genetic modification of the monolignol pathway in mulberry.

Direct evidence of drought stress memory in mulberry from a physiological perspective: Antioxidative, osmotic and phytohormonal regulations

Drought stress commonly happens more than once during the life cycle of perennial trees. Stress memory endows better capacity to cope with repeated stresses for plants, while the underlying mechanisms are not fully elucidated. In this study, 2-month-old saplings of two mulberry cultivars (Husang32 and 7307 of Morus multicaulis) with or without an early soil water deficit were subjected to subsequent drought for 9 days. The shoot height growth, biomass production, stable carbon isotope discrimination, phytohormones, reactive oxygen species (ROS), osmotic substances and antioxidant enzymes were analyzed after the first and the second drought, respectively. Drought priming saplings sustained comparable or slightly higher biomass accumulation under the second drought than those non-priming. They also exhibited decreased levels of soluble sugars, free proline and soluble proteins, lower accumulation of malonaldehyde (MDA) and superoxide anion (O₂^•-), reduced activities of superoxide dismutase (SOD) and peroxidase (POD) compared to non-priming plants. Moreover, cultivar Husang32 exhibited elevated abscisic acid (ABA) and jasmonic acid (JA) where 7307 displayed opposite changes. PCA suggests that MDA, H₂O₂, free proline, SOD and POD in roots, and ROS, soluble sugars and glutamate reductase in leaves are dominant factors influenced by stress memory. ABA and JA in leaves also play important roles in exerting drought imprints. Collectively, stress memory can confer mulberry resistance to recurrent drought via combined regulations of antioxidative protection, osmotic adjustment and phytohormonal responses.

The Ethylene Response Factor ERF5 Regulates Anthocyanin Biosynthesis in 'Zijin' Mulberry Fruits by Interacting with MYBA and F3H Genes

Ethylene promotes ripening in fruits as well as the biosynthesis of anthocyanins in plants. However, the question of which ethylene response factors (ERFs) interact with the genes along the anthocyanin biosynthesis pathway is yet to be answered. Herein, we conduct an integrated analysis of transcriptomes and metabolome on fruits of two mulberry genotypes ('Zijin', ZJ, and 'Dashi', DS, with high and low anthocyanin abundance, respectively) at different post-flowering stages. In total, 1035 upregulated genes were identified in ZJ and DS, including MYBA in the MBW complex and anthocyanin related genes such as F3H. A KEGG analysis suggested that flavonoid biosynthesis and plant hormone signaling transduction pathways were significantly enriched in the upregulated gene list. In particular, among 103 ERF genes, the expression of ERF5 showed the most positive correlation with the anthocyanin change pattern across both genotypes and in the post-flowering stages, with a Pearson correlation coefficient (PCC) of 0.93. Electrophoresis mobility shift assay (EMSA) and luciferase assay suggested that ERF5 binds to the promoter regions of MYBA and F3H and transcriptionally activates their gene expression. We elucidated a potential mechanism by which ethylene enhances anthocyanin accumulation in mulberry fruits and highlighted the importance of the ERF5 gene in controlling the anthocyanin content in mulberry species. This knowledge could be used for engineering purposes in future mulberry breeding programs.

Integrating Transcriptomic and Metabolomic Analyses to Explore the Effect of Color Under Fruit Calyx on That of Fruit Apex in Eggplant (Solanum melongena L.)

Fruit color is an important commercial characteristic of eggplant (Solanum melongena L.), which affects both the profits of growers and consumer choice. Two eggplant inbred lines were discovered: “Z,” which is a light purple color under the fruit calyx, with purple on the fruit apex; and “L,” fruits of which are green under the calyx and at the apex. To determine the molecular mechanisms underlying the effect of fruit peel color under the calyx on that at the fruit apex, we conducted a combined transcriptomic and metabolomic analyses of the Z and L inbred eggplant lines. Transcriptome analysis of peel samples from three fruit regions (under the calyx, the apex, and the middle surface) of each line was conducted by RNA sequencing, and generated a total of 791,512,404 clean reads from 18 samples (three biological replicates). Differentially expressed genes (DEGs; n = 424) were identified in comparisons of peel samples from the three sites of L line fruits. Gene ontology analysis showed that “catalytic activity” was extremely significantly enriched. Further, DEGs (n = 8) were enriched in the Kyoto Encyclopedia of Genes and Genomes pathway “flavonoid biosynthesis.” Levels of CHI, LDOX, F3′5′H, and dihydroflavonol reductase were higher in the Z line than the L line. In addition, metabolome analysis showed that, 10 differentially accumulated metabolites were detected between peel samples from the apex of L and Z line fruit. The most significant DAM was delphinidin-3-O-rutinoside (Z line content, 34.89 μg/g vs. L line content 0.01 μg/g). Combined transcriptomic and metabolomic analyses indicated that DFR and F3′5′H were closely related to content of the metabolites, cyanidin and delphinidin, and that some downstream metabolites differed significantly between the L and Z lines. Content levels of delphinidin-3-O-rutinoside, delphinidin-3-O-glucoside, cyanidin-3-O-glucoside, and cyanidin-3-O-rutinoside were markedly down-regulated in the L line. Altogether, increased CHI levels could up-regulate the downstream genes, LDOX, F3′5′H, and DFR, which further lead to increasing the content of delphindin. Thus, the uniform purple color was presented at the apex of fruits in Z plants. These findings not only identify key candidate genes, but will also improve understanding of the genetics and the efficiency of breeding for eggplant fruit color.

Comprehensive analysis of the MYB transcription factor gene family in Morus alba

BACKGROUND

The V-myb myeloblastosis viral oncogene homolog (MYB) family of proteins is large, containing functionally diverse transcription factors. However, MYBs in Morus are still poorly annotated and a comprehensive functional analysis of these transcription factors is lacking.

RESULTS

In the present study, a genome-wide identification of MYBs in Morus alba was performed. In total 166 MaMYBs were identified, including 103 R2R3-MYBs and four 3R-MaMYBs. Comprehensive analyses, including the phylogenetic analysis with putative functional annotation, motif and structure analysis, gene structure organization, promoter analysis, chromosomal localization, and syntenic relationships of R2R3-MaMYBs and 3R-MaMYBs, provided primary characterization for these MaMYBs. R2R3-MaMYBs covered the subgroups reported for R2R3-MYBs in Arabidopsis and Populus, and had two Morus-specific subgroups, indicating the high retention of MYBs in Morus. Motif analysis revealed high conservative residues at the start and end of each helix and residues consisting of the third helix in R2 and R3 repeats. Thirteen intron/exon patterns (a-m) were summarized, and the intron/exon pattern of two introns with phase numbers of 0 and 2 was the prevalent pattern for R2R3-MaMYBs. Various cis-elements in promoter regions were identified, and were mainly related to light response, development, phytohormone response, and abiotic and biotic stress response and secondary metabolite production. Expression patterns of R2R3-MaMYBs in different organs showed that MaMYBs involved in secondary cell wall components and stress responsiveness were preferentially expressed in roots or stems. R2R3-MaMYBs involved in flavonoid biosynthesis and anthocyanin accumulation were identified and characterized based on functional annotation and correlation of their expression levels with anthocyanin contents.

CONCLUSION

Based on a comprehensive analysis, this work provided functional annotation for R2R3-MYBs and an informative reference for further functional dissection of MYBs in Morus.

Functional Characterization of Flavanone 3-Hydroxylase (F3H) and Its Role in Anthocyanin and Flavonoid Biosynthesis in Mulberry

Mulberry (Morus spp., Moraceae) is an important economic crop plant and is rich in flavonoids and anthocyanidins in ripe fruits. Anthocyanins are glycosides of anthocyanidins. Flavanone 3-hydroxylase (F3H) catalyzes the conversion of naringenin into dihydroflavonols and is responsible for the biosynthesis of flavonols and anthocyanidins. In this study, MazsF3H was cloned and characterized from Morus atropurpurea var. Zhongshen 1. Conserved motif analysis based on alignment and phylogenetic analysis indicated that MazsF3H belonged to 2-oxoglutarate-dependent dioxygenase and MazsF3H clustered with F3Hs from other plants. MazsF3H was located in both nucleus and cytosol. MazsF3H was expressed in stems, leaves, stigmas and ovaries, except buds. F3H expression levels showed a positive and close relationship with anthocyanin content during the anthocyanin-rich fruit ripening process, while it showed a negative correlation with anthocyanin content in LvShenZi, whose fruits are white and would not experience anthocyanin accumulation during fruit ripening. Significantly different F3H expression levels were also found in different mulberry varieties that have quite different anthocyanin contents in ripe fruits. Overexpression MazsF3H in tobacco showed unexpected results, including decreased anthocyanin content. Down-regulation of F3H expression levels resulted in co-expression of the genes involved in anthocyanin biosynthesis and a significant decrease in anthocyanin content, but the change in total flavonoid content was subtle. Our results indicated that F3H may play quite different roles in different varieties that have quite different fruit colors. In addition, possible complex regulation of flavonoid biosynthesis should be further explored in some of the featured plant species.

The Flavonoid Biosynthesis Network in Plants

Flavonoids are an important class of secondary metabolites widely found in plants, contributing to plant growth and development and having prominent applications in food and medicine. The biosynthesis of flavonoids has long been the focus of intense research in plant biology. Flavonoids are derived from the phenylpropanoid metabolic pathway, and have a basic structure that comprises a C15 benzene ring structure of C6-C3-C6. Over recent decades, a considerable number of studies have been directed at elucidating the mechanisms involved in flavonoid biosynthesis in plants. In this review, we systematically summarize the flavonoid biosynthetic pathway. We further assemble an exhaustive map of flavonoid biosynthesis in plants comprising eight branches (stilbene, aurone, flavone, isoflavone, flavonol, phlobaphene, proanthocyanidin, and anthocyanin biosynthesis) and four important intermediate metabolites (chalcone, flavanone, dihydroflavonol, and leucoanthocyanidin). This review affords a comprehensive overview of the current knowledge regarding flavonoid biosynthesis, and provides the theoretical basis for further elucidating the pathways involved in the biosynthesis of flavonoids, which will aid in better understanding their functions and potential uses.

Photoprotection of Arabidopsis leaves under short-term high light treatment: The antioxidant capacity is more important than the anthocyanin shielding effect

Photoprotection strategies that have evolved in plants to cope with high light (HL) stress provide plants with the ability to resist HL. However, it has not been clearly confirmed which photoprotection strategy is the major HL resistance mechanism. To reveal the major photoprotection mechanism against short-term high light (STHL), the physiological and biochemical responses of three Arabidopsis mutants (Col, chi and ans) under STHL were analyzed in this study. After STHL treatment, the most serious photosynthetic pigment damage was observed in chi plants. At the same time, the degrees of membrane and Rubisco damage in chi was the highest, followed by Col, and ans was the smallest. The results showed that ans with high antioxidant capacity showed higher resistance to STHL treatment than Col containing anthocyanins, while chi with no anthocyanin accumulation and small antioxidant capacity had the lowest resistance. In addition, the gene expression results showed that plants tend to synthesize anthocyanin precursor flavonoids with antioxidant capacity under STHL stress. To further determine the major mechanism of photoprotection under STHL, we also analyzed Arabidopsis lines (Col, CHS1, CHS2 and tt4) that had the same anthocyanin content but different antioxidant capacities. It was found that CHS2 with high antioxidant capacity had higher cell viability, smaller maximal quantum yield of PSII photochemistry (F_v/F_m) reduction and less reactive oxygen species (ROS) accumulation under HL treatment of their mesophyll protoplasts. Therefore, the antioxidant capacity provided by antioxidant substances was the major mechanism of plant photoprotection under STHL treatment.

Applications of virus-induced gene silencing for identification of gene function in fruit

With the development of bioinformatics, it is easy to obtain information and data about thousands of genes, but the determination of the functions of these genes depends on methods for rapid and effective functional identification. Virus-induced gene silencing (VIGS) is a mature method of gene functional identification developed over the last 20 years, which has been widely used in many research fields involving many species. Fruit quality formation is a complex biological process, which is closely related to ripening. Here, we review the progress and contribution of VIGS to our understanding of fruit biology and its advantages and disadvantages in determining gene function.