MADS-box Transcription Factor Gene Research Articles

A novel type of malformed floral organs mutant in barley was conferred by loss-of-function mutations of the MADS-box gene HvAGL6.

The advanced model of floral morphogenesis is based largely on data from Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa), but this process is less well understood in the Triticeae. Here, we investigated a sterile barley (Hordeum vulgare) mutant with malformed floral organs (designated mfo1), of which the paleae, lodicules, and stamens in each floret were all converted into lemma-like organs, and the ovary was abnormally shaped. Combining bulked-segregant analysis, whole-genome resequencing, and TILLING approaches, the mfo1 mutant was attributed to loss-of-function mutations in the MADS-box transcription factor gene HvAGL6, a key regulator in the ABCDE floral morphogenesis model. Through transcriptomic analysis between young inflorescences of wild-type and mfo1 plants, 380 genes were identified as differentially expressed, most of which function in DNA binding, protein dimerization, cell differentiation, or meristem determinacy. Regulatory pathway enrichment showed HvAGL6 associates with transcriptional abundance of many MADS-box genes, including the B-class gene HvMADS4. Mutants with deficiency in HvMADS4 exhibited the conversion of stamens into supernumerary pistils, producing multiple ovaries resembling the completely sterile multiple ovaries 3.h (mov3.h) mutant. These findings demonstrate that the regulatory model of floral morphogenesis is conserved across plant species and provides insights into the interactions between HvAGL6 and other MADS-box regulators.

Regulatory role of Prunus mume DAM6 on lipid body accumulation and phytohormone metabolism in the dormant vegetative meristem.

Bud dormancy is a crucial process in the annual growth cycle of woody perennials. In Rosaceae fruit tree species, DORMANCY-ASSOCIATED MADS-box (DAM) transcription factor genes regulating bud dormancy have been identified, but their molecular roles in meristematic tissues have not been thoroughly characterized. In this study, molecular and physiological analyses of transgenic apple plants overexpressing the Japanese apricot DAM6 gene (PmDAM6) and Japanese apricot cultivars and F1 individuals with contrasting dormancy characteristics revealed the metabolic pathways controlled by PmDAM6. Our transcriptome analysis and transmission electron microscopy examination demonstrated that PmDAM6 promotes the accumulation of lipid bodies and inhibits cell division in the dormant vegetative meristem by down-regulating the expression of lipid catabolism genes (GDSL ESTERASE/LIPASE and OIL BODY LIPASE) and CYCLIN genes, respectively. Our findings also indicate PmDAM6 promotes abscisic acid (ABA) accumulation and decreases cytokinin (CTK) accumulation in vegetative buds by up-regulating the expression of the ABA biosynthesis gene ARABIDOPSIS ALDEHYDE OXIDASE and the CTK catabolism gene CYTOKININ DEHYDROGENASE, while also down-regulating the expression of the CTK biosynthesis genes ISOPENTENYL TRANSFERASE (IPT) and CYP735A. Additionally, PmDAM6 modulates gibberellin (GA) metabolism by up-regulating GA2-OXIDASE expression and down-regulating GA3-OXIDASE expression. Furthermore, PmDAM6 may also indirectly promote lipid accumulation and restrict cell division by limiting the accumulation of CTK and GA in buds. In conclusion, using our valuable genetic platform, we clarified how PmDAM6 modifies diverse cellular processes, including lipid catabolism, phytohormone (ABA, CTK, and GA) biosynthesis and catabolism, and cell division, in the dormant vegetative meristem.

Candidate Gene Identification and Transcriptome Analysis of Tomato male sterile-30 and Functional Marker Development for ms-30 and Its Alleles, ms-33, 7B-1, and stamenless-2.

Male sterility is a valuable trait for hybrid seed production in tomato (Solanum lycopersicum). The mutants male sterile-30 (ms-30) and ms-33 of tomato exhibit twisted stamens, exposed stigmas, and complete male sterility, thus holding potential for application in hybrid seed production. In this study, the ms-30 and ms-33 loci were fine-mapped to 53.3 kb and 111.2 kb intervals, respectively. Tomato PISTILLATA (TPI, syn. SlGLO2), a B-class MADS-box transcription factor gene, was identified as the most likely candidate gene for both loci. TPI is also the candidate gene of tomato male sterile mutant 7B-1 and sl-2. Allelism tests revealed that ms-30, ms-33, 7B-1, and sl-2 were allelic. Sequencing analysis showed sequence alterations in the TPI gene in all these mutants, with ms-30 exhibiting a transversion (G to T) that resulted in a missense mutation (S to I); ms-33 showing a transition (A to T) that led to alternative splicing, resulting in a loss of 46 amino acids in protein; and 7B-1 and sl-2 mutants showing the insertion of an approximately 4.8 kb retrotransposon. On the basis of these sequence alterations, a Kompetitive Allele Specific PCR marker, a sequencing marker, and an Insertion/Deletion marker were developed. Phenotypic analysis of the TPI gene-edited mutants and allelism tests indicated that the gene TPI is responsible for ms-30 and its alleles. Transcriptome analysis of ms-30 and quantitative RT-PCR revealed some differentially expressed genes associated with stamen and carpel development. These findings will aid in the marker-assisted selection for ms-30 and its alleles in tomato breeding and support the functional analysis of the TPI gene.

Genome-wide analysis of MADS-box transcription factor gene family in wild emmer wheat (Triticum turgidum subsp. dicoccoides).

The members of MADS-box gene family have important roles in regulating the growth and development of plants. MADS-box genes are highly regarded for their potential to enhance grain yield and quality under shifting global conditions. Wild emmer wheat (Triticum turgidum subsp. dicoccoides) is a progenitor of common wheat and harbors valuable traits for wheat improvement. Here, a total of 117 MADS-box genes were identified in the wild emmer wheat genome and classified to 90 MIKCC, 3 MIKC*, and 24 M-type. Furthermore, a phylogenetic analysis and expression profiling of the emmer wheat MADS-box gene family was presented. Although some MADS-box genes belonging to SOC1, SEP1, AGL17, and FLC groups have been expanded in wild emmer wheat, the number of MIKC-type MADS-box genes per subgenome is similar to that of rice and Arabidopsis. On the other hand, M-type genes of wild emmer wheat is less frequent than that of Arabidopsis. Gene expression patterns over different tissues and developmental stages agreed with the subfamily classification of MADS-box genes and was similar to common wheat and rice, indicating their conserved functionality. Some TdMADS-box genes are also differentially expressed under drought stress. The promoter region of each of the TdMADS-box genes harbored 6 to 48 responsive elements, mainly related to light, however hormone, drought, and low-temperature related cis-acting elements were also present. In conclusion, the results provide detailed information about the MADS-box genes of wild emmer wheat. The present work could be useful in the functional genomics efforts toward breeding for agronomically important traits in T. dicoccoides.

Genome-wide characterization and expression analysis of MADS-box transcription factor gene family in Perilla frutescens.

MADS-box transcription factors are widely involved in the regulation of plant growth, developmental processes, and response to abiotic stresses. Perilla frutescens, a versatile plant, is not only used for food and medicine but also serves as an economical oil crop. However, the MADS-box transcription factor family in P. frutescens is still largely unexplored. In this study, a total of 93 PfMADS genes were identified in P. frutescens genome. These genes, including 37 Type I and 56 Type II members, were randomly distributed across 20 chromosomes and 2 scaffold regions. Type II PfMADS proteins were found to contain a greater number of motifs, indicating more complex structures and diverse functions. Expression analysis revealed that most PfMADS genes (more than 76 members) exhibited widely expression model in almost all tissues. The further analysis indicated that there was strong correlation between some MIKCC-type PfMADS genes and key genes involved in lipid synthesis and flavonoid metabolism, which implied that these PfMADS genes might play important regulatory role in the above two pathways. It was further verified that PfMADS47 can effectively mediate the regulation of lipid synthesis in Chlamydomonas reinhardtii transformants. Using cis-acting element analysis and qRT-PCR technology, the potential functions of six MIKCC-type PfMADS genes in response to abiotic stresses, especially cold and drought, were studied. Altogether, this study is the first genome-wide analysis of PfMADS. This result further supports functional and evolutionary studies of PfMADS gene family and serves as a benchmark for related P. frutescens breeding studies.

Transcriptome analysis during vernalization in wheat (Triticum aestivum L.)

BackgroundVernalization, as a vital process in the life cycle of winter cereal, has important effects on floral organ formation and flowering time. Many morphological changes together with molecular changes occur during the vernalization period. Here, we used transcriptome sequencing to analyze the transcriptomic changes in wheat leaves before, during and after vernalization using the winter wheat cultivar ‘Shiluan02-1’.ResultsA total of 16,370 differentially expressed genes were obtained across different vernalization periods. Gene Ontology enrichment analysis revealed that photoperiodism, photoprotection, photosynthesis, lipid transport and biosynthetic process, and chlorophyll metabolic process were closely related to vernalization. In addition, AP2/ERF, C2H2, bHLH, WRKY, MYB, MYB-related, and NAC transcription factors were significantly enriched during vernalization, and the transcription factor expression patterns suggested the intricate regulation of transcription factor modules in plant vernalization pathways. Analysis of gene expression patterns of the MADS-box transcription factor genes showed different expression patterns during vernalization phases, among which VERNALIZATION1 (VRN1) genes were found to gradually increase during vernalization periods from V0 to V35, while decline in the V42 phase, then increase after vernalization. The Tavrt-2 gene cooperated with Tavrn1 to regulate flowering induced by vernalization, and its expression level was rapidly increased by vernalization but declined in the V42 phase and then increased after vernalization. Some genes from the ICE-CBF-COR pathway were also identified, and additional analysis indicated that some key genes related to phytohormone biosynthesis and signal transduction were enriched during the vernalization period, such as gibberellic acid, ethylene, abscisic acid and jasmonic acid biosynthesis and signaling pathway genes.ConclusionsOur study provides valuable molecular information for future studies on wheat vernalization regulation and also serves as an excellent reference for future wheat breeding.

Genome-Wide Identification and Analysis of the MADS-Box Transcription Factor Genes in Blueberry (Vaccinium spp.) and Their Expression Pattern during Fruit Ripening

MADS-box is a class of transcriptional regulators that are ubiquitous in plants and plays important roles in the process of plant growth and development. Identification and analysis of blueberry MADS-box genes can lay a foundation for their function investigations. In the present study, 249 putative MADS-box genes were identified in the blueberry genome. Those MADS-box genes were distributed on 47 out of 48 chromosomes. The phylogenetic and evolutionary analyses showed that blueberry MADS-box genes were divided into 131 type I members and 118 type II members. The type I genes contained an average of 1.89 exons and the type II genes contained an average of 7.83 exons. Motif analysis identified 15 conserved motifs, of which 4 were related to the MADS domain and 3 were related to the K-box domain. A variety of cis-acting elements were found in the promoter region of the blueberry MADS-box gene, indicating that the MADS-box gene responded to various hormones and environmental alterations. A total of 243 collinear gene pairs were identified, most of which had a Ka/Ks value of less than 1. Nine genes belonging to SEP, AP3/PI, and AGL6 subfamilies were screened based on transcriptomic data. The expression patterns of those nine genes were also verified using quantitative PCR, suggesting that VcMADS6, VcMADS35, VcMADS44, VcMADS58, VcMADS125, VcMADS188, and VcMADS212 had potential functions in blueberry fruit ripening. The results of this study provide references for an in-depth understanding of the biological function of the blueberry MADS-box genes and the mechanism of blueberry fruit ripening.

Candidate gene based SSR and SNP markers for gynoecy in bitter gourd (Momordica charantia L.).

Even though the bitter gourd hybrids are shown to have significant heterosis for many of the economic traits, processes such as manual bagging and hand pollination make the hybrid seed production labour-intensive. Use of gynoecious line as female parent makes hybrid seed production more economical. This work was performed with the objective to identify the candidate gene based molecular markers for gynoecy in bitter gourd. Seven putative genes for flowering and sex expression, isolated from the monoecious (MC-136) and gynoecious (KAU-MCGy-101) bitter gourd accessions, were sequence characterized. MADS-box transcription factor genes AG6 and McAG2 had nucleotide polymorphisms at five sites each and were potential candidates for marker development. An In/Del polymorphism of 48bp ([TC]24) in AG6 gene was used to develop an SSR marker and a transition mutation of [A/G] in this gene was used to develop a set of SNP markers. These markers have developed distinct polymorphism between the monoecious and gynoecious genotypes and were found suited for the marker assisted selection. MADS box transcription factor genes AG6 and McAG2 are identified as candidates for sex expression in bitter gourd. Based on the InDels and transition in the intronic region of AG6, SSR marker BGAG6 and an SNP marker set segregating with the sex forms were developed. The markers have been validated using four other monoecious lines and are routinely used in our bitter gourd hybrid seed production programmes.

MIKC-type MADS-box transcription factor gene family in peanut: Genome-wide characterization and expression analysis under abiotic stress.

Peanut (Arachis hypogaea) is one of the most important economic crops around the world, especially since it provides vegetable oil and high-quality protein for humans. Proteins encoded by MADS-box transcription factors are widely involved in regulating plant growth and development as well as responses to abiotic stresses. However, the MIKC-type MADS-box TFs in peanut remains currently unclear. Hence, in this study, 166 MIKC-type MADS-box genes were identified in both cultivated and wild-type peanut genomes, which were divided into 12 subfamilies. We found a variety of development-, hormone-, and stress-related cis-acting elements in the promoter region of peanut MIKC-type MADS-box genes. The chromosomal distribution of peanut MADS-box genes was not random, and gene duplication contributed to the expansion of the MADS-box gene family. The interaction network of the peanut AhMADS proteins was established. Expression pattern analysis showed that AhMADS genes were specifically expressed in tissues and under abiotic stresses. It was further confirmed via the qRT-PCR technique that five selected AhMADS genes could be induced by abiotic and hormone treatments and presented different expressive profiles under various stresses. Taken together, these findings provide valuable information for the exploration of candidate genes in molecular breeding and further study of AhMADS gene functions.

Nitrilases NIT1/2/3 Positively Regulate Flowering by Inhibiting MAF4 Expression in Arabidopsis.

Three of the nitrilases (NITs), NIT1, NIT2, and NIT3, are ubiquitously existing in plant kingdom, which catalyze indole-3-acetonitrile into the most important auxin indole-3-acetic acid. Auxin is an indispensable hormone, which plays the important roles in almost all processes of plant growth and development. However, there are few reports on the regulation of flowering-time mediated by auxin. Here, we found that in Arabidopsis, nit1/2/3 showed a late flowering phenotype in short days. To explore the molecular mechanism by which NIT1/2/3 regulate flowering time, we performed transcriptome sequencing of nit1/2/3. The results showed that the expression of a MADS-box transcription factor gene MADS AFFECTING FLOWERING4 (MAF4) was dramatically increased in nit1/2/3 comparing to wild type (WT). MAF4 is one of the paralogs of the potent flowering inhibitor FLOWERING LOCUS C (FLC). There are four other paralogs in FLC clade in Arabidopsis, including FLOWERING LOCUS M (FLM/MAF1), MAF2, MAF3, and MAF5. The late flowering phenotype of nit1/2/3 could not be observed in the maf4 background, indicating that the phenotype was specifically dependent on MAF4 rather than other FLC clade members. Interestingly, the expression of a lncRNA gene MAS, which is transcribed in the opposite direction of MAF4, was found significantly increased in nit1/2/3. Also, MAS has been reported to activate MAF4 transcription by promoting histone 3 lysine 4 trimethylation (H3K4me3). As expected, H3K4me3 deposition at MAF4 locus in nit1/2/3 was highly enriched and significantly higher than that of WT. In summary, we show that NITs, NIT1/2/3, positively regulate flowering by repressing MAF4 through manipulating H3K4me3 modification. Further study needs to be performed to explore the largely unknown mechanisms behind it.

Genome-wide analysis of the MADS-box gene family in Rhododendron hainanense Merr. and expression analysis under heat and waterlogging stresses

The MADS-box transcription factor gene family plays an important role in the growth and development of plants as well as in biotic and abiotic stress. We conducted a genome-wide identification of the members of the MADS-box family of Rhododendron hainanense to determine the molecular evolutionary characteristics of the MADS-box gene family and the expression profile of this gene family under different abiotic stress conditions. A total of 55 MADS-box gene family members with complete domains were identified, which were unevenly distributed on 13 chromosomes. The construction of a phylogenetic tree showed that the 55 MADS-box proteins were divided into five categories and distributed on 8 chromosomes unevenly. Conserved motif analysis shows that motif 1 and motif 2 are highly conserved in most RhMADS proteins. Proteins belonging to the same category show similar gene structures. Analysis of gene replication events suggested that there were one pair of tandem repeats and eight pairs of fragment repeat events. In addition, analysis of cis-acting elements and protein interaction networks indicated that some genes are involved in abiotic stress processes in plants. The transcriptome data were used to analyze the expression of the members of the MADS-box family under different temperatures and waterlogging period treatments, which were then verified by qRT-PCR. The expressions of RhMADS24, RhMADS25, RhMADS39 and RhMADS44 were significantly regulated under temperature and waterlogging stresses. The identified MADS-box candidate genes of R. hainanense play an important role in resisting abiotic stress and lay the foundation for future applications in breeding and gardening.

Alternative splicing of the dormancy-associated MADS-box transcription factor gene PpDAM1 is associated with flower bud dormancy in ‘Dangshansu’ pear (Pyrus pyrifolia white pear group)

Alternative splicing (AS) plays a crucial role in plant growth, development and response to various environmental changes. However, whether alternative splicing of MADS-box transcription factors contributes to the flower bud dormancy process in fruit trees still remains unknown. In this work, the AS profile of genes in the dormant flower buds of ‘Dangshansu’ pear tree were examined. A total number of 3661 alternatively spliced genes were identified, and three mRNA isoforms of the dormancy associated MADS box (DAM) gene, PpDAM1, derived by alternative splicing, designated as PpDAM1.1, PpDAM1.2 and PpDAM1.3, were characterized. Bimolecular fluorescence complementation (BiFC) analysis indicated that AS of PpDAM1 didn't affect the nucleus localization and homo-/heterodimerization of PpDAM1.1, PpDAM1.2 and PpDAM1.3 proteins, but disturbed the translocation of PpDAM1.1/PpDAM1.1, PpDAM1.3/PpDAM1.3, PpDAM1.1/PpDAM1.3, and PpDAM1.2/PpDAM1.3 dimers to the nucleus. Constitutive expression of PpDAM1.2, but not PpDAM1.1 and PpDAM1.3, in Arabidopsis retarded the growth and development of transgenic plants. Further comparative expression analyses of PpDAM1.1, PpDAM1.2 and PpDAM1.3 in the flower buds of ‘Dangshansu’ and a less dormant pear cultivar, ‘Cuiguan’, exhibited that the expression of all the three isoforms in ‘Dangshansu’ were significantly higher than in ‘Cuiguan’, especially PpDAM1.2, which showed a predominantly higher expression than PpDAM1.1 and PpDAM1.3 in both cultivars. Our results suggest that alternative splicing of PpDAM1 could play a crucial role in pear flower bud dormancy process.

TaMADS2-3D, a MADS transcription factor gene, regulates phosphate starvation responses in plants

Soil inorganic phosphate (Pi) levels are frequently suboptimal for the growth and development of crop plants. Although MADS-box genes participate in diverse plant developmental processes, their involvement in phosphate starvation responses (PSRs) remains unclear. We identified a type I MADS-box transcription factor gene, TaMADS2-3D, which was rapidly induced under low-Pi stress in roots of wheat (Triticum aestivum). A TaMADS2-3D-GFP fusion protein was found located in the nucleus. Transgenic Arabidopsis plants overexpressing TaMADS2-3D (TaMADS2-3DOE) showed shortened primary roots, increased lateral root density, and retarded seedling growth under high-Pi (HP) conditions, accompanied by increased Pi contents in their shoots and roots. The Arabidopsis TaMADS2-3DOE plants showed similar PSR phenotypes under low Pi (LP) conditions. These results indicate constitutive activation of PSRs by overexpression of TaMADS2-3D in Arabidopsis. Reactive oxygen species (ROS), H2O2 and O2−, levels were increased in root tips of Arabidopsis TaMADS2-3DOE plants under HP conditions. Transcriptome analysis of Arabidopsis TaMADS2-3DOE plants under different Pi regimes revealed expression changes for a variety of PSR genes including AtZAT6. Overexpression of TaMADS2-3D in wheat also led to constitutive activation of PSRs. We propose that TaMADS2-3D regulates plant PSRs probably by modulating ROS homeostasis, root development, PSR gene expression, and Pi uptake. This study increases our understanding of plant PSR regulation and provides a valuable gene for improving phosphorus-use efficiency in wheat and other crops.

New insights into the role of MADS-box transcription factor gene CmANR1 on root and shoot development in chrysanthemum (Chrysanthemum morifolium)

BackgroundMADS-box transcription factors (TFs) are the key regulators of multiple developmental processes in plants; among them, a chrysanthemum MADS-box TF CmANR1 has been isolated and described as functioning in root development in response to high nitrate concentration signals. However, how CmANR1 affects root and shoot development remains unclear.ResultsWe report that CmANR1 plays a positive role in root system development in chrysanthemum throughout the developmental stages of in vitro tissue cultures. Metabolomics combined with transcriptomics assays show that CmANR1 promotes robust root system development by facilitating nitrate assimilation, and influencing the metabolic pathways of amino acid, glycolysis, and the tricarboxylic acid cycle (TCA) cycle. Also, we found that the expression levels of TFs associated with the nitrate signaling pathways, such as AGL8, AGL21, and LBD29, are significantly up-regulated in CmANR1-transgenic plants relative to the wild-type (WT) control; by contrast, the expression levels of RHD3-LIKE, LBD37, and GATA23 were significantly down-regulated. These results suggest that these nitrate signaling associated TFs are involved in CmANR1-modulated control of root development. In addition, CmANR1 also acts as a positive regulator to control shoot growth and development.ConclusionsThese findings provide potential mechanisms of MADS-box TF CmANR1 modulation of root and shoot development, which occurs by regulating a series of nitrate signaling associated TFs, and influencing the metabolic pathways of amino acid and glycolysis, as well as TCA cycle and nitrate assimilation.

The MADS-Box Gene MdDAM1 Controls Growth Cessation and Bud Dormancy in Apple

Apple trees require a long exposure to chilling temperature during winter to acquire competency to flower and grow in the following spring. Climate change or adverse meteorological conditions can impair release of dormancy and delay bud break, hence jeopardizing fruit production and causing substantial economic losses. In order to characterize the molecular mechanisms controlling bud dormancy in apple we focused our work on the MADS-box transcription factor gene MdDAM1. We show that MdDAM1 silencing is required for the release of dormancy and bud break in spring. MdDAM1 transcript levels are drastically reduced in the low-chill varieties ‘Anna’ and ‘Dorsett Golden’ compared to ‘Golden Delicious’ corroborating its role as a key genetic factor controlling the release of bud dormancy in Malus species. The functional characterization of MdDAM1 using RNA silencing resulted in trees unable to cease growth in winter and that displayed an evergrowing, or evergreen, phenotype several years after transgenesis. These trees lost their capacity to enter in dormancy and produced leaves and shoots regardless of the season. A transcriptome study revealed that apple evergrowing lines are a genocopy of ‘Golden Delicious’ trees at the onset of the bud break with the significant gene repression of the related MADS-box gene MdDAM4 as a major feature. We provide the first functional evidence that MADS-box transcriptional factors are key regulators of bud dormancy in pome fruit trees and demonstrate that their silencing results in a defect of growth cessation in autumn. Our findings will help producing low-chill apple variants from the elite commercial cultivars that will withstand climate change.

Functional and expressional analyses of apple FLC-like in relation to dormancy progress and flower bud development.

We previously identified the FLOWERING LOCUS C (FLC)-like gene, a MADS-box transcription factor gene that belongs to Arabidopsis thaliana L. FLC clade, in apple (Malus $\times$ domestica Borkh.), and its expression in dormant flower buds is positively correlated with cumulative cold exposure. To elucidate the role of the MdFLC-like in the dormancy process and flower development, we first characterized the phenotypes of MdFLC-like overexpressing lines with the Arabidopsis Columbia-0 background. The overexpression of MdFLC-like significantly delayed the bolting date and reduced the plant size, but it did not significantly affect the number of rosette leaves or flower organ formation. Thus, MdFLC-like may affect vegetative growth and development rather than flowering when expressed in Arabidopsis, which is not like Arabidopsis FLC that affects development of flowering. We compared seasonal expression patterns of MdFLC-like in low-chill 'Anna' and high-chill 'Fuji' and 'Tsugaru' apples collected from trees grown in a cold winter region in temperate zone and found an earlier upregulation in 'Anna' compared with 'Fuji' and 'Tsugaru'. Expression patterns were also compared in relation to developmental changes in the flower primordia during the chilling accumulation period. Overall, MdFLC-like was progressively upregulated during flower primordia differentiation and development in autumn to early winter and reached a maximum expression level at around the same time as the genotype-dependent chilling requirements were fulfilled in high-chill cultivars. Thus, we hypothesize MdFLC-like may be upregulated in response to cold exposure and flower primordia development during the progress of endodormancy. Our study also suggests MdFLC-like may have a growth-inhibiting function during the end of endodormancy and ecodormancy when the temperature is low and unfavorable for rapid bud outgrowth.

Overexpression of zmm28 increases maize grain yield in the field

Increasing maize grain yield has been a major focus of both plant breeding and genetic engineering to meet the global demand for food, feed, and industrial uses. We report that increasing and extending expression of a maize MADS-box transcription factor gene, zmm28, under the control of a moderate-constitutive maize promoter, results in maize plants with increased plant growth, photosynthesis capacity, and nitrogen utilization. Molecular and biochemical characterization of zmm28 transgenic plants demonstrated that their enhanced agronomic traits are associated with elevated plant carbon assimilation, nitrogen utilization, and plant growth. Overall, these positive attributes are associated with a significant increase in grain yield relative to wild-type controls that is consistent across years, environments, and elite germplasm backgrounds.

CaMADS, a MADS-box transcription factor from pepper, plays an important role in the response to cold, salt, and osmotic stress

MADS-box family transcription factors play essential roles in the growth and development of plants, and some MADS-box genes have also been found to participate in the stress-response. At present, little information regarding stress-related MADS-box genes is available in pepper. We isolated a MADS-box transcription factor gene from Capsicum annuum, which we named CaMADS. CaMADS expression is induced by low and high temperature, salt, and osmotic stress, and also by abscisic acid (ABA), salicylic acid (SA), methyl-jasmonic acid (MeJA), and CaCl2. To understand the function of CaMADS in the abiotic stress response, we generated pepper plants in which CaMADS expression was down-regulated using VIGS (Virus-induced Gene Silencing), and also transgenic Arabidopsis plants overexpressing CaMADS. We found that CaMADS-down-regulated seedlings were more seriously injured than WT after cold, NaCl, and mannitol treatment, and showed increased electrolyte leakage, malondialdehyde (MDA) levels, and lower chlorophyll content. CaMADS-overexpressing Arabidopsis plants were more tolerant to these stresses than WT, and showed significantly high survival rates and lower H2O2 and super oxide radical contents after cold treatment. CaMADS-overexpressing plants had higher germination rates and percentages of green cotyledons following NaCl and mannitol treatment. Root lengths and fresh weight in CaMADS-overexpressing plants were also significantly longer and higher, respectively, than in WT plants. Taken together, our results suggest that CaMADS functions as a positive stress-responsive transcription factor in the cold, salt, and osmotic stress signaling pathways.

Genome-wide survey of potato MADS-box genes reveals that StMADS1 and StMADS13 are putative downstream targets of tuberigen StSP6A

BackgroundMADS-box genes encode transcription factors that are known to be involved in several aspects of plant growth and development, especially in floral organ specification. To date, the comprehensive analysis of potato MADS-box gene family is still lacking after the completion of potato genome sequencing. A genome-wide characterization, classification, and expression analysis of MADS-box transcription factor gene family was performed in this study.ResultsA total of 153 MADS-box genes were identified and categorized into MIKC subfamily (MIKCC and MIKC*) and M-type subfamily (Mα, Mβ, and Mγ) based on their phylogenetic relationships to the Arabidopsis and rice MADS-box genes. The potato M-type subfamily had 114 members, which is almost three times of the MIKC members (39), indicating that M-type MADS-box genes have a higher duplication rate and/or a lower loss rate during potato genome evolution. Potato MADS-box genes were present on all 12 potato chromosomes with substantial clustering that mainly contributed by the M-type members. Chromosomal localization of potato MADS-box genes revealed that MADS-box genes, mostly MIKC, were located on the duplicated segments of the potato genome whereas tandem duplications mainly contributed to the M-type gene expansion. The potato MIKC subfamily could be further classified into 11 subgroups and the TT16-like, AGL17-like, and FLC-like subgroups found in Arabidopsis were absent in potato. Moreover, the expressions of potato MADS-box genes in various tissues were analyzed by using RNA-seq data and verified by quantitative real-time PCR, revealing that the MIKCC genes were mainly expressed in flower organs and several of them were highly expressed in stolon and tubers. StMADS1 and StMADS13 were up-regulated in the StSP6A-overexpression plants and down-regulated in the StSP6A-RNAi plant, and their expression in leaves and/or young tubers were associated with high level expression of StSP6A.ConclusionOur study identifies the family members of potato MADS-box genes and investigate the evolution history and functional divergence of MADS-box gene family. Moreover, we analyze the MIKCC expression patterns and screen for genes involved in tuberization. Finally, the StMADS1 and StMADS13 are most likely to be downstream target of StSP6A and involved in tuber development.

The MADS transcription factor CmANR1 positively modulates root system development by directly regulating CmPIN2 in chrysanthemum

Plant root systems are essential for many physiological processes, including water and nutrient absorption. MADS-box transcription factor (TF) genes have been characterized as the important regulators of root development in plants; however, the underlying mechanism is largely unknown, including chrysanthemum. Here, it was found that the overexpression of CmANR1, a chrysanthemum MADS-box TF gene, promoted both adventitious root (AR) and lateral root (LR) development in chrysanthemum. Whole transcriptome sequencing analysis revealed a series of differentially expressed unigenes (DEGs) in the roots of CmANR1-transgenic chrysanthemum plants compared to wild-type plants. Functional annotation of these DEGs by alignment with Gene Ontology (GO) terms and biochemical pathway Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that CmANR1 TF exhibited “DNA binding” and “catalytic” activity, as well as participated in “phytohormone signal transduction”. Both chromatin immunoprecipitation–polymerase chain reaction (ChIP-PCR) and gel electrophoresis mobility shift assays (EMSA) indicated the direct binding of CmPIN2 to the recognition site CArG-box motif by CmANR1. Finally, a firefly luciferase imaging assay demonstrated the transcriptional activation of CmPIN2 by CmANR1 in vivo. Overall, our results provide novel insights into the mechanisms of MADS-box TF CmANR1 modulation of both AR and LR development, which occurs by directly regulating auxin transport gene CmPIN2 in chrysanthemum.