Differential Expression Patterns In Response Research Articles

Genome-Wide Analysis of Potato CCT Family Genes and Its Response to Auxin Substances

The control of flowering time plays an important role in the growth and development of potato tubers. The CCT (CO, COL and TOC1) gene family is involved in the flowering process of plants. In this study, a total of 32 StCCT family genes were identified and further classified into five subfamilies, including COL (17 members), PRR (4 members), ZIM (3 members), ASML2 (6 members) and TCR1 (2 members), based on their phylogenetic relationship. An analysis of the gene structure, motif compositions and conserved domain provided support for this classification. The StCCT genes were unevenly distributed on 12 chromosomes of the potato plant. In total, six gene duplication events were observed, which played a crucial role in the expansion of the StCCT family genes in the potato. The expression profiles exhibited diverse expression patterns of the StCCT genes in six tissues (leaf, shoot, root, tuber, stolon, and flower), StCCT32 is only expressed in flowers, while StCCT19 and StCCT8 are highly expressed in flowers and tubers, respectively. The StCCT genes exhibit different expression patterns in response to IAA and TIBA treatments at different concentrations across three tissues (leaf, stem, and tuber). After IAA and TIBA treatments, it was found that the expression level of StCCT7 was low in leaves and stems but significantly increased in tubers. Collectively, this study provided valuable information for the further study of potato formation and development and provided candidate genes for molecular breeding in the potato.

Feeding and growth are regulated by light and opsins-mediated phototransduction in sea cucumber Apostichopus japonicus

Light is a crucial environmental ecological factor that affects physiological processes including feeding and growth of marine invertebrates. Although nonvisual photosensitivity has long been known in echinoderms, the underlying molecular regulation mechanism remains unclear. Here, we firstly reported opsins-mediated phototransduction signaling and the cross-talk between light and feeding/growth in Apostichopus japonicus, an important economic species with high medicinal and nutritional values. Molecular characterization analysis of Ajopsins revealed that they were mainly distributed in the epidermis of potential photosensitive tissues (tentacles, papillae and tube feet). And all four Ajopsins including Rhodopsin 5-like (AjRH5), long-wavelength-sensitive opsin (AjLWS), peropsin (AjPOP), and peropsin-like (AjPOPL) exhibited different expression patterns in response to different light conditions. Moreover, four Ajopsins all conjugated with Gαi/o to reduce intracellular cAMP levels. Besides, three Ajopsins (AjRH5, AjPOP and AjPOPL) conjugated with Gαq to activate Gαq/Ca2+/PKC signaling. And all four opsins could activate downstream ERK1/2 phosphorylation. In addition, the photosensitivities of these four Ajopsins were different in response to different wavelength of light, AjPOP and AjPOPL were sensitive to short-medium-long wavelength light, AjRH5 and AjLWS were sensitive to medium-long wavelength light. Furthermore, indoor aquaculture experiment showed that 150 lx and 300 lx light intensity could significantly promote feeding and growth of A. japonicus, which might be mediated by AjOXP1 and AjMAP2K4. Under different light wavelength treatment, red light (655–665 nm) significantly promoted the feeding and growth of A. japonicus, which may be mediated by AjOXP1/2, AjMAP2K4 and AjMegf6. And siRNA experiment further confirmed the crosstalk between AjPOPL and AjOXP1, suggesting AjPOPL may regulate feeding by AjOXP1 in A. japonicus. Our findings showed a comprehensive description of Ajopsins signaling, providing new insights on the molecular mechanism of photoreception involved in regulating feeding and growth in A. japonicus and suggested the optimum light conditions for optimizing the lighting scheme of A. japonicus aquaculture.

Genome-wide characterization of the GRF transcription factors in potato (Solanum tuberosum L.) and expression analysis of StGRF genes during potato tuber dormancy and sprouting.

Growth-regulating factors (GRFs) are transcription factors that play a pivotal role in plant growth and development. This study identifies 12 Solanum tuberosum GRF transcription factors (StGRFs) and analyzes their physicochemical properties, phylogenetic relationships, gene structures and gene expression patterns using bioinformatics. The StGRFs exhibit a length range of 266 to 599 amino acids, with a molecular weight of 26.02 to 64.52 kDa. The majority of StGRFs possess three introns. The promoter regions contain a plethora of cis-acting elements related to plant growth and development, as well as environmental stress and hormone response. All the members of the StGRF family contain conserved WRC and QLQ domains, with the sequences of these two conserved domain modules exhibiting high levels of conservation. Transcriptomic data indicates that StGRFs play a significant role in the growth and development of stamens, roots, young tubers, and other tissues or organs in potatoes. Furthermore, a few StGRFs exhibit differential expression patterns in response to Phytophthora infestans, chemical elicitors, heat, salt, and drought stresses, as well as multiple hormone treatments. The results of the expression analysis indicate that StGRF1, StGRF2, StGRF5, StGRF7, StGRF10 and StGRF12 are involved in the process of tuber sprouting, while StGRF4 and StGRF9 may play a role in tuber dormancy. These findings offer valuable insights that can be used to investigate the roles of StGRFs during potato tuber dormancy and sprouting.

Genome-wide identification and expression analysis of protein arginine methyltransferase and JmjC domain-containing family in apple.

Histone methylation is an important type of histone modification that regulates gene expression in plants. In this study, we identified 14 arginine methylation-related genes (Protein Arginine Methyltransferase, MdPRMT) and 32 demethylation-related genes (JmjC Domain-Containing Family, MdJMJ) in apple. Furthermore, we investigated the phylogenetic relationship, chromosome distribution, gene structure, motif analysis, promoter sequence analysis, and expression patterns of MdPRMT and MdJMJ genes. Homology analysis showed a high degree of conservation and homology between PRMT and JMJ genes in Arabidopsis and apple. We identified the types of duplicated genes in the MdJMJ and MdPRMT gene families, found a large number of whole-genome duplicates (WGD) gene pairs and a small number of tandem duplicates (TD) pairs, transposed duplication (TRD) gene pairs as well as proximal duplicates (PD) pairs, and discussed the possible evolutionary pathways of the gene families from the perspective of duplicated genes. Homology analysis showed a high degree of conservation and homology between PRMT and JMJ genes in Arabidopsis and apple. In addition, the promoter regions of MdPRMT and MdJMJ contain numerous cis-acting elements involved in plant growth and development, hormone response, and stress responses. Based on the transcriptional profiles of MdPRMT and MdJMJ in different tissues and developmental stages, it was found that MdPRMT and MdJMJ may play multiple roles in apple growth and development, for example, MdJMJ21 may be involved in the regulation of apple endosperm formation. MdPRMT and MdJMJ exhibit different expression patterns in response to hormone signaling in apple, MdJMJ3, MdJMJ18, MdJMJ30, MdPRMT2, MdPRMT13, and MdPRMT14 may play roles in apple response to drought stress, while the expression of MdJMJ13, MdPRMT3, MdPRMT4, and MdPRMT6 is affected by cold stress. Our study provides a foundation for determining the functional roles of MdPRMT and MdJMJ genes in apple.

Functional and regulatory diversity of homeobox-leucine zipper transcription factors BnaHB6 under dehydration and salt stress in Brassica napus L.

The plant-specific homeodomain-leucine zipper I subfamily is involved in the regulation of various biological processes, particularly growth, development and stress response. In the present study, we characterized four BnaHB6 homologues from Brassica napus. All BnaHB6 proteins have transcriptional activation activity. Structural and functional data indicate the complex role of BnaHB6 genes in regulating biological processes, with some functions conserved and others diverged. Transcriptional analyzes revealed that they are induced in a similar manner in different tissues but show different expression patterns in response to stress and circadian rhythm. Only the BnaA09HB6 and BnaC08HB6 genes are expressed under dehydration and salt stress, and in darkness. The partial transcriptional overlap of BnaHB6s with the evolutionarily related genes BnaHB5 and BnaHB16 was also observed. Transgenic Arabidopsis thaliana plants expressing a single proBnaHB6::GUS partially confirmed the expression results. Bioinformatic analysis allowed the identification of TF-binding sites in the BnaHB6 promoters that may control their expression under stress and circadian rhythm. ChIP-qPCR analysis revealed that BnaA09HB6 and BnaC08HB6 bind directly to the promoters of the target genes BnaABF4 and BnaDREB2A. Comparison of their expression patterns in the WT plants and the bnac08hb6 mutant showed that BnaC08HB6 positively regulates the expression of the BnaABF4 and BnaDREB2A genes under dehydration and salt stress. We conclude that four BnaHB6 homologues have distinct functions in response to stress despite high sequence similarity, possibly indicating different binding preferences with BnaABF4 and BnaDREB2A. We hypothesize that BnaC08HB6 and BnaA09HB6 function in a complex regulatory network under stress.

Identification and expression analysis of the Xyloglucan transglycosylase/hydrolase (XTH) gene family under abiotic stress in oilseed (Brassica napus L.)

XTH genes are key genes that regulate the hydrolysis and recombination of XG components and plays role in the structure and composition of plant cell walls. Therefore, clarifying the changes that occur in XTHs during plant defense against abiotic stresses is informative for the study of the plant stress regulatory mechanism mediated by plant cell wall signals. XTH proteins in Arabidopsis thaliana was selected as the seed sequences in combination with its protein structural domains, 80 members of the BnXTH gene family were jointly identified from the whole genome of the Brassica napus ZS11, and analyzed for their encoded protein physicochemical properties, phylogenetic relationships, covariance relationships, and interoperating miRNAs. Based on the transcriptome data, the expression patterns of BnXTHs were analyzed in response to different abiotic stress treatments. The relative expression levels of some BnXTH genes under Al, alkali, salt, and drought treatments after 0, 6, 12 and 24 h were analyzed by using qRT-PCR to explore their roles in abiotic stress tolerance in B. napus. BnXTHs showed different expression patterns in response to different abiotic stress signals, indicating that the response mechanisms of oilseed rape against different abiotic stresses are also different. This paper provides a theoretical basis for clarifying the function and molecular genetic mechanism of the BnXTH gene family in abiotic stress tolerance in rapeseed.

Genome-Wide Analysis Revealed NBS-LRR Gene Candidates Associated with Bacterial Wilt Resistance in Eggplant (Solanum melongena L.)

NBS-LRR genes constitute one of the largest resistance gene families in plants, which play key roles in resistance to pathogens. Although the identification and characterization of the NBS-LRR gene family has been extensively reported in various species, a comprehensive analysis in eggplant has not been previously documented. In this study, a total of 269 SmNBS genes were identified in the eggplant genome. Based on domain classification and phylogenetic analysis, SmNBSs were divided into three subgroups 231 CNLs (CC-NBS-LRR), 36 TNLs (TIR-NBS-LRR), and 2 RNLs (RPW8-NBS-LRR). Chromosomal mapping analysis revealed an uneven distribution of SmNBSs in clusters across chromosomes, with a predominant presence on chromosomes 10, 11, and 12. Structural analysis identified eight conserved motifs previously reported in SmNBSs, exhibiting high conservation in both amino acid sequences and their order. Evolutionary analysis demonstrated that tandem duplication events mainly contributed to the expansion of SmNBS. Subsequently, qRT-PCR analysis demonstrated that nine SmNBSs exhibited differential expression patterns in response to R. solanacearum stress, with EGP05874.1 potentially involved in the resistance response. In conclusion, this study provides a comprehensive insight into SmNBSs, which will enhance the research on eggplant disease resistance and facilitate the breeding of new disease-resistant varieties.

Cytochrome P450 superfamily in spotted sea bass: Genome-wide identification and expression profiles under trichlorfon and environmental stresses

Cytochrome P450s (CYPs), as one of the most diverse enzyme superfamilies in nature, play critical functions in antioxidant reactions against endogenous and exogenous compounds. In this study, we performed genome-wide characterization of CYP superfamily members and analyzed their expression patterns under several abiotic stresses in spotted sea bass, which is known as an economically important fish species in the Chinese aquaculture industry. A total of 55 CYP genes were identified and divided into 17 families within 10 clans. The analysis of phylogeny, gene structure, and syntenic relationships provided evidence for the evolution of CYP genes and confirmed their annotation and orthology. The expression of CYP genes was examined in the liver during trichlorfon stress using quantitative real-time PCR. The results showed that 20 tested CYP genes displayed significant mRNA expression changes, indicating that they may play crucial roles in the metabolism of trichlorfon and can be potential biomarkers for trichlorfon pollution. Moreover, by screening transcriptomic databases, 10, 3 and 19 CYP genes exhibited differential expression patterns in response to hypoxia, alkalinity and heat stress, respectively. Taken together, this study provided insights into the regulation of CYP genes by toxicological and environmental stresses, laid basis for extensive functional studies of the CYP superfamily in spotted sea bass and other teleost species.

Comparative Transcriptome Profiling Reveals Key MicroRNAs and Regulatory Mechanisms for Aluminum Tolerance in Olive.

Aluminum toxicity (Al) is one of the major constraints to crop production in acidic soils. MicroRNAs (miRNAs) have emerged as key regulatory molecules at post-transcriptional levels, playing crucial roles in modulating various stress responses in plants. However, miRNAs and their target genes conferring Al tolerance are poorly studied in olive (Olea europaea L.). Here, genome-wide expression changes in miRNAs of the roots from two contrasting olive genotypes Zhonglan (ZL, Al-tolerant) and Frantoio selezione (FS, Al-sensitive) were investigated by high-throughput sequencing approaches. A total of 352 miRNAs were discovered in our dataset, consisting of 196 conserved miRNAs and 156 novel miRNAs. Comparative analyses showed 11 miRNAs have significantly different expression patterns in response to Al stress between ZL and FS. In silico prediction identified 10 putative target gene of these miRNAs, including MYB transcription factors, homeobox-leucine zipper (HD-Zip) proteins, auxin response factors (ARF), ATP-binding cassette (ABC) transporters and potassium efflux antiporter. Further functional classification and enrichment analysis revealed these Al-tolerance associated miRNA-mRNA pairs are mainly involved in transcriptional regulation, hormone signaling, transportation and metabolism. These findings provide new information and perspectives into the regulatory roles of miRNAs and their target for enhancing Al tolerance in olives.

Genome-wide identification glutathione-S-transferase gene superfamily in Daphnia pulex and its transcriptional response to nanoplastics

Glutathione S-transferases (GSTs) are key multifunctional phase II detoxification enzymes involved in the regulation of growth, development, and stress responses. However, the knowledge of GSTs in the model invertebrate organism Daphnia pulex at the genomic level remains limited. In the present study, 35 GST genes were identified in D. pulex (Dp-GST), belonging to eight subfamilies, with the sigma, mu, and delta/epsilon subfamilies constituting approximately 29 %, 20 %, and 20 % of the GST superfamily, respectively. Chromosome tandem duplication of genes within the same subfamily was observed, which may be the main force driving GST expansion in D. pulex. DpGST genes showed different expression patterns in response to nanoplastic exposure for 96 h and 21 days. Some homologous GST genes in D. pulex showed similar expression patterns in response to nanoplastic exposure, likely owing to their unique motifs. For example, motif 9 is found in all delta/epsilon GST genes, whereas motifs 1, 2, 3, 5, and 7 are highly conserved in sigma GST genes. The characterization of D. pulex GSTs extending the knowledge of GST-mediated environmental contaminants, especially nanoplastics.

Identification of Peanut AhMYB44 Transcription Factors and Their Multiple Roles in Drought Stress Responses.

MYB transcription factors (TFs) comprise a large gene family that plays an important role in plant growth, development, stress responses, and defense regulation. However, their functions in peanut remain to be further elucidated. Here, we identified six AhMYB44 genes (AhMYB44-01/11, AhMYB44-05/15, and AhMYB44-06/16) in cultivated peanut. They are typical R2R3-MYB TFs and have many similarities but different expression patterns in response to drought stress, suggesting different functions under drought stress. Homologous genes with higher expression in each pair were selected for further study. All of them were nuclear proteins and had no self-transactivation activity. In addition, we compared the performances of different lines at germination, seedling, and adult stages under drought stress. After drought treatment, the overexpression of AhMYB44-11 transgenic plants resulted in the longest root length at the seedling stage. Levels of proline, soluble sugar and chlorophyll, and expression levels of stress-related genes, including P5CS1, RD29A, CBF1, and COR15A, were higher than those of the wild type (WT) at the adult stage. While the overexpression of AhMYB44-16 significantly increased the drought sensitivity of plants at all stages, with differential ABA content, the expression levels of the ABA-related genes PP2CA and ABI1 were significantly upregulated and those of ABA1 and ABA2 were significantly downregulated compared with the WT. AhMYB44-05 showed similar downregulated expression as AhMYB44-16 under drought stress, but its overexpression in Arabidopsis did not significantly affect the drought resistance of transgenic plants. Based on the results, we propose that AhMYB44-11 plays a role as a positive factor in drought tolerance by increasing the transcription abundance of stress-related genes and the accumulation of osmolytes, while AhMYB44-16 negatively regulates drought tolerance through its involvement in ABA-dependent stress response pathways.

Identification of the GAPDH gene family in Citrullus lanatus and functional characteristics of ClGAPC2 in Arabidopsis thaliana.

Members of the GAPDH family play important roles in plant growth and development, as well as in stress responses. Our aim was to identify stress resistance genes through systematic analysis of the GAPDH family in watermelon. This could not only provide genetic resources for stress resistance breeding, but also form a basis for the study of plant stress resistance mechanisms. Eight GAPDHs representing four types of plant GAPDH in watermelon were identified (ClGAPA/B, ClGAPC1-3, ClGAPCp1-2 and ClGAPN). A comprehensive analysis of physicochemical properties, chromosome distribution, evolutionary relationships, exon-intron structure and conserved motifs of watermelon GAPDHs was performed using bioinformatics. Expression characteristics were assessed by RT-qPCR. Based on RT-qPCR results, ClGAPC2 was screened as a candidate for subcellular localization analysis and functional verification in Arabidopsis thaliana. Eight GAPDHs were classified into four subfamilies. GAPDHs in each subgroup were generally conserved and shared similarities in structure and conserved motifs. ClGAPDHs had notable tissue specificity and different expression patterns in response to H2 O2 , chilling, salt, osmotic stress, heat, salicylic acid, gibberellin, brassinosterol, ethylene and abscisic acid treatments. Three ClGAPC genes, especially ClGAPC2, were markedly induced by several treatments. ClGAPC2 was located in the nucleus and cytoplasm of tabacum epidermal cells. The ClGAPC2 transgenic Arabidopsis showed enhanced tolerance to salinity at the germination stage. We suggest that ClGAPC2 plays important roles in the adaptation of watermelon to salinity. Our findings provided candidate genes for further improving the salt tolerance of watermelon.

Comprehensive Analysis of NAC Genes Reveals Differential Expression Patterns in Response to Pst DC3000 and Their Overlapping Expression Pattern during PTI and ETI in Tomato.

NAC (NAM/ATAF/CUC) transcription factors belong to a unique gene family in plants, which play vital roles in regulating diverse biological processes, including growth, development, senescence, and in response to biotic and abiotic stresses. Tomato (Solanum lycopersicum), as the most highly valued vegetable and fruit crop worldwide, is constantly attacked by Pseudomonas syringae pv. tomato DC3000 (Pst DC3000), causing huge losses in production. Thus, it is essential to conduct a comprehensive identification of the SlNAC genes involved in response to Pst DC3000 in tomato. In this study, a complete overview of this gene family in tomato is presented, including genome localization, protein domain architectures, physical and chemical features, and nuclear location score. Phylogenetic analysis identified 20 SlNAC genes as putative stress-responsive genes, named SSlNAC 1-20. Expression profiles analysis revealed that 18 of these 20 SSlNAC genes were significantly induced in defense response to Pst DC3000 stress. Furthermore, the RNA-seq data were mined and analyzed, and the results revealed the expression pattern of the 20 SSlNAC genes in response to Pst DC3000 during the PTI and ETI. Among them, SSlNAC3, SSlNAC4, SSlNAC7, SSlNAC8, SSlNAC12, SSlNAC17, and SSlNAC19 were up-regulated against Pst DC3000 during PTI and ETI, which suggested that these genes may participate in both the PTI and ETI pathway during the interaction between tomato and Pst DC3000. In addition, SSlNAC genes induced by exogenous hormones, including indole-3-acetic acid (IAA), abscisic acid (ABA), salicylic acid (SA), and methyl jasmonic acid (MeJA), were also recovered. These results implied that SSlNAC genes may participate in the Pst DC3000 stress response by multiple regulatory pathways of the phytohormones. In all, this study provides important clues for further functional analysis and of the regulatory mechanism of SSlNAC genes under Pst DC3000 stress.

Heat shock transcriptional factors (HSFs) are expressed in response to hydrogen peroxide production in grapevines inoculated with Colletotrichum Species

Heat shock transcriptional factors (HSFs) are expressed in plants due to external stress, high temperatures, or pathogenic infections. This study was undertaken to analyze the expression of HSF genes in grapevines inoculated with pathogens. Spores of Colletotrichum acutatum and C. gloeosporioides were inoculated on the leaves, and on immature and mature fruits of ‘Campbell Early’ and creeping grapevine (Vitis flexuosa). The real-time PCR of RNA isolated from infected leaves and fruits showed specific upregulation of HSF11, HSF12, HSF14, and HSF15 subsequent to both high temperature and pathogen infections. However, HSF16 and HSF17 were up-regulated specifically by pathogenic infections only and showed different expression patterns in response to wounding. Among the hydrogen peroxide-related genes, the expression of catalase (CAT) and superoxide dismutase (SOD) was up-regulated by pathogen infections. Concurrently, expression of six HSFs (HSF11, HSF12, HSF14, HSF15, HSF16, and HSF17) dose-dependently increased with accumulation of hydrogen peroxide in the leaves and fruits of grapevines. The expression of selected HSF genes was up-regulated differentially as a defense reaction in ‘Campbell Early’ and V. flexuosa grapevine in response to external stress (such as wounding) and pathogen inoculation. This indicates that expression of some HSFs is regulated through the hydrogen peroxide-mediated pathways in response to pathogens. Further studies determining the mechanism of HSF gene expression induced by external stress are required.

Reconstructing ethanol oxidation pathway in Pseudomonas putida KT2440 for bio-upgrading of ethanol to biodegradable polyhydroxybutanoates

Ethanol has recently been demonstrated as a suitable carbon source for acetyl-CoA-derived products with high theoretical yield. Herein, the short-chain-length polyhydroxyalkanoates production pathway was constructed in an industrial platform P. putida KT2440, allowing the engineered strain to produce 674.97 ± 22.3 mg/L of Polyhydroxybutyrate (PHB) from ethanol as sole carbon source. Furthermore, the ethanol catabolic pathway was reconstructed to enhance the acetyl-coA pool by expressing the novel Aldehyde dehydrogenases from Klebsiella pneumonia and Dickeya zeae, resulting in a titer of 1385.34 ± 16.5 mg/L and 9300 ± 0.56 mg/L of PHB in shake flask and fermenter, respectively. Furthermore, transcriptome analysis was conducted to provide insights into the central metabolic pathways and different expression patterns in response to changes in substrate. Additionally, the production of co-polymer poly(3-hydroxybutyrate-co-3-hydroxypropionate) was shown using glycerol and ethanol as co-substrates from recombinant P. putida KT2440. This work demonstrates the potential of P. putida KT2440 as a promising industrial platform for short-chain-length PHAs production from structurally unrelated carbon sources.

Identification of WRKY transcription factor family genes in Pinus massoniana Lamb. and their expression patterns and functions in response to drought stress

BackgroundPinus massoniana Lamb. is the timber species with the widest distribution and the largest afforestation area in China, providing a large amount of timber, turpentine and ecological products. Seasonal drought caused by climate warming severely constrains the quality and growth of P. massoniana forests. WRKY transcription factors play an important role in plant responses to abiotic stress. In this study, the molecular mechanisms by which P. massoniana responds to drought stress were analysed based on the P. massoniana WRKY (PmWRKY) family of genes.ResultsForty-three PmWRKYs are divided into three major families, 7 sub-families, and the conserved motifs are essentially the same. Among these 43 PmWRKYs express under drought stress but with different expression patterns in response to stress. PmWRKYs respond to drought stress induced by exogenous hormones of SA, ABA, and MeJA. The expression of PmWRKY6, PmWRKY10, and PmWRKY30 up-regulate in different families and tissues under drought stress, while PmWRKY22 down-regulate. Transgenetic tobaccos of PmWRKY31 are with lower malondialdehyde (MDA) content and higher proline (Pro) content than wild type (WT) tobaccos. In transgenic tobaccos of PmWRKY31, expression levels of related genes significantly improve, and drought tolerance enhance.ConclusionsThis study analysed the molecular biological characteristics of PmWRKYs and investigated the expression patterns and functions of PmWRKYs in response to drought stress in P. massoniana. The results of this study provide a basis for in-depth research of the molecular functions of PmWRKYs in response to drought stress.

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.

Comprehensive Analysis of the Hsp20 Gene Family in Canavalia rosea Indicates Its Roles in the Response to Multiple Abiotic Stresses and Adaptation to Tropical Coral Islands

Heat shock protein 20 (Hsp20) is a major family of heat shock proteins that mainly function as molecular chaperones and are markedly accumulated in cells when organisms are subjected to environmental stress, particularly heat. Canavalia rosea is an extremophile halophyte with good adaptability to environmental high temperature and is widely distributed in coastal areas or islands in tropical and subtropical regions. In this study, we identified a total of 41 CrHsp20 genes in the C. rosea genome. The gene structures, phylogenetic relationships, chromosome locations, and conserved motifs of each CrHsp20 or encoding protein were analyzed. The promoters of CrHsp20s contained a series of predicted cis-acting elements, which indicates that the expression of different CrHsp20 members is regulated precisely. The expression patterns of the CrHsp20 family were analyzed by RNA sequencing both at the tissue-specific level and under different abiotic stresses, and were further validated by quantitative reverse transcription PCR. The integrated expression profiles of the CrHsp20s indicated that most CrHsp20 genes were greatly upregulated (up to dozens to thousands of times) after 2 h of heat stress. However, some of the heat-upregulated CrHsp20 genes showed completely different expression patterns in response to salt, alkaline, or high osmotic stresses, which indicates their potential specific function in mediating the response of C. rosea to abiotic stresses. In addition, some of CrHsp20s were cloned and functionally characterized for their roles in abiotic stress tolerance in yeast. Taken together, these findings provide a foundation for functionally characterizing Hsp20s to unravel their possible roles in the adaptation of this species to tropical coral reefs. Our results also contribute to the understanding of the complexity of the response of CrHsp20 genes to other abiotic stresses and may help in future studies evaluating the functional characteristics of CrHsp20s for crop genetic improvement.

Integrated linkage mapping and genome-wide association study to dissect the genetic basis of zinc deficiency tolerance in maize at seedling stage

Zinc (Zn) deficiency is the most widespread micronutrient deficiency, affecting yield and quality of crops worldwide. Identifying genes associated with Zn-deficiency tolerance in maize is a basis for elucidating its genetic mechanism. A K22 × CI7 recombinant inbred population consisting of 210 lines and an association panel of 508 lines were used to identify genetic loci influencing Zn-deficiency tolerance. Under –Zn and –Zn/CK conditions, 15 quantitative trait loci (QTL) were detected, each explaining 5.7%–12.6% of phenotypic variation. Sixty-one significant single-nucleotide polymorphisms (SNPs) were identified at P < 10−5 by genome-wide association study (GWAS), accounting for 5%–14% of phenotypic variation. Among respectively 198 and 183 candidate genes identified within the QTL regions and the 100-kb regions flanking these significant SNPs, 12 were associated with Zn-deficiency tolerance. Among these candidate genes, four genes associated with hormone signaling in response to Zn-deficiency stress were co-localized with QTL or SNPs, including the genes involved in the auxin (ZmARF7), and ethylene (ZmETR5, ZmESR14, and ZmEIN2) signaling pathways. Three candidate genes were identified as being responsible for Zn transport, including ZmNAS3 detected by GWAS, ZmVIT and ZmYSL11 detected by QTL mapping. Expression of ZmYSL11 was up-regulated in Zn-deficient shoots. Four candidate genes that displayed different expression patterns in response to Zn deficiency were detected in the regions overlapping peak GWAS signals, and the haplotypes for each candidate gene were further analyzed.

Genome-Wide Identification and Functional Analysis of the Calcineurin B-like Protein and Calcineurin B-like Protein-Interacting Protein Kinase Gene Families in Chinese Cabbage (Brassica rapa ssp. pekinensis).

In plants, calcineurin B-like proteins (CBL) are a unique set of calcium sensors that decode calcium signals by activating a plant-specific protein kinase family called CBL-interacting protein kinases (CIPKs). The CBL–CIPK family and its interacting complexes regulate plant responses to various environmental stimuli. Chinese cabbage (Brassica rapa ssp. pekinensis) is an important vegetable crop in Asia; however, there are no reports on the role of the CBLs–CIPKs’ signaling system in response to abiotic stress during cabbage growth. In this study, 18 CBL genes and 47 CIPK genes were identified from the Chinese cabbage genome. Expansion of the gene families was mainly due to tandem repeats and segmental duplication. An analysis of gene expression patterns showed that different duplicate genes exhibited different expression patterns in response to treatment with Mg2+, K+, and low temperature. In addition, differences in the structural domain sequences of NAF/FISL and interaction profiles in yeast two-hybrid assays suggested a functional divergence of the duplicate genes during the long-term evolution of Chinese cabbage, a result further validated by potassium deficiency treatment using trans-BraCIPK23.1/23.2/23.3 Arabidopsis thaliana. Our results provide a basis for studies related to the functional divergence of duplicate genes and in-depth studies of BraCBL–BraCIPK functions in Chinese cabbage.