Avian Myeloblastosis Viral Oncogene Homolog Research Articles

A generalist regulator: MYB transcription factors regulate active ingredient biosynthesis in medicinal plants.

Medicinal plants are rich in a variety of secondary metabolites with therapeutic value. However, the yields of these metabolites are generally very low, making their extraction both time- and labour-consuming. Transcription factor (TF)-targeted secondary metabolic engineering can efficiently regulate the biosynthesis and accumulation of secondary metabolites in medicinal plants. v-Myb avian myeloblastosis viral oncogene homolog (MYB) TFs are involved in regulating various morphological and developmental processes, responses to stress, and the biosynthesis of secondary metabolites in plants. This review discusses the biological functions and transcription regulation mechanisms of MYB TFs and summarises the research progress concerning MYB TFs involved in the biosynthesis of representative active components. In the transcriptional regulatory network, MYB TFs regulate multiple synthase genes to mediate active ingredient biosynthesis. This study will serve as a reference for the in-depth analysis of the MYB TF family in medicinal plants.

Blue light treatment delays postharvest ripening of kiwifruit by suppressing ethylene biosynthesis, starch degradation, and cell wall metabolism

The study aimed to investigate the effects of blue light (BL) on the postharvest ripening and softening of kiwifruit. The postharvest ripening of kiwifruit were significantly inhibited by BL; 100 μmol m−2 s−1 light intensity exhibited the best effect. The delay of postharvest ripening of kiwifruit by BL was associated with the inhibition of total soluble solids accumulation, reduction in respiratory rate and ethylene production as well as 1-aminocyclopropane-1-carboxylate synthase and 1-aminocyclopropane-1-carboxylic acid oxidase activities. Moreover, it also inhibited starch degradation and related enzyme activities (α-amylase and β-amylase), prevented the degradation of protopectin, cellulose and hemicellulose while promoting the accumulation of water soluble pectin. Additionally, it suppressed the activities of polygalacturonase, pectinlyase, pectin methylesterase, and cellulase. Transcriptome and gene expression analyses showed that BL-treated kiwifruit had lower expression levels of genes involved in ethylene biosynthesis, starch degradation, and cell wall metabolism, compared with the dark controls. BL also altered transcription factor responses to light, such as v-myb avian myeloblastosis viral oncogene homolog (MYB) and basic helix-loop-helix (bHLH) families. In summary, this study analyzed the physiological and molecular mechanisms by which BL delays the postharvest ripening of kiwifruit and provides a new preservation method for the postharvest quality maintenance of kiwifruit.

Plasma membrane intrinsic proteins SlPIP2;5 gene regulates tolerance to high VPD in tomato

Plasma membrane intrinsic proteins (PIPs) play important roles in plant growth, development, and abiotic stress responses. However, the functions and regulatory mechanisms of PIPs under high vapor pressure deficit (VPD) stress are not yet well understood. In this study, we used tobacco rattle virus (TRV) - mediated virus-induced gene silencing (VIGS) technology to discover that SlPIP2;5 is involved in the acclimation process of tomato plants to high VPD. Under high VPD, the TRV-SlPIP2;5 strain exhibited improved growth compared to the TRV strain, and silencing SlPIP2;5 increased the enzyme activities of the antioxidant system of tomato plants and reduced the sensitivity of plants to atmospheric drought stress by eliminating reactive oxygen species produced by the plants. Additionally, leaf structure was improved, with decreased thickness of the epidermis and spongy tissue, leading to enhanced water transport efficiency. Furthermore, the TRV-SlPIP2;5 strain had increased stomatal length and individual stomatal area, which changed net assimilation rate and stomatal conductance to air drought. In addition, SlPIP2;5 was localized on the plasma membrane, and its promoter region contained numerous core elements and V-myb avian myeloblastosis viral oncogene homolog (MYB) binding sites. Yeast One-Hybrid Assay (Y1H) and Dual Luciferase (LUC) assays showed that the transcription factor SlMYB110 can bind to SlPIP2;5 and regulate its expression. qRT-PCR analysis revealed that high VPD inhibited the expression of SlMYB110, consistent with the expression pattern of SlPIP2;5. Therefore, we speculate that under high VPD, SlMYB110 negatively regulates the expression of SlPIP2;5, thereby modulating the tolerance of tomato plants to atmospheric drought. These findings provide a theoretical basis for improving tomato response to high VPD, and SlPIP2;5 was added to the high VPD-responsive gene pool as a valuable gene that could be used to improve high VPD tolerance in tomato through genetic engineering.

The R2R3-MYB Transcriptional Repressor TgMYB4 Negatively Regulates Anthocyanin Biosynthesis in Tulips (Tulipa gesneriana L.).

Anthocyanins play a paramount role in color variation and significantly contribute to the economic value of ornamental plants. The conserved activation complex MYB-bHLH-WD40 (MBW; MYB: v-myb avian myeloblastosis viral oncogene homolog; bHLH: basic helix-loop-helix protein; WD40:WD-repeat protein) involved in anthocyanin biosynthesis has been thoroughly researched, but there have been limited investigations into the function of repressor factors. In this study, we characterized TgMYB4, an R2R3-MYB transcriptional repressor which is highly expressed during petal coloration in red petal cultivars. TgMYB4-overexpressing tobaccos exhibited white or light pink petals with less anthocyanin accumulation compared to control plants. TgMYB4 was found to inhibit the transcription of ANTHOCYANIDIN SYNTHASE (TfANS1) and DIHYDRO-FLAVONOL-4-REDUCTASE (AtDFR), although it did not bind to their promoters. Moreover, the TgMYB4 protein was able to compete with the MYB activator to bind to the :bHLHprotein, thereby suppressing the function of the activator MBW complex. These findings demonstrate that TgMYB4 plays a suppressive role in the regulation of anthocyanin synthesis during flower pigmentation.

Distinct roles of core autophagy-related genes in zebrafish definitive hematopoiesis

ABSTRACT Despite the well-described discrepancy between ATG (macroautophagy/autophagy-related) genes in the regulation of hematopoiesis, varying essentiality of core ATG proteins in vertebrate definitive hematopoiesis remains largely unclear. Here, we employed zebrafish (Danio rerio) to compare the functions of six core atg genes, including atg13, becn1 (beclin1), atg9a, atg2a, atg5, and atg3, in vertebrate definitive hematopoiesis via clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 ribonucleoprotein and morpholino targeting. Zebrafish with various atg mutations showed autophagic deficiency and presented partially consistent hematopoietic abnormalities during early development. All six atg mutations led to a declined number of spi1b + (Spi-1 proto-oncogene b) myeloid progenitor cells. However, only becn1 mutation resulted in the expansion of myb + (v-myb avian myeloblastosis viral oncogene homolog) hematopoietic stem and progenitor cells (HSPCs) and transiently increased coro1a + (coronin, actin binding protein, 1A) leukocytes, whereas atg3 mutation decreased the number of HSPCs and leukocytes. Proteomic analysis of caudal hematopoietic tissue identified sin3aa (SIN3 transcription regulator family member Aa) as a potential modulator of atg13- and becn1-regulated definitive hematopoiesis. Disruption of sin3aa rescued the expansion of HSPCs and leukocytes in becn1 mutants and exacerbated the decrease of HSPCs in atg13 mutants. Double mutations were also performed to examine alternative functions of various atg genes in definitive hematopoiesis. Notably, becn1 mutation failed to induce HSPCs expansion with one of the other five atg mutations. These findings demonstrated the distinct roles of atg genes and their interplays in zebrafish definitive hematopoiesis, thereby suggesting that the vertebrate definitive hematopoiesis is regulated in an atg gene-dependent manner. Abbreviations: AGM: aorta-gonad-mesonephros; AO: acridine orange; atg: autophagy related; becn1: beclin 1, autophagy related; CHT: caudal hematopoietic tissue; CKO: conditional knockout; coro1a: coronin, actin binding protein, 1A; CQ: chloroquine; CRISPR: clustered regularly interspaced short palindromic repeats; dpf: days post fertilization; FACS: fluorescence-activated cell sorting; hbae1.1: hemoglobin, alpha embryonic 1.1; HSCs: hematopoietic stem cells; HSPCs: hematopoietic stem and progenitor cells; KD: knockdown; KO: knockout; map1lc3/lc3: microtubule-associated protein 1 light chain 3; MO: morpholino; mpeg1.1: macrophage expressed 1, tandem duplicate 1; mpx: myeloid-specific peroxidase; myb: v-myb avian myeloblastosis viral oncogene homolog; PE: phosphatidylethanolamine; p-H3: phospho-H3 histone; PtdIns3K: class 3 phosphatidylinositol 3-kinase; rag1: recombination activating 1; rb1cc1/fip200: RB1-inducible coiled-coil 1; RFLP: restriction fragment length polymorphism; RNP: ribonucleoprotein; sin3aa: SIN3 transcription regulator family member Aa; spi1b: Spi-1 proto-oncogene b; ulk: unc-51 like autophagy activating kinase; vtg1: vitellogenin 1; WISH: whole-mount in situ hybridization.

Genome-wide identification and expression analysis of the NRT genes in Ginkgo biloba under nitrate treatment reveal the potential roles during calluses browning

Nitrate is a primary nitrogen source for plant growth, and previous studies have indicated a correlation between nitrogen and browning. Nitrate transporters (NRTs) are crucial in nitrate allocation. Here, we utilized a genome-wide approach to identify and analyze the expression pattern of 74 potential GbNRTs under nitrate treatments during calluses browning in Ginkgo, including 68 NITRATE TRANSPORTER 1 (NRT1)/PEPTIDE TRANSPORTER (PTR) (NPF), 4 NRT2 and 2 NRT3. Conserved domains, motifs, phylogeny, and cis-acting elements (CREs) were analyzed to demonstrate the evolutionary conservation and functional diversity of GbNRTs. Our analysis showed that the NPF family was divided into eight branches, with the GbNPF2 and GbNPF6 subfamilies split into three groups. Each GbNRT contained 108–214 CREs of 19–36 types, especially with binding sites of auxin and transcription factors v-myb avian myeloblastosis viral oncogene homolog (MYB) and basic helix-loop-helix (bHLH). The E1X1X2E2R motif had significant variations in GbNPFs, indicating changes in the potential dynamic proton transporting ability. The expression profiles of GbNRTs indicated that they may function in regulating nitrate uptake and modulating the signaling of auxin and polyphenols biosynthesis, thereby affecting browning in Ginkgo callus induction. These findings provide a better understanding of the role of NRTs during NO3− uptake and utilization in vitro culture, which is crucial to prevent browning and develop an efficient regeneration and suspension production system in Ginkgo.

Comparative Physiological and Transcriptome Analyses Reveal Mechanisms of Salicylic-Acid-Reduced Postharvest Ripening in 'Hosui' Pears (Pyrus pyrifolia Nakai).

Postharvest ripening of sand pear fruit leads to quality deterioration, including changes in texture, flavor, and fruit color. Salicylic acid (SA), an important defense-related hormone, delays fruit ripening and maintains fruit quality, but the underling mechanism remains unclear. Herein, we evaluated the efficacy of SA in delaying the ripening process of Pyrus pyrifolia cv. 'Hosui' pear fruit, as evidenced by the reduction in fruit weight loss, inhibition of firmness loss, cell wall degradation and soluble sugars, and retention of total phenols. Based on comparative transcriptomic data, a total of 3837 and 1387 differentially expressed genes (DEGs) were identified during room-temperature storage of control fruit and between SA-treated and control fruit, respectively. Further KEGG analysis revealed that the DEGs were mainly implicated in plant hormone signal transduction, starch and sugar metabolism, and cell wall modification. Moreover, exogenous SA treatment also altered the expression of many transcription factor (TF) families, including those in the ethylene-responsive factor (ERF), NAM, ATAF, CUC (NAC), basic helix-loop-helix (bHLH), basic leucine zipper (bZIP), and v-myb avian myeloblastosis viral oncogene homolog (MYB) families. Together, the results offer important insights into the role of SA-responsive genes in controlling fruit ripening in sand pears.

CsTT8 regulates anthocyanin accumulation in blood orange through alternative splicing transcription.

A homologous gene of basic-helix-loop-helix AtTT8 in Arabidopsis thaliana was identified in juice sac cells of pulp tissues from blood orange (Citrus sinensis cv 'Tarocco'), which was designated as CsTT8 in this study. Additionally, the mRNA levels of TT8 with the full-length open reading frame were significantly higher in 'Tarocco' than in mutant fruit lacking pigment in pulp or peel tissues. However, an alternative splicing transcript, Δ15-TT8, with the fourth exon skipped, was also identified from transcripts different in length from that in 'Tarocco'. The mRNA levels of Δ15-TT8 were higher in mutant fruit lacking pigment in pulp or peel tissues than in the wild type. Therefore, the TT8/Δ15-TT8 mRNA level ratio was found to be crucial for sufficient pigment in either pulp or peel tissues. TT8 from blood orange fruit demonstrated the capacity for nucleus localization and binding to other proteins. In contrast, Δ15-TT8, lacking the fourth exon, lost its ability to interact with RUBY1 and to localize at the nucleus. Using a dual luciferase reporter assay and transient overexpression in tobacco, we proved that two regulatory complexes formed by a functional TT8 with different MYB(v-myb avian myeloblastosis viral oncogene homolog)-type partners significantly promoted expression of an anthocyanin biosynthetic gene and a proton pumping gene, leading to anthocyanin and citrate production. Our findings suggest that TT8, rather than dysfunctional Δ15-TT8, is possibly involved in modulating anthocyanin biosynthesis and its transport into vacuoles by proton gradients. However, increased mRNA levels of the dysfunctional alternative splicing transcript may act as a negative feedback to downregulate TT8 expression and limit anthocyanin accumulation in blood oranges.

Genome-Wide Identification and Expression Analysis of the RADIALIS-like Gene Family in Camellia sinensis.

The RADIALIS-like (RL) proteins are v-myb avian myeloblastosis viral oncogene homolog (MYB)-related transcription factors (TFs), and are involved in many biological processes, including metabolism, development, and response to biotic and abiotic stresses. However, the studies on the RL genes of Camellia sinensis are not comprehensive enough. Therefore, we undertook this study and identified eight CsaRLs based on the typical conserved domain SANT Associated domain (SANT) of RL. These genes have low molecular weights and theoretical pI values ranging from 5.67 to 9.76. Gene structure analysis revealed that six CsaRL genes comprise two exons and one intron, while the other two contain a single exon encompassing motifs 1 and 2, and part of motif 3. The phylogenetic analysis divided one hundred and fifty-eight RL proteins into five primary classes, in which CsaRLs clustered in Group V and were homologous with CssRLs of the Shuchazao variety. In addition, we selected different tissue parts to analyze the expression profile of CsaRLs, and the results show that almost all genes displayed variable expression levels across tissues, with CsaRL1a relatively abundant in all tissues. qRT-PCR (real-time fluorescence quantitative PCR) was used to detect the relative expression levels of the CsaRL genes under various abiotic stimuli, and it was found that CsaRL1a expression levels were substantially higher than other genes, with abscisic acid (ABA) causing the highest expression. The self-activation assay with yeast two-hybrid system showed that CsaRL1a has no transcriptional activity. According to protein functional interaction networks, CsaRL1a was well connected with WIN1-like, lysine histidine transporter-1-like, β-amylase 3 chloroplastic-like, carbonic anhydrase-2-like (CA2), and carbonic anhydrase dnaJC76 (DJC76). This study adds to our understanding of the RL family and lays the groundwork for further research into the function and regulatory mechanisms of the CsaRLs gene family in Camellia sinensis.

Genome-wide characterization and functional identification of MYB genes in Malus sieversii infected by Valsa mali.

Among the most important transcription factors in plants, the v-myb avian myeloblastosis viral oncogene homolog (MYB) regulates the expression network of response genes under stresses such as fungal infection. In China, the canker disease Valsa mali threatens the survival of Malus sieversii, an ancestor of cultivated apples. Using the M. sieversii genome, we identified 457 MsMYB and 128 R2R3-MsMYB genes that were randomly distributed across 17 chromosomes. Based on protein sequence and structure, the R2R3-MsMYB genes were phylogenetically divided into 29 categories, and 26 conserved motifs were identified. We further predicted cis-elements in the 2000-kb promoter region of R2R3-MsMYBs based on the genome. Transcriptome analysis of M. sieversii under V. mali infection showed that 27 R2R3-MsMYBs were significantly differentially expressed, indicating their key role in the response to V. mali infection. Using transient transformation, MsMYB14, MsMYB24, MsMYB39, MsMYB78, and MsMYB108, which were strongly induced by V. mali infection, were functionally identified. Among the five MsMYBs, MsMYB14 and MsMYB78 were both important in enhancing resistance to diseases, whereas MsMYB24 inhibited resistance. Based on the results of this study, we gained a better understanding of the MsMYB transcription factor family and laid the foundation for a future research program on disease prevention strategies in M. sieversii.

R2R3-type LoMYB21 affects jasmonate-regulated development and dehiscence of anthers in lily (Lilium oriental hybrids)

Lilies are widely cultivated for cut flowers, but their large anthers carry a considerable amount of colored pollen that is dispersed easily. Studying the molecular mechanism of anther development and dehiscence could help solve this problem. LoMYB21, encoding a putative R2R3 v-myb avian myeloblastosis viral oncogene homolog (MYB) transcription factor, was identified from oriental lilies (Lilium ‘Siberia’). Real-time quantitative PCR analysis showed that LoMYB21 was mainly expressed in the anther, filament and stigma and had high expression during the late stages of lily anther development. LoMYB21 had transactivation activity and was located in the nucleus through yeast one-hybrid assays and transient expression in Nicotiana benthamiana. Suppression of LoMYB21 by virus-induced gene silencing (VIGS) in Lilium ‘Siberia’ led to anther indehiscence and reduced the expression of genes related to Jasmonate acid (JA) biosynthesis and signal transduction. Induction of LoMYB21 in DEX::LoMYB21 transgenic Arabidopsis caused procumbent inflorescences that became infertile, accompanied by higher expression of JA biosynthetic and signaling genes. These results demonstrated that JA content and signaling were abnormal in silenced lily and transgenic LoMYB21 Arabidopsis, which affected anther development. Our study indicated that LoMYB21 could regulate lily anther dehiscence through JA biosynthesis and signaling during the late stages of anther development.

FvMYB44, a Strawberry R2R3-MYB Transcription Factor, Improved Salt and Cold Stress Tolerance in Transgenic Arabidopsis

MYB (v-MYB avian myeloblastosis viral oncogene homolog) transcription factor (TF) family has numerous members with complex and diverse functions, which perform an integral role in regulating the plant’s response to adversity. This study used cloning to obtain a novel MYB TF gene from the diploid strawberry Fragaria vesca, which was given the designation FvMYB44. Subcellular localization results showed that the protein of FvMYB44 was a nuclear localization protein. The resistance of Arabidopsis thaliana to salt and low temperature stresses was greatly enhanced by the overexpression of FvMYB44. When subjected to salt and temperature stress, transgenic plants showed higher proline and chlorophyll concentrations and higher superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities than wild-type (WT) and unloaded line (UL) of A. thaliana. In contrast, WT and UL lines had higher malondialdehyde (MDA) content and reactive oxygen species ROS (O2− and H2O2) content. These findings suggest that FvMYB44 may perform a role in controlling the response of A. thaliana to cold and salt stress.

Physiological and transcriptomic responses to magnesium deficiency in Neolamarckia Cadamba

Magnesium (Mg2+) is a critical component of chlorophyll and enzymes involved in various physiological and biochemical processes essential for plant growth, biomass accumulation, and photosynthesis. Mg2+ deficiency (MgD) is common in hot and rainy subtropical areas due to its easy loss from soil. Neolamarckia cadamba, an important tropical tree in South Asia, faces severe effects of MgD, however, the responses of N. cadamba to MgD stress remain unclear. In here, effects of N. cadamba under MgD stress were investigated. The study revealed that MgD had lower plant biomass, fresh and dry weight, root length, root volume, and surface area compared to CK (normal Mg2+). As treatment time increased, the leaves began to yellow, and lesions appeared. Chlorophyll a, chlorophyll b, and total chlorophyll content, along with fluorescence-related parameters and leaf photosynthetic capacity, were significantly reduced in MgD stress compared to CK treatment. Transcriptome analysis showed that transporters as well as transcription factors (TFs) from MYC (v-myc avian myelocytomatosis viral oncogene homolog), MYB (v-myb avian myeloblastosis viral oncogene homolog), bHLH (basic helix-loop-helix) and WRKY families were upregulated in leaves at 10 d of MgD stress, indicating that magnesium signaling transduction might be activated to compensate MgD. In addition, genes including chlorophyll(ide) b reductase (NYC1/NOL) chlorophyll/bacteriochlorophyll synthase (G4) and 7-hydroxymethyl chlorophyll a reductase synthesizing (HCAR) chlorophyll a and chlorophyll b were down-regulated in leaves, while those scavenging reactive oxygen species (ROS) were mainly up-regulated at 10 d of MgD stress. These results shed light on underlying MgD in N. cadamba.

Genome-wide characterization and expression analysis of MYB transcription factors in Chrysanthemum nankingense

BackgroundChrysanthemum is a popular ornamental plant worldwide. MYB (v-myb avian myeloblastosis viral oncogene homolog) transcription factors play an important role in everything from stress resistance to plant growth and development. However, the MYB family of chrysanthemums has not been the subject of a detailed bioinformatics and expression investigation.ResultsIn this study, we examined 324 CnMYB transcription factors from Chrysanthemum nankingense genome data, which contained 122 Cn1R-MYB, 183 CnR2R3-MYB, 12 Cn3R-MYB, 2 Cn4R-MYB, and 5 atypical CnMYB. The protein motifs and classification of CnMYB transcription factors were analyzed. Among them, motifs 1, 2, 3, and 4 were found to encode the MYB DNA-binding domain in R2R3-MYB proteins, while in other-MYB proteins, the motifs 1, 2, 3, 4, 5, 6, 7, and 8 encode the MYB DNA-binding domain. Among all CnMYBs, 44 genes were selected due to the presence of CpG islands, while methylation is detected in three genes, including CnMYB9, CnMYB152, and CnMYB219. We analyzed the expression levels of each CnMYB gene in ray floret, disc floret, flower bud, leaf, stem, and root tissues. Based on phylogenetic analysis and gene expression analysis, three genes appeared likely to control cellulose and lignin synthesis in stem tissue, and 16 genes appeared likely to regulate flowering time, anther, pollen development, and flower color. Fifty-one candidate genes that may be involved in stress response were identified through phylogenetic, stress-responseve motif of promoter, and qRT-PCR analyses. According to genes expression levels under stress conditions, six CnMYB genes (CnMYB9, CnMYB172, CnMYB186, CnMYB199, CnMYB219, and CnMYB152) were identified as key stress-responsive genes.ConclusionsThis research provides useful information for further functional analysis of the CnMYB gene family in chrysanthemums, as well as offers candidate genes for further study of cellulose and lignin synthesis, flowering traits, salt and drought stress mechanism.

Overexpression of a Fragaria vesca 1R-MYB Transcription Factor Gene (FvMYB114) Increases Salt and Cold Tolerance in Arabidopsis thaliana

The MYB (v-MYB avian myeloblastosis viral oncogene homolog) transcription factor (TF) family has numerous members with complex and diverse functions, which play an indispensable role in regulating the response of plants to stress. In this study, a new 1R-MYB TF gene was obtained from Fragaria vesca (a diploid strawberry) by cloning technology and given a new name, FvMYB114. According to the subcellular localization results, FvMYB114 protein was a nuclear localization protein. Overexpression of FvMYB114 greatly enhanced the adaptability and tolerance of Arabidopsis thaliana to salt and low temperature. Under salt and cold stress, the transgenic plants had greater proline and chlorophyll contents and higher activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) than the wild-type (WT) and unloaded-line (UL) A. thaliana. However, malondialdehyde (MDA) was higher in the WT and UL lines. These results suggested that FvMYB114 may be involved in regulating the response of A. thaliana to salt stress and cold stress. FvMYB114 can also promote the expression of genes, such as the genes AtSOS1/3, AtNHX1 and AtLEA3 related to salt stress and the genes AtCCA1, AtCOR4 and AtCBF1/3 related to cold stress, further improving the tolerance of transgenic plants to salt and cold stress.

Identification and Phylogenetic Analysis of the R2R3-MYB Subfamily in Brassica napus.

The R2R3-MYB sub-family proteins are composed of most members of MYB (v-Myb avian myeloblastosis viral oncogene homolog) protein, a plant-specific transcription factor (TF) that is classified into four classes depending on the number of MYB repeats. R2R3-MYB TFs are involved in physiological and biochemical processes. However, the functions of the Brassica napus R2R3-MYB genes are still mainly unknown. In this study, 35 Brassica napus MYB (BnaMYB) genes were screened in the genome of Brassica napus, and details about their physical and chemical characteristics, evolutionary relationships, chromosome locations, gene structures, three-dimensional protein structures, cis-acting promoter elements, and gene duplications were uncovered. The BnaMYB genes have undergone segmental duplications and positive selection pressure, according to evolutionary studies. The same subfamilies have similar intron-exon patterns and motifs, according to the genes' structure and conserved motifs. Additionally, through cis-element analysis, many drought-responsive and other stress-responsive cis-elements have been found in the promoter regions of the BnaMYB genes. The expression of the BnaMYB gene displays a variety of tissue-specific patterns. Ten lignin-related genes were chosen for drought treatment. Our research screened four genes that showed significant upregulation under drought stress, and thus may be important drought-responsive genes. The findings lay a new foundation for understanding the complex mechanisms of BnaMYB in multiple developmental stages and pathways related to drought stress in rapeseed.

Genetic Variation, DIMBOA Accumulation, and Candidate Gene Identification in Maize Multiple Insect-Resistance.

Maize seedlings contain high amounts of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), and the effect of DIMBOA is directly associated with multiple insect-resistance against insect pests such as Asian corn borer and corn leaf aphids. Although numerous genetic loci for multiple insect-resistant traits have been identified, little is known about genetic controls regarding DIMBOA content. In this study, the best linear unbiased prediction (BLUP) values of DIMBOA content in two ecological environments across 310 maize inbred lines were calculated; and their phenotypic data and BLUP values were used for marker-trait association analysis. We identified nine SSRs that were significantly associated with DIMBOA content, which explained 4.30-20.04% of the phenotypic variation. Combined with 47 original genetic loci from previous studies, we detected 19 hot loci and approximately 11 hot loci (in Bin 1.04, Bin 2.00-2.01, Bin 2.03-2.04, Bin 4.00-4.03, Bin 5.03, Bin 5.05-5.07, Bin 8.01-8.03, Bin 8.04-8.05, Bin 8.06, Bin 9.01, and Bin 10.04 regions) supported pleiotropy for their association with two or more insect-resistant traits. Within the 19 hot loci, we identified 49 candidate genes, including 12 controlling DIMBOA biosynthesis, 6 involved in sugar metabolism/homeostasis, 2 regulating peroxidases activity, 21 associated with growth and development [(auxin-upregulated RNAs (SAUR) family member and v-myb avian myeloblastosis viral oncogene homolog (MYB)], and 7 involved in several key enzyme activities (lipoxygenase, cysteine protease, restriction endonuclease, and ubiquitin-conjugating enzyme). The synergy and antagonism interactions among these genes formed the complex defense mechanisms induced by multiple insect pests. Moreover, sufficient genetic variation was reported for DIMBOA performance and SSR markers in the 310 tested maize inbred lines, and 3 highly (DIMBOA content was 402.74-528.88 μg g-1 FW) and 15 moderate (DIMBOA content was 312.92-426.56 μg g-1 FW) insect-resistant genotypes were major enriched in the Reid group. These insect-resistant inbred lines can be used as parents in maize breeding programs to develop new varieties.

Transcriptome analysis reveals the molecular patterns regulating prickle reduction in grafted Zanthoxylum armatum

Grafting has been found to effectively reduce the prickly nature of Zanthoxylum armatum seedlings, but the molecular mechanisms are unclear. A comparative transcriptome analysis was performed on stems (JJ) and leaves (JY) of grafted stems (SJ) and leaves (SY) of non-grafted Zanthoxylum armatum seedlings. The authors obtained 3097, 2124, 5995, and 5043 differentially expressed genes from JJ vs. SJ, JY vs. SY, JY vs. JJ, and SY vs. SJ with 17 co-expressed genes. The RNA-seq results were confirmed by qRT-PCR analysis. Function annotations showed that many DEGs enriched plant hormone signal transduction, phenylpropanoid biosynthesis, and plant-pathogen interaction. Secondary metabolites associated with stress-related hormones and defense were noticeably up-regulated in grafted plants. However, key enzymes regulating lignin synthesis were slightly down-regulated in grafted plants. Additionally, grafted plants had several noticeable up-regulated stress-response TFs (transcription factors), including NAC (NAM, ATAF1/2, CUC1/2), ERF (ethylene response factor), MYB (v-myb avian myeloblastosis viral oncogene homolog), bHLH (basic helix-loop-helix), and WRKY. This study generated abundant sequences for elucidating the genetic differences between grafted and non-grafted Z. armatum.

Key factors for differential drought tolerance in two contrasting wild materials of Artemisia wellbyi identified using comparative transcriptomics

BackgroundDrought is a significant condition that restricts vegetation growth on the Tibetan Plateau. Artemisia wellbyi is a unique semi-shrub-like herb in the family Compositae, which distributed in northern and northwest of Tibetan Plateau. It is a dominant species in the community that can well adapt to virous environment stress, such as drought and low temperature. Therefore, A. wellbyi. has a potential ecological value for soil and water conservation of drought areas. Understanding the molecular mechanisms of A. wellbyi. that defense drought stress can acquire the key genes for drought resistance breeding of A. wellbyi. and provide a theoretical basis for vegetation restoration of desertification area. However, they remain unclear. Thus, our study compared the transcriptomic characteristics of drought-tolerant “11” and drought-sensitive “6” material of A. wellbyi under drought stress.ResultsA total of 4875 upregulated and 4381 downregulated differentially expressed genes (DEGs) were induced by drought in the tolerant material; however, only 1931 upregulated and 4174 downregulated DEGs were induced by drought in the sensitive material. The photosynthesis and transcriptional regulation differed significantly with respect to the DEGs number and expression level. We found that CDPKs (calmodulin-like domain protein kinases), SOS3 (salt overly sensitive3), MAPKs (mitogen-activated protein kinase cascades), RLKs (receptor like kinase), and LRR-RLKs (repeat leucine-rich receptor kinase) were firstly involved in response to drought stress in drought tolerant A. wellbyi. Positive regulation of genes associated with the metabolism of ABA (abscisic acid), ET (ethylene), and IAA (indole acetic acid) could play a crucial role in the interaction with other transcriptional regulatory factors, such as MYBs (v-myb avian myeloblastosis viral oncogene homolog), AP2/EREBPs (APETALA2/ethylene-responsive element binding protein family), WRKYs, and bHLHs (basic helix-loop-helix family members) and receptor kinases, and regulate downstream genes for defense against drought stress. In addition, HSP70 (heat shock protein70) and MYB73 were considered as the hub genes because of their strong association with other DEGs.ConclusionsPositive transcriptional regulation and negative regulation of photosynthesis could be associated with better growth performance under drought stress in the drought-tolerant material. In addition, the degradation of sucrose and starch in the tolerant A. wellbyi to alleviate osmotic stress and balance excess ROS. These results highlight the candidate genes that are involved in enhancing the performance of drought-tolerant A. wellbyi and provide a theoretical basis for improving the performance of drought-resistant A. wellbyi.

The physiological and transcriptomic study of secondary growth in Neolamarckia cadamba stimulated by the ethylene precursor ACC

Though many biological roles of ethylene have been investigated intensively, the molecular mechanism of ethylene's action in woody plants remains unclear. In this study, we investigated the effects of exogenous 1-aminocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene, on the growth of Neolamarckia cadamba seedlings, a fast-growing tropical tree. After 14 days of ACC treatment, the plants showed a reduced physiological morphology while stem diameter increased; however, this did not occur after the addition of 1-MCP. Meanwhile, the lignin content of N. cadamba also increased. Transcriptome analysis revealed that the expression of the ethylene biosynthesis and signaling genes ACC oxidase (ACO) and ethylene insensitive 3 (EIN3) were up-regulated mainly at the 6th hour and the 3rd day of the ACC treatment, respectively. The transcription levels of transcription factors, mainly in the basic helix-loop-helix (bHLH), ethylene response factor (ERF), WRKY and v-myb avian myeloblastosis viral oncogene homolog (MYB) families, involved in the ethylene signaling and secondary growth also increased significantly. Furthermore, in accordance to the increased lignification of the stem, the transcriptional level of key enzymes in the phenylalanine pathway were elevated after the ACC treatment. Our results revealed the physiological and molecular mechanisms underlying the secondary growth stimulated by exogenous ACC treatment on N. cadamba seedlings.