Corrigendum: Phenylpropane biosynthesis and alkaloid metabolism pathways involved in resistance of Amorphophallus spp. against soft rot disease.

[This corrects the article DOI: 10.3389/fpls.2024.1334996.].

Phenylpropane biosynthesis and alkaloid metabolism pathways involved in resistance of Amorphophallus spp. against soft rot disease.

Soft rot of konjac (Amorphophallus spp.) is a devastating disease caused by the bacterium Pectobacterium carotovorum subsp. carotovorum (Pcc) with serious adverse effects on plantation development, corm quality and crop yield due to the current lack of effective control measures. The main objective of the present study was to elucidate the mechanisms underlying plant resistance to soft rot disease. A combination of transcriptomic and metabolomic analyses demonstrated significant enrichment of differentially expressed genes (DEG) and differentially accumulated metabolites (DAM) associated with plant hormones, phenylpropanoid biosynthesis and, in particular, alkaloid metabolism, in Amorphophallus muelleri following Pcc infection compared with A. konjac, these data implicate alkaloid metabolism as the dominant mechanism underlying disease resistance of A. muelleri. Quantitative real-time polymerase chain reaction analysis further revealed involvement of PAL, CYP73A16, CCOAOMT1, RBOHD and CDPK20 genes in the response of konjac to Pcc. Analysis of the bacteriostatic activities of total alkaloid from A. muelleri validated the assumption that alkaloid metabolism positively regulates disease resistance of konjac. Our collective results provide a foundation for further research on the resistance mechanisms of konjac against soft rot disease.

Effect of nutritional intervention in child health care on improving growth and development and disease prevention of infants.

Objective: To explore the outcome of nutritional intervention in child health care on infant growth and disease prevention. Methods: It was a retrospective study. Ninty-two infants who received child health intervention in The Affiliated Hospital of Southwest Medical University from September 2020 to June 2022 were selected as the research objects. According to the random number table method, they were divided into control group (46 cases, routine health intervention) and observation group (46 cases, nutritional intervention based on the control group) using the sealed envelope system. The growth and development, nutritional diseases and guardian satisfaction of the two groups were compared. Results: The scores of the observation group were higher than those of the control group in gross motor, fine motor, language and individual-social aspects. The total incidence of nutritional diseases in the observation group (2.17%) was lower than that in the control group (17.39%); In terms of total satisfaction rate, the observation group (100.00%) was higher than the control group (86.96%), with a statistical difference (P<0.05). Conclusion: Applying nutrition intervention to child health care plays an important role in maintaining the healthy growth and development of infants and reducing the incidence of nutritional diseases such as anemia and rickets. It needs to be promoted in clinical practice.

The complete chloroplast genome sequence of Amorphophallus konjac (Araceae) from Yunnan, China and its phylogenetic analysis in the family Araceae.

This work determined and analyzed the complete chloroplast genome sequence of Amorphophallus konjac K. Koch ex N.E.Br 1858 from Yunnan, China. The genome size was 167,470 bp, of which contains a large single-copy region (LSC 93,443 bp), a small single-copy region (SSC 21,575 bp), and a pair of inverted repeat regions (IR 26,226 bp). The chloroplast genome has 131 genes, including 86 protein-coding genes, 37 tRNAs, and eight rRNAs. A previous study reported deletion of accD, psbE, and trnG-GCC genes in the A. konjac chloroplast genome. Our study supports the conservative structure of A. konjac and does not support the gene deletion mentioned above. Phylogenetic analysis indicated that A. konjac shares a close relationship with another A. konjac (collected from Guizhou) and A. titanium by forming a clade in the genus Amorphophallus. Our results provide some useful information to the evolution of the family Araceae.

Melatonin, a phytohormone for enhancing the accumulation of high-value metabolites and stress tolerance in microalgae: Applications, mechanisms, and challenges.

High-value metabolites, such as carotenoids, lipids, and proteins, are synthesized by microalgae and find applications in various fields, including food, health supplements, and cosmetics. However, the potential of the microalgal industry to serve these sectors is constrained by low productivity and high energy consumption. Environmental stressors can not only stimulate the accumulation of secondary metabolites in microalgae but also induce oxidative stress, suppressing cell growth and activity, thereby resulting in a decrease in overall productivity. Using melatonin (MT) under stressful conditions is an effective approach to enhance the productivity of microalgal metabolites. This review underscores the role of MT in promoting the accumulation of high-value metabolites and enhancing stress resistance in microalgae under stressful and wastewater conditions. It discusses the underlying mechanisms whereby MT enhances metabolite synthesis and improves stress resistance. The review also offers new perspectives on utilizing MT to improve microalgal productivity and stress resistance in challenging environments.

Characteristics of Amorphophallus konjac as indicated by its genome.

Amorphophallus konjac, belonging to the genus Amorphophallus of the Araceae family, is an economically important crop widely used in health products and biomaterials. In the present work, we performed the whole-genome assembly of A. konjac based on the NovaSeq platform sequence data. The final genome assembly was 4.58 Gb with a scaffold N50 of 3212 bp. The genome includes 39,421 protein-coding genes, and 71.75% of the assemblies were repetitive sequences. Comparative genomic analysis showed 1647 gene families have expanded and 2685 contracted in the A. konjac genome. Likewise, genome evolution analysis indicated that A. konjac underwent whole-genome duplication, possibly contributing to the expansion of certain gene families. Furthermore, we identified many candidate genes involved in the tuber formation and development, cellulose and lignification synthesis. The genome of A. konjac obtained in this work provides a valuable resource for the further study of the genetics, genomics, and breeding of this economically important crop, as well as for evolutionary studies of Araceae family.

Comparative metabolomics analysis reveals dynamic changes in carbohydrate profiles of corms during the "relay growth" of konjac (Amorphophallus muelleri).

The type and content of carbohydrates in konjac corms are an essential factors in determining the quality of konjac; however, the pattern of carbohydrate changes and the mechanism regulating the development of mother and daughter corms in the "relay growth" process of Amorphophallus muelleri remain unclear. This study aimed to investigate changes in corm carbohydrates during the growth cycle of A. muelleri and to compare the carbohydrate composition and the expression of related genes between mother and daughter corms. Integrated metabolome and RNA-seq analyses identified 37 differential metabolites as well as 8074 genes that were differentially expressed between mother and daughter corms, the majority of which were involved in starch and sucrose metabolism. More than 80% of the differential metabolites, including sucrose and starch, tended to accumulate in the mother corms; however, konjac glucomannan (KGM), as one of the most important carbohydrates and its major component of the corm, accumulated in higher amounts in the daughter corms. In addition, the expression of invertase and alpha-amylase that promote the breakdown of sucrose and starch was 351.78- and 15.63-fold higher, respectively, in the daughter corm, whereas that of the starch synthesis gene AkWAXY was only 0.096 times as high as in the mother corms. Furthermore, the level of cellulose synthase-like protein G, which promotes KGM synthesis, was 3.85 times higher in daughter corms compared to mother corms. Thus, we inferred that the daughter and mother corms had two distinct carbohydrate utilization strategies. This study provides insights into temporal changes in carbohydrates during the growth cycle of A. muelleri.

Amorphophallus muelleri activates ferulic acid and phenylpropane biosynthesis pathways to defend against Fusarium solani infection.

Amorphophallus sp. is an economically important crop for rural revitalization in southwest China. However, Fusarium solani often infects Amorphophallus sp. corms during storage, damaging the corm quality and affecting leaf elongation and flowering in the subsequent crop. In this study, the mechanism of resistance to F. solani was investigated in the leaf bud and flower bud corms of Amorphophallus muelleri through transcriptome and metabolome analyses. A total of 42.52 Gb clean reads and 1,525 metabolites were detected in a total of 12 samples including 3 samples each of disease-free leaf bud corms (LC), leaf bud corms inoculated with F. solani for three days (LD), disease-free flower bud corms (FC), and flower bud corms inoculated with F. solani for three days (FD). Transcriptome, metabolome, and conjoint analyses showed that 'MAPK signal transduction', 'plant-pathogen interaction', 'plant hormone signal transduction', and other secondary metabolite biosynthesis pathways, including 'phenylpropane biosynthesis', 'arachidonic acid metabolism', 'stilbene, diarylheptane and gingerolin biosynthesis', and 'isoquinoline alkaloids biosynthesis', among others, were involved in the defense response of A. muelleri to F. solani. Ultimately, the expression of six genes of interest (AmCDPK20, AmRBOH, AmWRKY33, Am4CL, Am POD and AmCYP73A1) was validated by real-time fluorescence quantitative polymerase chain reaction, and the results indicated that these genes were involved in the response of A. muelleri to F. solani. Ferulic acid inhibited the growth of F. solani, reducing the harm caused by F. solani to A. muelleri corms to a certain extent. Overall, this study lays a strong foundation for further investigation of the interaction between A. muelleri and F. solani, and provides a list of genes for the future breeding of F. solani-resistant A. muelleri cultivars.

Synergistic effects of gamma-aminobutyric acid and melatonin on seed germination and cadmium tolerance in tomato.

The effects of exogenous γ-aminobutyric acid (GABA) and melatonin (MT) on tomato seed germination and shoot growth exposed to cadmium stress were investigated. On the one hand, treatment with MT (10-200 µM) or GABA (10-200 µM) alone could significantly relieve cadmium stress in tomato seedlings, which is reflected in increasing the germination rate, vigor index, fresh weight, dry weight and radicle lengths of tomato seeds, as well as the soluble content compared to the absence of exogenous treatment, and the alleviating effect reached the peak in the 200 µM GABA or 150 µM MT alone. On the other hand, exogenous MT and GABA showed synergistic effects on the germination of tomato seed under cadmium stress. Moreover, the application of 100 µM GABA combined with 100 µM MT markedly decreased the contents of Cd and MDA by upregulating the activities of antioxidant enzymes, thereby alleviating the toxic effect of cadmium stress on tomato seeds. Collectively, the combinational strategy showed significant positive effects on seed germination and cadmium stress resistance in tomato.

First report of Athelia rolfsii associated with southern blight disease of Amorphophallus muelleri in China.

Amorphophallus muelleri, known as konjac, is widely used in the biomedicine and food processing due to its richness in glucomannan. Between the years of 2019 to 2022, severe outbreaks of southern blight on Am. muelleri were observed during August and September in the main planting region of Mile city. The average disease incidence was 20%, resulted in 15.3% of economic losses in approximately 10,000 m2. Infected plants showed wilting and rotting and were covered with white dense mats of mycelia and sclerotia on both petiole base and tubers. Am. muelleri petiole base covered with mycelial mats were collected for pathogen isolation. The infected tissues (n=20) were washed with sterile water and surface disinfected with 75% alcohol for 60 seconds, rinsed three times with sterile water, cultured on rose bengal agar (RBA) and incubated at 27 ℃ for two days (Adre et al. 2022). Individual hyphae were transferred to new RBA plates and incubated at 27 ℃ for 15 days to obtain purified cultures. Five representative isolates were subsequently obtained and exhibited identical morphological characteristics. All isolates produced dense, cotton-white aerial mycelia and had a daily growth rate of 1.6 ± 0.2 mm (n=5). After 10 days, all isolates formed sclerotia in spherical (diameter range 1.1 to 3.5 mm, aver. 2.0 ± 0.5 mm; n=30) and irregular shapes. The number of sclerotia per plate ranged from 58 to 113 (aver=82; n=5). These sclerotia were initially white and gradually turned brown as they matured. A representative isolate (17B-1) was selected for molecular identification and the translation elongation factor (TEF, 480 nt.), internal transcribed spacer (ITS, 629 nt.), large subunit (LSU, 922 nt.), and small subunit (SSU, 1016 nt.) regions were amplified with the primers EF595F/EF1160R (Wendland and Kothe 1997), ITS1/ITS4 (Utama et al. 2022), NS1/NS4, and LROR/LR5 (Moncalvo et al. 2000), respectively. The ITS (GenBank accession no. OP658949), LSU (OP658955), SSU (OP658952), and TEF (OP679794) sequences were 99.19%, 99.78%, 99.31%, and 99.58% similar to those of At. rolfsii isolates (MT634388, MT225781, MT103059, and MN106270, respectively). Thus, the fungus represented by isolate 17B-1 was identified as At. rolfsii, corroborating the identification of Sclerotium rolfsii Sacc., the anamorph, based on cultural and morphological features. Pathogenicity tests were performed on six-month-old asymptomatic Am. muelleri plants (n=30) grown in pots with sterile soil in a greenhouse at 27 °C and 80% relative humidity. The petiole base was scratched with a sterile blade and 20 plants were inoculated by placing a 5 mm2 mycelial plug of five-day-old isolate 17B-1 on the wound. Sterile RBA plugs were used on 10 wounded control plants. After 12 days, all inoculated plants exhibited symptoms similar to those observed in the field, while the control plants showed no symptoms. The morphological and molecular identification of the fungus reisolated from inoculated petioles confirmed its identity as At. Rolfsii, fulfilling Koch's postulates. S. rolfsii was first reported on Am. campanulatus in India (Sarma et al. 2002). As At. rolfsii causes konjac diseases in all Amorphophallus growing areas (Pravi et al. 2014), the importance of At. rolfsii as an endemic pathogen of Am. muelleri in China needs to be recognized, and its prevalence should be determined as a first step to managing this disease.

Different Response Mechanisms of Rhizosphere Microbial Communities in Two Species of Amorphophallus to Pectobacterium carotovorum subsp. carotovorum Infection.

Soft rot is a widespread, catastrophic disease caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) that severely damages the production of Amorphophallus spp. This study evaluated the rhizosphere bacterial and fungal communities in Pcc-infected and uninfected plants of two species of Amorphophallus, A. muelleri and A. konjac. Principal component analysis showed that the samples formed different clusters according to the Pcc infection status, indicating that Pcc infection can cause a large number of changes in the bacterial and fungal communities in the Amorphophallus spp. rhizosphere soil. However, the response mechanisms of A. muelleri and A. konjac are different. There was little difference in the overall microbial species composition among the four treatments, but the relative abundances of core microbiome members were significantly different. The relative abundances of Actinobacteria, Chloroflexi, Acidobacteria, Firmicutes, Bacillus, and Lysobacter were lower in infected A. konjac plants than in healthy plants; in contrast, those of infected A. muelleri plants were higher than those in healthy plants. For fungi, the relative abundances of Ascomycota and Fusarium in the rhizosphere of infected A. konjac plants were significantly higher than those of healthy plants, but those of infected A. muelleri plants were lower than those of healthy plants. The relative abundance of beneficial Penicillium fungi was lower in infected A. konjac plants than in healthy plants, and that of infected A. muelleri plants was higher than that of healthy plants. These findings can provide theoretical references for further functional research and utilization of Amorphophallus spp. rhizosphere microbial communities in the future.

Integrated metabolome and transcriptome analysis provides insights on the floral scent formation in Hydrangea arborescens.

Hydrangea (Hydrangea arborescens var. "Annabelle") flowers are composed of sweet aroma sepals rather than true petals and can change color. Floral volatiles plays important roles in plants, such as attracting pollinators, defending against herbivores, and signaling. However, the biosynthesis and regulatory mechanisms underlying fragrance formation in H. arborescens during flower development remain unknown. In this study, a combination of metabolite profiling and RNA sequencing (RNA-seq) was employed to identify genes associated with floral scent biosynthesis mechanisms in "Annabelle" flowers at three developmental stages (F1, F2, and F3). The floral volatile data revealed that the "Annabelle" volatile profile includes a total of 33 volatile organic compounds (VOCs), and VOCs were abundant during the F2 stage of flower development, followed by the F1 and F3 stages, respectively. Terpenoids and benzenoids/phenylpropanoids were abundant during the F2 and F1 stages, with the latter being the most abundant, whereas fatty acid derivatives and other compounds were found in large amounts during the F3 stage. According to ultra-performance liquid chromatography-tandem mass spectrometer analysis, benzene and substituted derivatives, carboxylic acids and derivatives, and fatty acyls play a significant role in the floral metabolite profile. The transcriptome data revealed a total of 17,461 differentially expressed genes (DEGs), with 7585, 12,795, and 9044 DEGs discovered between the F2 and F1, F3 and F1, and F2 and F3 stages, respectively. Several terpenoids and benzenoids/phenylpropanoids biosynthesis-related DEGs were identified, and GRAS/bHLH/MYB/AP2/WRKY were more abundant among transcription factors. Finally, DEGs interlinked with VOCs compounds were determined using Cytoscape and k-means analysis. Our results pave the way for the discovery of new genes, critical data for future genetic studies, and a platform for the metabolic engineering of genes involved in the production of Hydrangea's signature floral fragrance.

Effect of marigold (Tagetes erecta L.) on soil microbial communities in continuously cropped tobacco fields.

Root-knot nematode disease is a catastrophic soil-borne disease in tobacco production. The regulation of natural microbial communities is considered a good disease management approach to suppress the incidence of soilborne diseases. In this study, the effects of tobacco (Nicotiana tabacum L.)-marigold (Tagetes erecta L.) rotation on the diversity and structure of soil microbial communities in continuously cropped tobacco fields were analyzed to manage this devastating pathogen. The results showed that the soil bacterial OTUs increased after marigold rotation and that the bacterial Shannon, ACE, Chao1 index, and fungal Shannon index were higher in the tobacco-marigold rotation fields than in the continuously cropped tobacco fields by 3.98%, 10.37%, 5.46%, and 3.43%, respectively. After marigold rotation, the relative abundances of Actinobacteria, Acidobacteria, and Ascomycota increased by 28.62%, 107.50%, and 57.44%, respectively, and the proportion of beneficial bacterial genera such as Nocardioides, Gemmatimonas, and Bradyrhizobium increased. In addition, our results also showed that rotation of marigold could effectively reduce the incidence of root-knot nematodes in the next crop of tobacco. These results indicate that marigold rotation had a positive effect on the soil microecological environment of continuously cropped tobacco fields, reducing the obstacles to continuous cropping of tobacco.

Dynamic changes in the endophytic bacterial community during maturation of Amorphophallus muelleri seeds.

The seed microbiota is considered to be the starting point of the accumulation of plant microbiota, which is conducive to the preservation and germination of seeds and the establishment and development of seedlings. Our understanding of the colonization and migration dynamics of microbial taxa during seed development and maturation is still limited. This study used 16S rRNA high-throughput sequencing to investigate the dynamic changes in the composition and diversity of the endophytic bacterial community during maturation of Amorphophallus muelleri seeds. The results showed that as seeds matured (green to red), the Shannon index of their endophytic bacterial community first decreased and then increased, and the ACE and Chao1 indices of the endophytic bacterial community decreased gradually. The Shannon, ACE, and Chao1 indices of the endophytic bacterial community in the seed coat first decreased and then increased. Principal coordinate analysis of the bacterial communities revealed that the seed coat at different maturity stages showed significantly distinct bacterial communities and formed different clusters according to maturity stage. The bacterial communities of green and red seeds showed a clear separation, but they both overlapped with those of yellow seeds, indicating that some core taxa were present throughout seed maturation, but their relative abundance was dynamically changing. As the seeds grew more mature, the relative abundance of some bacterial communities with plant growth-promoting traits and others correlated with plant resistance (e.g., Burkholderia-Caballeronia-Paraburkholderia, Bacillus, Pseudomonas, Bradyrhizobium, Streptomyces) tended to increase and peaked in fully mature seeds and seed coats. The endophytic bacterial community of A. muelleri seeds seems to be driven by the seed maturation state, which can provide a theoretical basis for a comprehensive understanding of the assembly process of the microbial community during A. muelleri seed maturation.

A high trans-zeatin nucleoside concentration in corms may promote the multileaf growth of Amorphophallus muelleri.

Amorphophallus muelleri has a multileaf growth pattern different from that of other konjacs; however, the hormonal mechanism underlying this phenomenon is not clear. In this study, the levels of hormones closely related to the sprouting of the axillary bud, including five types of cytokinins, indole-3-acetic acid (IAA) and abscisic acid (ABA) were measured. In the second leaf sprouting stage, the content of trans-zeatin riboside (tZR) in corms increased more than 5000-fold over that in the dormancy period. Surprisingly, although the expression of CYP735A1 and CYP735A2, which synthesize the precursors for tZR was elevated at the second leaf sprouting stage, the expression of IPTs, which have key roles in cytokinin biosynthesis, did not change significantly. In addition, most cytokinin contents in leaves during the same period were significantly lower than those in corms. We speculate that the high cytokinin contents in the corms may not biosynthesized de novo in corms. In addition, the IAA content in the corms also considerably increased during the second leaf sprouting stage. Indole-3-acetaldehyde oxidase (AO1) and auxin efflux carrier PIN1A, presented relatively high expression levels in the same period. In contrast, ABA content, and the expression of NCED1, a rate-limiting enzyme in ABA biosynthesis, were suppressed at the second leaf sprouting stage. It is worth mentioning that N6-(Δ2-isopentenyl) adenosine (iP)-type cytokinins have a high content in corms in the dormant period that significantly decreases after the first leaf sprouting stage, which is completely different from the trend of tZR. By treating dormant corms with iP, the percentage of multibud plants increased, and the growth performance in terms of bud and root length was significantly higher than those of the control. This implies that iP-type cytokinins tend to play a role in promoting first seedling sprouting. Furthermore, there was a remarkable increase of the IAA content in both corms and roots under iP treatment but an inhibitory effect in buds. We speculate that the increase in the IAA content induced by iP is tissue specific. These results will assist in the understanding of the role of hormones, especially cytokinins, in the multileaf growth type of konjac.

Acute myeloid leukemia with myelodysplasia-related changes and blasts of the mixed T/myeloid phenotype: a case report.

A rare but clinically important diagnostic dilemma arises when cases meet the criteria for both acute myeloid leukemia with myelodysplasia-related changes (AML-MRC) and mixed phenotype acute leukemia, especially those that evolve from myelodysplastic syndrome. We describe a 56-year-old male patient who presented with cytopenias and was initially diagnosed with myelodysplastic syndrome with single lineage dysplasia. Nearly 1 year later, this patient progressed to acute leukemia, and his blast cells simultaneously expressed T-lymphoid and myeloid antigens. Cytogenetic analysis showed a 20q deletion, and next-generation sequencing showed mutations of ASXL1, NRAS, PHF6, RUNX1, TP53, and PIGA. He was diagnosed with AML-MRC with blasts of the mixed T/myeloid phenotype according to the latest World Health Organization guidelines. In accordance with the treatment principles of AML-MRC, we chose an AML-like regimen for four cycles, but the patient did not achieve remission. Finally, we adhered to the treatment principles of mixed phenotype acute leukemia, and he achieved remission after a course of ALL-like regimen chemotherapy.

Effect of Bacterial Wilt on Fungal Community Composition in Rhizosphere Soil of Tobaccos in Tropical Yunnan.

Bacterial wilt, which is a major soil-borne disease with widespread occurrence, poses a severe danger in the field of tobacco production. However, there is very limited knowledge on bacterial wilt-induced microecological changes in the tobacco root system and on the interaction between Ralstonia solanacearum and fungal communities in the rhizosphere soil. Thus, in this study, changes in fungal communities in the rhizosphere soil of tobaccos with bacterial wilt were studied by 18S rRNA gene sequencing. The community composition of fungi in bacterial wilt-infected soil and healthy soil in two tobacco areas (Gengma and Boshang, Lincang City, Yunnan Province, China) was studied through the paired comparison method in July 2019. The results showed that there were significant differences in fungal community composition between the rhizosphere soil of diseased plants and healthy plants. The changes in the composition and diversity of fungal communities in the rhizosphere soil of tobaccos are vital characteristics of tobaccos with bacterial wilt, and the imbalance in the rhizosphere microecosystem of tobacco plants may further aggravate the disease.

Molecular cloning, characterization and expression analysis of two 12-oxophytodienoate reductases (NtOPR1 and NtOPR2) from Nicotiana tabacum.

BACKGROUND: 12-oxophytodienoic acid (OPDA) is a signaling molecule involved in defense and stress responses in plants. 12-oxophytodienoate reductase (OPR) is involved in the biosynthesis of jasmonic acid and trigger the conversion of OPDA into 3-oxo-2(2'[Z]-pentenyl)-cyclopentane-1-octanoic acid (OPC-8:0). METHODS AND RESULTS: Sequence analysis revealed that Nicotiana tabacum 12-oxophytodienoate reductase 1 (OPR1) and OPR2 encoded polypeptides of 375 and 349 amino acids with molecular masses of 41.67 and 39.04 kilodaltons (kDa), respectively, while the deduced protein sequences of NtOPR1 and NtOPR2 showed high homology with other 12-oxophytodienoate reductases. BLAST (Basic local alignment search tool) analysis revealed that both NtOPRs belong to the family of Old Yellow Enzymes (OYE), and analysis of genomic DNA structure indicated that both genes include 5 exons and 4 introns. Phylogenetic analysis using MEGA X showed that NtOPR1 and NtOPR2 shared a close evolutionary relationship with Nicotiana attenuata 12-oxophytodienoate reductases. In silico analysis of subcellular localization indicated the probable locations of NtOPR1 and NtOPR2 to be the cytoplasm and the peroxisome, respectively. Tissue-specific expression assays via qRT-PCR revealed that NtOPR1 and NtOPR2 genes were highly expressed in Nicotiana tabacum roots, temperately expressed in leaves and flowers, while low expression was observed in stem tissue. CONCLUSIONS: Presently, two 12-oxophytodienoate reductase genes (NtOPR1 and NtOPR2) were cloned and comprehensively characterized. Our findings provide comprehensive analyses that may guide future deep molecular studies of 12-oxophytodienoate reductases in Nicotiana tabacum.

Comprehensive characterization of Guanosine monophosphate synthetase in Nicotiana tabacum.

BACKGROUND: Guanosine monophosphate (GMP) synthetase is an enzyme that converts xanthosine monophosphate to GMP. GMP plays an essential role in plant development and responses to internal and external stimuli. It also plays a crucial role in several plant physiochemical processes, such as stomata closure, cation flux regulation, pathogen responses and chloroplast development. METHODS AND RESULTS: The mRNA sequences of NtGMP synthase in tobacco (Nicotiana tabacum) were rapidly amplified from cDNA. The GMP synthase open reading frame contains a 1617 bp sequence encoding 538 amino acids. A sequence analysis showed that this sequence shares high homology with that of Nicotiana sylvestris, Nicotiana attenuata, N. tomentosiformis, Solanum tuberosum, Lycopersicon pennellii, L. esculentum, Capsicum annuum, C. chinense and C. baccatum GMP synthase. A BLAST analysis with a tobacco high-throughput genomic sequence database revealed that the tobacco GMP synthase gene has five introns and six exons. A phylogenetic analysis showed a close genetic evolutionary relationship with N. sylvestris GMP synthase. The tissue-specific expression profile was evaluated using quantitative real-time PCR. The data showed that NtGMP synthase was highly expressed in leaves and moderately expressed in roots, flowers, and stems. The subcellular localization was predicted using the WOLF PSORT webserver, which strongly suggested that it might be localized to the cytoplasm. CONCLUSIONS: In the current study, we cloned and comprehensively characterized GMP synthase in tobacco (Nicotiana tabacum). Our results establish a basis for further research to explore the precise role of this enzyme in tobacco.

Identification, methylation profiling, and expression analysis of stress-responsive cytochrome P450 genes in rice under abiotic and phytohormones stresses.

The cytochrome P450 (CYP) is a large and complex eukaryotic gene superfamily with enzymatic activities involved in several physiological and regulatory processes. As an objective, an in-silico genome-wide DNA methylation (5mC) analysis was performed in rice (Oryza sativa cv. Zhonghua11), and the epigenetic role of CYPs in two abiotic stresses was observed. Being a stable representative mark, DNA-methylation alters the gene expression under stressful environmental conditions. Rice plants under salinity and drought stresses were analyzed through MeDIP-chip hybridization, and 14 unique genes of the CYP family were identified in the rice genome with varying degrees of methylation. The gene structure, promoter sequences, and phylogenetic analysis were performed. Furthermore, the responses of CYPs to various abiotic stresses, including salinity, drought, and cold were revealed. Similarly, the expression profile of potential CYPs was also investigated under various phytohormone stresses, which revealed the potential involvement of CYPs to hormone regulations. Overall, the current study provides evidence for CYP's stress regulation and fundamental for further characterization and understanding their epigenetic roles in gene expression regulation and environmental stress regulation in higher plants.