摘要：
Pepper (Capsicum annuum L.), recognized as a globally preeminent vegetable, holds substantial economic and nutritional value. The BTB (broad-complex, tramtrack, and bric-a-brac) family of proteins, characterized by a highly conserved BTB domain, also denoted as the POZ domain, are intricately involved in a diverse array of biological processes. However, the existing corpus of research regarding pepper BTB genes remains relatively meager. In this study, a total of 72 CaBTB gene members were meticulously identified from the entire genome of pepper. Phylogenetic analysis illuminated the presence of conspicuous collinear relationships between the CaBTB genes and those of its closely affiliated species. Gene expression profiling and RT-qPCR analysis revealed that multiple CaBTB genes exhibited pronounced differential expression under diverse treatment regimens. Expression pattern analysis unveiled that CaBTB25 manifested a remarkably elevated abundance in leaves. Moreover, its promoters were replete with an abundance of light-responsive cis-elements. Our comprehensive and in-depth explorations into subcellular localization revealed that CaBTB25 was predominantly detected to localize within the nucleus and lacked transcriptional activation. This research provides a crucial theoretical edifice, enabling a more profound understanding of the biological functions of the BTB gene family in pepper, thereby underscoring its potential significance within the intricate network of gene-environment interactions.
通讯机构：
[Zou, XX; Ou, LJ ; Liu, ZB] H;[Zou, XX ] N;Hunan Agr Univ, Coll Hort, Engn Res Ctr Hort Crop Germplasm Creat & New Varie, Key Lab Vegetable Biol Hunan Prov,Minist Educ, Changsha 410125, Peoples R China.;Nanjing Agr Univ, Coll Hort, 1 Weigang, Nanjing 210095, Peoples R China.;Yuelushan Lab, Changsha 410128, Peoples R China.
摘要：
Carotenoids play indispensable roles in the ripening process of fleshy fruits. Capsanthin is a widely distributed and utilized natural red carotenoid. However, the regulatory genes involved in capsanthin biosynthesis remain insufficient. Here, we identified the MADS-box transcription factor RIPENING INHIBITOR (MADS-RIN) in pepper (Capsicum annuum), which regulates ripening in climacteric tomato (Solanum lycopersicum) fruits, using weighted gene co-expression network analysis. We found MADS-RIN can directly bind to the promoters of carotenoid biosynthetic genes phytoene synthase 1 (PSY1) and capsanthin/capsorubin synthase (CCS) and the promoter of DIVARICATA1 to activate their expression, thereby regulating carotenoid biosynthesis directly or indirectly. The physical interaction between MADS-RIN and DIVARICATA1 enhances the transactivation effect on PSY1 and CCS. The self-transactivation of MADS-RIN demonstrates its capability to expedite the above process under specific conditions. Interestingly, chromatin immunoprecipitation sequencing assays revealed consistency and divergence of potential targets of MADS-RIN in climacteric tomato and nonclimacteric pepper fruits, suggesting potential conservation and variation of MADS-RIN in regulating ripening and carotenoid metabolism. The present study illustrates the regulatory mechanism of the MADS-RIN-DIVARICATA1 module in capsanthin biosynthesis in pepper, providing targets for breeding high-quality peppers. These findings enrich our understanding of the regulatory network of carotenoid biosynthesis and offer insights into the complex mechanisms of MADS-RIN in climacteric/nonclimacteric fruit ripening and carotenoid biosynthesis. A MADS-box transcription factor, RIPENING INHIBITOR (MADS-RIN), regulates carotenoid biosynthesis in nonclimacteric pepper fruits through its dominant MADS-RIN-DIVARICATA1 module.
摘要：
Pepper ( Capsicum annuum L.) is a typical self-pollinating crop with obvious heterosis in hybrids. Consequently, the use of morphological markers during the pepper seedling stage is crucial for pepper breeding. The color of hypocotyl is widely used as a phenotypic marker in crossing studies of pepper. Pepper accessions generally have purple hypocotyls, which are mainly due to the anthocyanin accumulation in seedlings, and green hypocotyls are rarely observed in pepper. Here we reported the characterization of a green hypocotyl mutant of pepper, Cha1 , which was identified from a pepper ethyl methanesulfonate (EMS) mutant library. Fine mapping revealed that the causal gene, CaTTG1 , belonging to the WD40 repeat family, controlled the green hypocotyl phenotype of the mutant. Virus-induced gene silencing (VIGS) confirmed that CaTTG1 regulated anthocyanin accumulation. RNA-seq data showed that expression of structural genes CaDFR , CaANS , and CaUF3GT in the anthocyanin biosynthetic pathway was significantly decreased in Cha1 compared to the wild type. Yeast two-hybrid (Y2H) experiments also confirmed that CaTTG1 activated the synthesis of anthocyanin structural genes by forming a MBW complex with CaAN1 and CaGL3. In summary, this study provided a green hypocotyl mutant of pepper, and the Kompetitive Allele Specific PCR (KASP) marker developed based on the mutation site of the underlying gene would be helpful for pepper breeding.
Pepper ( Capsicum annuum L.) is a typical self-pollinating crop with obvious heterosis in hybrids. Consequently, the use of morphological markers during the pepper seedling stage is crucial for pepper breeding. The color of hypocotyl is widely used as a phenotypic marker in crossing studies of pepper. Pepper accessions generally have purple hypocotyls, which are mainly due to the anthocyanin accumulation in seedlings, and green hypocotyls are rarely observed in pepper. Here we reported the characterization of a green hypocotyl mutant of pepper, Cha1 , which was identified from a pepper ethyl methanesulfonate (EMS) mutant library. Fine mapping revealed that the causal gene, CaTTG1 , belonging to the WD40 repeat family, controlled the green hypocotyl phenotype of the mutant. Virus-induced gene silencing (VIGS) confirmed that CaTTG1 regulated anthocyanin accumulation. RNA-seq data showed that expression of structural genes CaDFR , CaANS , and CaUF3GT in the anthocyanin biosynthetic pathway was significantly decreased in Cha1 compared to the wild type. Yeast two-hybrid (Y2H) experiments also confirmed that CaTTG1 activated the synthesis of anthocyanin structural genes by forming a MBW complex with CaAN1 and CaGL3. In summary, this study provided a green hypocotyl mutant of pepper, and the Kompetitive Allele Specific PCR (KASP) marker developed based on the mutation site of the underlying gene would be helpful for pepper breeding.
摘要：
Natural genetic variation can be used to improve important crop agronomic traits, and understanding the genetic basis of natural variation in fruit shape can help breeders develop pepper varieties that meet market demand. In this study, we identified a QTL controlling fruit length-width ratio by conventional genetic mapping, encoding a previously uncharacterized gene CaIQD1. Reduced CaIQD1 expression resulted in short and wide fruits in pepper, whereas heterologous overexpression of CaIQD1 resulted in narrower fruits in tomato. Further experiments suggested that CaIQD1 regulates fruit shape in pepper by affecting cell proliferation, expansion and morphological changes. CaIQD1 also has a direct protein interaction with CaOFP20 in CaTRM-like-CaOFP20. Reduced CaOFP20 expression caused pepper fruits to become elongated and curved, whereas reduced CaTRM-like expression led to the formation of rounder fruits. These gene expression changes had a significant effect on the expression of genes related to the cell cycle and cell expansion. The CaTRM-like-CaOFP20-CaIQD1 module may thus represent a conserved regulatory pathway for controlling pepper fruit shape. CaIQD1 also showed direct interactions with the pepper calmodulin CaCaM7, the tubulin CaMAP70-2 and the microtubule motor protein CaKLCR1, suggesting that the regulation of fruit shape by CaIQD1 is related to changes in microtubule dynamics mediated by Ca(2+)-CaM. We also found that CaIQD1 interacts with several homologues of genes that typically regulate fruit shape in other plant species. In summary, our results show that CaIQD1 acts as a core hub in regulating pepper fruit shape through interactions with multiple proteins.
通讯机构：
[Zou, XX; Ou, LJ ] H;[Hou, XL; Zou, XX ] N;Nanjing Agr Univ, Coll Hort, 1 Weigang, Nanjing 210095, Peoples R China.;Hunan Agr Univ, Coll Hort, Engn Res Ctr Hort Crop Germplasm Creat & New Varie, Key Lab Vegetable Biol Hunan Prov,Minist Educ, Changsha 410125, Peoples R China.;Yuelushan Lab, Changsha 410128, Peoples R China.
关键词：
Red pepper;Metabolomics;Transcriptomics;Natural pigment;Flavonoid;Carotenoid;Regulatory gene
摘要：
Pepper is highly popular as a vegetable, spice, and natural red pigment material. However, little is known about metabolite accumulation dynamics in red pepper pericarp, which limits the full utilization of nutrients at different stages of pepper pericarp development. Moreover, few regulatory genes responsible for natural pigment flavonoids and carotenoids biosynthesis were reported in peppers, resulting in a constrained understanding of the molecular mechanisms that contribute to their formation. Here, we identified 1429 metabolites for the first time during the development and ripening processes of three color-transition types of red peppers (white/purple/green transition to red, respectively), by widely-targeted and carotenoid-targeted metabolomics analysis. Metabolites’ weighted gene co-expression network analysis (mWGCNA) was performed to analyze the accumulation patterns of metabolites in widely-targeted metabolomics. Among them, 290 flavonoids and 68 carotenoids were identified, revealing the material basis of the natural purple color and red color peppers. The formation of the purple color in '5' is crucially dependent on delphinidin-3-O-(2′''-O-p-coumaroyl) rutinoside-5-O-glucoside and delphinidin-3-O-(2′''-O-p-coumaroyl) rutinoside-7-O-glucoside, especially the former, while capsanthin plays a crucial role in the appearance of the red color in peppers. Integrating transcriptome and metabolome data for WGCNA, potential regulatory genes MYB113, TT8, TT8 - like, TTG1 , and BRF for anthocyanins biosynthesis, and DIVARICATA1, MADS - RIN, AGL9 - like , and Y subunit for capsanthin biosynthesis were identified. Our research is crucial for maximizing the edible and industrial application of pepper. The identified potential regulatory genes for anthocyanins and capsanthin provide a reference for an in-depth study of natural pigment biosynthetic mechanisms in pepper.
Pepper is highly popular as a vegetable, spice, and natural red pigment material. However, little is known about metabolite accumulation dynamics in red pepper pericarp, which limits the full utilization of nutrients at different stages of pepper pericarp development. Moreover, few regulatory genes responsible for natural pigment flavonoids and carotenoids biosynthesis were reported in peppers, resulting in a constrained understanding of the molecular mechanisms that contribute to their formation. Here, we identified 1429 metabolites for the first time during the development and ripening processes of three color-transition types of red peppers (white/purple/green transition to red, respectively), by widely-targeted and carotenoid-targeted metabolomics analysis. Metabolites’ weighted gene co-expression network analysis (mWGCNA) was performed to analyze the accumulation patterns of metabolites in widely-targeted metabolomics. Among them, 290 flavonoids and 68 carotenoids were identified, revealing the material basis of the natural purple color and red color peppers. The formation of the purple color in '5' is crucially dependent on delphinidin-3-O-(2′''-O-p-coumaroyl) rutinoside-5-O-glucoside and delphinidin-3-O-(2′''-O-p-coumaroyl) rutinoside-7-O-glucoside, especially the former, while capsanthin plays a crucial role in the appearance of the red color in peppers. Integrating transcriptome and metabolome data for WGCNA, potential regulatory genes MYB113, TT8, TT8 - like, TTG1 , and BRF for anthocyanins biosynthesis, and DIVARICATA1, MADS - RIN, AGL9 - like , and Y subunit for capsanthin biosynthesis were identified. Our research is crucial for maximizing the edible and industrial application of pepper. The identified potential regulatory genes for anthocyanins and capsanthin provide a reference for an in-depth study of natural pigment biosynthetic mechanisms in pepper.
通讯机构：
[Xiong, C; Zhu, F; Liu, F ] H;Hunan Agr Univ, Coll Hort, Engn Res Ctr Germplasm Innovat & New Varieties Bre, Key Lab Vegetable Biol Hunan Prov, Changsha 410128, Peoples R China.
摘要：
Chlorophylls and carotenoids are 2 pivotal photosynthetic pigments directly influencing the economic value of pepper (Capsicum annuum L.) fruits. However, the coordinated regulatory mechanisms governing the accumulation of both chlorophylls and carotenoids during pepper fruit development remain elusive. In this study, pepper B-box 10 (CaBBX10), a candidate hub transcription factor, was found to play dual roles in the early development of pepper fruit. CaBBX10 virus-induced gene silencing and overexpression experiments demonstrated that the encoded transcription factor promotes both chlorophyll and carotenoid accumulation in pepper fruit. Further comprehensive analyses showed that CaBBX10 directly binds to the promoter of magnesium chelatase subunit D subunit (CaCHLD) and phytoene synthase 1 (CaPSY1), thereby activating their expression in the chlorophyll and carotenoid biosynthesis pathways, respectively. Additionally, the photomorphogenic factor CaCOP1 was found to physically interact with CaBBX10 and lead to its degradation. Therefore, CaBBX10 may serve as a critical link connecting chlorophyll and carotenoid biosynthesis to light signaling. Altogether, our findings reveal a mechanism for the complex transcriptional regulation that simultaneously promotes chlorophyll and carotenoid accumulation in pepper fruit.
通讯机构：
[Ou, LJ ; Qin, D; Qin, D ] H;Hunan Agr Univ, Coll Hort, Changsha 410128, Peoples R China.;Hunan Agr Univ, Engn Res Ctr Hort Crop Germplasm Creat & New Varie, Minist Educ, Changsha 410128, Peoples R China.;Hunan Agr Univ, Coll Food Sci & Technol, Changsha 410128, Peoples R China.
关键词：
fresh chili pepper;fermented chopped chili pepper;process adaptability;quality appraisal;sensory appraisal
摘要：
Fermented chopped chili pepper (FCCP) is the most important fermented and processed chili pepper product, and most pepper varieties can be processed with obvious flavor differences. Many studies have tried to explain these differences using the results of component analysis, processing technology, the microbes involved, etc., but few have examined the characteristics of these varieties along with the flavor of products. We conducted a physiochemical characteristic analysis of 35 kinds of fresh chili peppers with different genotypes and made fermented products from 17 varieties, using principal component analysis (PCA) and cluster analysis (CA) to correlate their components with FCCP products. The results were as follows: (1) Protein, total acids, a* (representation of the object’s red and green color), protopectin, and fruit thickness are the five key indexes that affect the quality of fresh chili peppers the most. (2) Protein, total acids, a*, protopectin, and fruit thickness are also the key indexes that affect the quality of FCCP. (3) Suitable ranges of fresh chili pepper to manufacture FCCP are 1.3–2.0 g/100 g for protein, 2.5–4.0 g/kg for total acids, 10–15 g/100 g for protopectin, 30–39 for a*, and 1.2–2.0 mm for fruit thickness. (4) Sensory appraisal shows crispness is the most important mouthfeel sensation and can decrease during the process. The varieties with the top three scores were A12 (21G675), A13 (20Z663), and A14 (21Z698) with scores of 87.92, 74.08, and 74.15, respectively. The varieties in the top three scores are pod peppers. The PCA and CA showed that pod peppers were the most suitable materials for making FCCP. Our results will benefit others in selecting fresh chili peppers for making FCCP and provide data support for directing processable variety breeding.
关键词：
CaAFR1;CaMYB61;Khib;cellulose and hemicellulose;histone deacetylases;stem lodging
摘要：
Plant stems constitute the most abundant renewable resource on earth. The function of lysine (K)-2-hydroxyisobutyrylation (K(hib)), a novel post-translational modification (PTM), has not yet been elucidated in plant stem development. Here, by assessing typical pepper genotypes with straight stem (SS) and prostrate stem (PS), we report the first large-scale proteomics analysis for protein K(hib) to date. K(hib)-modifications influenced central metabolic processes involved in stem development, such as glycolysis/gluconeogenesis and protein translation. The high K(hib) level regulated gene expression and protein accumulation associated with cell wall formation in the pepper stem. Specially, we found that CaMYB61 knockdown lines that exhibited prostrate stem phenotypes had high K(hib) levels. Most histone deacetylases (HDACs, e.g., switch-independent 3 associated polypeptide function related 1, AFR1) potentially function as the "erasing enzymes" involved in reversing K(hib) level. CaMYB61 positively regulated CaAFR1 expression to erase K(hib) and promote cellulose and hemicellulose accumulation in the stem. Therefore, we propose a bidirectional regulation hypothesis of "K(hib) modifications" and "K(hib) erasing" in stem development, and reveal a novel epigenetic regulatory network in which the CaMYB61-CaAFR1 molecular module participating in the regulation of K(hib) levels and biosynthesis of cellulose and hemicellulose for the first time.
摘要：
Cytoplasmic male sterility (CMS) is pivotal in plant breeding and widely employed in various crop hybrids, including pepper. However, the functional validation of the restorer of fertility (Rf) gene in pepper has been lacking until now. This study identifies and characterizes CaRf, a single dominant locus crucial for restoring CMS in the pepper strong recovery inbred line Zhangshugang. The CaRf gene encodes a mitochondria-targeted pentatricopeptide repeat protein, validated through the induction of male sterility upon its silencing in hybrid F(1) plants. To enhance pepper breeding efficiency, 176 important pepper breeding parent materials were resequenced, and a PepperSNP50K liquid-phase breeding chip was developed, comprising 51 172 markers. Integration of CaRf functional characterization and PepperSNP50K facilitated the development of a high-quality red pepper hybrid. These findings provide significant insights and practical strategies for advancing molecular-designed breeding in peppers.
摘要：
Higher plants survive terrestrial water deficiency and fluctuation by arresting cellular activities (dehydration) and resuscitating processes (rehydration). However, how plants monitor water availability during rehydration is unknown. Although increases in hypo-osmolarity-induced cytosolic Ca2+ concentration (HOSCA) have long been postulated to be the mechanism for sensing hypo-osmolarity in rehydration(1,2), the molecular basis remains unknown. Because osmolarity triggers membrane tension and the osmosensing specificity of osmosensing channels can only be determined in vivo(3-5), these channels have been classified as a subtype of mechanosensors. Here we identify bona fide cell surface hypo-osmosensors in Arabidopsis and find that pollen Ca2+ spiking is controlled directly by water through these hypo-osmosensors-that is, Ca2+ spiking is the second messenger for water status. We developed a functional expression screen in Escherichia coli for hypo-osmosensitive channels and identified OSCA2.1, a member of the hyperosmolarity-gated calcium-permeable channel (OSCA) family of proteins(6). We screened single and high-order OSCA mutants, and observed that the osca2.1/osca2.2 double-knockout mutant was impaired in pollen germination and HOSCA. OSCA2.1 and OSCA2.2 function as hypo-osmosensitive Ca2+-permeable channels in planta and in HEK293 cells. Decreasing osmolarity of the medium enhanced pollen Ca2+ oscillations, which were mediated by OSCA2.1 and OSCA2.2 and required for germination. OSCA2.1 and OSCA2.2 convert extracellular water status into Ca2+ spiking in pollen and may serve as essential hypo-osmosensors for tracking rehydration in plants.
摘要：
Pepper ( Capsicum spp.) is highly popular due to its unique flavor. However, there was limited research on the primary volatiles that influence the different flavors of fresh peppers. In this study, peppers with three aroma compound types denoted as “grassy,” “fruity,” and “no special aroma” (control) were analyzed using sensory evaluation combined with gas chromatography–mass spectrometry (GC–MS) and gas chromatography–olfactometry (GC–O). Altogether, 393 volatiles were identified by GC–MS, and the main volatiles in peppers ( C. chinense Jacq.) were esters and terpenoids. GC–O and relative odor activity value analysis revealed that 2-isobutyl-3-methoxypyrazine had a highly bitter, spicy aroma intensity in all peppers. Hexanal and trans -2-hexenal were the main aroma-active compounds in grassy peppers. In addition, citronellal was determined to be a crucial aroma-active compound in fruity peppers. This study offers a theoretical foundation for guiding the growth of the pepper processing industry and breeding.
Pepper ( Capsicum spp.) is highly popular due to its unique flavor. However, there was limited research on the primary volatiles that influence the different flavors of fresh peppers. In this study, peppers with three aroma compound types denoted as “grassy,” “fruity,” and “no special aroma” (control) were analyzed using sensory evaluation combined with gas chromatography–mass spectrometry (GC–MS) and gas chromatography–olfactometry (GC–O). Altogether, 393 volatiles were identified by GC–MS, and the main volatiles in peppers ( C. chinense Jacq.) were esters and terpenoids. GC–O and relative odor activity value analysis revealed that 2-isobutyl-3-methoxypyrazine had a highly bitter, spicy aroma intensity in all peppers. Hexanal and trans -2-hexenal were the main aroma-active compounds in grassy peppers. In addition, citronellal was determined to be a crucial aroma-active compound in fruity peppers. This study offers a theoretical foundation for guiding the growth of the pepper processing industry and breeding.
