NCED Genes Research Articles

Identification of ARF Genes and Elucidation of the Regulatory Effects of PsARF16a on the Dormancy of Tree Peony Plantlets.

The low survival rate of transplanted plantlets, which has limited the utility of tissue-culture-based methods for the rapid propagation of tree peonies, is due to plantlet dormancy after rooting. We previously determined that the auxin response factor PsARF may be a key regulator of tree peony dormancy. To clarify the mechanism mediating tree peony plantlet dormancy, PsARF genes were systematically identified and analyzed. Additionally, PsARF16a was transiently expressed in the leaves of tree peony plantlets to examine its regulatory effects on a downstream gene network. Nineteen PsARF genes were identified and divided into four classes. All PsARF genes encoded proteins with conserved B3 and ARF domains. The number of motifs, exons, and introns varied between PsARF genes in different classes. The overexpression of PsARF16a altered the expression of NCED, ZEP, PYL, GA2ox1, GID1, and other key genes in abscisic acid (ABA) and gibberellin (GA) signal transduction pathways, thereby promoting ABA synthesis and decreasing GA synthesis. Significant changes to the expression of some key genes contributing to starch and sugar metabolism (e.g., AMY2A, BAM3, BGLU, STP, and SUS2) may be associated with the gradual conversion of sugar into starch. This study provides important insights into PsARF functions in tree peonies.

Identification and Expression Profile of NCED Genes in Arachis hypogaea L. during Drought Stress.

Peanut (Arachis hypogaea L.) is an important crop that provides essential proteins and oils for human and animal consumption. 9-cis-epoxycarotenoid dioxygenase (NCED) have been found can play a vital role in abscisic acid (ABA) biosynthesis and may be a response to drought stress. Until now, in Arachis hypogaea, no information about the NCED gene family has been reported and the importance of NCED-related drought tolerance is unclear. In this study, eight NCED genes in Arachis hypogaea, referred to as AhNCEDs, are distributed across eight chromosomes, with duplication events in AhNCED1 and AhNCED2, AhNCED3 and AhNCED4, and AhNCED6 and AhNCED7. Comparative analysis revealed that NCED genes are highly conserved among plant species, including Pisum sativum, Phaseolus vulgaris, Glycine max, Arabidopsis thaliana, Gossypium hirsutum, and Oryza sativa. Further promoter analysis showed AhNCEDs have ABA-related and drought-inducible elements. The phenotyping of Arachis hypogaea cultivars NH5 and FH18 demonstrated that NH5 is drought-tolerant and FH18 is drought-sensitive. Transcriptome expression analysis revealed the differential regulation of AhNCEDs expression in both NH5 and FH18 cultivars under drought stress. Furthermore, compared to the Arachis hypogaea cultivar FH18, the NH5 exhibited a significant upregulation of AhNCED1/2 expression under drought. To sum up, this study provides an insight into the drought-related AhNCED genes, screened out the potential candidates to regulate drought tolerance and ABA biosynthesis in Arachis hypogaea.

Identification of the NCED gene family in tomato (Solanum lycopersicum) and functional analysis of SlNCED2 in response to drought stress

When under drought stress, plants experience hindrances in photosynthesis and cell division, which consequently leads to a decrease in their growth rates. Abscisic acid (ABA) regulates the exchange of water and gases between plants and the external environment by controlling stomatal opening and closing. This hormone plays a significant role in enhancing plant resistance to stressful conditions. Pivotal rate-limiting enzymes involved in the biosynthesis of plant ABA are encoded by genes belonging to the NCED (9-cis-epoxy-carotenoid dioxygenase) family. Therefore, the present study investigated the functions and mechanisms of the tomato NCED gene family in drought resistance. Bioinformatic analysis revealed that the promoters of most SlNCED genes harbored cis-acting elements associated with stress responses. The quantitative reverse transcription-polymerase chain reaction (qRT-PCR) results showed that SlNCED2 may be a key gene in drought stress resistance in this family. After drought treatment, the SlNCED2 silenced tomato plants had significantly diminished ABA and Pro-levels compared to the control plants, the stomatal opening proportion was significantly higher, oxidative stress was more intensive, and drought tolerance was significantly diminished. In addition, SlNCED2 interacted with loxC, a key protein in plant resistance to stress responses. Therefore, the SlNCED2 gene serves as a crucial enhancer of drought tolerance in tomatoes. In summary, this study elucidated the evolutionary patterns and functional distinctions within the NCED family of tomato genes, providing a deeper understanding of the regulatory mechanisms governing plant resistance to drought stress.

Metabolome integrated with transcriptome reveals the mechanism of three different color formations in Taxus mairei arils.

Maire yew (Taxus mairei), an evergreen conifer, has high ornamental and medicinal value. The arils of this species has three different colors. However, the variation mechanisms of arils color formation remains unclear. Here, the gene expression and metabolite concentration were profiled for red (RTM), yellow (YTM), and purple (PTM) arils in different developmental stages. A total of 266 flavonoids and 35 carotenoids were identified. The predominant pigments identified in YTM were epiafzelechin, lutein, and β-Cryptoxanthin, while malvidin-3,5-di-O-glucoside and apigenin played crucial roles in PTM. And significant differential expression was observed among the HCT, DFR, LAR, ANS, crtB, NCED, and CCoAOMT genes across different color arils. During the maturation of yellow arils, the upregulation of HCT was strongly correlated with the accumulation of epiafzelechin. The diminished expression of DFR, LAR, and ANS seemed to inhibit the production of delphinidin-3-O-rutinoside. The decrease in crtB expression and concurrent increase in NCED expression potentially regulate the heightened accumulation of lutein. Meanwhile, the accumulation of β-cryptoxanthin appeared seemed to be positively influenced by NCED. As aril turning purple, the decreased expression of CCoAOMT seemed to facilitate the synthesis of apigenin. The substantial upregulation of DFR promoted the production of malvidin-3,5-di-O-glucoside. Additionally, the overexpression of MYBs may plays the important role in regulating the formation of different colored arils. In total, 14 genes were selected for qRT-PCR validation, the results indicated the reliability of the transcriptome sequences data. Our findings could provide valuable insight into the molecular breeding, development, and application of Maire yew resources.

The strawberry transcription factor FaWRKY48 transactivates the FaNCED1 promoter as revealed by yeast-one hybrid and Nicotiana benthamiana transfection assays

Abscisic acid (ABA) positively regulates strawberry fruit ripening. ABA accumulation is tightly linked with 9-cis-epoxycarotenoid dioxygenase (NCED) expression, a gene that encodes for a key enzyme in the ABA synthesis pathway. In turn, WRKY transcription factors have been reported as one of the activators of NCED transcription in Arabidopsis, but no information about the regulation of NCED expression in strawberry has been reported. Therefore, we analyzed the transcriptional profiles of three WRKY and NCED genes at different developmental stages of strawberry fruit. FaNCED1 and FaWRKY48 showed the highest gene expression according to the advance of ripening. WRKY-recognition cis-elements (W-box) were found in the FaNCED1 promoter sequence and the FaWRKY48 binding to the FaNCED1 promoter was demonstrated by yeast one-hybrid (Y1H) and in vivo transactivation assays. Agroinfiltration of Nicotiana benthamiana leaves with FaWRKY48 and FaNCED1 promoter constructs showed an increment in GUS activity, suggesting that FaWRKY48 could regulate FaNCED1 transcription. Our study is an approach to elucidate one of the molecular triggers of ABA biosynthesis in strawberry.

Expression profile of the NCED/CCD genes in chickpea and lentil during abiotic stress reveals a positive correlation with increased plant tolerance

Carotenoid cleavage dioxygenase (CCD) gene family is organized in two subfamilies: (i) 9-cis epoxycarotenoid dioxygenase (NCED) genes and (ii) CCD genes. NCED genes are essential for catalyzing the first step of the abscisic-acid (ABA) biosynthesis, while CCD genes produce precursors of the strigolactones hormone. The functional characterization of these gene subfamilies has not been yet performed in chickpea and lentil. Herein, were identified and systematically characterized two NCED and five CCD genes in the chickpea and two NCED and six CCD genes in lentil. After in silico sequence analysis and phylogeny, the expression profile of the NCED/CCD genes was determined by meta-analysis and real-time PCR in plants under different stress conditions. Sequence data revealed that NCED/CCD genes are highly conserved between chickpea and lentil. This conservation was observed both at gene and protein sequence levels and phylogenetic relationships. Analysis of the promoter sequences revealed that all NCED/CCD genes have a considerable number of cis-regulatory elements responsive to biotic and abiotic stress. Protein sequence analysis evidenced that NCED/CCD genes share several conserved motifs and that they have a highly interconnected interaction network. Furthermore, the three-dimensional structure of these proteins was determined and indicated that some proteins have structures with considerable similarity. The meta-analysis revealed that NCED/CCD genes are dynamically modulated in different organs and under different stress conditions, but they have a positive correlation with plant tolerance. In accordance, real-time PCR data showed that both NCED and CCD genes are differentially modulated in plants under drought stress. In particular, CaNCED2, CaCCD5, LcNCED2, LcCCD1, and LcCCD2 genes have a positive correlation with improved plant tolerance to drought stress. Therefore, this study presented a detailed characterization of the chickpea and lentil NCED/CCD genes and provided new insights to improve abiotic stress tolerance in these two important crops.

Genome-Wide Identification and Expression Profiling of the NCED Gene Family in Cold Stress Response of Prunus mume Siebold & Zucc

The 9-cis-epoxy carotenoid dioxygenase (NCED) is an enzyme that is crucial in abscisic acid (ABA) biosynthesis, and its role is vital in plant development and abiotic stress. However, the function of the NCED family in Rosaceae plant species remains unclear. Through genome-wide screening, we identified 10, 10, 11, 12 and 13 NCED genes in Prunus mume, Prunus apricot, Prunus salicina, Prunus persica, and Rosa chinensis, respectively. Phylogenetic analysis showed that these NCED genes were divided into six groups. Gene structure analysis showed that the number and size of introns were relatively constant in each subfamily, while the motif composition differed significantly among them. Collinearity analysis revealed a high homology of NCEDs in the Prunus genus. Promoter cis-acting element analysis showed that eight PmNCEDs contained abscisic acid-responsive elements (ABRE). Furthermore, expression profile analysis based on qRT-PCR revealed that PmNCED3, PmNCED8 and PmNCED9 were up-regulated in response to low temperature stress, suggesting their significant role in the plant’s response to cold stress. These findings provide insights into the structure and evolution of PmNCEDs and lay the foundation for further studies regarding their function during cold stress.

The Influence of Lead and Acyrthosiphon pisum (Harris) on Generation of Pisum sativum Defense Signaling Molecules and Expression of Genes Involved in Their Biosynthesis.

The main aim of this study was to understand the regulation of the biosynthesis of phytohormones as signaling molecules in the defense mechanisms of pea seedlings during the application of abiotic and biotic stress factors. It was important to identify this regulation at the molecular level in Pisum sativum L. seedlings under the influence of various concentrations of lead-i.e., a low concentration increasing plant metabolism, causing a hormetic effect, and a high dose causing a sublethal effect-and during feeding of a phytophagous insect with a piercing-sucking mouthpart-i.e., pea aphid (Acyrthosiphon pisum (Harris)). The aim of the study was to determine the expression level of genes encoding enzymes of the biosynthesis of signaling molecules such as phytohormones-i.e., jasmonates (JA/MeJA), ethylene (ET) and abscisic acid (ABA). Real-time qPCR was applied to analyze the expression of genes encoding enzymes involved in the regulation of the biosynthesis of JA/MeJA (lipoxygenase 1 (LOX1), lipoxygenase 2 (LOX2), 12-oxophytodienoate reductase 1 (OPR1) and jasmonic acid-amido synthetase (JAR1)), ET (1-aminocyclopropane-1-carboxylate synthase 3 (ACS3)) and ABA (9-cis-epoxycarotenoid dioxygenase (NCED) and aldehyde oxidase 1 (AO1)). In response to the abovementioned stress factors-i.e., abiotic and biotic stressors acting independently or simultaneously-the expression of the LOX1, LOX2, OPR1, JAR1, ACS3, NCED and AO1 genes at both sublethal and hormetic doses increased. Particularly high levels of the relative expression of the tested genes in pea seedlings growing at sublethal doses of lead and colonized by A. pisum compared to the control were noticeable. A hormetic dose of lead induced high expression levels of the JAR1, OPR1 and ACS3 genes, especially in leaves. Moreover, an increase in the concentration of phytohormones such as jasmonates (JA and MeJA) and aminococyclopropane-1-carboxylic acid (ACC)-ethylene (ET) precursor was observed. The results of this study indicate that the response of pea seedlings to lead and A. pisum aphid infestation differed greatly at both the gene expression and metabolic levels. The intensity of these defense responses depended on the organ, the metal dose and direct contact of the stress factor with the organ.

Overexpression of 9-cis-Epoxycarotenoid Dioxygenase Gene, IbNCED1, Negatively Regulates Plant Height in Transgenic Sweet Potato.

Plant height is one of the key agronomic traits for improving the yield of sweet potato. Phytohormones, especially gibberellins (GAs), are crucial to regulate plant height. The enzyme 9-cis-epoxycarotenoid dioxygenase (NCED) is the key enzyme for abscisic acid (ABA) biosynthesis signalling in higher plants. However, its role in regulating plant height has not been reported to date. Here, we cloned a new NCED gene, IbNCED1, from the sweet potato cultivar Jishu26. This gene encoded the 587-amino acid polypeptide containing an NCED superfamily domain. The expression level of IbNCED1 was highest in the stem and the old tissues in the in vitro-grown and field-grown Jishu26, respectively. The expression of IbNCED1 was induced by ABA and GA3. Overexpression of IbNCED1 promoted the accumulation of ABA and inhibited the content of active GA3 and plant height and affected the expression levels of genes involved in the GA metabolic pathway. Exogenous application of GA3 could rescue the dwarf phenotype. In conclusion, we suggest that IbNCED1 regulates plant height and development by controlling the ABA and GA signalling pathways in transgenic sweet potato.

Genome-wide identification of the NCED gene family and functional characterization of PavNCED5 related to bud dormancy in sweet cherry

Abscisic acid (ABA) is involved in responding to various stresses and regulating the dormancy of flower buds in fruit trees. The cleavage of carotenoids is catalyzed by 9-cis epoxy carotenoid dioxygenase (NCED), and is a key step in ABA biosynthesis. Although NCED genes have been identified in a variety of plants, the characteristics of these genes in sweet cherry (Prunus avium L.) trees have been seldom reported. In the present study, 10 PavNCED genes were identified in the sweet cherry genome and distributed on three chromosomes. Cis-element analysis of PavNCEDs indicated that they might be related to hormone regulation, stress responses, and plant development. Through co-expression network analysis, the transcription factors were identified, such as ERF, bHLH and TCP, which might be involved in the regulation of PavNCEDs. Expression pattern analysis of the PavNCED family genes showed that PavNCED1–5 genes were highly expressed during the flower bud dormancy. Importantly, the expression of PavNCED5 was decreased with the decline of ABA content in the sweet cherry. Additionally, the overexpression of PavNCED5 in Arabidopsis showed dormancy deficiency of seeds. This implies that PavNCED5 may play an important role during the dormancy stage of sweet cherry. In general, we characterized the NCED family in sweet cherry and revealed the essential role of PavNCED5 in flower bud dormancy. These findings open up future research directions and provide valuable information for the further functional study of PavNCEDs in sweet cherry.

Genome-Wide Identification and Expression Analysis of NCED Gene Family in Pear and Its Response to Exogenous Gibberellin and Paclobutrazol.

The 9-cis-epoxycarotenoid dioxygenase (NCED) is a key enzyme for the process of ABA synthesis that plays key roles in a variety of biological processes. In the current investigation, genome-wide identification and comprehensive analysis of the NCED gene family in 'Kuerle Xiangli' (Pyrus sinkiangensis Yu) were conducted using the pear genomic sequence. In total, nineteen members of PbNCED genes were identified from the whole genome of pear, which are not evenly distributed over the scaffolds, and most of which were focussed in the chloroplasts. Sequence analysis of promoters showed many cis-regulatory elements, which presumably responded to phytohormones such as abscisic acid, auxin, etc. Synteny block indicated that the PbNCED genes have experienced strong purifying selection. Multiple sequence alignment demonstrated that these members are highly similar and conserved. In addition, we found that PbNCED genes were differentially expressed in various tissues, and three PbNCED genes (PbNCED1, PbNCED2, and PbNCED13) were differentially expressed in response to exogenous Gibberellin (GA3) and Paclobutrazol (PP333). PbNCED1 and PbNCED13 positively promote ABA synthesis in sepals after GA3 and PP333 treatment, whereas PbNCED2 positively regulated ABA synthesis in ovaries after GA3 treatment, and PbNCED13 positively regulated ABA synthesis in the ovaries after PP333 treatment. This study was the first genome-wide report of the pear NCED gene family, which could improve our understanding of pear NCED proteins and provide a solid foundation for future cloning and functional analyses of this gene family. Meanwhile, our results also give a better understanding of the important genes and regulation pathways related to calyx abscission in 'Kuerle Xiangli'.

Elucidating Biological Functions of 9-cis-Epoxycarotenoid Dioxygenase Genes Involved in Seed Dormancy in Paeonia lactiflora

Abscisic acid (ABA) is a major phytohormone affecting seed dormancy and germination in plants. ABA is synthesized mainly through the C40 carotenoid pathway. In the ABA biosynthesis pathway, 9-cis-epoxycarotenoid dioxygenase (NCED) is a key rate-limiting enzyme that regulates the accumulation and content of ABA. However, the role of the NCED gene in perennial plants with complex seed dormancy remains largely unknown. Here, we cloned two differentially expressed paralogs of herbaceous peony NCED genes, named PlNCED1 and PlNCED2, and further identified their involvement in seed dormancy from perennial herbaceous peony experiencing complex double seed dormancy. The deduced PlNCED amino acid sequences had high sequence homology with NCED sequences from other plants and contained the typical conserved RPE65 domain of the NCED family. Phylogenetic analysis showed that PlNCED1 and PlNCED2 have a close relationship with PoNCED in Paeonia ostii and VvNCED6 in Vitis vinifera, respectively. A subcellular localization assay demonstrated that the PlNCED1 protein resided within the nucleus, while the PlNCED2 protein was located in the cytoplasm, indicating their different roles in the biosynthesis of ABA. Furthermore, the content of endogenous ABA in transgenic calluses showed that PlNCEDs were positively correlated with ABA content. Both PlNCED transgenic Arabidopsis lines and the functional complementation of Arabidopsis NCED mutants found that PlNCEDs promoted seed dormancy and delayed seed germination. These results reveal that PlNCEDs participate in the seed dormancy of herbaceous peony by regulating the accumulation of endogenous ABA.

9-cis-epoxycarotenoid dioxygenase 1 confers heat stress tolerance in rice seedling plants.

High temperature is one of the main constraints affecting plant growth and development. It has been reported that abscisic acid (ABA) synthesis gene 9-cis-epoxycarotenoid dioxygenase (NCED) positively regulates plant resistance to salt, cold, and drought stresses. However, little is known about the function of the NCED gene in heat tolerance of rice. Here, we found that OsNCED1 was a heat stress inducible gene. Rice seedlings overexpressing OsNCED1 showed enhanced heat tolerance with more abundant ABA content, whereas the knockout mutant osnced1 accumulated less ABA and showed more sensitive to heat stress. Under heat stress, increased expression of OsNCED1 could reduce membrane damage and reactive oxygen species (ROS) level of plants, and elevate the activity of antioxidant enzymes. Moreover, real time-quantitative PCR (RT-qPCR) analysis showed that overexpression of OsNCED1 significantly activated the expression of genes involved in antioxidant enzymes, ABA signaling pathway, heat response, and defense. Together, our results indicate that OsNCED1 positively regulates heat tolerance of rice seedling by raising endogenous ABA contents, which leads to the improved antioxidant capacity and activated expression of heat and ABA related genes.

Xylem functionality controlling blossom-end rot incidence in transgenic ALC::NCED tomato plants

Fruit susceptibility to the physiological disorder known as blossom-end rot (BER) is an important limitation in tomato production. Abscisic acid (ABA) is known to reduce leaf transpiration, which can enhance plant water use efficiency (WUE), as well as increase fruit xylem functionality, Ca2+ uptake and oxidative stress defenses, which has been suggested to reduce BER incidence. However, the role of ABA on most of these factors determining fruit susceptibility to BER remains poorly understood. ABA production is mainly regulated by the expression of 9-cis-epoxycarotenoid dioxygenase (NCED) genes. Manipulation of NCED gene expression by the alcohol inducible promoter (ALC) could be an alternative approach to stimulate ABA production and its beneficial effects on inhibiting BER incidence. The objectives of this study were to use ALC::NCED transgenic tomato plants to decrease BER incidence and investigate which mechanisms were involved in BER. In this study, two transgenic tomato lines (1 and 2) were developed with the ALC::NCED construct. This construct allows the inducible activation of the ALC promoter by treating the plants with ethanol vapor that drives NCED expression and ABA synthesis. According to the results, after full bloom, weekly spraying transgenic plants with ethanol (2%) decreased BER incidence in both transgenic lines, compared to the wild type ‘New Yorker’ plants. The transgenic line 1 had higher NCED expression in response to ethanol than the transgenic line 2 and wild type ‘New Yorker’. At 15 and 30 days after pollination, transgenic lines 1 and 2 had higher number of functional xylem vessels which helped to increase Ca2+ concentration in the distal end of the fruit, compared to the wild type fruit. In response to higher NCED expression, WUE and antioxidant content in leaves and fruit were higher in both transgenic lines, compared to the wild type, helping to explain the lower BER incidence. Therefore, our study shows that stimulating NCED expression with an inducible system increases the number of functional xylems and Ca2+ uptake into the fruit, improving plant WUE and reducing BER incidence.

Joint metabolome and transcriptome analysis of the effects of exogenous GA3 on endogenous hormones in sweet cherry and mining of potential regulatory genes.

Gibberellin (GA) is an important phytohormone that can participate in various developmental processes of plants. The study found that application of GA3 can induce parthenocarpy fruit and improve fruit set. However, the use of GA3 affects endogenous hormones in fruits, thereby affecting fruit quality. This study mainly investigates the effect of exogenous GA3 on endogenous hormones in sweet cherries. The anabolic pathways of each hormone were analyzed by metabolome and transcriptome to identify key metabolites and genes that affect endogenous hormones in response to exogenous GA3 application. Results showed that exogenous GA3 led to a significant increase in the content of abscisic acid (ABA) and GA and affected jasmonic acid (JA) and auxin (IAA). At the same time, the key structural genes affecting the synthesis of various hormones were preliminarily determined. Combined with transcription factor family analysis, WRKY genes were found to be more sensitive to the use of exogenous GA3, especially the genes belonging to Group III (PaWRKY16, PaWRKY21, PaWRKY38, PaWRKY52, and PaWRKY53). These transcription factors can combine with the promoters of NCED, YUCCA, and other genes to regulate the content of endogenous hormones. These findings lay the foundation for the preliminary determination of the mechanism of GA3's effect on endogenous hormones in sweet cherry and the biological function of WRKY transcription factors.

Genome-wide analysis of the carotenoid cleavage dioxygenases gene family in Forsythia suspensa: Expression profile and cold and drought stress responses.

Forsythia suspensa is a famous ornamental and medicinal plant in Oleaceae. CCD family is involved in the synthesis of pigments, volatiles, strigolactones, and abscisic acid (ABA) in plants. In this study, the CCD family in F. suspensa was analyzed at the genome level. A total of 16 members of the CCD family were identified, which included 11 members of the carotenoid cleavage dioxygenases (CCD) subfamily and 5 members of the 9-cis epoxycarotenoid dioxygenases (NCED) subfamily. The expression analysis of different tissues demonstrated that three FsCCD1 genes might be involved in the synthesis of pigments and volatiles in flowers and fruits. Three CCD4 genes were effectively expressed in flowers, while only FsCCD4-3 was effectively expressed in fruits. Comparison of CCD4 between Osmanthus fragrans and F. suspensa showed that the structure of FsCCD4-1 is was comparable that of OfCCD4-1 protein, indicating that the protein might be performing, especially in catalyzing the synthesis of β-ionone. However, further comparison of the upstream promoter regions showed that the proteins have major differences in the composition of cis-elements, which might be responsible for differences in β-ionone content. On the other hand, four NCED genes were significantly up-regulated under cold stress while two were up-regulated in drought stress. The data showed that these genes might be involved in the synthesis of ABA. Taken together, our data improves understanding of the CCD family and provides key candidate genes associated with cold and drought stresses in F. suspensa.

Molecular and Enzymatic Characterization of 9-Cis-epoxycarotenoid Dioxygenases from Mulberry.

Abscisic acid (ABA) is involved in many physiological regulatory processes in plants, such as leaf shedding, stomatal closure, inhibition of cell elongation, as well as responses to multi-abiotic stress, and 9-cis epoxy carotenoid dioxygenase (NCED) is related to the indirect synthesis of ABA. However, NCED genes involved in multi-abiotic stress and ABA synthesis pathway in mulberry (Morus alba L.) are still unknown. Here, two NCED genes cloned from mulberry (MaNCED) and their function were preliminarily identified. Interestingly, MaNCED2 responded strongly to drought stress while MaNCED1 responded strongly to pathogen stress. Then, two MaNCED proteins were successfully obtained by prokaryotic expression, and the degradation products of MaNCED1 and MaNCED2 were analyzed using UPLC-MS. The results show that recombinant MaNCED1 and MaNCED2 both cleave 9-cis-violaxanthin to form C15 xanthoxin,involved in the formation of the precursor of ABA.

Balance of Carotenoid Synthesis and Degradation Contributes to the Color Difference between Chinese Narcissus and Its Yellow-Tepal Mutant

Chinese narcissus (Narcissus tazetta var. chinensis) was introduced to China 1300–1400 years ago, and has grown naturally in southeastern China. It is a popular Chinese traditional potted flower and a well-known flowering bulb cultivated worldwide with only two white-tepal triploid cultivars, ‘Jinzhan Yintai’ and ‘Yulinglong’. Recently, a mutant with yellow tepals was observed and promptly became popular. To clarify the key pigment for color difference and its molecular mechanism of accumulation, we conducted pigment metabolite analysis and comparative transcriptome analysis on ‘Jinzhan Yintai’ and the yellow-flowered mutant. The results showed that there was no significant difference in total flavonoid content between the mutant and ‘Jinzhan Yintai’, whereas the total carotenoid content of the mutant was more than 10-fold higher than that of ‘Jinzhan Yintai’. Based on the RNA-sequencing results, sixty-four unigenes, corresponding to 29 enzymes associated with the carotenoid biosynthesis pathway, were analyzed in detail. A comparative KEGG pathway enrichment analysis, in conjunction with quantitative real-time PCR data, revealed the opposite gene expression mode of the carotenoid biosynthesis pathway. Compared with ‘Jinzhan Yintai ’, PSY and PDS were up-regulated in the three mid-flowering stages of the mutant, whereas NCED genes were strongly down-regulated, which likely contributed to carotenoid accumulation in chromoplasts of the tepals in the mutant.

Investigation of proteins' interaction network and the expression pattern of genes involved in the ABA biogenesis and antioxidant system under methanol spray in drought-stressed rapeseed.

Drought is one of the most critical abiotic stresses, which significantly impair rapeseed (Brassica napus L.) productivity. Several factors can regulate the stress response, including changes in gene expression in biological pathways, extensive protein interaction networks, and post-translational regulatory factors like microRNAs. External factors can also affect the intensity of the stress response. Therefore, this study investigated protein-protein interactions of some essential genes involved in abscisic acid (ABA) production, antioxidant system, and Krebs cycle. The expression of phyton synthase (PSY), 9-cis-epoxycarotenoid dioxygenase (NCED3), aldehyde oxidase (AAO3), thioredoxin reductase (NTRC), and glutathione reductase (GR) genes in two rapeseed genotypes, i.e., Hyola308 (drought-sensitive) and SLM046 (drought-tolerant) were evaluated using qRT-PCR technique under 72h of drought stress and methanol foliar application. In the SLM046 (tolerant) genotype, the expression levels of PYS, NCED, AAO3, and GR genes were increased after 8h of foliar application. The expression level of the NTR gene was increased 8 and 24h after stress and methanol treatment. In the Hyola308 genotype, PYS, AAO3, NTR, and GR genes' expression level was increased 8h after methanol foliar application, and the NCED gene was increased 24h after stress with methanol treatment. In general, methanol foliar application increased the expression levels of several genes. Particularly, the gene expression was considerably higher in the SLM046 genotype than in Hyola308. Bioinformatics prediction of microRNAs targeting PSY, NCED, GR, NTRC, and AAO3 genes was performed, and 38, 38, 13, 11, and 11 microRNAs were predicted for these genes, respectively. The study of effective microRNAs showed that sometimes more than one type of microRNA could affect the desired gene, and in some cases, a conserved family of microRNAs caused the main effect on gene expression. Overall, our results lay the foundation for functional characterization of these genes or gene-miRNA modules in regulating drought stress tolerance in rapeseed.

Transcriptomic and physiological analyses identifying Lanzhou lily (Lilium davidii var. unicolor) drought adaptation strategies

Drought stress is the main limiting plant growth factor in arid and semiarid regions. The Lanzhou lily (Lilium davidii var. unicolor) is the only sweet-tasting lily grown in these regions of China that offers highly edible, medicinal, health, and ornamental value. The Tresor lily is an ornamental flower known for its strong resistance. Plants were grown under three different drought intensity treatments, namely, being watered at intervals of 5, 15, and 25 d (either throughout the study or during specific growth stages). We measured the biomass, leaf area, photosynthetic response, chlorophyll content (SPAD value), and osmoregulation of both the Lanzhou lily and the Tresor lily (Lilium ‘Tresor'). Additionally, we employed RNA sequencing (RNA-Seq) and qRT-PCR to investigate transcriptomic changes of the Lanzhou lily in response to drought stress. Results showed that under drought stress, the decreasing rate in the Lanzhou lily bulb weight was lower than the corresponding Tresor lily bulb rate; the net photosynthetic rate, transpiration rate, and stomatal conductance of the Lanzhou lily were all higher compared to the Tresor lily; osmoregulation constituents, such as glucose, fructose, sucrose, trehalose, and soluble sugar, in the Lanzhou lily were comparatively higher; PYL, NCED, and ERS genes were significantly expressed in the Lanzhou lily. Under moderate drought, the biosynthesis of flavonoids, circadian rhythms, and the tryptophan metabolism pathway of the Lanzhou lily were all significant. Under severe drought stress, fatty acid elongation, photosynthetic antenna protein, plant hormone signal transduction, flavone and flavonol biosynthesis, and the carotenoid biosynthesis pathway were all significant. The Lanzhou lily adapted to drought stress by coordinating its organs and the unique role of its bulb, regulating photosynthesis, increasing osmolyte content, activating circadian rhythms, signal transduction, fatty acid elongation metabolism, and phenylalanine and flavonoid metabolic pathways, which may collectively be the main adaptation strategy and mechanisms used by the Lanzhou lily under drought stress.