R2R3-MYB Transcription Factor NtMYB330 Regulates Proanthocyanidin Biosynthesis and Seed Germination in Tobacco (Nicotiana tabacum L.)

Proanthocyanidins (PAs) are important phenolic compounds and PA biosynthesis is regulated by a ternary MBW complex consisting of a R2R3-MYB regulator, a bHLH factor and a WDR protein. In this study, a tobacco R2R3-MYB factor NtMYB330 was characterized as the PA-specific regulator in which the PA biosynthesis was promoted in the flowers of NtMYB330-overexpressing lines while decreased in the flowers of ntmyb330 mutants. NtMYB330 can interact with flavonoid-related bHLH partner NtAn1b and WDR protein NtAn11-1, and the NtMYB330-NtAn1b complex is required to achieve strong transcriptional activation of the PA-related structural genes NtDFR1, NtANS1, NtLAR1 and NtANR1. Our data reveal that NtMYB330 regulates PA biosynthesis in seeds and affects seed germination, in which NtMYB330-overexpressing lines showed higher PA accumulations in seed coats and inhibited germination, while ntmyb330 mutants had reduced seed coat PAs and improved germination. NtMYB330 affects seed germination possibly through two mechanisms: modulating seed coat PAs to affect coat-imposed dormancy. In addition, NtMYB330 regulates the expressions of abscisic acid (ABA) and gibberellin acid (GA) signaling-related genes, affecting ABA-GA crosstalk and seed germination. This study reveals that NtMYB330 specifically regulates PA biosynthesis via formation of the MBW complex in tobacco flowers and affects germination through adjustment of PA concentrations and ABA/GA signaling in tobacco seeds.

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MdMYB4, an R2R3-Type MYB Transcription Factor, Plays a Crucial Role in Cold and Salt Stress in Apple Calli

Journal of the American Society for Horticultural Science ◽

10.21273/jashs04030-17 ◽

2017 ◽

Vol 142 (3) ◽

pp. 209-216 ◽

Cited By ~ 5

Author(s):

Ruigang Wu ◽

Yi Wang ◽

Ting Wu ◽

Xuefeng Xu ◽

Zhenhai Han

Keyword(s):

Salt Stress ◽

Cold Stress ◽

Stress Responses ◽

Transcriptional Activation ◽

Myb Transcription Factor ◽

Abiotic Stress Response ◽

Physiological Processes ◽

In The Wild ◽

Polymerase Chain ◽

R2r3 Myb

MYB (v-myb avian myeloblastosis viral oncogene homologs) transcription factors (TFs) are involved in diverse physiological processes, including cell shape determination, cell differentiation, and secondary metabolism, as well as abiotic stress response. In the present study, MdMYB4, an R2R3-MYB protein that is a homolog of Arabidopsis thaliana MYB4, was identified and characterized. Quantitative real-time polymerase chain reaction (qRT-PCR) expression analysis demonstrated that MdMYB4 is extensively expressed in various apple (Malus domestica) tissues and that its expression is induced by cold, osmotic, and salt stress. An MdMYB4-GFP fusion protein was localized in the nucleus of transformed onion (Allium cepa) epidermal cells and had a certain transcriptional activation activity by yeast one-hybrid assay. Overexpression of the MdMYB4 gene remarkably enhanced the tolerance of stably transgenic apple calli to severe salt and cold stress, and both the relative conductivity and malondialdehyde (MDA) accumulation of transgenic calli under salt and cold stress were significantly lower than in the wild type control. Taken together, these results suggest that MdMYB4 may play a positive regulatory role in both cold and salt stress responses.

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Overexpression of the Wild Soybean R2R3-MYB Transcription Factor GsMYB15 Enhances Resistance to Salt Stress and Helicoverpa Armigera in Transgenic Arabidopsis

International Journal of Molecular Sciences ◽

10.3390/ijms19123958 ◽

2018 ◽

Vol 19 (12) ◽

pp. 3958 ◽

Cited By ~ 9

Author(s):

Xin-Jie Shen ◽

Yan-Yan Wang ◽

Yong-Xing Zhang ◽

Wei Guo ◽

Yong-Qing Jiao ◽

...

Keyword(s):

Salt Stress ◽

Transgenic Plants ◽

Transcriptional Activation ◽

Transgenic Arabidopsis ◽

Wild Soybean ◽

Stress Factors ◽

Myb Transcription Factor ◽

Molecular Evidence ◽

Expression Levels ◽

R2r3 Myb

Plant R2R3-MYB transcription factors (TFs) have been suggested to play crucial roles in the response to diverse abiotic and biotic stress factors but there is little molecular evidence of this role in soybean plants. In this work, we identified and functionally characterized an R2R3-MYB TF, namely, GsMYB15, from the wild soybean ED059. Protein and promoter sequence analysis indicated that GsMYB15 is a typical R2R3-MYB TF and contains multiple stress-related cis-elements in the promoter region. GsMYB15 is located in the nucleus and exhibits transcriptional activation activity. QPCR assays suggested that the expression of GsMYB15 could be induced by NaCl, insect attacks and defense-related hormones (MeJA and SA). Furthermore, GsMYB15 exhibited highest expression in pods compared to other tissues. Functional analysis of GsMYB15 demonstrated that overexpression of GsMYB15 could increase salt tolerance and enhance the resistance to H. armigera larvae in transgenic Arabidopsis plants. Moreover, overexpression of GsMYB15 also affected the expression levels of salt stress- and defense-related genes in the transgenic plants. Feeding with transgenic Arabidopsis plant leaves could significantly suppress the expression levels of immunity-related genes in H. armigera larvae. Overexpression of GsMYB15 also increased mesophyll cell levels in transgenic plants. Taken together, these results provide evidence that GsMYB15 is a positive regulator of salt stress tolerance and insect resistance in transformed Arabidopsis plants.

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An R2R3-MYB Transcription Factor OsMYBAS1 Promotes Seed Germination under Different Sowing Depths in Transgenic Rice

Plants ◽

10.3390/plants11010139 ◽

2022 ◽

Vol 11 (1) ◽

pp. 139

Author(s):

Xiaomin Wang ◽

Rong Wu ◽

Tongshu Shen ◽

Zhenan Li ◽

Chengyong Li ◽

...

Keyword(s):

Transcription Factor ◽

Seed Germination ◽

Transgenic Rice ◽

Seedling Establishment ◽

Myb Transcription Factor ◽

Rice Seed ◽

Sowing Depth ◽

Rice Plants ◽

Transgenic Rice Plants ◽

R2r3 Myb

MYB-type transcription factors play essential regulatory roles in seed germination and the response to seedling establishment stress. This study isolated a rice R2R3-MYB gene, OsMYBAS1, and functionally characterized its role in seed germination by generating transgenic rice plants with the overexpression and knockout of OsMYBAS1. Gene expression analysis suggested that OsMYBAS1 was highly expressed in brown rice and root, respectively. Subcellular localization analysis determined that OsMYBAS1 was localized in the nucleus. No significant differences in seed germination rate were observed among wild-type (WT) and transgenic rice plants at the 0-cm sowing depth. However, when sown at a depth of 4 cm, higher germination rates, root lengths and seedling heights were obtained in OsMYBAS1-overexpressing plants than in WT. Furthermore, the opposite results were recorded between the osmybas1 mutants and WT. Moreover, OsMYBAS1-overexpressing plants significantly enhanced superoxide dismutase (SOD) enzyme activity and suppressed the accumulation of malondialdehyde (MDA) content at the 4-cm sowing depth. These results indicate that the MYB transcription factor OsMYBAS1 may promote rice seed germination and subsequent seedling establishment under deep-sowing conditions. These findings can provide valuable insight into rice seed-quality breeding to facilitate the development of a dry, direct-seeding production system.

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A SlMYB75-centred transcriptional cascade regulates trichome formation and sesquiterpene accumulation in tomato

Journal of Experimental Botany ◽

10.1093/jxb/erab086 ◽

2021 ◽

Author(s):

Zehao Gong ◽

Yingqing Luo ◽

Wenfa Zhang ◽

Wei Jian ◽

Lu Zhang ◽

...

Keyword(s):

Transcriptional Activation ◽

Glandular Trichomes ◽

Spider Mites ◽

Terpene Synthase ◽

Myb Transcription Factor ◽

Type Ii ◽

Rnai Line ◽

Trichome Formation ◽

Myb Genes ◽

R2r3 Myb

Abstract Tomato trichomes act as a mechanical and chemical barrier against pests. An R2R3 MYB transcription factor gene, SlMYB75, is highly expressed in type II, V, and VI trichomes. SlMYB75 protein is located in the nucleus and possesses transcriptional activation activity. Down-regulation of SlMYB75 increased the formation of type II, V, and VI trichomes, accumulation of δ-elemene, β-caryophyllene, and α-humulene in glandular trichomes, and tolerance to spider mites in tomato. In contrast, overexpression of SlMYB75 inhibited trichome formation and sesquiterpene accumulation, and increased plant sensitivity to spider mites. RNA-Seq analyses of the SlMYB75 RNAi line indicated massive perturbation of the transcriptome, with a significant impact on several classes of transcription factors. Expression of the MYB genes SlMYB52 and SlTHM1 was strongly reduced in the RNAi line and increased in the SlMYB75-overexpressing line. SlMYB75 protein interacted with SlMYB52 and SlTHM1 and activated their expression. SlMYB75 directly targeted the promoter of the cyclin gene SlCycB2, increasing its activity. The auxin response factor SlARF4 directly targeted the promoter of SlMYB75 and inhibited its expression. SlMYB75 also bound to the promoters of the terpene synthase genes SlTPS12, SlTPS31, and SlTPS35, inhibiting their transcription. Our findings indicate that SlMYB75 perturbation affects several transcriptional circuits, resulting in altered trichome density and metabolic content.

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A single nucleotide polymorphism in an R2R3 MYB transcription factor gene triggers the male sterility in soybean ms6 (Ames1)

Theoretical and Applied Genetics ◽

10.1007/s00122-021-03920-0 ◽

2021 ◽

Author(s):

Junping Yu ◽

Guolong Zhao ◽

Wei Li ◽

Ying Zhang ◽

Peng Wang ◽

...

Keyword(s):

Transcription Factor ◽

Glycine Max ◽

Male Sterility ◽

Bulked Segregant Analysis ◽

Soybean Protein ◽

Anther Development ◽

Hybrid Breeding ◽

Myb Transcription Factor ◽

Male Sterile ◽

R2r3 Myb

Abstract Key message Identification and functional analysis of the male sterile gene MS6 in Glycine max. Abstract Soybean (Glycine max (L.) Merr.) is an important crop providing vegetable oil and protein. The male sterility-based hybrid breeding is a promising method for improving soybean yield to meet the globally growing demand. In this research, we identified a soybean genic male sterile locus, MS6, by combining the bulked segregant analysis sequencing method and the map-based cloning technology. MS6, highly expressed in anther, encodes an R2R3 MYB transcription factor (GmTDF1-1) that is homologous to Tapetal Development and Function 1, a key factor for anther development in Arabidopsis and rice. In male sterile ms6 (Ames1), the mutant allele contains a missense mutation, leading to the 76th leucine substituted by histidine in the DNA binding domain of GmTDF1-1. The expression of soybean MS6 under the control of the AtTDF1 promoter could rescue the male sterility of attdf1 but ms6 could not. Additionally, ms6 overexpression in wild-type Arabidopsis did not affect anther development. These results evidence that GmTDF1-1 is a functional TDF1 homolog and L76H disrupts its function. Notably, GmTDF1-1 shows 92% sequence identity with another soybean protein termed as GmTDF1-2, whose active expression also restored the fertility of attdf1. However, GmTDF1-2 is constitutively expressed at a very low level in soybean, and therefore, not able to compensate for the MS6 deficiency. Analysis of the TDF1-involved anther development regulatory pathway showed that expressions of the genes downstream of TDF1 are significantly suppressed in ms6, unveiling that GmTDF1-1 is a core transcription factor regulating soybean anther development.

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Genetic Mapping and Identification of the Candidate Gene for White Seed Coat in Cucurbita maxima

International Journal of Molecular Sciences ◽

10.3390/ijms22062972 ◽

2021 ◽

Vol 22 (6) ◽

pp. 2972

Author(s):

Yuzi Shi ◽

Meng Zhang ◽

Qin Shu ◽

Wei Ma ◽

Tingzhen Sun ◽

...

Keyword(s):

Seed Coat ◽

Molecular Breeding ◽

Coat Color ◽

Recessive Gene ◽

Myb Transcription Factor ◽

Cucurbita Maxima ◽

Seed Coat Color ◽

Rna Seq ◽

Edible Seed ◽

Segregating Population

Seed coat color is an important agronomic trait of edible seed pumpkin in Cucurbita maxima. In this study, the development pattern of seed coat was detected in yellow and white seed coat accessions Wuminglv and Agol. Genetic analysis suggested that a single recessive gene white seed coat (wsc) is involved in seed coat color regulation in Cucurbita maxima. An F2 segregating population including 2798 plants was used for fine mapping and a candidate region containing nine genes was identified. Analysis of 54 inbred accessions revealed four main Insertion/Deletion sites in the promoter of CmaCh15G005270 encoding an MYB transcription factor were co-segregated with the phenotype of seed coat color. RNA-seq analysis and qRT-PCR revealed that some genes involved in phenylpropanoid/flavonoid metabolism pathway displayed remarkable distinction in Wuminglv and Agol during the seed coat development. The flanking InDel marker S1548 was developed to predict the seed coat color in the MAS breeding with an accuracy of 100%. The results may provide valuable information for further studies in seed coat color formation and structure development in Cucurbitaceae crops and help the molecular breeding of Cucurbita maxima.

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Conserved and non-conserved functions of the rice homologs of the Arabidopsis trichome initiation-regulating MBW complex proteins

BMC Plant Biology ◽

10.1186/s12870-021-03035-0 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Kaijie Zheng ◽

Xutong Wang ◽

Yating Wang ◽

Shucai Wang

Keyword(s):

Transcription Factor ◽

Anthocyanin Biosynthesis ◽

Transcriptional Activator ◽

Myb Transcription Factor ◽

Bhlh Transcription Factor ◽

Seed Color ◽

Transcription Activator ◽

Root Hair Formation ◽

Protoplast Transfection ◽

Mbw Complex

Abstract Background Trichome initiation in Arabidopsis is regulated by a MYB-bHLH-WD40 (MBW) transcriptional activator complex formed by the R2R3 MYB transcription factor GLABRA1 (GL1), MYB23 or MYB82, the bHLH transcription factor GLABRA3 (GL3), ENHANCER OF GLABRA3 (EGL3) or TRANSPARENT TESTA8 (TT8), and the WD40-repeat protein TRANSPARENT TESTA GLABRA1 (TTG1). However, the functions of the rice homologs of the MBW complex proteins remained uncharacterized. Results Based on amino acid sequence identity and similarity, and protein interaction prediction, we identified OsGL1s, OsGL3s and OsTTG1s as rice homologs of the MBW complex proteins. By using protoplast transfection, we show that OsGL1D, OsGL1E, OsGL3B and OsTTG1A were predominantly localized in the nucleus, OsGL3B functions as a transcriptional activator and is able to interact with GL1 and TTG1. By using yeast two-hybrid and protoplast transfection assays, we show that OsGL3B is able to interact with OsGL1E and OsTTG1A, and OsGL1E and OsTTG1A are also able to interact with GL3. On the other hand, we found that OsGL1D functions as a transcription activator, and it can interact with GL3 but not OsGL3B. Furthermore, our results show that expression of OsTTG1A in the ttg1 mutant restored the phenotypes including alternations in trichome and root hair formation, seed color, mucilage production and anthocyanin biosynthesis, indicating that OsTTG1A and TTG1 may have similar functions. Conclusion These results suggest that the rice homologs of the Arabidopsis MBW complex proteins are able to form MBW complexes, but may have conserved and non-conserved functions.

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Asymbiotic germination of Vanilla planifolia in relation to the timing of seed collection and seed pretreatments

Botanical Studies ◽

10.1186/s40529-021-00311-y ◽

2021 ◽

Vol 62 (1) ◽

Author(s):

Chih-Hsin Yeh ◽

Kai-Yi Chen ◽

Yung-I. Lee

Keyword(s):

Seed Germination ◽

Seed Development ◽

Seed Coat ◽

Germination Percentage ◽

Vanilla Planifolia ◽

Outermost Layer ◽

Seed Collection ◽

Seed Pretreatment ◽

Immature Seeds ◽

Mature Seeds

Abstract Background Vanilla planifolia is an important tropical orchid for production of natural vanilla flavor. Traditionally, V. planifolia is propagated by stem cuttings, which produces identical genotype that are sensitive to virulent pathogens. However, propagation with seed germination of V. planifolia is intricate and unstable because the seed coat is extremely hard with strong hydrophobic nature. A better understanding of seed development, especially the formation of impermeable seed coat would provide insights into seed propagation and conservation of genetic resources of Vanilla. Results We found that soaking mature seeds in 4% sodium hypochlorite solution from 75 to 90 min significantly increased germination. For the culture of immature seeds, the seed collection at 45 days after pollination (DAP) had the highest germination percentage. We then investigated the anatomical features during seed development that associated with the effect of seed pretreatment on raising seed germination percentage. The 45-DAP immature seeds have developed globular embryos and the thickened non-lignified cell wall at the outermost layer of the outer seed coat. Seeds at 60 DAP and subsequent stages germinated poorly. As the seed approached maturity, the cell wall of the outermost layer of the outer seed coat became lignified and finally compressed into a thick envelope at maturity. On toluidine blue O staining, the wall of outer seed coat stained greenish blue, indicating the presence of phenolic compounds. As well, on Nile red staining, a cuticular substance was detected in the surface wall of the embryo proper and the innermost wall of the inner seed coat. Conclusion We report a reliable protocol for seed pretreatment of mature seeds and for immature seeds culture based on a defined time schedule of V. plantifolia seed development. The window for successful germination of culturing immature seed was short. The quick accumulation of lignin, phenolics and/or phytomelanins in the seed coat may seriously inhibit seed germination after 45 DAP. As seeds matured, the thickened and lignified seed coat formed an impermeable envelope surrounding the embryo, which may play an important role in inducing dormancy. Further studies covering different maturity of green capsules are required to understand the optimal seed maturity and germination of seeds.

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QTL analysis of seed germination traits in tobacco (Nicotiana tabacum L.)

Journal of Applied Genetics ◽

10.1007/s13353-021-00623-6 ◽

2021 ◽

Author(s):

Monika Agacka-Mołdoch ◽

Mian Abdur Rehman Arif ◽

Ulrike Lohwasser ◽

Teresa Doroszewska ◽

Ramsey S. Lewis ◽

...

Keyword(s):

Nicotiana Tabacum ◽

Seed Germination ◽

Doubled Haploid ◽

Mapping Population ◽

Area Under The Curve ◽

Linkage Groups ◽

Polygenic Control ◽

Nicotiana Tabacum L ◽

Controlled Deterioration ◽

Germination Traits

AbstractGenetic mapping of seed germination traits has been performed with many plant species. In tobacco, however, investigations are rare. In the present study, a bi-parental mapping population consisting of 118 doubled haploid lines and derived from a cross between ‘Beinhart-1000’ and ‘Hicks’ was investigated. Four germination-related traits, total germination (TG), normal germination (NG), time to reach 50% of total germination (T50), and the area under the curve after 200 h of germination (AUC) were considered by examining seeds either untreated or after a moderate controlled deterioration (CD). Quantitative trait loci were found for all traits distributed on 11 out of the 24 linkage groups. It was demonstrated that, as in many other species, germination-related traits are very complex and under polygenic control.

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